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Renal cell carcinoma (RCC) is one of the deadliest malignant tumors. Despite significant advances in RCC treatment over the past decade, complete remission is rarely achieved. Consequently, there is an urgent need to explore and develop new therapies to improve the survival rates and quality of life for patients. In recent years, the development of tumor organoid technology has attracted widespread attention as it can more accurately simulate the spatial structure and physiological characteristics of tumors within the human body. In this review, we summarize the main methods currently used to construct kidney cancer organoids, as well as their various biological and clinical applications. Furthermore, combining organoids with other technologies, such as co-culture techniques and microfluidic technologies, can further develop organoids and address their limitations, creating more practical models. This approach summarizes the interactions between different tissues or organs during tumor progression. Finally, we also provide an outlook on the construction and application of kidney cancer organoids. These rapidly evolving kidney cancer organoids may soon become a focal point in the development of in vitro clinical models and therapeutic research for kidney cancer. [ABSTRACT FROM AUTHOR]

In vitro neuronal culture is an important research platform in cellular and network neuroscience. However, neurons cultured on a homogeneous scaffold form dense, randomly connected networks and display excessively synchronized activity; this phenomenon has limited their applications in network‐level studies, such as studies of neuronal ensembles, or coordinated activity by a group of neurons. Herein, polydimethylsiloxane‐based microfluidic devices are developed to create small neuronal networks exhibiting a hierarchically modular structure resembling the connectivity observed in the mammalian cortex. The strength of intermodular coupling is manipulated by varying the width and height of the microchannels that connect the modules. Neuronal activity recording via calcium imaging shows that the spontaneous activity in networks with smaller microchannels (2.2–5.5 µm2) has lower synchrony and exhibits a threefold variety of neuronal ensembles. Optogenetic stimulation demonstrates that a reduction in intermodular coupling enriches evoked neuronal activity patterns and that repeated stimulation induces plasticity in neuronal ensembles in these networks. These findings suggest that cell engineering technologies based on microfluidic devices enable in vitro reconstruction of the intricate dynamics of neuronal ensembles, thus providing a robust platform for studying neuronal ensembles in a well‐defined physicochemical environment. [ABSTRACT FROM AUTHOR]

Electrically controlled droplet manipulation is attractive for lots of applications ranging from material synthesis and drug delivery. However, the present techniques using bulky and expensive power supplies to generate high‐voltage electrical signals are easy to cause electrode electrolysis, bubble formation in buffer solution, and are incapable for point‐of‐care testing. Herein, a novel and portable electrical method for self‐powered emulsion droplet core coalescence and release based on triboelectric nanogenerator (TENG) is presented. The electrical signal with a 2.25 kV open‐voltage and a 35 µA short‐circuit current can be conveniently generated via frictional electrification effect, and the harmful electrochemical reaction in solutions can be avoided. The high transient pulse voltage and stable sinusoidal signal between two electrodes in microfluidic device can generate a strong electric field, which causes apparent Maxwell electrical stresses at droplet interfaces and subsequently promotes the core coalescence and release of double‐emulsions. By adjusting the voltage magnitude, the core coalescence and release behaviors of double‐emulsion droplets can be controllably achieved, followed by the synthesis copper‐based metal–organic framework (Cu‐MOF) nanoparticles. Thus, this portable, effective and self‐powered droplet manipulation technique can be attractive for those droplet‐based applications. [ABSTRACT FROM AUTHOR]

Inflammatory microenvironments often become acidic (pH < 7.4) due to tissue oxygen deprivation and lactate release in glycolysis by activated immune cells. Although neutrophils are known to accumulate in such microenvironments, the effects of pH on their migration are not fully understood. Here, we first investigated the pH control around cultured cells with a microfluidic device, which was equipped with two gas channels above three parallel media channels. By supplying gas mixtures with predefined carbon dioxide (CO2) concentrations to the gas channels, the gas exchange adjusted the dissolved CO2 and affected the chemical equilibrium of sodium hydrogen carbonate in the cell culture medium. A pH gradient from 8.3 to 6.8 was generated along the media channels when gas mixtures containing 1% and 50% CO2 were supplied to the left and right gas channels, respectively. Neutrophil-like differentiated human promyelocytic leukemia cells (HL-60) were then seeded to the fibronectin-coated media channels and their migratory behaviors were quantified while varying the pH. The cell migration became more active and faster under high pH than under low pH conditions. However, no directional migration along the pH gradient was detected during the three-hour observation. Thus, the microfluidic device is useful to elucidate pH-dependent cellular dynamics. [ABSTRACT FROM AUTHOR]

A significant challenge in the treatment of central nervous system (CNS) disorders is represented by the presence of the blood--brain barrier (BBB), a highly selective membrane that regulates molecular transport and restricts the passage of pathogens and therapeutic compounds. Traditional in vivo models are constrained by high costs, lengthy experimental timelines, ethical concerns, and interspecies variations. In vitro models, particularly microfluidic BBB-on-a-chip devices, have been developed to address these limitations. These advanced models aim to more accurately replicate human BBB conditions by incorporating human cells and physiological flow dynamics. In this framework, here we developed an innovative microfluidic system that integrates thin-film electrodes for non-invasive, real-time monitoring of BBB integrity using electrochemical impedance spectroscopy (EIS). EIS measurements showed frequencydependent impedance changes, indicating BBB integrity and distinguishing well-formed from non-mature barriers. The data from EIS monitoring was confirmed by permeability assays performed with a fluorescence tracer. The model incorporates human endothelial cells in a vessel-like arrangement to mimic the vascular component and three-dimensional cell distribution of human astrocytes and microglia to simulate the parenchymal compartment. By modeling the BBB-on-a-chip with an equivalent circuit, a more accurate trans-endothelial electrical resistance (TEER) value was extracted. The device demonstrated successful BBB formation and maturation, confirmed through live/dead assays, immunofluorescence and permeability assays. Computational fluid dynamics (CFD) simulations confirmed that the device mimics in vivo shear stress conditions. Drug crossing assessment was performed with two chemotherapy drugs: doxorubicin, with a known poor BBB penetration, and temozolomide, conversely a specific drug for CNS disorders and able to cross the BBB, to validate the model predictive capability for drug crossing behavior. The proposed sensorized microfluidic device represents a significant advancement in BBB modeling, offering a versatile platform for CNS drug development, disease modeling, and personalized medicine. [ABSTRACT FROM AUTHOR]

Detecting glucose levels is crucial for diabetes patients as it enables timely and effective management, preventing complications and promoting overall health. In this endeavor, we have designed a novel, affordable point-of-care diagnostic device utilizing microfluidic principles, a smartphone camera, and established laboratory colorimetric methods for accurate glucose estimation. Our proposed microfluidic device comprises layers of adhesive poly-vinyl films stacked on a poly methyl methacrylate (PMMA) base sheet, with micro-channel contours precision-cut using a cutting printer. Employing the gold standard glucose-oxidase/peroxidase reaction on this microfluidic platform, we achieve enzymatic glucose determination. The resulting colored complex, formed by phenol and 4-aminoantipyrine in the presence of hydrogen peroxide generated during glucose oxidation, is captured at various glucose concentrations using a smartphone camera. Raw images are processed and utilized as input data for a 2-D convolutional neural network (CNN) deep learning classifier, demonstrating an impressive 95% overall accuracy against new images. The glucose predictions done by CNN are compared with ISO 15197:2013/2015 gold standard norms. Furthermore, the classifier exhibits outstanding precision, recall, and F1 score of 94%, 93%, and 93%, respectively, as validated through our study, showcasing its exceptional predictive capability. Next, a user-friendly smartphone application named "GLUCOLENS AI" was developed to capture images, perform image processing, and communicate with cloud server containing the CNN classifier. The developed CNN model can be successfully used as a pre-trained model for future glucose concentration predictions. [ABSTRACT FROM AUTHOR]

