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Detailed contact angle measurements are performed for protein drops on phenylcarbamide (PC), polymethyl methacrylate (PMMA), silicon nitride, and glass substrates by goniometer-sessile drop technique. Drop sizes are ranged from 0.1 to 6 w l with radius of curvature less than 1 mm. The bovine serum albumin (BSA) protein concentrations are 0.0, 0.1, 1.0, and 10 mg/ml. The results show weak dependence of the drop size for deionized water drops on all substrates and increased dependence of the drop size for protein drops with different protein concentrations. The significance of drop size effect varies from substrate to substrate; the effect is strongest for PC substrate, which is a nearly hydrophobic surface. The drop size dependence can be partly explained by the modified Young's equation.

Three-dimensional (3D) spheroid culture provides opportunities to model tumor growth closer to its natural context. The collagen network in the extracellular matrix supports autonomic tumor cell proliferation, but its presence and role in tumor spheroids remain unclear. In this research, we developed an in vitro 3D co-culture model in a microwell 3D (μ-well 3D) cell-culture array platform to mimic the tumor microenvironment (TME). The modular setup is used to characterize the paracrine signaling molecules and the role of the intraspheroidal collagen network in cancer drug resistance. The μ-well 3D platform is made up of poly(dimethylsiloxane) that contains 630 round wells for individual spheroid growth. Inside each well, the growth surface measured 500 μm in diameter and was functionalized with the amphiphilic copolymer. HCT-8 colon cancer cells and/or NIH3T3 fibroblasts were seeded in each well and incubated for up to 9 days for TME studies. It was observed that NIH3T3 cells promoted the kinetics of tumor organoid formation. The two types of cells self-organized into core-shell chimeric tumor spheroids (CTSs) with fibroblasts confined to the shell and cancer cells localized to the core. Confocal microscopy analysis indicated that a type-I collagen network developed inside the CTS along with increased TGF-β1 and α-SMA proteins. The results were correlated with a significantly increased stiffness in 3D co-cultured CTS up to 52 kPa as compared to two-dimensional (2D) co-culture. CTS was more resistant to 5-FU (IC50 = 14.0 ± 3.9 μM) and Regorafenib (IC50 = 49.8 ± 9.9 μM) compared to cells grown under the 2D condition 5-FU (IC50 = 12.2 ± 3.7 μM) and Regorafenib (IC50 = 5.9 ± 1.9 μM). Targeted collagen homeostasis with Sclerotiorin led to damaged collagen structure and disrupted the type-I collagen network within CTS. Such a treatment significantly sensitized collagen-supported CTS to 5-FU (IC50 = 4.4 ± 1.3 μM) and to Regorafenib (IC50 = 0.5 ± 0.2 μM). In summary, the efficient formation of colon cancer CTSs in a μ-well 3D culture platform allows exploration of the desmoplastic TME. The novel role of intratumor collagen quality as a drug sensitization target warrants further investigation.

LED healthy light source by using a blue LED chip to excite phosphor was prepared successfully. Four kinds of LED commercial phosphors (cyan phosphor with a peak wavelength of 498 nm, green phosphor with 520 nm, yellow-green phosphor with 546 nm, and red phosphor with 628 nm) were selected that could be excited by blue light. A series of experimental studies were carried out on the different amounts of glue, different powder-glue ratio, different combinations of phosphors, and the influence of different driving currents. Trough the optimization of the experimental scheme, we obtained a LED healthy light source spectrum with luminous efficiency higher than 124 lm/w, color rendering index higher than 80, color temperature around 4000 k. These spectra are in good agreement with the full spectrum of sunlight, and the spectral continuity and uniformity are better, which accord with the requirements of bright (dark) vision, and the proportion of the blue spectrum is less than 2.4%, which meets the high quality and healthy lighting requirements of safety and comfort.

