Search

Hydrogen peroxide (H 2 O 2 ) release during blood flow is commonly provoked by the cyclic stretch and dynamic shear stress of endothelial cells and is of vital significance for maintaining vascular function. Flexible and stretchable electrochemical sensors show great capability in retrieving mechanical stimulation-induced H 2 O 2 variation; however, cell secretions, especially electroactive constituents' interferences, remain a big concern for sensing accuracy. Herein, we developed a stretchable electrochemiluminescence (ECL) sensor by synthesizing L012-reduced gold nanospheres and decorating them onto a polydimethylsiloxane film-supported gold nanotubes substrate (Au NTs/PDMS) to form dual gold nanostructure-modified meshwork interface. Given the specific reaction between L012 and H 2 O 2 , the as-prepared Au-L012/Au NTs/PDMS exhibited outstanding selectivity toward H 2 O 2 quantification. Through culturing human umbilical vein endothelial cells (HUVECs), real-time monitoring of transient H 2 O 2 release from mechanically sensitive HUVECs in stretching states was realized. This work successfully incorporated the ECL sensing model into in situ cellular sensing, therefore expanding the application mode of the ECL approach for health care and biomedical investigation.

In this study, we developed a flexible, biocompatible, and high-output electrical performance triboelectric nanogenerator (TENG) employing a silk fibroin (SF)-MXene composite film (SF-MXene-F) and a PDMS film as the friction layer. The inclusion of MXene in the SF film increased its surface charge density, presenting a practical approach to designing high-performance SF composite film-based TENGs. At a MXene content of 40%, our SF-MXene composite film-based TENG (SF-MXene-FTENG) achieved optimal output electrical performance, featuring a maximum open-circuit voltage (Voc) of 418 V, a maximum short-circuit current (Isc) of 11.6 μA, and a maximum output power density of 9.92 W/m 2 . The Voc and power densities of the SF-MXene-FTENG surpassed previously reported optimal values for SF-based TENGs by 1.6 and 3.8 times, respectively. Furthermore, leveraging the exceptional biocompatibility and light shading performance of TENGs, we designed a wearable smart TENG eye mask capable of diagnosing insomnia symptoms and monitoring sleep quality in real time. The SF-MXene-FTENG holds promising application potential as a wearable electronic device for diagnosing sleep-related diseases.

Urea, synthesized exclusively in the liver, is primarily transported through the bloodstream to the kidneys, where it is excreted in urine, accounting for 80-90% of nitrogen excretion in humans. Elevated blood urea levels, indicative of kidney dysfunction, make it a crucial biomarker for assessing renal function. Previous studies on urea detection using microdevices have largely focused on conductometric methods. In this study, we demonstrated the application of a continuous flow miniaturized system for rapid spectrophotometric urea quantification using polydimethylsiloxane (PDMS) microdevices. The microdevice featured two distinct zones: an enzymatic reaction zone, where urease-conjugated magnetic nanoparticles were immobilized, and a detection zone, where reagents were incorporated to produce a colored reaction product via a modified Berthelot reaction. Integrating magnetic nanoparticles as a solid support for the enzyme enabled the reuse of PDMS microdevices without compromising the analytical signal. Spectrophotometric detection was performed in an additional microdevice acting as a microflow cell coupled with optical fibers. A calibration curve was constructed using urea standards diluted in phosphate buffer solution (PBS), yielding a linear range of 0.12-3.00 mg dL -1 . The method demonstrated detection and quantification limits of 0.04 mg dL -1 and 0.12 mg dL -1 , respectively. Precision and accuracy assessments yielded a repeatability of 0.90% and intermediate precision of 4.52%, with recovery rates near 100%. The method was applied to plasma and urine samples, showing urea concentrations within normal physiological ranges and an analysis throughput of 36 measurements per hour.

This study investigates various microfluidic chip fabrication techniques, highlighting their applicability and limitations in the context of urgent diagnostic needs showcased by the COVID-19 pandemic. Through a detailed examination of methods such as computer numerical control milling of a polymethyl methacrylate, soft lithography for polydimethylsiloxane-based devices, xurography for glass-glass chips, and micromachining-based silicon-glass chips, we analyze each technique's strengths and trade-offs. Hence, we discuss the fabrication complexity and chip thermal properties, such as heating and cooling rates, which are essential features of chip utilization for a polymerase chain reaction. Our comparative analysis reveals critical insights into material challenges, design flexibility, and cost-efficiency, aiming to guide the development of robust and reliable microfluidic devices for healthcare and research. This work underscores the importance of selecting appropriate fabrication methods to optimize device functionality, durability, and production efficiency., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

In recent years, there have been advancements in high-performance soft sensors with simultaneous moderate sensitivity and wide linearity. However, it remains challenging to combine high-efficiency production and high performance for soft sensors. The skin and hair structure provide an elegantly simple sensing model, where hair acts as signal receptors and basal skin acts as signal processors. Herein, we used efficient electrostatic flocking and extrusion printing to engineer comb-shaped electrodes with conductive polydimethylsiloxane (PDMS) flocked with conductive silk fibers as a biomimetic flexible sensor. The mechanical and electrical properties of modified PDMS and silk fibers were characterized to optimize the functionalization process. The sensor unit exhibited a high linear range up to 2,000 kPa and a competitively good sensitivity of 0.0285 kPa -1 in the contact mode with conductive materials, as well as good resolution in the noncontact mode. Such sensors and a sensor array demonstrated potential applications for detecting pressure disturbances from acoustic activity and for human-robot interactions. We anticipate that the straightforward design and facile fabrication of soft sensors with vertical fibrous morphology for perception will open new avenues for the next generation of high-performance soft sensors integrated with artificial intelligence.

This study reports development of a microfluidic device for highly sensitive and selective detection of a β-amyloid peptide (Aβ 1-42 ) in simulated cerebrospinal fluid, using surface-enhanced Raman spectroscopy (SERS). The device ensemble comprises a purine ligand (Pu) and its interaction with silver nanoparticles (AgNPs) to generate SERS hotspots. The low surface energy of the synthesized Pu ligand and high surface energy of AgNPs are utilized for the functionalization and formation of a Pu-AgNP SERS substrate. We have integrated a novel polydimethylsiloxane (PDMS) microfluidic device with Pu-AgNPs using a combination of photo- and soft lithography fabrication, sealed by thermal cross-linking with another layer of PDMS, to produce an effective screening platform for Aβ 1-42 . The SERS spectrum from the microfluidic device affords almost noise-free measurements, with excellent limit-of-detection values.

Somatic cell nuclear transfer (SCNT), referred to as somatic cell cloning, is a pivotal biotechnological technique utilized across various applications. Although robotic SCNT is currently available, the subsequent oocyte electrical activation/reconstructed embryo electrofusion is still manually completed by skilled operators, presenting challenges in efficient manipulation due to the uncontrollable positioning of the reconstructed embryo. This study introduces a robotic SCNT-electrofusion system to enable high-precision batch SCNT cloning. The proposed system integrates optical tweezers and microfluidic technologies. An optical tweezer is employed to facilitate somatic cells in precisely reaching the fusion site, and a specific polydimethylsiloxane (PDMS) chip is designed to assist in positioning and pairing oocytes and somatic cells. Enhancement in the electric field distribution between two parallel electrodes by PDMS pillars significantly reduces the required external voltage for electrofusion/electrical activation. We employed porcine oocytes and porcine fetal fibroblasts for SCNT experiments. The experimental results show that 90.56% of oocytes successfully paired with somatic cells to form reconstructed embryos, 76.43% of the reconstructed embryos successfully fused, and 70.55% of these embryos underwent cleavage. It demonstrates that the present system achieves the robotic implementation of oocyte electrical activation/reconstructed embryo electrofusion. By leveraging the advantages of batch operations using microfluidics, it proposes an innovative robotic cloning procedure that scales embryo cloning.