Simple Summary: Interactions between breast cancer (BCa) cells and carcinoma-associated fibroblasts (CAFs) in the tumor microenvironment (TME) are critical for cancer development and progression and can mitigate responses to therapies. Historically, it has been difficult to replicate in vivo long-term interactions between BCa cells and CAFs for in vitro studies and to define the precise roles of CAFs in BCa cell progression. Our novel microfluidic-capable culture devices called TAME (tissue architecture and microenvironment engineering) devices enable us to study cell-cell interactions of human breast cancer (BCa) cells and human CAFs through their secretome in 3D cultures for extended periods, up to and beyond 70 days. Using these systems, we observed that CAFs enhance BCa cell progression to an invasive phenotype. Moreover, secretome-mediated reciprocal interactions of BCa cells and CAFs promote their migration toward each other, suggesting that targeting signaling pathways to mediate interactions between BCa cells and CAFs could be a potential therapeutic approach for the prevention of BCa progression. Background/Objectives: Carcinoma-associated fibroblasts (CAFs), a prominent cell type in the tumor microenvironment (TME), significantly contributes to cancer progression through interactions with cancer cells and other TME components. Consequently, targeting signaling pathways driven by CAFs has potential to yield new therapeutic approaches to inhibit cancer progression. However, the mechanisms underlying their long-term interactions with cancer cells in vivo remains poorly understood. Methods: To address this, we developed a three-dimensional (3D) parallel coculture model of human triple-negative breast cancer (TNBC) cells and CAFs using our innovative TAME devices. This model allowed for the analysis of TNBC paracrine interactions via their secretome over extended culture periods (at least 70 days). Results: Using TNBC cell lines (MDA-MB-231, MCF10.DCIS, and HCC70), we found that TNBC spheroids in 3D parallel cocultures with CAFs exhibited more pronounced invasive finger-like outgrowths than those in cocultures of TNBC cells and normal fibroblasts (NFs) over a period of 50–70 days. We also established that the CAF-derived secretome affects TNBC migration towards the CAF secretome region. Additionally, we observed a preferential migration of CAFs, but not NFs, toward TNBC spheroids. Conclusions: Overall, our results suggest that paracrine interactions between TNBC cells and CAFs enhance TNBC invasive phenotypes and promote reciprocal migration. [ABSTRACT FROM AUTHOR]

Polydimethylsiloxane (PDMS) is the most studied organosilicon polymer, finding broad applications in soft lithography of microfluidic devices, wearable electronics insulation, medical tubing, shielding coatings, and sealant elements. However, their cross‐linked forms swell severely in nonpolar oils due to the comparable solubility parameters. Here, an oil‐stable cross‐linked PDMS discovered by grafting flexible PDMS chains onto its polymeric networks is reported, which enables surface‐exposed chains with high dynamics. It is found that the synergetic effect of mobile nanopore filling and quasi‐liquid lubrication of PDMS brushes endows the cross‐linked matrix with a reduced oil absorption ratio of up to 91.7% without altering its surface composition. Moreover, stretching polymeric networks can be re‐arranged with an adequate grafting of PDMS chains, further enhancing the antipenetration performance. This discovery of the oil‐stable surface configuration of cross‐linked PDMS breaks the constraint of siloxane elastomers not being applicable in nonpolar soluble liquid, opening a new era of research in organosilicon chemistry. [ABSTRACT FROM AUTHOR]

Electrode fabrication in microfluidic devices is often avoided due to the smaller footprint of the platform, associated complexity in the process, and absence of a well-established method. In this article a glass microchip with chemically modified and vapor deposited gold internal electrode was fabricated and used for biomolecule immobilization and electrochemical applications. The silanol (-OH) on glass surface of the microdevice was modified with (3-mercaptopropyl)trimethoxysilane prior to gold deposition to achieve a strong attachment of the metal film using the gold-thiol binding. The practical utility of the microdevice with gold surface was demonstrated by performing quantitative enzyme linked immunosorbent assay (ELISA) of human interferon gamma (IFN-γ) antigen, yielding a limit of detection (LOD) of 0.15 pg/mL compared to 4 pg/mL in the microplate assay. Additionally, the functionality of the internal electrode was established by performing cyclic voltammetry (CV) and linear sweep voltammetry (LSV) of potassium ferricyanide (III) in potassium chloride (KCl) solution using the proposed gold patterned electrode in the microchip, offering limits of detection of 0.14 and 0.11 mM for CV and LSV respectively. Both the ELISA and electrochemical assays were validated by generating calibration curves and using a control sample for the electroanalytical sensing applications. The measurements yielded experimental results that agreed with control concentration with 7% relative standard deviation (RSD). The promising reproducibility of the electrode in fabrication with no/minimum failure rate and its outstanding performance in immunosensor applications as well as an electron exchange surface makes our technique of gold electrode fabrication in microchips a state of the art. [ABSTRACT FROM AUTHOR]

Microfluid-derived liposomes (M-Lipo) exhibit great potential as drug and functional substance carriers in pharmaceutical and food science. However, the low liposome membrane stability, attributed to the liquid core, limits their application range. Oleosin, a natural surfactant protein, can improve the stability of the lipid nanoparticle membrane against various environmental stresses, such as heat, drying, and pH change; in addition, it can enable sustained drug release. Here, we proposed the fabrication of oleosin-coated M-Lipo (OM-Lipo) through self-assembly on a microfluidic chip and the evaluation of its anticancer drug (carmustine) delivery efficiency. Nanoparticle characterization revealed that the oleosin coating slightly lowered the membrane potential of M-Lipo and greatly improved their dispersibility. Additionally, the in vitro drug release profile showed that the oleosin coating improved the sustained release of the hydrophobic drug from the phospholipid bilayer in body temperature. Our results suggest that OM-Lipo has sufficient potential in various fields, based on its easy production, excellent stability, and biocompatibility. [ABSTRACT FROM AUTHOR]

The importance of microfluidics research is growing, especially in the fields of chemistry, biology or medicine. This is coupled with a growing demand for specialized capillary equipment that allows advanced research at the microscale. Conventional methods of manufacturing such devices are expensive, time-consuming and do not guarantee good results. An alternative to these methods is the use of 3D printing technology. Despite the existence of numerous works presenting the possibilities of 3D printing in the context of creating microfluidic devices, there is a lack of comprehensive works presenting qualitative analysis of printed objects. This paper presents a method of producing microcapillary structures for microfluidics research with the help of 3D printing using stereolithography technology. The quality requirements that the printed objects should meet are defined and all stages of production are characterized. A qualitative analysis of the obtained objects was carried out, taking into account both the influence of individual printing parameters and print processing methods. The results of microfluidic tests using printed objects are also presented. This work is aimed at providing specific knowledge that allows the manufacture of precision devices for microfluidics purposes at low cost. [ABSTRACT FROM AUTHOR]

The slow growth and complex life cycle of Haematococcus lacustris pose significant challenges for cost-effective astaxanthin production. This study explores the use of microfluidic collision treatment to stimulate the germination of dormant seed cysts, thereby improving photosynthetic cell growth and astaxanthin productivity in H. lacustris cultivated in well plate and flask cultures. The flow rate (1.0–3.0 mL/min) and the number of T-junction loops (3–30) were optimized in the microfluidic device. Under optimal conditions (a flow rate of 2.0 mL/min with 10 loops), the total cell number density in well plate cultures increased by 44.5% compared to untreated controls, reaching 28.9 ± 2.0 × 104 cells/mL after 72 h. In flask cultures, treated cysts showed a 21% increase in astaxanthin productivity after 30 d, reaching 0.95 mg/L/d, due to higher biomass concentrations, while the astaxanthin content per cell remained constant. However, excessive physical collision stress at higher flow rates and loop numbers resulted in reduced cell viability and cell damage. These findings suggest that carefully controlled cyst mechanostimulation can be an effective and environmentally friendly strategy for Haematococcus biorefining, enabling the production of multiple bioactive products. [ABSTRACT FROM AUTHOR]