We report infrared (IR) pulse laser-activated highly efficient parallel intracellular delivery by using an array of titanium microdish (TMD) device. Upon IR laser pulse irradiation, a two-dimensional array of TMD device generated photothermal cavitation bubbles to disrupt the cell membrane surface and create transient membrane pores to deliver biomolecules into cells by a simple diffusion process. We successfully delivered the dyes and different sizes of dextran in different cell types with variations of laser pulses. Our platform has the ability to transfect more than a million cells in a parallel fashion within a minute. The best results were achieved for SiHa cells with a delivery efficiency of 96% and a cell viability of around 98% for propidium iodide dye using 600 pulses, whereas a delivery efficiency of 98% and a cell viability of 100% were obtained for dextran 3000 MW delivery using 700 pulses. For dextran 10,000 MW, the delivery efficiency was 92% and the cell viability was 98%, respectively. The device is compact, easy-to-use, and potentially applicable for cellular therapy and diagnostic purposes.

In this work, we aim to study zinc oxide (ZnO)-based functional materials over cotton fabrics and their effects after gamma ray exposure of 9 kGy. We found that the binding of the nanoparticles with cotton fabrics can be enhanced after irradiation. This could be due to the oxygen deficiency or defects created in the interface between ZnO and cotton fabrics after irradiation. Near-edge X-ray absorption fine structure and X-ray photoelectron spectroscopy (XPS) were used to detect the oxygen inadequacies generated in the interior and at the surface of the ZnO nanoparticles after gamma ray exposure. XPS results showed that the binding energy of Zn shifts by 2 eV at 1.5 kGy and by 4 eV at 9 kGy. This huge shift of about 4 eV is completely different from other works due to the reaction that takes place on the interface between ZnO nanostructures and cotton fabrics after gamma ray irradiation. Overall, this work suggests that after gamma ray irradiation, there is an enhanced level of binding between the coated functional nanoparticles and cotton fabrics, which can be advantageous for the textile industries.

In this paper, a phosphoric acid fuel cell integrated with reformer and evaporator is demonstrated. Oxidative steam reforming of methanol (OSRM) process is employed in this system in cooperated with a high efficient evaporator, and the reacted gas is sent into a phosphorus-acid fuel cell (PAFC) for direct power generation after surplus methanol/water filtration. The results show that the maximum power density of this hybrid system achieves 277 mW/cm2 without CO2 removal, while it achieves 485 mW/cm2 when employing pure hydrogen as the fuel.

Multifunctional lanthanide-doped upconversion nanoparticles (UCNPs) have spread their wings in the fields of flexible optoelectronics and biomedical applications. One of the ongoing challenges lies in achieving UCNP-based nanocomposites, which enable a continuous-wave (CW) laser action at ultralow thresholds. Here, gold sandwich UCNP nanocomposites [gold (Au

Debris avalanches generally have massive mobility and extensive deposited area, which have strong relation to the granular effect. The granular effect is an outcome from the interaction (based on frictional mechanism) among particles. Discrepancy of grain composition, for instance the difference of particle size and their proportion of particles, is a key factor to influence granular effect. A series of laboratory tests have been conducted to research the granular effects on depositional processes of debris avalanches containing fine- and coarse-grained particles. The velocity of debris front, the morphology characteristics and runout distance of the debris avalanche are considered in detail, and the mass parameter and the size parameter are introduced in analysis for the research of granular effect. The experimental results indicate that the granular effects can decrease the dissipation of momentum and increase the accumulation region, leading to further runout distance and more extensive deposited areas. Further, the velocity, the range of depositions of debris avalanches are larger than that in other conditions when the proportion of fine-grained particles is 30%, especially the materials consist of heterogeneous granular. It means there have a critical mass parameter in experiments which lead to the high efficiency of granular effects, and the granular effect is weakening in homogeneous granular composition.