Topical administration is the commonly preferred method of administering ophthalmic formulations, with the majority of available medications in the form of eye drops or ointments. However, the topical application of ophthalmological medications has less bioavailability and a short residence time because of the physiological and anatomical constraints of the eye, making efficient ophthalmic drug delivery a challenging task. Microfluidic contact lenses have the advantage of delivering drugs into the eye in a controlled and on-demand manner. Here, we showcase the use of hydrogel-embedded microcavities on PDMS-based contact lenses for ocular drug delivery applications. The fabrication technique adopted here is the spontaneous formation of the spherical cavity by hydrogel monomer droplet, followed by the simultaneous thermal curing of hydrogel and PDMS, creating a spherical cavity as small as 150 μm. The spherical cavity is embedded with pH-responsive hydrogel for on-demand drug delivery. The drug loaded in the hydrogel matrix is released into the ocular environment by diffusion. The spherical cavity with a narrow opening restricts the diffusion to a minimum under normal ocular pH conditions(pH > 6). When the ocular pH reduces (pH < 6), the pH-responsive hydrogel inside the spherical cavity deswell and accelerates the drug release.

Solid Phase Microextraction (SPME) is a commonly used, robust method for characterization of aroma profiles in food matrices. However, challenges such as saturation, swelling, and competition can occur when sampling such complex matrices, resulting in decreased accuracy in the quantitation of polar compounds. In this study, sequential thin film micro-extraction (TFME) was employed to study the aroma profile of sparkling wine, with a focus to evaluate the displacement of polar analytes at extraction times longer than their corresponding equilibrium time. This investigation also describes advancements in the production of TFME devices, specifically the overcoating of hydrophilic-lipophilic balance/polydimethylsiloxane (HLB/PDMS) thin films to increase their matrix compatibility. Sequential thin film micro-extraction and overcoated HLB/PDMS thin films were evaluated for characterization of sparkling wine samples. The results were encouraging, showing that these advancements can decrease competition phenomena and increase the calibration linearity range compared to traditional micro-extraction approaches more commonly used for the characterization of such samples. In addition, multiphase equilibria investigation involving micellar systems enabled by the microextraction technology provides better understanding between wine aroma and its composition., Competing Interests: Declaration of competing interest We declare that we have no conflicts of interest related to this manuscript. We affirm that this declaration is accurate and complete to the best of our knowledge., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

In response to the growing demand for global health monitoring, we report a nonintrusive health detection method using a compact, conformal wearable ultraviolet (UV)-assisted gas-sensing system based on an intrinsically flexible porous polydimethylsiloxane (PDMS)-zinc oxide (ZnO) composite layer (PPZL) for the breath acetone (BrAce) detection and breath event analysis. The enhanced acetone response is attributed to the synergistic effect of UV irradiation and the high surface area of the porous structure, which also improves the mechanical robustness. The UV-assisted wearable sensor reliably detects acetone concentrations ranging from 1 to 100 ppm at room temperature under 4.05 mW/cm 2 UV intensity, even under mechanical strains such as a bending radius of 5 mm and 60% tensile strain. It accurately analyzes different breathing patterns (12-20 breaths per minute) and BrAce concentrations, maintaining a stable performance over 20 days with less than 5% signal degradation. The sensor exhibits response and recovery times of average 110-150 and 130-180 s, respectively, and maintains a consistent 3 ppm BrAce response under varying humidity levels up to 70% relative humidity, ensuring accurate detection of BrAce concentrations during real-world breath tests. Additionally, the sensor targets only specific gases, and the sensor's selectivity is not a key concern. This flexible acetone gas sensor offers a portable solution for health management and a fabrication method for designing flexible metal oxide materials.

A viscoelastic flow focusing device is presented that enables simple and robust focusing of submicron-sized particles in the channel center by optimizing operating conditions such as channel length, flow rate and poly(ethylene oxide) (PEO) concentration. Submicron-sized particles (up to 100 nm) can be easily focused to the channel center under viscoelastic fluid flow without any external force via a simply fabricated microchannel with a long channel length and a large square cross-section. The device was fabricated using a common soft lithography technique for the polydimethylsiloxane (PDMS) channel, which has a width of 50 μm, a height of 50 μm and a channel length of 27 cm. The extralong channel enabled submicron-sized particle focusing, even in a channel of a relatively large size with high flow rate, which can realize flow cytometric applications. The focusing performance was first demonstrated using submicron-sized polystyrene (PS) beads ranging from 870 nm to 50 nm and then using biological particles such as E. coli bacteria to demonstrate the biological feasibility of the device. The PS beads, which ranged in diameter from 870 nm to 100 nm, were focused to the center of the channel, achieving over 90% focusing efficiency for beads as small as 510 nm and 62% focusing efficiency for 100-nm beads. The device could also align a bacterial suspension in the center of the channel at flow rates up to 30 µL/min, demonstrating its biological importance. The ability of the developed device to align submicron-sized particles within a narrow flow stream in a highly robust manner is promising for various biological and clinical applications, such as distinguishing pathogenic bacteria and evaluating individual antibiotic responses in a single experiment., Competing Interests: Declarations Ethical approval Not applicable. Competing interests The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Methods such as gas stripping and vacuum-assisted gas stripping (VAGS) result in significant removal of water from the bioreactor, thus requiring continuous water replenishment in the bioreactor. In this study, we developed a hydrophobic stainless steel meshes capable of selectively recovering concentrated ABE stream from the bioreactor during VAGS. Three stainless steel meshes with pore sizes of 180 µm, 300 µm, and 425 µm were made hydrophobic and oleophilic with zinc oxide (ZnO) and polydimethylsiloxane (PDMS). Butanol concentrations in the model solutions range from 3 to 10 g/L which mimic concentrations typically produced during batch ABE fermentation. The meshes were integrated in a 5-L bioreactor containing 2.5 L of operational ABE model solution followed by the evaluation of selective extraction of ABE from both cell-free and Clostridium beijerinckii-rich ABE model solutions. The results show that the 180-µm ZnO/PDMS-coated mesh retained 54-64% more water in the bioreactor without C. beijerinckii cells and 61-65% more water with cells compared to the uncoated mesh. Furthermore, the butanol concentration of condensates recovered with 180-µm ZnO-PDMS-coated mesh was up to 10.8-fold greater than that of uncoated counterpart. Our data demonstrate that the developed ZnO-PDMS mesh can recover high concentrations of ABE while selectively retaining water in the bioreactor. Additionally, this technology demonstrates the potential for real-time ABE recovery during the fermentation of lignocellulosic and colloidal materials, without the concern of clogging the separation system. KEY POINTS: • Hydrophobic mesh enhanced water retention in the bioreactor by up to 1.65-fold. • Butanol concentration in the collected condensate was increased by up to 10.8-fold. • Hydrophobic mesh is compatible with fermentation of lignocellulose., (© 2024. The Author(s).)

Wearable electronic devices with multifunctions such as flexible, integrated, and self-powered play a crucial role in the fields of health monitoring, motion monitoring, and human-computer interaction. However, their core basic components, flexible pressure sensors, face challenges including poor long-term stability and insufficient real-time sensing accuracy. In order to solve the challenges of long-term, stable, and accurate sensing of the sensor, this paper prepares polydimethylsiloxane (SHPDMS) with intrinsic self-healing property and designs a high-sensitivity self-healing capacitive flexible pressure sensor with dual microstructures (grating microstructured electrodes and microporous dielectric layer) as the substrate based on SHPDMS. Specifically speaking, the self-healing of the sensor under mild conditions was realized by introducing reversible imine bonds with low bonding energy into the polydimethylsiloxane (PDMS) flexible substrate, which solved the problem of the material's long-term service durability. A grating-like microstructure was introduced into the flexible electrode by using a spotted bamboo taro leaf as a template, and a dual microstructure sensor was constructed by combining it with a microporous dielectric layer doped with single-walled carbon nanotubes. This way reduces the elastic modulus of the dielectric layer, improves the dielectric constant of the sensor under loading, and thus significantly improves the sensor's sensitivity and extends the measurement accuracy in a low-stress range. The prepared self-healing flexible sensor achieves a sensitivity of 3.6 kPa -1 , a minimum detection limit of 5 Pa, a response recovery time of less than 80 ms, and stability over 5000 cycles, which exceeds most previously reported silicone rubber-based capacitive flexible sensors.