Emerging diagnostic scenarios, such as population surveillance by pooled testing and on‐site rapid diagnosis, highlight the importance of advanced microfluidic systems for in vitro diagnostics. However, the widespread adoption of microfluidic technology faces challenges due to the lack of standardized design paradigms, posing difficulties in managing macro‐micro fluidic interfaces, reagent storage, and complex macrofluidic operations. This paper introduces a novel modular‐based mesoscopic design paradigm, featuring a core "needle‐plug/piston" structure with versatile variants for complex fluidic operations. These structures can be easily coupled with various microfluidic platforms to achieve truly self‐contained microsystems. Incorporated into a "3D extensible" design architecture, the mesoscopic design meets the demands of function integration, macrofluid manipulations, and flexible throughputs for point‐of‐care nucleic acid testing. Using this approach, an ultra‐sensitive nucleic acid detection system is developed with a limit of detection of ten copies of SARS‐CoV‐2 per mL. This system efficiently conducts large‐scale pooled testing from 50 pharyngeal swabs in a tube with an uncompromised sensitivity, enabling a truly "sample‐in‐answer‐out" microsystem with exceptional performance. [ABSTRACT FROM AUTHOR]

Although the interaction between microswimmers and walls during near-wall swimming has been extensively studied, the effect of microswimmer shapes and slip boundary conditions on the dynamic characteristics of near-wall microswimmers has received less attention. In this study, elliptical microswimmer models have been developed with various aspect ratios based on circular microswimmers. The lattice Boltzmann method has been used for the numerical simulation of the dynamic behaviour of microswimmers near walls. Under slip boundary conditions, the escape or capture of microswimmers by the walls is influenced by the swimming Reynolds number (Res), wall slip length (ls) and the aspect ratio (Cab) of a microswimmer. Changes in the Cab value of a microswimmer considerably affect its swimming state, especially for puller-type microswimmers. The tendency of pullers to be captured by the wall increases with increasing Cab. Moreover, changes in ls within the slip boundary condition of a puller can induce a transition in its movement state from a wall oscillation state to a stable sliding state and eventually to a wall lock-up state, a process influenced by the Cab value of the puller. Pusher-type microswimmers show a considerably increased tendency to escape from walls with increasing Cab and no wall lock-up state is observed, which is opposite to the case of pullers. Pushers and pullers show an increased tendency to be captured by the wall with increasing initial swimming angle of the microswimmer. The findings of this study enhance our understanding of the swimming patterns of natural microswimmers near walls and are of substantial importance for the design of artificial microswimmers and microfluidic devices. [ABSTRACT FROM AUTHOR]

This review delves into the pivotal role of circulating tumor cells (CTCs) in colorectal cancer (CRC) metastasis, focusing on their biological properties, interactions with the immune system, advanced detection techniques, and clinical implications. We explored how metastasis-competent CTCs evade immune surveillance and proliferate, utilizing cutting-edge detection and isolation technologies, such as microfluidic devices and immunological assays, to enhance sensitivity and specificity. The review highlights the significant impact of CTC interactions with immune cells on tumor progression and patient outcomes. It discusses the application of these findings in clinical settings, including non-invasive liquid biopsies for early diagnosis, prognosis, and treatment monitoring. Despite advancements, challenges remain, such as the need for standardized methods to consistently capture and analyze CTCs. Addressing these challenges through further molecular and cellular research on CTCs could lead to improved interventions and outcomes for CRC patients, underscoring the importance of unraveling the complex dynamics of CTCs in cancer progression. [ABSTRACT FROM AUTHOR]

The "Lab on a Chip" journal, published by The Royal Society of Chemistry, features various papers on micro- and nanoscale devices and applications. The current issue includes topics such as surface modification of paper-based microfluidic devices, reversible bonding in thermoplastic elastomer microfluidic platforms, and multiplexed ultrasensitive detection of cancer biomarkers. Other papers cover areas like neuroplasticity investigations, miRNA detection in skin interstitial fluid, and artificial intelligence performance in testing microfluidics for point-of-care applications. The journal also explores topics such as magnetophoresis in millifluidic systems, dynamic sampling from ex vivo adipose tissue, and inertial co-focusing of heterogeneous particles in hybrid microfluidic channels. [Extracted from the article]

Pathologies in adipose (fat) tissue function are linked with human diseases such as diabetes, obesity, metabolic syndrome, and cancer. Dynamic, rapid release of metabolites has been observed in adipocyte cells and tissue, yet higher temporal resolution is needed to adequately study this process. In this work, a microfluidic device with precise and regular valve-automated droplet sampling, termed a microfluidic analog-to-digital converter (μADC), was used to sample secretions from ∼0.75 mm diameter adipose explants from mice, and on-chip salt water electrodes were used to merge sampled droplets with reagent droplets from two different fluorometric coupled enzyme assays. By integrating sampling and assays on-chip, either glycerol or non-esterified fatty acids (NEFA), or both, were quantified optically within merged 12 nanoliter droplets using a fluorescence microscope with as high as 20 second temporal resolution. Limits of detection were 6 μM for glycerol (70 fmol) and 0.9 μM for NEFA (10 fmol). Multiple ex vivo adipose tissue explants were analyzed with this system, all showing clear increases in lipolytic function after switching from feeding to fasting conditions. Enabled by high temporal resolution, lipolytic oscillations of both glycerol and NEFA were observed for the first time in the range of 0.2 to 1.6 min−1. Continuous wavelet transform (CWT) spectrograms and burst analyses (0.1 to 4.0 pmol bursts) revealed complex dynamics, with multiplexed assays (duplex for glycerol and NEFA) from the same explants showing mostly discordant bursts. These data support separate mechanisms of NEFA and glycerol release, although the connection to intracellular metabolic oscillations remains unknown. Overall, this device allowed automated and highly precise temporal sampling of tissue explants at high resolution and programmable downstream merging with multiple assay reagents, revealing unique biological information. Such device features should be applicable to various other tissue or spheroid types and to other assay formats. [ABSTRACT FROM AUTHOR]

We report on the use of a microfluidic antisolvent crystallization method to investigate the effect of solution volume on the chiral symmetry breaking (CSB) phenomena of enantiomeric sodium chlorate crystals. The utilization of a microfluidic device is capable of periodically producing emulsion droplets of uniform size and facilitates the quantitative analysis and visualization of crystallization phenomena occurring within the individual emulsions immersed in an oil continuous medium (i.e., dodecane). To promote nucleation and crystallization, a small amount of an antisolvent (i.e., ethanol) is introduced into the continuous phase. We observe that 100% CSB occurs within a certain critical emulsion volume. Beyond this critical volume, the probability of forming two different enantiomeric crystal particles increases. This solution volume-dependent CSB phenomenon can be attributed to the rapid depletion of surrounding molecules by spontaneous crystal growth after the formation of the initial nucleus within the critical volume, thereby suppressing further primary nucleation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Paper-based microfluidic devices offer an ideal platform for biological and environmental detection because they are low-cost, small, disposable, and fill by natural capillary action. In this tutorial review, we discuss the surface modification of paper-based microfluidic devices with functional polymers using the initiated chemical vapor deposition (iCVD) process. The iCVD process is solventless and therefore ideal for coating cellulose paper because there are no surface tension effects or solvent compatibility issues. The process can also be scaled up for roll-to-roll manufacturing. The chemical functionality of the iCVD coating can be tuned by varying the monomer and the structure of the coating can be tuned by varying the processing parameters. [ABSTRACT FROM AUTHOR]