Electrodynamic systems for bioanalytical applications constantly suffer from biofouling due to electrical field-induced nonspecific bioadsorption on electrode surfaces. To minimize this issue, surface modification using anti-biofouling and conductive materials is necessary to not only protect the electrode surface from nonspecific bioadsorption but also maintain desired electrodynamic properties for electrode operation. In this study, we designed and prepared a conductive, zwitterionic, and self-doped sulfonated polyaniline (SPANI) coating on Au electrode surfaces for anti-biofouling applications. The zwitterionic coating was fabricated by electrochemical polymerization of aniline on the Au electrode surface functionalized with cysteamine (HS-CH2CH2-NH2) and then a post-polymerization treatment with fuming sulfuric acid. We found that the SPANI-coated electrodes exhibited an excellent anti-biofouling ability in dielectrophoresis (DEP) capturing-and-releasing processes, with a very low average residual mass rate of 1.44% for the SPANI-5s electrode, whereas electrodes modified with poly(ethylene glycol) (PEG) gave an average residual mass rate of 14.30%. Even under continuous operation for more than 1 h, the SPANI-5s electrode still showed stable anti-biofouling ability for an 11-cycle E. coli capturing-and-releasing DEP process, with the residual mass rate for all 11 cycles being kept at or below 2.18% to give an average residual mass rate of 1.62% with a standard deviation of 0.40%. This study demonstrates that electrodynamic systems with zwitterionic SPANI coated on open electrode surfaces can excellently function with decent conductance and anti-biofouling performance.

The ability to deliver foreign cargos into single living cells is of great interest in cell biology and therapeutic research. Here, we have reported a single or multiple position based nano-localized single-cell nano-electroporation platform. The device consists of an array of triangular shape ITO nano-electrodes with a 70 nm gap between two nano-electrodes, each having a 40 nm tip diameter. The voltage is applied between nano-electrodes to generate an intense electric field, which electroporates multiple nano-localized regions of the targeted single-cell membrane, and biomolecules are gently delivered into cells by pressurizing pump flow, without affecting cell viability. The platform successfully delivers dyes, QDs, and plasmids into different cell types with the variation of field strength, pulse duration, and the number of pulses. This new approach allows us to analyze delivery of different biomolecules into single living cells with high transfection efficiency (>96%, for CL1-0 cells) and high cell viability (∼98%), which are potentially beneficial for cellular therapy and diagnostic purposes.

A comparative study of the hydrogen spillover phenomenon on pristine graphene and anatase (101)-supported Pt4 catalysts has been carried out by using density functional theory with Hubbard correcti...

Targeted intracellular delivery of biomolecules and therapeutic cargo enables the controlled manipulation of cellular processes. Laser-based optoporation has emerged as a versatile, non-invasive technique that employs light-based transient physical disruption of the cell membrane and achieves high transfection efficiency with low cell damage. Testing of the delivery efficiency of optoporation-based techniques has been conducted on single cells in monolayers, but its applicability in three-dimensional (3D) cell clusters/spheroids has not been explored. Cancer cells grown as 3D tumor spheroids are widely used in anti-cancer drug screening and can be potentially employed for testing delivery efficiency. Towards this goal, we demonstrated the optoporation-based high-throughput intracellular delivery of a model fluorescent cargo (propidium iodide, PI) within 3D SiHa human cervical cancer spheroids. To enable this technique, nano-spiked core–shell gold-coated polystyrene nanoparticles (ns-AuNPs) with a high surface-to-volume ratio were fabricated. ns-AuNPs exhibited high electric field enhancement and highly localized heating at an excitation wavelength of 680 nm. ns-AuNPs were co-incubated with cancer cells within hanging droplets to enable the rapid aggregation and assembly of spheroids. Nanosecond pulsed-laser excitation at the optimized values of laser fluence (45 mJ cm(−2)), pulse frequency (10 Hz), laser exposure time (30 s), and ns-AuNP concentration (5 × 10(10) particles per ml) resulted in the successful delivery of PI dye into cancer cells. This technique ensured high delivery efficiency (89.6 ± 2.8%) while maintaining high cellular viability (97.4 ± 0.4%), thereby validating the applicability of this technique for intracellular delivery. The optoporation-based strategy can enable high-throughput single cell manipulation, is scalable towards larger 3D tissue constructs, and may provide translational benefits for the delivery of anti-cancer therapeutics to tumors.