Technologies for axon guidance for in vitro disease models and bottom up investigations are increasingly being used in neuroscience research. One of the most prevalent patterning methods is using polydimethylsiloxane (PDMS) microstructures due to compatibility with microscopy and electrophysiology which enables systematic tracking of axon development with precision and efficiency. Previous investigations of these guidance platforms have noted axons tend to follow edges and avoid sharp turns; however, the specific impact of spatial constraints remains only partially explored. We investigated the influence of microchannel width beyond a constriction point, as well as the number of available microchannels, on axon growth dynamics. Further, by manipulating the size of micron/submicron-sized PDMS tunnels we investigated the space restriction that prevents growth cone penetration showing that restrictions smaller than 350 nm were sufficient to exclude axons. This research offers insights into the interplay of spatial constraints, axon development, and neural behavior. The findings are important for designing in vitro platforms and in vivo neural interfaces for both fundamental neuroscience and translational applications in rapidly evolving neural implant technologies.

Despite the exceptional biocompatibility and degradability of Poly ( L -lactic acid) (PLLA), its brittleness, low melting strength, and poor bone induction makes it challenging to utilize for bone repair. This study used a simple, efficient solid hot drawing (SHD) method to produce high-strength PLLA, using supercritical CO 2 (SC-CO 2 ) foaming technology to give PLLA a bionic microporous structure to enhance its toughness, while precisely controlling micropore homogeneity and improving the melt strength by using Polydimethylsiloxane (PDMS). This PDMS-regulated oriented microporous structure resembled that of natural bone, displaying a maximum tensile strength of 165.9 MPa and a maximum elongation at break of 164.2 %. Furthermore, this bionic structure promoted the polarization of mouse bone marrow macrophages (iBMDM), exhibiting a simultaneous pro- and anti-inflammatory effect. This structure also contributed to the adhesion and growth of mouse embryonic fibroblasts (NIH-3 T3), promoting osteogenic differentiation, which paved the way for developing degradable PLLA bone-repair load-bearing materials., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Medical device-associated infections are a pervasive global healthcare concern, often leading to severe complications. Bacterial biofilms that form on indwelling medical devices, such as catheters, are significant contributors to infections like bloodstream and urinary tract infections. This study addresses the challenge of biofilms on medical devices by introducing a portable antimicrobial catheter insert (PACI) designed to be efficient, biocompatible, and anti-infective. The PACI utilizes nitric oxide (NO), known for its potent antimicrobial properties, to deter bacterial adhesion and biofilm formation. To achieve this, a photoinitiated NO donor, S-nitroso-N-acetylpenicillamine (SNAP), is covalently linked to a polydimethylsiloxane (PDMS) polymer. This design allows for higher NO loading for long-term impact and prevents premature donor leaching, a common challenge with SNAP-blended polymers. The SNAP-PDMS material was applied to a side-glowing fiber optic and connected to a wearable light module emitting 450 nm light, creating a functional antimicrobial insert. Activation of the fiber optic, accomplished with a one-click mechanism, enables real-time NO release, maintaining controlled NO levels for a minimum of 24  hours. The therapeutic levels of NO released via photocatalysis from the PACI demonstrated remarkable efficacy, with >90 % reduction in bacterial viability against S. aureus, S. epidermidis, and P. mirabilis without any cytotoxic impact on mammalian cells. This study underscores the potential of the NO-releasing insert in clinical settings, providing a portable and adaptable solution for preventing catheter-associated infections., Competing Interests: Declaration of competing interest Dr. Elizabeth J. Brisbois is the founder of a startup company involved in exploring the possibility of using nitric oxide-releasing materials for medical applications., (Copyright © 2024. Published by Elsevier B.V.)

The development of biomaterials such as synthetic scaffolds for peripheral nerve regeneration requires a precise knowledge of the mechanical properties of the nerve in physiological-like conditions. Mechanical properties (Young's modulus, maximum stress and strain at break) for peripheral nerves are scarce and large discrepancies are observed in between reports. This is due in part to the absence of a robust testing device for nerves. To overcome this limitation, a custom-made tensile device (CMTD) has been built. To evaluate its reproducibility and accuracy, the imposed speed and distance over measured speed and distance was performed, followed by a validation using poly(dimethylsiloxane) (PDMS), a commercial polymer with established mechanical properties. Finally, the mechanical characterization of rodents (mice and rats) sciatic nerves using the CMTD was performed. Mouse and rat sciatic nerves Young's modulus were 4.57 ± 2.04 and 19.2 ± 0.86 MPa respectively. Maximum stress was 1.26 ± 0.56 MPa for mice and 3.81 ± 1.84 MPa for rats. Strain at break was 53 ± 17% for mice and 32 ± 12% for rats. The number of axons per sciatic nerve was found to be twice higher for rats. Statistical analysis of the measured mechanical properties revealed no sex-related trends, for both mice and rats (except for mouse maximum stress with p=0.03). Histological evaluation of rat sciatic nerve corroborated these findings. By developing a robust CMTD to establish the key mechanical properties (Young's modulus, maximum stress and strain at break) values for rodents sciatic nerves, our work represent an essential step toward the development of better synthetic scaffolds for peripheral nerve regeneration., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this article., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Scoliosis often occurs in adolescents and seriously affects physical development and health. Traditionally, medical imaging is the most common means of evaluating the corrective effect of bracing during treatment. However, the imaging approach falls short in providing real-time feedback, and the optimal corrective force remains unclear, potentially slowing the patient's recovery progress. To tackle these challenges, an all-in-one integrated array of pressure sensors and sEMG electrodes based on hierarchical MXene/chitosan/polydimethylsiloxane (PDMS)/polyurethane sponge and MXene/polyimide (PI) is developed. Benefiting from the microstructured electrodes and the modulus enhancement of PDMS, the sensor demonstrates a high sensitivity of 444.3 kPa -1 and a broad linear detection range (up to 81.6 kPa). With the help of electrostatic attraction of chitosan and interface locking of PDMS, the pressure sensor achieves remarkable stability of over 100 000 cycles. Simultaneously, the sEMG electrodes offer exceptional stretchability and flexibility, functioning effectively at 60% strain, which ensures precise signal capture for various human motions. After integrating the developed all-in-one arrays into a commercial scoliosis brace, the system can accurately categorize human motion and predict Cobb angles aided by deep learning. This study provides real-time insights into brace effectiveness and patient progress, offering new ideas for improving the efficiency of scoliosis treatment., (© 2024 Wiley‐VCH GmbH.)