Unidirectional liquid transport, a special self‐propelled wetting phenomenon observed in natural structures like the Nepenthes pitcher plant peristome, Araucaria leaves, and Crassula muscosa shoots, has inspired scientists to develop various novel microfluidic devices for liquid collection, physical/chemical reactions, and irrigation. Recently, the concept of capillary transistors is proposed to enable a programmable transport area and a significant increase in unidirectional capillary height, which is expected to greatly expand the applications of conventional microfluidic chips. In this work, using black resin as the three‐dimensional (3D) printing material, we construct microfluidic chips with capillary transistors for photothermal‐responsive unidirectional liquid transport. The transistors consist of asymmetric overhanging structures with connected overhangs, allowing for fast, long‐distance, and large‐area unidirectional liquid transport, with a unidirectional capillary height exceeding 90.0 mm—more than double the values reported in most previous studies. Furthermore, smart control of capillary height is achieved by applying external photothermal stimuli to the capillary transistors, demonstrating their potential applications in photothermal‐responsive unidirectional liquid transport and mixing in 3D space. It is envisioned that additional functions such as liquid patterning, desalination, and biochemical microreactions would be developed by engineering capillary transistors and their responsiveness. [ABSTRACT FROM AUTHOR]

Digital nucleic acid quantification has emerged as an exceptionally valuable technique in molecular diagnosis, capturing significant attention in the biomedical field. This study introduces a novel multi‐volume digital loop‐mediated isothermal amplification (dLAMP) chip that offers an extensive detection range and user‐friendly operation. The chip consists of 1024 large chambers with the volume of 7.2 nL and 6400 small chambers with the volume of 0.064 nL. The ingenious combination of chambers with volume difference beyond a 100‐fold on the single chip enables a broad dynamic range exceeding 105 for nucleic acid quantification. Furthermore, this chip incorporates an automated strategy, enabling the rapid loading and partitioning of the reaction mixture into subvolumes within 4 min. In order to evaluate the quantitative capability of the multi‐volume dLAMP chip, a 10‐fold serial dilution of the β‐actin DNA template is measured. Additionally, the chip is tested for β‐actin DNA concentration in plasma samples from colorectal cancer patients and healthy individuals. By providing enhanced automation, wide dynamic range, and improved accuracy, this chip paves the way for broader applications and the advancement of biomedical research fields. [ABSTRACT FROM AUTHOR]

Multilayer structures are ubiquitous in constructing microfluidic devices for manipulating fluids to realize various frontier applications, including energy harvesting and invisibility cloaking. In this study, we develop a mathematical framework for analyzing electro-osmotic flow (EOF) within multilayer microfluidic structures. These structures are formed by Hele--Shaw configurations, with cross-sectional shapes that are concentric disks or confocal ellipses, and each layer is filled with a fluid material characterized by a zeta potential. The number of layers can vary, and the zeta potentials in each layer may differ. By dynamically adjusting the zeta potential, the multilayer EOF structure can effectively manipulate fluids without requiring metamaterials in microfluidic devices. Considering the impingement of an arbitrary nonuniform incident field on the multilayer structure, we first establish the representation formula of the solution of the coupled system using the layer potential techniques, and then the concept of contracted hydrodynamic Generalized Polarization Tensors (GPTs) is defined by multipolar expansion. Utilizing Fourier series and spectral theory, we derive a closed-form solution for the coupled system in the control region with multilayer concentric disks or confocal ellipses. This framework provides a convenient algebraic approach for studying hydrodynamic cloaking and shielding in multilayer structures, laying the groundwork for various microfluidic applications. [ABSTRACT FROM AUTHOR]

Fungal keratitis (FK), a severe eye infection that leads to vision impairment and blindness, poses a high risk to contact lens users, and Candida albicans remains the most common underpinning fungal pathogen in temperate climates. Patients are initially treated empirically (econazole 1% drops hourly for 24–48 h), and if there is no response, amphotericin B (AmB) 0.15% eye drops (extemporaneously manufactured to be stable for a week) are the gold-standard treatment. Here, we aim to develop a sustained-release AmB ocular film to treat FK with an enhanced corneal retention time. As there is a paucity of reliable in vitro models to evaluate ocular drug release and antifungal efficacy under flow, we developed a 3D-printed microfluidic device based on four chambers stacked in parallel, in which lenses previously inoculated with a C. albicans suspension were placed. Under the flow of a physiological fluid over 24 h, the release from the AmB-loaded film that was placed dry onto the surface of the wetted contact lenses was quantified, and their antifungal activity was assessed. AmB sodium deoxycholate micelle (dimeric form) was mixed with sodium alginate and hyaluronic acid (3:1 w/w) and cast into films (0.48 or 2.4%), which showed sustained release over 24 h and resulted in a 1.23-fold reduction and a 5.7-fold reduction in CFU/mL of C. albicans, respectively. This study demonstrates that the sustained delivery of dimeric AmB can be used for the treatment of FK and provides a facile in vitro microfluidic model for the development and testing of ophthalmic antimicrobial therapies. [ABSTRACT FROM AUTHOR]

The demand for rapid, high-quality, and controlled mixing at the microscale has led to the development of various types of micromixers. Micromixers are commonly categorised as active, or passive based on whether they utilise external energy to enhance mixing. Passive micromixers utilise a complex geometry to enhance the diffusion coefficient at lower Reynolds numbers and induce chaotic advection at higher Reynolds numbers for effectively mixing fluids without external energy. Active micromixers, on the other hand, achieve precise, fast, and controllable mixing by employing external energy sources such as pressure, electric, magnetic, or acoustic fields. Some active methods such as magnetic field-driven micromixers need fluids with specific properties. Others, such as acoustic field-driven micromixers apply to various types of fluids. Bubbles can be used as membranes or stirrers in microfluidic devices for both passive and active micromixers. They are easy to use, compatible with microfluidic systems, low cost, and effective. Improvements in manufacturing methods, notably, 3D printing have emerged as promising methods for the development of new micromixer designs. In this paper, a wide range of micromixer types is reviewed and the main mechanism for enhanced mixing is investigated. This study aims to guide researchers proposing innovative designs. Furthermore, it is shown that combining different methods can lead to the development of more effective micromixers, promising further advancements in microscale mixing technology. [ABSTRACT FROM AUTHOR]