A novel composite membrane consisting glass microfiber (GMF) and polytetrafluoroethylene (PTFE) nanoporous film is applied to phosphoric acid fuel cell (PAFC) for performance enhancement and reducing electrolyte leakage. With 93% high porosity, the GMF can fully load phosphoric acid to maintain high proton conductivity. However, the large opening of the GMF membrane cannot effectively prevent the leakage of phosphoric acid. Therefore, in this study, a 25 μm thick PTFE thin film with pore size 50–400 nm is employed to cover the surface of GMF for preventing phosphoric acid leakage. This composite proton exchange membrane possesses both thermal and chemical stability at the working temperature of phosphoric acid fuel cell, while providing high proton conductivity. The proton conductivity of the composite membrane (0.71 S/cm at 150 °C) is much higher than those of reported phosphoric acid porous membranes (∼10−2 S/cm at 150 °C). The fuel cell using the composite membrane with Pt/C catalyst exhibits excellent performance with peak power density of 614 mW/cm2 and current density of 1761 mA/cm2 at 140 °C under pure H2 and O2 supply, while proton conductivity is maintained 2.6 times higher than that of the pure GMF membrane due to the less phosphoric acid leakage by using PTFE film.

We demonstrate the successful fabrication of all-solid-state flexible micro-supercapacitors (μSCs) on commercial polyethylene terephthalate (PET) sheet using a commercial laser printer. The interdigitated in-planar electrodes of the μSC are fabricated by commercial toner cartridge and their self-aligned stacking configurations are made by depositing Pt thin films and hydrous ruthenium oxide (RuO·xH2O, hRuO2) layers on the PET sheets using a post-low-temperature annealing process. The μSC cells can be combined in parallel or series by an arbitrary printing process operated on a personal computer, thereby avoiding unnecessary external connections and improving the capacitive behavior. The fabricated hRuO2-based μSCs exhibit excellent electrochemical-energy storage, along with ultrahigh volumetric power density (73460 mW cm−3) and energy density (24.9 mWh cm−3). This facile and simplified strategy constructs μSCs with tailored self-aligned electrodes of arbitrary design, excellent mechanical stability, and high flexibility. Therefore, it offers a high-productivity, low-cost, photolithography-free microfabrication of μSCs for microscale supercapacitor applications.

Bovine serum albumin (BSA)-encapsulated copper sulfide nanocrystals (CuS NCs) were prepared by heating an alkaline solution containing copper ions and BSA without an additional sulfur source. At a high BSA concentration (0.8 mM), nanoassembly of the as-formed CuS NCs occurs to form BSA-CuS NCs as a result of the formation of BSA gel-like structures. In addition to their intrinsic photothermal properties, the BSA-CuS NCs possess rich surface vacancies and thus exhibit enzyme-like and photodynamic activities. Spontaneous generation of hydrogen peroxide (H2O2) led to the in situ formation of copper peroxide (CPO) nanodots on the BSA-CuS NCs to catalyze singlet oxygen radical generation. The antimicrobial response was enhanced by >60-fold upon NIR laser irradiation, which was ascribed to the combined effect of the photodynamic and photothermal inactivation of bacteria. Furthermore, BSA-CuS NCs were transdermally administered onto a methicillin-resistant Staphylococcus aureus-infected wound and eradicated >99% of bacteria in just 1 min under NIR illumination due to the additional peroxidase-like activity of BSA-CuS NCs, transforming H2O2 at the infection site into hydroxyl radicals and thus increasing the synergistic effect from photodynamic and photothermal treatment. The BSA-CuS NCs exhibited insignificant in vitro cytotoxicity and hemolysis and thus can serve as highly biocompatible bactericides in preclinical applications to effectively eradicate bacteria.

Cellular transfection is a method by which exogenous biomolecules can be introduced into the cells. In the fields of molecular and cellular biology, cellular transfection is considered an essential tool, specifically for applications such as drug delivery, cellular therapy, and biomedical imaging. Photoporation based cellular transfection approach uses high-intensity light energy to create membrane pores, sometimes nanoparticles are incorporated to achieve the result at low intensity. In this work, hybrid nanoparticles, composed of gold and polystyrene are used to mediate the photoporation. Laser fluence, exposure time, wavelength, the concentration of nanoparticles, and concentration of exogenous molecules are optimized for the successful delivery of propidium iodide dye, quantum dots, and plasmid into CL1-0, AGS, and P-19 cells. The best results (delivery efficiency of 92% and cell viability of 98%) are achieved in delivering propidium iodide dye into CL1-0 cells.