Endothelial cells are sensitive to mechanical force and can convert it into biochemical signals to trigger mechano-chemo-transduction. Although conventional techniques have been used to investigate the subsequent modifications of cellular expression after mechanical stimulation, the in situ and real-time acquiring the transient biochemical information during mechanotransduction process remains an enormous challenge. In this work, we develop a flexible and multi-functional three-dimensional conductive scaffold that integrates cell growth, mechanical stimulation, and electrochemical sensing by in situ growth of enokitake-like Au nanowires on a three-dimensional porous polydimethylsiloxane substrate. The conductive scaffold possesses stable and desirable electrochemical sensing performance toward nitric oxide under mechanical deformation. The prepared e-AuNWs/CC/PDMS scaffold exhibits a good electrocatalytic ability to NO with a linear range from 2.5 nM to 13.95 μM and a detection limit of 8 nM. Owing to the excellent cellular compatibility, endothelial cells can be cultured directly on the scaffold and the real-time inducing and recording of nitric oxide secretion under physiological and pathological conditions were achieved. This work renders a reliable sensing platform for real-time monitoring cytomechanical signaling during endothelial mechanotransduction and is expected to promote other related biological investigations based on three-dimensional cell culture., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Bacterial cellulose (BC) is gathering increased attention due to its remarkable physico-chemical features. The high biocompatibility, hydrophilicity, and mechanical and thermal stability endorse BC as a suitable candidate for biomedical applications. Nonetheless, exploiting BC for tissue regeneration demands three-dimensional, intricately shaped implants, a highly ambitious endeavor. This challenge is addressed here by growing BC within a sacrificial viscoelastic medium consisting of an agarose gel cast inside polydimethylsiloxane (PDMS) molds imprinted with the features of the desired implant. BC produced with and without agarose has been compared through SEM, TGA, FTIR, and XRD, probing the mild impact of the agarose on the BC properties. As a first proof of concept, a PDMS mold shaped as a doll's ear was used to produce a BC perfect replica, even for the smallest features. The second trial comprised a doll face imprinted on a PDMS mold. In that case, the BC production included consecutive deactivation and activation of the aerial oxygen stream. The resulting BC face clone fitted perfectly and conformally with the template doll face, while its rheological properties were comparable to those of collagen. This streamlining concept conveys to the biosynthesized nanocelluloses broader opportunities for more advanced prosthetics and soft tissue engineering uses., Competing Interests: Declaration of competing interest The authors declare that they have no competing financial or personal interests that may influence the work reported in this study., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The aim of this study was to develop a practical orbital shaker-assisted magnetic solid phase extraction (OSA-MSPE) method for the determination of lead by FAAS. A new magnetic poly linoleic acid-polystyrene-polydimethylsiloxane (PSt-PLina-PDMS) hydrophobic graft copolymer was synthesized and characterized by NMR, FT-IR, SEM-EDX, DSC, TGA, BET and used as adsorbent for the extraction of Pb (II). This adsorbent can be used at least 50 times without any decrease of its adsorption properties for the adsorption and elution of analyte ions. Several analytical parameters including pH, adsorbent amount, sample volume, shaking time, etc. were optimized. Multivariate optimization was used for the investigation of different parameters. The linear range at optimum operating condition was 1.7-84 μg L -1 . The limit of detection (LOD) and limit of quantification (LOQ) were 0.5 μg L -1 , 1.7 μg L -1 , respectively. Intraday and interday relative standard deviation (RSD %), enhancement factor (EF) and adsorbent capacity were found as 1.9%, 3.3%, 166.7, 50 mg g -1 , respectively. OSA-MSPE method was tested with certified reference materials including LGC-6010 (Hard Drinking Water), NCS ZC73032 Celery and CS-M-3 Control Sample Microelements in Mushroom Powder for the accuracy. Experimental results for lead were confirmed with certified values. Present method was successfully applied to various liquid and solid food samples. The OSA-MSPE method has some important features such as selective, sensitive, low LOD, LOQ and RSD, pre-concentration factor (PF) and high enhancement factor (EF). High tolerance limits against matrix ions were achieved., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Flexible pressure sensors have a wide range of applications in the field of human motion signal detection, but the electromagnetic radiation generated during the monitoring process has become an unavoidable problem. Nowadays, it is still a challenge to develop high-performance pressure sensors with excellent electromagnetic interference (EMI) shielding performance. Herein, the Ti 3 C 2 T X MXene/carbon fiber/multiwalled carbon nanotube/polydimethylsiloxane (MXene/CMP) films with a micropyramidal structure were developed by the technology of vacuum high-temperature hot pressing and spray deposition. Benefiting from the dielectric loss of the conductive fillers and the presence of the microstructure, the MXene/CMP film exhibits excellent EMI shielding performance, and the EMI shielding efficiency (SE) can reach 49.37 dB. Besides, the introduction of CF effectively improves the mechanical properties of the MXene/CMP films, and the MXene nanosheets deposited on the surface of the film can reduce stress concentration, which in turn delays the expansion of cracks. Furthermore, the MXene/CMP sensor exhibits high sensitivity (89.76 kPa -1 ) and fast response/recovery time (61/60 ms). The deformation of microstructure and the construction of conductive networks enable the sensor to realize the monitoring of human motion signals (such as finger bending, knee bending, wrist bending, etc.). Meanwhile, the sensor maintains sensing stability even after 2000 pressure cycles, which can be attributed to the improvement in mechanical properties. In summary, the developed high-performance flexible pressure sensor with micropyramid structure has great application prospects in wearable devices and healthcare.

Blood and lymphatic vessels in the body are central to molecular and cellular transport, tissue repair, and pathophysiology. Several approaches have been employed for engineering microfabricated blood and lymphatic vessels in vitro , yet traditionally these approaches require specialized equipment, facilities, and research training beyond the capabilities of many biomedical laboratories. Here we present xurography as an inexpensive, accessible, and versatile rapid prototyping technique for engineering cylindrical and lumenized microvessels. Using a benchtop xurographer, or a cutting plotter, we fabricated modular multi-layer poly(dimethylsiloxane) (PDMS)-based microphysiological systems (MPS) that house endothelial-lined microvessels approximately 260 μm in diameter embedded within a user-defined 3-D extracellular matrix (ECM). We validated the vascularized MPS (or vessel-on-a-chip) by quantifying changes in blood vessel permeability due to the pro-angiogenic chemokine CXCL12. Moreover, we demonstrated the reconfigurable versatility of this approach by engineering a total of four distinct vessel-ECM arrangements, which were obtained by only minor adjustments to a few steps of the fabrication process. Several of these arrangements, such as ones that incorporate close-ended vessel structures and spatially distinct ECM compartments along the same microvessel, have not been widely achieved with other microfabrication strategies. Therefore, we anticipate that our low-cost and easy-to-implement fabrication approach will facilitate broader adoption of MPS with customizable vascular architectures and ECM components while reducing the turnaround time required for iterative designs.

The fabrication of microarray chips and the precise dispensing of nanoliter to microliter liquids are fundamental for high-throughput parallel biochemical testing. Conventional microwells, typically featuring a uniform cross section, fill completely in a single operation, complicating the introduction of multiple reagents for stepwise and combinatorial analyses. To overcome this limitation, we developed an innovative valved microwell array. Using ultraviolet (UV)-curing resin three-dimensional (3D) printing, these multilayer configurations can be rapidly fabricated through direct template printing and polydimethylsiloxane (PDMS) casting. Each microwell incorporates a microvalve structure, truncating fluids within the upper metering well and allowing transfer to the bottom reservoir well under centrifugal force. Sequential operations enable the introduction of multiple reagents, facilitating orthogonal combinations for complex assays. We explored four types of valving methods: DeepWell, Expansion, Bottleneck, and Membrane valve, each offering varying degrees of design complexity, operational efficiency, robustness, and precision. These methods constitute a versatile toolkit to accommodate a broad spectrum of analytical requirements. Our innovative approach redefines microwell architecture, direct manufacturing techniques, and stepwise fluid dispensation in microarrays.

Hydrogen peroxide (H 2 O 2 ) levels play a vital role in redox regulation and maintaining the physiological balance of living cells, especially in cell mechanotransduction. Despite the achievements on strain-induced cellular H 2 O 2 monitoring, the applied voltage for H 2 O 2 electrooxidation possibly gave rise to an abnormal expression and inadequate accuracy, which was still an inescapable concern. Hence, we decorated an interlaced CuO@TiO 2 nanowires (NWs) semiconductor meshwork onto a polydimethylsiloxane film-supported gold nanotubes substrate (Au NTs/PDMS) to construct a flexible photoelectrochemical (PEC) sensing platform. Under white light irradiation, CuO@TiO 2 NWs synergistically exhibited great stretchability and the PEC platform enabled stable photocurrent responses from the reduction of H 2 O 2 even during mechanical deformation. Moreover, the admirable biocompatibility and an almost negligible open circuit voltage of +0.18 V for the CuO@TiO 2 NWs/Au NTs/PDMS sensor guaranteed human umbilical vein endothelial cells (HUVECs) adhesion tightly thereon even under continuous illumination for 30 min. Finally, the as-proposed stretchable PEC sensor achieved sensitive and true-to-life monitoring of transient H 2 O 2 release during HUVECs deformation, in which H 2 O 2 release was positively correlated to mechanical strains. This investigation opens a new shade path on in situ cellular sensing and meanwhile greatly expands the application mode of the PEC approach.