STUDY QUESTION Can a functional in vitro model, containing the main cellular components of the uterine wall, be generated from cells derived from patient tissues? SUMMARY ANSWER We present a three-dimensional (3D) physiologically relevant, organ-on-a-chip model of the uterine wall containing primary endometrial and myometrial cellular participants, generated from human uterine tissue. WHAT IS KNOWN ALREADY As a highly dynamic reproductive organ, the human uterus plays fundamental physiological roles in menstruation and childbirth. The endometrial–myometrial junction (EMJ) defines the interface between the inner mucosal layer (endometrium) and outer smooth muscle zone (myometrium) that comprises the uterine wall. The EMJ is implicit in several uterine pathologies of unknown aetiology, including adenomyosis and abnormally invasive placenta; however, despite this, no patient-derived in vitro models of the uterine wall containing all EMJ participants currently exist. STUDY DESIGN, SIZE, DURATION We employed microfluidic technology to characterize multiple miniaturized models of the uterine wall. Protocols were tested that included variations in the seeding order of endometrial and myometrial fractions, and the addition of a low viscosity extracellular matrix to influence cell behaviour. Ultimately, functional hormone responses of patient-derived uterine wall models were assessed. PARTICIPANTS/MATERIALS, SETTING, METHODS Endometrial (n = 9) and myometrial biopsies (n = 4) were enzymatically dissociated to create epithelial, stromal and myometrial cellular fractions. Cell suspensions were seeded into non-adhesive poly(dimethylsiloxane) microfluidic devices containing 5 × 5 microwell arrays. The fate of individual cell types was monitored in real-time using fluorescent tracers, and cell phenotype was characterized by immunocytochemistry. Model functionality was assessed by measuring Ca2+ responses to agonist stimulation, and both insulin-like growth factor binding protein 1 (IGFBP-1) and osteopontin secretion in response to hormone stimulation. MAIN RESULTS AND THE ROLE OF CHANCE When subjected to microfluidic culture in isolation, endometrial stromal cells and smooth muscle myocytes formed compact spheroids, whilst epithelial cells produced diffuse aggregates. Tri-cultures were established by sequential seeding of individual or combined cell fractions at various ratios. Regardless of the protocol, epithelial cells localized to the outer periphery of tri-culture spheroids, which varied in morphology across the protocols. Incorporation of 5% [v/v] Matrigel® improved the reproducibility of 3D aggregates which exhibited robust self-assembly of a stromal/smooth muscle core encased in epithelium. Exposure of tri-cultures to oestradiol, medroxyprogesterone acetate and cyclic adenosine monophosphate (cAMP) increased secretion of IGFBP-1, which indicates stromal decidualization, and enhanced epithelial cell osteopontin secretion. Stimulation with endothelin-1 induced Ca2+ signalling in myocytes. LIMITATIONS, REASONS FOR CAUTION Endometrial and myometrial tissue was collected from relatively few donors. Myometrial tissue was collected from pregnant donors, which may have influenced the myocyte phenotype. Furthermore, endometrial tissue sampling was from women not having a hysterectomy, thus may not include the deeper basalis region, which may limit the physiological mimicry of the final models. WIDER IMPLICATIONS OF THE FINDINGS Our novel approach to modelling the uterine wall in 3D captures all of the main cell types in a medium-throughput system, enabling the screening of hundreds of cultures in parallel from a single biopsy. This system shows great promise for examining the cellular interplay between physiological cues and EMJ pathologies, such as the impact of uterine peristalsis and cyclical hormones on the pathogenesis of adenomyosis. STUDY FUNDING/COMPETING INTEREST(S) C.B. was supported by an Organ-on-a-Chip Technologies Network Pump Priming Project grant. C.J.H. was supported by a Wellbeing of Women project grant (RG2137), SRI/Bayer and Wellcome Trust IFFS3. D.K.H. was supported by a Wellbeing of Women project grant (RG2137) and MRC clinical research training fellowship (MR/V007238/1). M.Z. is Director and Co-Founder of ScreenIn3D Limited. The other authors declare no conflict of interest. TRIAL REGISTRATION NUMBER N/A. [ABSTRACT FROM AUTHOR]

Shear stress plays a crucial role in modulating cell adhesion and signaling. We present a microfluidic shear stress generator used to investigate the adhesion dynamics of Dictyostelium discoideum, an amoeba cell model organism with well-characterized adhesion properties. We applied shear stress and tracked cell adhesion, motility, and detachment using time-lapse videomicroscopy. In the precise shear conditions generated on-chip, our results show cell migration patterns are influenced by shear stress, with cells displaying an adaptive response to shear forces as they alter their adhesion and motility behavior. Additionally, we observed that DH1-10 wild-type D. discoideum cells exhibit stronger adhesion and resistance to shear-induced detachment compared to phg2 adhesion-defective mutant cells. We also highlight the influence of cell density on detachment kinetics. [ABSTRACT FROM AUTHOR]

Background The enteric parasite Cryptosporidium remains a treatment challenge for drinking water utilities globally due to its resistance to chlorine disinfection. However, the lack of an in vitro culture system for Cryptosporidium that is both cost-effective and reliable remains a key bottleneck in Cryptosporidium research. Methods Here we report that the microfluidic culture of human ileocecal colorectal adenocarcinoma (HCT-8) cells under fluid shear stress enables the extended development of Cryptosporidium parvum. Specifically, the growth of C. parvum in a user-friendly pumpless microfluidic device was assessed using immunofluorescence assays, scanning electron microscopy, and quantitative polymerase chain reaction, which revealed that development continued for 10 days in total. Results Oocysts produced within the microfluidic device were infective to fresh HCT-8 monolayers; however, these oocysts were only present at low levels. Conclusions We anticipate that such microfluidic approaches will facilitate a wide range of in vitro studies on Cryptosporidium and may have the potential to be further developed as a routine infectivity assessment tool for the water industry. [ABSTRACT FROM AUTHOR]

Oral administration of mRNA-encapsulated lipid nanoparticles (mRNA-LNPs) is challenging due to various factors, including the low efficiency of mRNA-LNP uptake by small intestinal epithelial cells due to the low levels of apolipoprotein-E in gastrointestinal fluid. Therefore, in this study, we aimed to improve mRNA-LNP uptake by intestinal cells by modifying the surface of mRNA-LNPs with bile acids. Bile acids are recognized by bile acid transporters in the small intestine. We synthesized a polyethylene glycol (PEG)-lipid bound to cholic acid, a type of bile acid, and prepared cholic acid-modified mRNA-LNPs (Cholic-PEG-LNPs) using an ethanol dilution method with a microfluidic device. Uptake of Cholic-PEG-LNPs by differentiated Caco-2 cells was higher than that of unmodified PEG-LNPs. Moreover, protein expression induced by Cholic-PEG-LNPs was higher than that induced by unmodified PEG-LNPs in differentiated Caco-2 cells, and no difference was observed in bile acid transporter-negative MCF-7 cells. These results suggest that the cholic acid modification of mRNA-LNPs enhances bile acid transporter-mediated cellular uptake and protein expression. Our strategy can be used to enhance the functionality of oral mRNA-LNPs. [ABSTRACT FROM AUTHOR]

An incompressible boundary‐layer third‐grade nanomaterial stagnated flow confined by stretchy regime is formulated. The laminar magnetized thermal and solutal flow features the aspects of Brownian diffusion, generalized thermal‐flux, thermophoresis, and generalized solutal‐flux. The dimensionalized third‐grade steady‐state model is obtained by implementing appropriate variables. The subsequent nonlinear mathematical model is analytically computed by utilizing homotopy algorithm. The graphics demonstration of nondimensional fields (i.e., velocity, concentration, and temperature) for distinct physical variables is exhibited. The outcomes for the skin‐friction coefficient are calculated and confirmed to be precise. The analysis reveals that augmented values of material parameters escalate nanomaterial velocity while the Hartman number exhibits lower velocity. The temperature field displays a decaying trend for Prandtl number and thermal relaxation variable while contrary effects for nanoscale parameters (i.e., thermophoresis diffusive and Brownian diffusive) are reported. Besides, the nanomaterial concentration shows a decreasing trend with respect to the Schmidt number, Brownian motion, and solutal‐relaxation variable while thermophoresis parameter exhibits opposite effects. Furthermore, this study could be valuable for the design of various lab‐on‐a‐chip and thermal microfluidic devices in the field of biomedicine. Besides contributing to the creation of new devices, they may also be advantageous for performing genetic testing and developing innovative tools. [ABSTRACT FROM AUTHOR]