A solid substance is considered as a nanomaterial if it has at least one face in the dimension range of 1–100 nm. Nanomaterials, because of their small size and exceptionally high surface area, display electromagnetic, optical, and piezoelectric properties, and have enormous applications in various fields such as wastewater treatment, oil, and gas industry, energy storage, bio-imaging, and healthcare diagnostics and treatment. Nanomaterials provide flexibility to the sensing platforms and also even allow mobility between various detection techniques. In the last few decades, many nanomaterials have been developed for various applications, and considerable interest has been gained in the field of medical diagnosis and therapy in recent years. The innovations in nanomaterial preparation and their modifications have led to the development of devices and assays used for biomedical applications, which are faster, less expensive, accurate, and sensitive. Despite having excellent material properties, many nanomaterials are affected by the lack of surface heterogenic reactivity, which is critical for the surface immobilization of essential biomarkers. Thus the nanomaterials need to go through surface modifications to improve the adsorption capacity of biomolecules to the functionalized surface. In this chapter, various surface modifications of nanomaterials, including metallic nanoparticles, carbon nanomaterials, nanoceramics, and self-assembled materials, have been discussed for various applications in general and more attention has been given to biomedical applications in particular.

Stone coal is a kind of carbonaceous shale that contains vanadium. The sequential chemical extractions were adopted to analyze the vanadium phases of stone coal and its combustion fly ash. The results showed that the vanadium in stone coal mainly consisted in aluminosilicate. The vanadium in fly ash mainly existed in organic matter, aluminosilicate and Fe–Mn oxides, and the other vanadium existed in exchangeable fraction. Through the burning process, the vanadium was released and enriched in fly ash. Because of particular vanadium migration behaviors, the distribution of vanadium in phases became more scattered, and the leaching of vanadium in fly ash was easier than that in stone coal.

In this paper, a nanobiosensor with surface-enhanced Raman scattering (SERS) capability is introduced for highly sensitive miRNA detection in colorectal cancer. This sensor was designed and fabricated by employing a nanoshielding mechanism from nanopolystyrene beads to resist reactive ion etching and allow anisotropic electrochemical etching, producing high-aspect-ratio, surface-corrugated nanopillars (SiNPs) on a silicon wafer to create extensive hot spots along the nanopillars for improved SERS signals. SERS enhancements were correlated with nanorange roughness, indicating that hot spots along the pillars were the crucial factor to improve the SERS effect. We achieved the detection capability of a trace amount of R6G (10&minus, 8 M), and the SERS signal enhancement factor (EF) was close to 1.0 &times, 107 on surface-corrugated gold SiNPs. miRNA samples were also demonstrated on this sensor with good sensitivity and specificity. The target molecule miR-21-Cy5 was easily monitored through Raman spectrum variation with a PCR-comparable concentration at around 100 pM with clear nucleotide-specific Raman signals, which is also suitable for biomolecule sensing.

Here, an efficient intracellular delivery of molecules with high cell viability is reported using nanosecond-pulsed laser-activated plasmonic photoporation, mediated by high-aspect-ratio nano-corrugated mushroom-shaped gold-coated polystyrene nanoparticles (nm-AuPNPs) at near-infrared wavelength. Upon pulsed laser illumination, nm-AuPNPs exhibit greater plasmonic extinction than spherical AuPNPs, which increase their energy efficiency and reduce the necessary illumination of light, effectively controlling cell damage and improving the delivery efficiency. Nm-AuPNPs exhibit surface plasmon absorption at near infrared region with a peak at 945 nm. Pulsed laser illumination at this plasmon peak triggers explosive nanobubbles, which create transient membrane pores, allowing the delivery of dyes, quantum dots and plasmids into the different cell types. The results can be tuned by laser fluence, exposure time, molecular size and concentration of nm-AuPNPs. The best results are found for CL1-0 cells, which yielded a 94% intracellular PI dye uptake and ∼100% cell viability at 35 mJ cm−2 laser fluence for 945 nm wavelength. Thus, the presented approach has proven to have an inevitable potential for biological cell research and therapeutic applications.