Transplantable ready-made microvessels have therapeutic potential for tissue regeneration and cell replacement therapy. Inspired by the natural rapid angiogenic sprouting of microvessels in vivo , engineered injectable 3D microvessel networks are created using thermoplastic elastomer (TPE) microfluidic devices. The TPE material used here is flexible, optically transparent, and can be robustly yet reversibly bonded to a variety of plastic substrates, making it a versatile choice for microfluidic device fabrication because it overcomes the weak self-adhesion properties and limited manufacturing options of poly(dimethylsiloxane) (PDMS). By leveraging the reversible bonding characteristics of TPE material templates, we present their utility as an organ-on-a-chip platform for forming and handling microvessel networks, and demonstrate their potential for animal-free tissue generation and transplantation in clinical applications. We first show that TPE-based devices have nearly 6-fold higher bonding strength during the cell culture step compared to PDMS-based devices while simultaneously maintaining a full reversible bond to (PS) culture plates, which are widely used for biological cell studies. We also demonstrate the successful generation of perfusable and interconnected 3D microvessel networks using TPE-PS microfluidic devices on both single and multi-vessel loading platforms. Importantly, after removing the TPE slab, microvessel networks remain intact on the PS substrate without any structural damage and can be effectively harvested following gel digestion. The TPE-based organ-on-a-chip platform offers substantial advantages by facilitating the harvesting procedure and maintaining the integrity of microfluidic-engineered microvessels for transplant. To the best of our knowledge, our TPE-based reversible bonding approach marks the first confirmation of successful retrieval of organ-specific vessel segments from the reversibly-bonded TPE microfluidic platform. We anticipate that the method will find applications in organ-on-a-chip and microphysiological system research, particularly in tissue analysis and vessel engraftment, where flexible and reversible bonding can be utilized.

Bioelectrical signal measurements play a crucial role in clinical diagnosis and continuous health monitoring. Conventional wet electrodes, however, present limitations as they are conductive gel for skin irritation and/or have inflexibility. Here, we developed a cost-effective and user-friendly stretchable dry electrode constructed with a flexible network of Ag/AgCl nanowires embedded in polydimethylsiloxane (PDMS). We compared the performance of the stretched Ag/AgCl nanowire electrode with commonly used commercial wet electrodes to measure electrocardiogram (ECG), electromyogram (EMG), and electroencephalogram (EEG) signals. All the signal-to-noise ratios (SNRs) of the as-fabricated or stretched (50% tensile strain) Ag/AgCl nanowire electrodes are higher than that measured by commercial wet electrodes as well as other dry electrodes. The evaluation of ECG signal quality through waveform segmentation, the signal quality index (SQI), and heart rate variability (HRV) reveal that both the as-fabricated and stretched Ag/AgCl nanowire electrode produce high-quality signals similar to those obtained from commercial wet electrodes. The stretchable electrode exhibits high sensitivity and dependability in measuring EMG and EEG data, successfully capturing EMG signals associated with muscle activity and clearly recording α -waves in EEG signals during eye closure. Our stretchable dry electrode shows enhanced comfort, high sensitivity, and convenience for curved surface biosignal monitoring in clinical contexts.

Intelligent shape memory polymer can be potentially used in manufacturing implantable devices that enables a benign variation of implant dimensions with the external stimuli, thus effectively lowering insertion forces and evading associated risks. However, in surgical implantation, biomaterials-associated infection has imposed a huge burden to healthcare system that urgently requires an efficacious replacement of antibiotic usages. Preventing the initial attachment and harvesting a biocidal function upon native surfaces may be deemed as a preferable strategy to tackle the issues of bacterial infection. Herein, a functionalized polylactic acid (PLA) composite membrane assembled with graphene (GE, a widely used photothermal agent) was fabricated through a blending process and then polydimethylsiloxane utilized as binders to pack hydrophobic SiO 2 tightly onto polymer surface (denoted as PLA-GE/SiO 2 ). Such an active platform exhibited a moderate shape-memory performance upon near-infrared (NIR) light stimulation, which was feasible for programmed deformation and shape recovery. Particularly stirring was that PLA-GE/SiO 2 exerted a pronounced bacteria-killing effect under NIR illumination, 99.9 % of E. coli and 99.8 % of S. aureus were effectively eradicated in a lean period of 5 min. Furthermore, the obtained composite membrane manifested excellent antiadhesive properties, resulting in a bacteria-repelling efficacy of up to 99 % for both E. coli and S. aureus species. These findings demonstrated the potential value of PLA-GE/SiO 2 as a shape-restorable platform in "kill&repel" integration strategy, further expanding its applications for clinical anti-infective treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Embedded 3D printing (EMB3D) is an additive manufacturing technique that enables complex fabrication of soft materials including tissues and silicones. In EMB3D, a nozzle writes continuous filaments into a support bath consisting of a yield stress fluid. Lack of fusion defects between filaments can occur because the nozzle pushes support fluid into existing filaments, preventing coalescence. Interfacial tension was previously proposed as a tool to drive interfilament fusion. However, interfacial tension can also drive rupture and shrinkage of printed filaments. Here, we evaluate the efficacy of interfacial tension as a tool to control defects in EMB3D. Using polydimethylsiloxane (PDMS)-based inks with varying amounts of fumed silica and surfactant, printed into Laponite in water supports, we evaluate the effect of rheology, interfacial tension, print speeds, and interfilament spacings on defects. We print pairs of parallel filaments at varying orientations in the bath and use digital image analysis to quantify shrinkage, rupture, fusion, and positioning defects. By comparing disturbed filaments to printed pairs of filaments, we disentangle the effects of nozzle movement and filament extrusion. Critically, we find that capillary instabilities and interfilament fusion scale with the balance between support rheology and interfacial tension. Less viscous supports and higher interfacial tensions lead to more shrinkage and rupture at all points in the printing process, from relaxation after writing, to disturbance of the line, to writing of a second line. It is necessary to overextrude material to achieve interfilament fusion, particularly at high support viscosities and low interfacial tensions. Finally, fusion quality varies with printing orientation, and writing neighboring filaments causes displacement of existing structures. As such, specialized slicers are needed for EMB3D that consider the tighter spacings and orientation-dependent spacings necessary to achieve precise control over printed shapes.

Urbanizing global populations spend over 90% of their time indoors where microbiome abundance and diversity are low. Chronic exposure to microbiomes with low abundance and diversity have demonstrated negative long-term impacts on human health. Sequencing-based analyses of environmental nucleic acids are critical to understanding the impact of the indoor microbiome on human health, however low DNA yields indoors, alongside sample collection and processing inconsistencies, currently challenge study replicability. This study presents a comparative assessment of a novel, passive, easily replicable sampling strategy using polydimethylsiloxane (PDMS) sheets alongside a representative swab-based collection protocol. Deployable, customizable PDMS films designed for whole-sample insertion into standardized extraction kits demonstrated 43% higher DNA yields per sample, and 76% higher yields per cm 2 of sampler over swab-based protocols. These results indicate that this accessible, scalable method enables sufficient DNA collection to comprehensively evaluate indoor microbiome exposures and potential human health impacts using smaller, more space efficient samplers, representing an attractive alternative to swab-based collection. In addition, this process reduces the manual steps required for microbiome sampling which could address inter-study variability, transform the current microbiome sampling paradigm, and ultimately benefit the replicability and accessibility of microbiome exposure studies., (© 2024. The Author(s).)

This study reports the development of the first copolymer material that (i) is resistant to fungal attachment and hence biofilm formation, (ii) operates via a nonkilling mechanism, i.e., avoids the use of antifungal actives and the emergence of fungal resistance, (iii) exhibits sufficient elasticity for use in flexible medical devices, and (iv) is suitable for 3D printing (3DP), enabling the production of safer, personalized medical devices. Candida albicans ( C. albicans ) can form biofilms on in-dwelling medical devices, leading to potentially fatal fungal infections in the human host. Poly(dimethylsiloxane) (PDMS) is a common material used for the manufacture of medical devices, such as voice prostheses, but it is prone to microbial attachment. Therefore, to deliver a fungal-resistant polymer with key physical properties similar to PDMS (e.g., flexibility), eight homopolymers and 30 subsequent copolymers with varying glass transition temperatures ( T g ) and fungal antiattachment properties were synthesized and their materials/processing properties studied. Of the copolymers produced, triethylene glycol methyl ether methacrylate (TEGMA) copolymerized with (r)-α-acryloyloxy-β,β-dimethyl-γ-butyrolactone (AODMBA) at a 40:60 copolymer ratio was found to be the most promising candidate by meeting all of the above criteria. This included demonstrating the capability to successfully undergo 3DP by material jetting, via the printing of a voice prosthesis valve-flap using the selected copolymer.