Microfluidic devices have been the subject of considerable attention in recent years. The development of novel microfluidic devices, their evaluation, and their validation requires simulations. While common methods based on Computational Fluid Dynamics (CFD) can be time-consuming, 1D simulation provides an appealing alternative that leads to efficient results with reasonable quality. Current 1D simulation tools cover specific microfluidic applications; however, these tools are still rare and not widely adopted. There is a need for a more versatile and adaptable tool that covers novel applications, like mixing and the addition of membranes, and allows easy extension, resulting in one comprehensive 1D simulation tool for microfluidic devices. In this work, we present an open-source, modular, and extendable 1D simulation approach for microfluidic devices, which is available as an open-source software package at https://github.com/cda-tum/mmft-modular-1D-simulator. To this end, we propose an implementation that consists of a base module (providing the core functionality) that can be extended with dedicated application-specific modules (providing dedicated support for common microfluidic applications such as mixing, droplets, membranes, etc.). Case studies show that this indeed allows to efficiently simulate a broad spectrum of microfluidic applications in a quality that matches previous results or even fabricated devices. [ABSTRACT FROM AUTHOR]

Virus spread at the single-cell level is largely uncharacterized. We have designed and constructed a microfluidic device in which each nanowell contains a single, infected cell (donor) and a single, uninfected cell (recipient). Using a GFP-expressing poliovirus as our model, we observed both lytic and non-lytic spread. Donor cells supporting lytic spread established infection earlier than those supporting non-lytic spread. However, non-lytic spread established infections in recipient cells substantially faster than lytic spread and yielded higher rates of genome replication. While lytic spread was sensitive to the presence of capsid entry/uncoating inhibitors, non-lytic spread was not. Consistent with emerging models for non-lytic spread of enteroviruses using autophagy, reduction in LC3 levels in cells impaired non-lytic spread and elevated the fraction of virus in donor cells spreading lytically. The ability to distinguish lytic and non-lytic spread unambiguously will enable discovery of viral and host factors and host pathways used for non-lytic spread of enteroviruses and other viruses as well. [ABSTRACT FROM AUTHOR]

Organs-on-chips (OoCs) or microphysiological platforms are biomimetic systems engineered to emulate organ structures on microfluidic devices for biomedical research. These microdevices can mimic biological environments that enable cell--cell interactions on a small scale by mimicking 3D in vivo microenvironments outside the body. Thus far, numerous single and multiple OoCs that mimic organs have been developed, and they have emerged as forerunners for drug efficacy and cytotoxicity testing. This review explores OoC platforms to highlight their versatility in studies of drug safety, efficacy, and toxicity. We also reflect on the potential of OoCs to effectively portray disease models for possible novel therapeutics, which is difficult to achieve with traditional 2D in vitro models, providing an essential basis for biologically relevant research. [ABSTRACT FROM AUTHOR]

Technologies for rapid and high-throughput separation of rare cells from large populations of other types of cells have recently attracted much attention in the field of bioengineering. Among the various cell separation technologies proposed in the past, dielectrophoresis has shown particular promise because of its preciseness of manipulation and noninvasiveness to cells. However, one drawback of dielectrophoresis devices is that their application of high voltage generates Joule heat that exposes the cells within the device to high temperatures. To further explore this problem, this study investigated the temperature field in a previously developed cell separation device in detail. The temperature rise at the bottom of the microfluidic channel in the device was measured using a micro-LIF method. Moreover, the thermofluidic behavior of the cell separation device was numerically investigated by adopting a heat generation model that takes the electric-field-dependent heat generation term into account in the energy equation. Under the operating conditions of the previously developed cell separation device, the experimentally obtained temperature rise in the device was approximately 20 °C, and the numerical simulation results generally agreed well. Next, parametric calculations were performed with changes in the flow rate of the cell sample solution and the solution conductivity, and a temperature increase of more than 40 °C was predicted. The results demonstrated that an increase in temperature within the cell separation device may have a significant impact on the physiological functions of the cells, depending on the operating conditions of the device. [ABSTRACT FROM AUTHOR]

Human norovirus (HuNoV) is recognized as the leading causative agent of foodborne outbreaks of epidemic gastroenteritis. Consequently, there is a high demand for developing point-of-care testing for HuNoV. We developed an origami microfluidic device that facilitates rapid detection of murine norovirus 1 (MNV-1), a surrogate for HuNoV, encompassing the entire process from sample preparation to result visualization. This process includes RNA absorption via a paper strip, RNA amplification using recombinase polymerase amplification (RPA), and a lateral flow assay for signal readout. The on-chip detection of MNV-1 was completed within 35 min, demonstrating 100% specificity to MNV-1 in our settings. The detection limit of this microfluidic device for MNV-1 was 200 PFU/mL, comparable to the in-tube RPA reaction. It also successfully detected MNV-1 in lettuce and raspberries at concentrations of 170 PFU/g and 230 PFU/g, respectively, without requiring extra concentration steps. This device demonstrates high compatibility with isothermal nucleic acid amplification and holds significant potential for detecting foodborne viruses in agri-food products in remote and resourcelimited settings. IMPORTANCE HuNoV belongs to the family of Caliciviridae and is a leading cause of acute gastroenteritis that can be transmitted through contaminated foods. HuNoV causes around one out of five cases of acute gastroenteritis that lead to diarrhea and vomiting, placing a substantial burden on the healthcare system worldwide. HuNoV outbreaks can occur when food is contaminated at the source (e.g., wild mussels exposed to polluted water), on farms (e.g., during crop cultivation, harvesting, or livestock handling), during packaging, or at catered events. The research outcomes of this study expand the approaches of HuNoV testing, adding value to the framework for routine testing of food products. This microfluidic device can facilitate the monitoring of HuNoV outbreaks, reduce the economic loss of the agri-food industry, and enhance food safety. [ABSTRACT FROM AUTHOR]

Controlled and efficient droplet formation in microfluidic devices is highly desired in chemical and biological analysis, drug delivery, micro-reactor, and material synthesis, among others. Achieving desired droplet morphologies often depends on fine-tuning of fluid thermophysical properties and flow dynamics. Furthermore, microchannel geometry modification offers an efficient way of exploring controlled droplet generation in microfluidic devices. This work focuses on probing the influence of dispersed phase configurations on the droplet generation dynamics in T-junction microfluidic devices. Specifically, we investigate the dynamics of droplet formation in two different configurations involving "perpendicular" (θ = 90 °) and "head-on" (θ = 180 °) interactions of dispersed phase and continuous phase fluids at the junction. We perform comprehensive experiments to investigate the role of flow parameters such as capillary number (C a), and flow rate ratio (φ) on droplet generation in both configurations. Our experiments show that the head on geometry has increased droplet formation time compared to perpendicular geometry, which can be attributed to a lower interfacial drag on the dispersed phase fluid. We substantiate this hypothesis by performing micro particle image velocimetry (μ -PIV) experiments on both configurations. Furthermore, we show that the head-on geometry has higher vorticity inside the evolving dispersed phase droplet. This increased vorticity prevents interface deformation, slowing down the necking, and results in an increased dispersed film length in head-on configuration. [ABSTRACT FROM AUTHOR]

The traditional lipid preparation methods are complex, time-consuming, and consume a large amount of reagents, increasing costs and difficulties. Although microfluidic technology is considered a promising solution, achieving controllable liposome production with a simple and inexpensive microfluidic mixing device remains an important problem. This paper presents a wall-type micro-mixer based on coastal zone fractals. Four parameters related to the geometric shape of the coastline fractal in the microchannel are used as design variables, and the mixing index is the objective function. Single-objective optimization numerical analysis of the primary wall-type fractal baffle micromixer under four Reynolds numbers conditions yields the optimal structural configuration. Visualization experiments verify the correctness and accuracy of the numerical simulation, and the optimized mixer is used to produce liposomes. The results show that the micro-mixer with the optimal double-sidewall cross arrangement enhances chaotic convection and improves mixing efficiency. At Re = 0.1 and Re = 100, the mixing efficiency reaches 99%, 50.44% higher than the reference design. By changing the relative flow rates of lipid and aqueous solutions, microfluidic blank liposomes with a particle size of 165.12 ± 11.6 nm and a polydispersity index of 0.35± are obtained. This wall-type fractal micro-mixer has broad application prospects due to its high mixing efficiency. [ABSTRACT FROM AUTHOR]