We demonstrate the rapid capture, enrichment, and identification of bacterial pathogens using Adaptive Channel Bacterial Capture (ACBC) devices. Using controlled tuning of device backpressure in polydimethylsiloxane (PDMS) devices, we enable the controlled formation of capture regions capable of trapping bacteria from low cell density samples with near 100% capture efficiency. The technical demands to prepare such devices are much lower compared to conventional methods for bacterial trapping and can be achieved with simple benchtop fabrication methods. We demonstrate the capture and identification of seven species of bacteria with bacterial concentrations lower than 1000 cells per mL, including common Gram-negative and Gram-positive pathogens such as Escherichia coli and Staphylococcus aureus . We further demonstrate that species identification of the trapped bacteria can be undertaken in the order of one-hour using multiplexed 16S rRNA-FISH with identification accuracies of 70-98% with unsupervised classification methods across 7 species of bacteria. Finally, by using the bacterial capture capabilities of the ACBC chip with an ultra-rapid antimicrobial susceptibility testing method employing fluorescence imaging and convolutional neural network (CNN) classification, we demonstrate that we can use the ACBC chip as an imaging flow cytometer that can predict the antibiotic susceptibility of E. coli cells after identification.

Bacterial keratitis is a common form of inflammation caused by the bacterial invasion of the corneal stroma after trauma. In extreme cases, it can lead to severe visual impairment or even blindness; therefore, timely medical intervention is imperative. Unfortunately, widespread misuse of antibiotics has led to the development of drug resistance. In recent years, organ-on-chips that integrate multiple cell co-cultures have extensive applications in fundamental research and drug screening. In this study, immortalized human corneal epithelial cells and primary human corneal fibroblasts were co-cultured on a porous polydimethylsiloxane membrane to create a cornea-on-a-chip model. The developed multilayer epithelium closely mimicked clinical conditions, demonstrating high structural resemblance and repeatability. By introducing a consistently defective epithelium and bacterial infection using the space-occupying method, we successfully established an in vitro model of bacterial keratitis using S . aureus . We validate this model by evaluating the efficacy of antibiotics, such as levofloxacin, tobramycin, and chloramphenicol, through simultaneously observing the reactions of bacteria and the two cell types to these antibiotics. Our study has revealed the barrier function of epithelium of the model and differentiated efficacy of three drugs in terms of bactericidal activity, reducing cellular apoptosis, and mitigating scar formation. Altogether, the cornea on chip enables the assessment of ocular antibiotics, distinguishing the impact on corneal cells and structural integrity. This study introduced a biomimetic in vitro disease model to evaluate drug efficacy and provided significant insights into the extensive effects of antibiotics on diverse cell populations within the cornea.

Fluorescence polarization (FP) assays are widely used to quantify biomolecules, and their combination with microfluidic devices has the potential for application in onsite analysis. However, the hydrophobic surface of polydimethylsiloxane (PDMS)-based microfluidic devices and the amphiphilicity of the blocking agents can cause the nonspecific adsorption of biomolecules, which in turn reduces the sensitivity of the FP assay. To address this, we demonstrated an FP assay with improved sensitivity in microfluidic devices using a polyethylene glycol-based surface modification to avoid the use of blocking agents. We evaluated the effectiveness of the modification in inhibiting nonspecific protein adsorption and demonstrated the improved sensitivity of the FP immunoassay (FPIA). Our study addressed the lack of sensitivity of FP assays in microfluidic devices, particularly for the quantification of low-abundance analytes.

Microbial biofilm formation on medical devices paves the way for device-associated infections. Staphylococcus epidermidis is one of the most common strains involved in such infections as it is able to colonize numerous devices, such as intravenous catheters, prosthetic joints, and heart valves. We previously reported the antibiofilm activity against S. epidermidis of pentadecanoic acid (PDA) deposited by drop-casting on the silicon-based polymer poly(dimethyl)siloxane (PDMS). This material exerted an antibiofilm activity by releasing PDA; however, a toxic effect on bacterial cells was observed, which could potentially favor the emergence of resistant strains. To develop a PDA-functionalized material for medical use and overcome the problem of toxicity, we produced PDA-doped PDMS by either spray-coating or PDA incorporation during PDMS polymerization. Furthermore, we created a strategy to assess the kinetics of PDA release using ADIFAB, a very sensitive free fatty acids fluorescent probe. Spray-coating resulted in the most promising strategy as the concentration of released PDA was in the range 0.8-1.5 μM over 21 days, ensuring long-term effectiveness of the antibiofilm molecule. Moreover, the new coated material resulted biocompatible when tested on immortalized human keratinocytes. Our results indicate that PDA spray-coated PDMS is a promising material for the production of medical devices endowed with antibiofilm activity.

Exploring highly sensitive flexible electronic skins (e-skins) that can mimic the tactile and pain perception of human skin is an important prerequisite for achieving biomimetic robots and intelligent prosthetics. However, it is still difficult to realize both touch and pain sensing using a single pressure sensor. Herein, a novel flexible capacitive pressure sensor that can distinguish noxious pressure stimuli is proposed for detecting touch and pain, which is composed of a porous polydimethylsiloxane (PDMS) skeleton and a sodium alginate (SA) hydrogel core. The sensor employs two different working mechanisms depending on the range of external pressure, determining the mechanism of operation for transducing the sense of touch or pain. Such a unique structural design plays a crucial role in enhancing pain perception, leading to maximum sensitivity (14.25 kPa -1 ) in a large pressure regime (up to 400 kPa) and an adjustable pressure threshold. Moreover, the sensor also exhibits a fast response (45 ms) and recovery speed (70 ms), ensuring a sufficiently fast response to noxious pressure stimuli. Finally, we demonstrate the capabilities of a robotic hand based on the pressure sensor for precisely detecting both touch and pain, which shows great promise in developing intelligent robots and prosthetic limbs to prevent possible damage under external noxious stimuli.

Many medical devices implanted in patients to mitigate diseases and medical conditions have different types of topographic features. While appropriate textures can promote the integration of host cells and reduce scar tissue formation, some textured implants with inappropriate topographies have been associated with inflammation, bacterial colonization, or even malignant complications. To better understand how surface topography affects host immune response to colonizing bacteria, a protocol was developed to investigate phagocytosis of bacterial cells attached on polydimethylsiloxane (PDMS) surfaces with different square-shaped recessive patterns. The interaction between activated RAW 264.7 macrophages and Escherichia coli in recessive wells was visualized in 3D using multiple fluorescent markers. The results revealed that there is a threshold dimension of topography, below which phagocytosis of attached bacterial cells is significantly impeded. Specifically, under our experimental condition, up to 100-fold reduction in phagocytosis was observed in square-shaped patterns with 5 µm side length and 10 µm depth compared to the flat control and patterns with 10 µm or longer side length. The spacing between wells also showed significant effects; e.g., phagocytosis in the wells further decreased when spacing increased to 50 µm. These results are helpful for understanding how undesired topographies may contribute to bacterial colonization and thus infection and other associated complications. STATEMENT OF SIGNIFICANCE: Surface topography plays an important role in bacteria-material infections and thus the safety of implantable medical devices. Undesired topographic features can cause biofilm formation and related complications. However, how surface topography affects the capability of host immune cells to clear colonizing bacteria is not well understood. In this study, the interaction between macrophage RAW264.7 and colonizing E. coli cells on polydimethylsiloxane (PDMS) with recessive features is investigated. It was discovered that the size of recessive features and the spacing between these features have significant effects on phagocytosis of bacteria by macrophages. These new results are helpful for understanding the complex interaction among host cells, bacteria, and implanted biomaterials, which will help guide the rational design of safer medical devices., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Acta Materialia Inc. All rights reserved.)

Inspired by the synthesis of polyurethane, a multifunctional fabric with hydrophobic and long-lasting flame retardancy was prepared through the phase separation and interfacial reaction process between PEI (polyethyleneimine)/BX (borax) aqueous solution and isocyanate terminated polydimethylsiloxane (PDMS-NCO) in tetrahydrofuran solution. The limit oxygen index of the treated fabric increased from 18.0 % to 33.7 %, and the total heat release decreased by 34.2 %. The enhancement of flame retardant performance and thermal stability is attributed to the enhanced char-forming capacity. After 50 cycles of water washing, the cotton fabric can still pass the vertical flammability test because of the curing effect of PDMS-NCO on functional additives. Furthermore, SEM analysis revealed that the formation of nano-rough structures on the fibers was promoted by phase separation, thus leading an increased water contact angle of sample to 139°. The materials utilized in this modified process do not contain elements such as F, Cl, Br, and P, indicating its potential as an environmentally friendly methodology for fabric functionalization., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. All the authors listed have approved the manuscript enclosed., (Copyright © 2024. Published by Elsevier B.V.)

In drug discovery, human organ-on-a-chip (organ chip) technology has emerged as an essential tool for preclinical testing, offering a realistic representation of human physiology, real-time monitoring, and disease modeling. Polydimethylsiloxane (PDMS) is commonly used in organ chip fabrication owing to its biocompatibility, flexibility, transparency, and ability to replicate features down to the nanoscale. However, the porous nature of PDMS leads to unintended absorption of small molecules, critically affecting the drug response analysis. Addressing this challenge, the precision drug testing organ chip (PreD chip) is introduced, an innovative platform engineered to minimize small molecule absorption while facilitating cell culture. This chip features a PDMS microchannel wall coated with a perfluoropolyether-based lubricant, providing slipperiness and antifouling properties. It also incorporates an ECM-coated semi-porous membrane that supports robust multicellular cultures. The PreD chip demonstrates its outstanding antifouling properties and resistance to various biological fluids, small molecule drugs, and plasma proteins. In simulating the human gut barrier, the PreD chip demonstrates highly enhanced sensitivity in tests for dexamethasone toxicity and is highly effective in assessing drug transport across the human blood-brain barrier. These findings emphasize the potential of the PreD chip in advancing organ chip-based drug testing methodologies., (© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)

Gene transfection, which involves introducing nucleic acids into cells, is a pivotal technology in the life sciences and medical fields, particularly in gene therapy. Surface-mediated transfection, primarily targeting cells adhering to surfaces, shows promise for enhancing cell transfection by localizing and presenting surface-bound nucleic acids directly to the cells. However, optimizing endocytosis for efficient delivery remains a persistent challenge. Additionally, ensuring efficient and non-traumatic cell harvest capability is crucial for applications such as ex vivo cell-based therapy. To address these challenges, we developed a photothermal platform with enzymatic degradation capability for efficient gene transfection and cell harvest. This platform is based on carbon nanotubes (CNTs) doped with poly(dimethylsiloxane) and modified with polyelectrolyte multilayers (PEMs) containing hyaluronic acid and quaternized chitosan, allowing for substantial loading of poly(ethyleneimine)/plasmid DNA (pDNA) complexes through electrostatic interactions. Upon irradiation of near-infrared laser, the photothermal properties of CNTs enable high transfection efficiency by delivering pDNA into attached cells via a membrane disruption mechanism. The engineered cells can be harvested by treating with a non-toxic hyaluronidase solution to degrade PEMs, thus maintaining good viability for further applications. This platform has demonstrated remarkable efficacy across various cell lines (including Hep-G2 cells, Ramos cells and primary T cells), achieving a transfection efficiency exceeding 95 %, cell viability exceeding 90 %, and release efficiency surpassing 95 %, highlighting its potential for engineering living cells., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Multiplex detection of low-abundance protein biomarkers in biofluids can contribute to diverse biomedical fields such as early diagnosis and precision medicine. However, conventional techniques such as digital ELISA, microarray, and hydrogel-based assay still face limitations in terms of efficient protein detection due to issues with multiplexing capability, sensitivity, or complicated assay procedures. In this study, we present the degassed micromold-based particle isolation technique for highly sensitive and multiplex immunoassay with enzymatic signal amplification. Using degassing treatment of nanoporous polydimethylsiloxane (PDMS) micromold, the encoded particles are isolated in the mold within 5 min absorbing trapped air bubbles into the mold by air suction capability. Through 10 min of signal amplification in the isolated spaces by fluorogenic substrate and horseradish peroxidase labeled in the particle, the assay signal is amplified with one order of magnitude compared to that of the standard hydrogel-based assay. Using the signal amplification assay, vascular endothelial growth factor (VEGF) and chorionic gonadotropin beta (CG beta), the preeclampsia-related protein biomarkers, are quantitatively detected with a limit of detection (LoD) of 249 fg/mL and 476 fg/mL in phosphate buffer saline. The multiplex immunoassay is conducted to validate negligible non-specific detection signals and robust recovery rates in the multiplex assay. Finally, the VEGF and CG beta in real urine samples are simultaneously and quantitatively detected by the developed assay. Given the high sensitivity, multiplexing capability, and process simplicity, the presented particle isolation-based signal amplification assay holds significant potential in biomedical and proteomic fields., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In recent years, the automotive industry has made significant progress in integrating multifunctional sensors to improve vehicle performance, safety, and efficiency. As the number of integrated sensors keeps increasing, there is a growing interest in alternative energy sources. Specifically, self-powered sensor systems based on energy harvesting are drawing much attention, with a main focus on sustainability and reducing reliance on typical batteries. This paper demonstrates the use of triboelectric nanogenerators (TENGs) in a computer mouse for efficient energy harvesting and in automobile braking systems for safety applications using SrBi 2 Ta 2 O 9 (SBTO) perovskite, blended PDMS composite operating in free-standing mode with an interdigitated patterned aluminum electrode. This self-powered sensor is capable of distinguishing between normal and abnormal braking patterns using digital signal processing techniques. It is noteworthy that the addition of 15% wt. of the SBTO in PDMS composite-based TENG delivered 13.5 V, 45 nA, and an output power of 0.98 µW. This new combination of energy harvesting and safety applications enables real-time monitoring and predictive maintenance in the automotive industry., (© 2024 Wiley‐VCH GmbH.)

Water-in-water (W/W) Pickering emulsions, exhibit considerable potential in the food and pharmaceutical fields owing to their compartmentalization and high biocompatibility. However, constrained by the non-uniform distribution of shear forces during emulsification or the spatial obstruction in polydimethylsiloxane (PDMS) passive microfluidic platform, the existing methods cannot generate monodisperse W/W Pickering emulsions with high particle coverage rate, thereby limiting their applications. Herein, a novel microfluidic system is designed for the preparation of monodisperse and highly particle-covered W/W Pickering emulsions under mild conditions. pH-responsive Polyethylene glycol (PEG)/phosphate aqueous two-phase system (ATPS) is used for the emulsions' preparation. Notably, a coverage rate of 96 ± 3 % is obtained by adjusting the length of the helical coiled tube, as well as the size and contact angle of genipin cross-linked BSA (BSA-GP) particles. Moreover, these W/W Pickering emulsions, with surfaces almost completely covered, can maintain monodisperse (N coal = 1.18 ± 0.03) for one day. Furthermore, the results of ranitidine hydrochloride (RH) release demonstrated that the drug release rate of W/W Pickering emulsions in the simulated gastric fluid (SGF) was 10 times faster than that in the neutral solution. We believe that the highly particle-covered monodisperse W/W Pickering emulsions possess great potential applications in bioencapsulation for foods and drug delivery., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Phosphorus-containing flame retardants are prone to result in the buildup of biotoxins, while halogen flame retardants easily lead to hazardous gases. Therefore, it is crucial to develop a multifunctional flame-retardant cotton fabric without phosphorus and halogen. Herein, single-ended hydroxy-terminated polydimethylsiloxane (PDMS-ID) was synthesized through single-ended hydrosilicone oil and 1,4-butanediol, followed by the preparation of a waterborne polyurethane (RWPU) containing side chain polydimethylsiloxane through the reaction of PDMS-ID with isocyanate prepolymer. Characterization data shows that its particle size distribution is relatively dispersed while maintaining good emulsification performance. Based on this, a halogen-free and phosphorus-free multifunctional flame retardant cotton fabric (COF-BBN@RWPU) was successfully prepared through treatment with boric acid/borax/3-aminopropyltriethoxysilane solution and subsequent RWPU encapsulation. In vertical flammability test (VFT), COF-BBN@RWPU has a char length of 57 mm and a limiting oxygen index (LOI) of 42.3 % with a 11 % weight gain while pure cotton was burned through with a LOI of 18.0 %. In addition, the total heat release and total smoke release of COF-BBN@RWPU decreased by 80.0 % and 47.2 %, compared with pure cotton. Additionally, COF-BBN@RWPU can achieve a maximum contact angle of 140.1° with an oil-water separation rate of 98.4 %. This study presents an eco-friendly approach to achieving the multifunctionality of cellulose fabrics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. All the authors listed have approved the manuscript enclosed., (Copyright © 2024 Elsevier B.V. All rights reserved.)