Flow-based particle separation usually requires a sheath flow for particle manipulation. Sheath fluid is a specialized buffer solution that directs the alignment of particles or cells into the center of the stream. By utilizing sheath flow, the particles or cells can be focused on the middle line of the microchannel, where they can be individually analyzed. However, the method requires an additional design for creating a suitable sheath flow. Purity and separation efficiency may also be influenced by the sheath flow. In this study, we present a sheathless device for particle focusing and separation using standing surface acoustic waves (SSAWs). The device comprises two regions: the focusing and separation regions. In the focusing region, particles in a continuous flow are aligned in the middle of the microchannel by SSAWs; in the separation region, tilted-angle SSAW-based particle separation is used to control particle migration. Varying particle sizes were focused in the focusing region and then separated in the separation region in the sheathless device. Experiments and simulations were also utilized to optimize a sheathless device. 10 and 20 μm particle focusing and separation were conducted in a sheathless device for the first time. We demonstrate that the separation of particles with a diameter of 10 and 20 μm has 90.8 ± 1.75% and 99.5 ± 0.8% separation efficiency, and 98 ± 3.4 and 97.9 ± 0.9% purity. Compared with other focusing and separation technologies, our device can also provide high purity, high separation efficiency, and high device density. [ABSTRACT FROM AUTHOR]

Meeting the global diagnostic and monitoring demand has been a challenge, especially in places with limited laboratory facilities. To address this, microfluidic devices have been integrated into the diagnostic framework. Due to the nature of their usage, however, microfluidic devices for diagnosis and monitoring should be single- use and disposable. Since these devices are commonly made from thermoplastics derived from unrecyclable and/or nonrenewable sources, their production, use, and disposal are accompanied by a high carbon footprint. Using a Design for Sustainability approach, this work presents an optimization model for the development of a supply chain network that considers both the economic and the carbon footprint as objectives. The model is demonstrated using data derived from literature and the industry. Results of the analysis indicate that the entire polymer feed required for the hypothetical manufacturing plant can be composed solely of recycled polyethylene terephthalate regardless of which optimization parameter was prioritized. The models developed in the study reveal that production of the microfluidic device using recycled polyethylene terephthalate is accompanied by 0.13 kg CO2-eq/d per unit of product when carbon footprint is prioritized. This amount of emission also corresponds to a cost per unit of product of 0.0546 $/d when the minimization of the cost objective is prioritized. This proves that the use of recycled polymers can be a way to reduce the dependence of the microfluidics industry on unsustainable materials. [ABSTRACT FROM AUTHOR]

The aim of this research is to validate a new prototyping method for microfluidic devices which could compete with the widely used polydimethylsiloxane soft lithography. This alternative methodology uses laser‐etched glass and pre‐cured silicone as main materials. A dual approach is chosen for validation, testing prototypes of a mixing device well known in the scientific literature. Specifically the focus is to evaluate the mixing efficiency (ME) of two fluids flowing through the device. After fine‐tuning the fabrication process, the ME is experimentally evaluated, and the results are compared with a 3D computational fluid dynamic analysis. [ABSTRACT FROM AUTHOR]

Sphere formation assay is an accepted cancer stem cell (CSC) enrichment method. CSCs play a crucial role in chemoresistance and cancer recurrence. Therefore, CSC growth is studied in plates and microdevices to develop prediction chemotherapy assays in cancer. As counting spheres cultured in devices is laborious, time-consuming, and operator-dependent, a computational program called the Automatic Quantification of Spheres Algorithm (ASQA) that detects, identifies, counts, and measures spheres automatically was developed. The algorithm and manual counts were compared, and there was no statistically significant difference (p = 0.167). The performance of the AQSA is better when the input image has a uniform background, whereas, with a nonuniform background, artifacts can be interpreted as spheres according to image characteristics. The areas of spheres derived from LN229 cells and CSCs from primary cultures were measured. For images with one sphere, area measurements obtained with the AQSA and SpheroidJ were compared, and there was no statistically significant difference between them (p = 0.173). Notably, the AQSA detects more than one sphere, compared to other approaches available in the literature, and computes the sphere area automatically, which enables the observation of treatment response in the sphere derived from the human glioblastoma LN229 cell line. In addition, the algorithm identifies spheres with numbers to identify each one over time. The AQSA analyzes many images in 0.3 s per image with a low computational cost, enabling laboratories from developing countries to perform sphere counts and area measurements without needing a powerful computer. Consequently, it can be a useful tool for automated CSC quantification from cancer cell lines, and it can be adjusted to quantify CSCs from primary culture cells. CSC-derived sphere detection is highly relevant as it avoids expensive treatments and unnecessary toxicity. [ABSTRACT FROM AUTHOR]

Wearable microfluidic devices have become a popular method in real-time health monitoring, especially for the non-invasive harvest and detection of human sweat, which is closely related to physiological and metabolic status of human body. In this study, a yarn/fabric sweat sensor patch was fabricated based on colorimetric analysis and quantitative analysis of sweat sensing assisted by a smartphone. The microfluidic pattern was composed by the hydrophilic yarn and fabric as the microfluidic channel and reservoir constructed upon the hydrophobic patch. The colorimetric assay of the sensor comprises two aspects, including assessing the content of target analyte through comparison with the reference markers as well as through mobile phone app assistance. The correlation between RGB and content of the biomarkers in human sweat can be established for fast reading of wellness status with high accuracy and effectivity. These sensing patches were deployed on 6 healthy volunteers aged from 20 to 23 to follow the physiological parameter changes during exercise process. After 20 min running, pH, Cl− concentration and glucose concentration was recorded respectively as 5.18–6.92, 56.8–70.0 mM, and 44.9–87.6 µM, which consistent with the normal range of human body. The patch with the yarn/fabric patterned microfluidic analysis system has proposed a simple and feasible approach for non-invasive testing of human wellness assessment, exhibiting great potential in point-of-care diagnosis and healthcare issues. [ABSTRACT FROM AUTHOR]

The practice of conventional cell culture techniques affects the quality of biological research in mechanobiology by not replicating the cell's microenvironment adequately. Microfluidic devices resembling 3D in vivo cell culture offer viable alternatives for mechanobiology studies and other applications including cell screening, cell separation, and point-of-care diagnostics. This review highlights recent advances in additive manufacturing (AM) to fabricate microfluidic and millifluidic devices through fast design iterations and cost reduction compared with conventional device manufacturing. Key advances in AM technologies such as fused deposition modeling (FDM), stereolithography apparatus (SLA), and digital light processing (DLP) have allowed the direct manufacture of complex microfluidic devices with master molds and sacrificial structures using multiple material components. Currently, available 3D printed devices for the precise fabrication of milli- and microfluidic devices, essential to mimicking the cellular microenvironment, while economically reducing production costs by eliminating expensive clean-room environments and reducing material waste are highlighted. [ABSTRACT FROM AUTHOR]

In this study, with the aim of adapting an enzyme-linked immunosorbent assay (ELISA) system for point-of-care testing (POCT), we propose an image analysis method for ELISAs using a centrifugal microfluidic device that automatically executes the assay. The developed image analysis method can be used to quantify the color development reaction on a TMB (3,3′,5,5′-tetramethylbenzidine) substrate. In a conventional ELISA, reaction stopping reagents are required at the end of the TMB reaction. In contrast, the developed image analysis method can analyze color in the color-developing reaction without a reaction stopping reagent. This contributes to a reduction in total assay time. The microfluidic devices used in this study could execute reagent control for ELISAs by steady rotation. In the demonstration of the assay and image analysis, a calibration curve for mouse IgG detection was successfully prepared, and it was confirmed that the image analysis method had the same performance as the conventional analysis method. Moreover, the changes in the amount of color over time confirmed that a calibration curve equal to the endpoint analysis was obtained within 2 min from the start of the TMB reaction. As the assay time before the TMB reaction was approximately 7.5 min, the developed ELISA system could detect TMB in just 10 min. In conventional methods using a plate reader, the assay required a time of 90 min for manual handling using microwell plates, and in the case of using automatic microfluidic devices, 30 min were required. The time of 10 min realized by this proposed method is equal to the time required for detection in an immunochromatographic assay with a lateral flow assay; therefore, it is expected that ELISAs can be performed sufficiently to adapt to POCT. [ABSTRACT FROM AUTHOR]

Polydimethylsiloxane (PDMS) has become a popular material in microfluidic and macroscale in vitro models due to its elastomeric properties and versatility. PDMS-based biomodels are widely used in blood flow studies, offering a platform for improving flow models and validating numerical simulations. This review highlights recent advances in bioflow studies conducted using both PDMS microfluidic devices and macroscale biomodels, particularly in replicating physiological environments. PDMS microchannels are used in studies of blood cell deformation under confined conditions, demonstrating the potential to distinguish between healthy and diseased cells. PDMS also plays a critical role in fabricating arterial models from real medical images, including pathological conditions such as aneurysms. Cutting-edge applications, such as nanofluid hemodynamic studies and nanoparticle drug delivery in organ-on-a-chip platforms, represent the latest developments in PDMS research. In addition to these applications, this review critically discusses PDMS properties, fabrication methods, and its expanding role in micro- and nanoscale flow studies. [ABSTRACT FROM AUTHOR]

Microfluidic devices (µFDs) have been explored extensively in drug screening and studying cellular processes such as migration and metastasis. However, the fabrication and implementation of microfluidic devices pose cost and logistical challenges that limit wider-spread adoption. Despite these challenges, light-based 3D printing offers a potential alternative to device fabrication. This study reports on the development of millifluidic devices (MiFDs) for disease modeling and elucidates the methods and implications of the design, production, and testing of 3D-printed MiFDs. It further details how such millifluidic devices can be cost-efficiently and effortlessly produced. The MiFD was developed through an iterative process with analytical tests (flow tests, leak tests, cytotoxicity assays, and microscopic analyses), driving design evolution and determination of the suitability of the devices for disease modeling and cancer research. The design evolution also considered flow within tissues and replicates interstitial flow between the main flow path and the modules designed to house and support organ-mimicking cancer cell spheroids. Although the primary stereolithographic (SLA) resin used in this study showed cytotoxic potential despite its biocompatibility certifications, the MiFDs possessed essential attributes for cell culturing. In summary, SLA 3D printing enables the production of MiFDs as a cost-effective, rapid prototyping alternative to standard µFD fabrication for investigating disease-related processes. [ABSTRACT FROM AUTHOR]

The present study explores the application of X-ray scattering, using synchrotron radiation, to assess the diffusive transport of nanomedicines in tumor on a chip devices fabricated by 3D stereolithography using a resin with high optical and X-ray transmittance. Unlike conventional methods that require fluorescent labeling of nanoparticles, potentially altering their in vitro and in vivo behavior, this approach enables the investigation of the transport properties for unlabeled nanoparticles. In particular, the results presented confirm the influence of the porosity of the extracellular matrix-like microenvironment, specifically Matrigel, on the diffusive transport of oligonucleotide-functionalized gold nanoparticles. The analysis of the scattering patterns allows to create 2D maps showing the nanoparticle distribution with high spatial resolution. The proposed approach demonstrates the potential for studying other factors involved in nanoparticle diffusion processes. By implementing X-ray scattering to track unmodified nanomedicines within extracellular matrix-like microenvironments, increasingly accurate models for evaluating and predicting therapeutics transport behaviors can be developed. [ABSTRACT FROM AUTHOR]

Nanocarriers are essential for targeted and enhanced drug delivery. However, the use of toxic solvent and the complex of chemical functionalization have seriously limited their clinical translation. Here, a one‐step strategy is developed to direct the self‐assembly of biocompatible core‐shell nanocapsules with tunable surface functionality by microfluidics. Upon rapid mixing and solvent exchange of ethanol with water in a microfluidic device, drug, oil, polymer, and polymer‐PEG‐function co‐precipitate and self‐assemble into core‐shell nanocapsules with desired surface functionality as driven by energy minimization. The prepared PCL‐PEG‐FA core‐shell nanocapsules demonstrate a high encapsulation efficiency and loading capacity and exhibit excellent tumor‐targeting drug delivery performances both in vitro and in vivo via the binding of functional group on the nanocapsule surface with corresponding receptor on the tumor cell membrane. The immune activation in the tumor microenvironment is investigated in detail by flow cytometry and multiplex immunohistochemistry staining to reveal the underlying mechanism for enhanced anti‐tumor performances. The developed strategy is green, facile, versatile, scalable and offers a promising platform for the design of advanced nanocarriers with hierarchical structure and desired function for enhanced drug delivery. [ABSTRACT FROM AUTHOR]

Currently, despite the vast amounts of time and money invested in cancer treatment, cancer remains one of the primary threats to human life. The primary factor contributing to the low treatment efficacy is cancer heterogeneity. The unclear molecular mechanisms underlying tumorigenesis, coupled with the complexity of human physiology, and the inability of animal models to accurately replicate the human tumor microenvironment, pose significant hurdles in the development of novel cancer therapies. Tumor-microenvironment-on-chip (TMOC) represents a research platform that integrates three-dimensional cell culture with microfluidic systems, simulating the essential components and physiological traits of the in vivo tumor microenvironment. It offers a dynamic setting within the chip system to study tumor progression, potentially heralding a breakthrough in cancer research. In this review, we will summarize the current advancements in this platform, encompassing various types of TMOCs and their applications in different types of cancer. From our perspective, the TMOC platform necessitates enhanced integration with tissue engineering techniques and microphysiological environments before it can evolve into a more refined preclinical model for cancer research. [ABSTRACT FROM AUTHOR]

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the loss of motoneurons (MNs), and despite progress, there is no effective treatment. A large body of evidence shows that astrocytes expressing ALS-linked mutant proteins cause non-cell autonomous toxicity of MNs. Although MNs innervate muscle fibers and ALS is characterized by the early disruption of the neuromuscular junction (NMJ) and axon degeneration, there are controversies about whether muscle contributes to non-cell-autonomous toxicity to MNs. In this study, we generated primary skeletal myotubes from myoblasts derived from ALS mice expressing human mutant SOD1G93A (termed hereafter mutSOD1). Characterization revealed that mutSOD1 skeletal myotubes display intrinsic phenotypic and functional differences compared to control myotubes generated from non-transgenic (NTg) littermates. Next, we analyzed whether ALS myotubes exert non-cell-autonomous toxicity to MNs. We report that conditioned media from mutSOD1 myotubes (mutSOD1-MCM), but not from control myotubes (NTg-MCM), induced robust death of primary MNs in mixed spinal cord cultures and compartmentalized microfluidic chambers. Our study further revealed that applying mutSOD1-MCM to the MN axonal side in microfluidic devices rapidly reduces mitochondrial axonal transport while increasing Ca2 + transients and reactive oxygen species (i.e., H2O2). These results indicate that soluble factor(s) released by mutSOD1 myotubes cause MN axonopathy that leads to lethal pathogenic changes. [ABSTRACT FROM AUTHOR]