A high-quality filler within mixed matrix membranes, coupled with uniform dispersity, endows a high-efficiency transfer pathway for the significant improvement on separation performance. In this work, a zeolite-typed MCM-22 filler is reported that is doped into polydimethylsiloxane (PDMS) matrix by ultrafast photo-curing technique. The unique structure of nanosheets assembly layer by layer endows the continuous transfer channels towards penetrate molecules because of the inter-connective nanosheets within PDMS matrix. Furthermore, an ultrafast freezing effect produced by fast photo-curing is used to overcome the key issue, namely filler aggregation, and further eliminates defects. When pervaporative separating a 5 wt% ethanol aqueous solution, the resulting MCM-22/PDMS membrane exhibits an excellent membrane flux of 1486 g m -2 h -1 with an ethanol separation factor of 10.2. Considering a biobased route for ethanol production, the gas stripping and vapor permeation through this membrane also shows a great enrichment performance, and the concentrated ethanol is up to 65.6 wt%. Overall, this MCM-22/PDMS membrane shows a high separation ability for ethanol benefited from a unique structure deign of fillers and ultrafast curing speed of PDMS, and has a great potential for bioethanol separation from cellulosic ethanol fermentation., (© 2024 Wiley‐VCH GmbH.)

The development of multifunctional coatings is a trend. Here, a conductive and superhydrophobic coating with nest-like structure was prepared on the wood or polyurethane (PU) sponge by spraying or soaking methods. The coating contains lignin and carboxylated multi-wall carbon nanotubes (MWCNT) as the main materials, both methyl trimethoxysilane (MTMS) and polydimethylsiloxane (PDMS) as the modifiers. And benefiting from the protective effect of the nest-like structure, the coating exhibits excellent abrasion resistance (withstanding 43 abrasion cycles), stability, and UV resistance (little change in water contact angle after 240 h of ultraviolet (UV) irradiation) by optimizing the proportions. Additionally, the coating provides eminent deicing (complete removal after 142.7 s) and self-cleaning on the wood, as well as the superior sensing performance and oil absorption (15.0-49.6 g/g for various oils) on the PU sponge. When assembled into compressible piezoresistive sensor, it could clearly sense the signals of rapid, short, circulation, different speed and deformation, possessing a prosperous wearable device prospect. It is envisaged that the coating supplies a new platform for superhydrophobicity, wearable electronics and oil absorption., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Nanocomposite polymer coatings are being used as a new generation of marine antibiofouling coatings because of their toxin-free chemical composition and ease of large-scale adoption. Cellulose nanocrystal (CN) exhibits significant potential for composite reinforcement. Herein, CN was surface-modified via α,ω-bis(3-(2-hydroxyl-terminated polydimethylsiloxane (HTPDMS), resulting in dihydroxyl-terminated poly(dimethylsiloxane)-grafted CN (HP-g-CN). The amine-terminated PDMS as the foundational component was sequentially reacted with isophorone diisocyanate, isophthalaldehyde, and carbon disulfide to produce PDMS-based poly (urea-thiourea-imine) (PDMS-PUTI). Subsequently, a composite (PDMS-PUTI/HP-g-CN) was produced through physical blending. The intrinsic imine bonds and dynamic hydrogen-bonding network were responsible for the self-healing properties, which achieved a healing efficiency of up to 89.2 %. HP-g-CN was grafted with the non-leaching lubricant, HTPDMS, resulting in improved mechanical properties (1.38 MPa of ultimate strength) and adhesion strength (2.43 MPa), along with the self-cleaning and self-lubricating performance (0.700 coefficient) of the coating. Additionally, the fouling resistance to bovine serum albumin (BSA, 10.44 μg cm -2 ), bacteria (∼97.08 % and ∼ 98.05 % reduction for Pseudomonas sp. (P. sp.) and Shewanella sp. (S. sp.), respectively), and diatoms (∼27 cells mm -2 ) was further enhanced. Marine field tests conducted over 90 days revealed that the coatings were static fouling-resistant for an extended period. This study demonstrated a multifunctional, high-performance, and environmentally friendly nanocomposite polymer coating for preventing marine biofouling., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this paper, paper microfluidic channel fabricated by directly screen-printing of polydimethylsiloxane (PDMS) is proposed for paper spray mass spectrometry analysis of therapeutic drugs in the blood samples. Compared with traditional paper spray, PDMS-printed paper spray (PP-PS) allows fluid to flow to the tip of paper with less sample loss which significantly improved the signal intensity of target compounds in blood samples. As paper can reduce the matrix effect, PP-PS also has a greater advantage than electro-spray Ionization (ESI) when directly analyzing complex biological sample in terms of the detection efficiency. Linearity and limits of detection (LOD) were evaluated for five psychotropic drugs: olanzapine, quetiapine, 9-hydroxyrisperidone, clozapine, risperidone. As a result, PP-PS improved the signal intensity of the psychotropic drugs at a concentration of 250 ng/ml in blood samples by a factor of 2-5 times and lowered the relative standard deviation (RSD) by a factor of 2-5.6 times compared with traditional paper spray. And PP-PS also improved signal intensity by a factor of 9-33 times compared with ESI. Quantitative experiments of PP-PS mass spectrometry indicated that the linear range was 5-500 ng/ml and the LOD were improved by a factor of 5-71 times for all these drugs compared with traditional paper spray. In addition, PP-PS was applied to the home-made miniaturized mass spectrometer and the precursor ions of all five psychotropic drugs (250 ng/ml) in the mass spectrometry results were obtained as well. These could prove that PP-PS has the potential to analyze complex biological samples in application on the miniaturized mass spectrometer which can be used outside the laboratory., Competing Interests: Declaration of competing interest The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The membrane curvature of cells and intracellular compartments continuously adapts to enable cells to perform vital functions, from cell division to signal trafficking. Understanding how membrane geometry affects these processes in vivo is challenging because of the biochemical and geometrical complexity as well as the short time and small length scales involved in cellular processes. By contrast, in vitro model membranes with engineered curvature would provide a versatile platform for this investigation and applications to biosensing and biocomputing. Here, we present a strategy that allows fabrication of lipid membranes with designed shape by combining 3D micro-printing and replica-molding lithography with polydimethylsiloxane to create curved micrometer-sized scaffolds with virtually any geometry. The resulting supported lipid membranes are homogeneous and fluid. We demonstrate the versatility of the system by fabricating structures of interesting combinations of mean and Gaussian curvature. We study the lateral phase separation and how local curvature influences the effective diffusion coefficient. Overall, we offer a bio-compatible platform for understanding curvature-dependent cellular processes and developing programmable bio-interfaces for living cells and nanostructures.

An innovative method is introduced based on the combination of label-free surface-enhanced Raman scattering with advanced multivariate analysis. This technique allows both quantitative and qualitative assessment of Salmonella typhimurium and Escherichia coli on eggshells. Using silver nanocubes embedded in polydimethylsiloxane, we consistently achieved Raman spectra of bacteria. The stability of the Ag NCs@PDMS substrate is confirmed using rhodamine 6G over 30 days under standard conditions. Principal component analysis (PCA) effectively distinguishes between S. typhimurium and E. coli spectra. Partial least squares regression (PLS) models were developed for quantitative determination of bacteria on egg surfaces, yielding accurate results with minimal error. The S. typhimurium model achieves R c 2  = 0.9563 and RMSEC = 0.601 in calibration, and R v 2  = 0.9113 and RMSEV = 0.907 in validation. Similarly, the E. coli model achieves R c 2  = 0.9877 and RMSEC = 0.322 in calibration, and R v 2  = 0.9606 and RMSEV = 0.579 in validation. Recoveries validate PLS predictions by inoculating egg surfaces with varying bacterial amounts. Our study demonstrates the feasibility of SERS-PLS for quantitative determination of S. typhimurium and E. coli on eggshells, promising enhanced food safety protocols., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)