A microfluidic chip, which can separate and enrich leukocytes from whole blood, is proposed. The chip has 10 switchback curve channels, which are connected by straight channels. The straight channels are designed to permit the inertial migration effect and to concentrate the blood cells, while the curve channels allow the Dean flow to further classify the blood cells based on the cell sizes. Hydrodynamic suction is also utilized to remove smaller blood cells (e.g., red blood cell (RBC)) in the curve channels for higher separation purity. By employing the inertial migration, Dean flow force, and hydrodynamic suction in a continuous flow system, our chip successfully separates large white blood cells (WBCs) from the whole blood with the processing rates as high as 1 &times, 108 cells/sec at a high recovery rate at 93.2% and very few RBCs (~0.1%).

In this paper, we present an ultra-sensitive photonic refractive index (RI) sensor based on nanoporous silicon (NPS) one-dimensional (1D) microcavity structures for detecting heavy metal ions in water. Consisting of two distributed Bragg reflectors (DBR) symmetrically placed about a defect layer fabricated by successive electrochemical etchings (ECE), the 1D microcavity is employed to enhance the sensitivity of the sensors. Although these RI sensors possess the property of high sensitivity to RI change and high resolution due to high porosity and narrow resonance peak, respectively, however their selectivities to analytes are poor, and limit of detections (LOD) are also restricted owning to passive interaction between analytes and sensors. To solve these problems, we propose a new procedure for heavy metal ion detection that offers good selectivity and ultra-low LOD while keeping the advantages in sensitivity and resolution of the NPS sensor. In the procedure, an electrochemical reduction process is applied to actively/selectively pre-concentrate and reduce metal ions on the pore surfaces of the NPS that results in the improvement in selectivity and LOD. This ECA-NPS based photonic sensor was applied to detect cadmium ions in deionized water revealing a sensitivity of 342 nm/RIU and 0.152 ppb of LOD in DI water. LOD as low as 1.16 ppb with a selectivity over sodium, potassium, magnesium, calcium and nickel etc, has also been demonstrated with a longer reduction time of 20 min for 10 ppb cadmium ions spiked in lake water.

In this study, we controlled the growth of crystalline plane to synthesize the vertical platinum nanopelts onto fluorine doped tin oxide (FTO) glass to construct the platinum nanoroses (PtNRs) by an easy electrochemical deposition (ECD) method at room temperature in the normal atmospheric environment, and applied the PtNRs as a counter electrode (CE) for dye-sensitized solar cell (DSSC). The morphologies and crystalline nanostructures of the ECD PtNRs were examined by field emission scanning electron microscopy and the high-resolution transmission electron microscopy. The electrocatalytic properties of the ECD PtNRs were analyzed by cyclic voltammetry and electrochemical impedance spectrum. The power conversion efficiency (PCE) of the DSSC assembled with the ECD PtNRs CE was examined under the illumination of AM 1.5 (100 mWcm − 2 ). The ECD PtNRs showed well contact behavior with FTO surface and offered a large surface area to promote the redox reaction rates therefore increased the exchange current density. Due to the PtNRs showed the macroporous structure, the electrolyte can easily diffuse through the open space between the nanopelts, resulting in improved kinetics for charge-transfer processes and reduced the charge-transfer resistance. Our findings suggest that the catalytic efficiency of PtNRs with a specific crystal plane was significantly greater than that of a traditional Pt film catalyst. In combination with a N719 dye-sensitized TiO 2 working electrode and an iodine-based electrolyte, the DSSC assembled with the PtNRs CE achieved a PCE of 6.58%, almost 10% higher than that of a cell prepared with a conventional sputtering Pt film CE (6.00%). These results provide a potential strategy for electrochemical catalytic applications.

In this study, a pulse-mode electrochemical deposition technique was employed to deposit dense and homogeneous Ni nanoparticles on the three-dimensional graphene network (3DGN) as the catalysts for growing the vertical aligned one-dimensional carbon nanofibers (CNFs) to fabricate the full-carbon hybrid nanoarchitecture of CNFs/3DGN for the supercapacitors. When tested as electrode for a supercapacitor, the CNFs/3DGN hybrid nanoarchitecture demonstrated to possess a large surface area and showed an excellent specific capacitance of 59.28 F g −1 at a current density of 0.17 mA cm −2 , also displayed good cycle stability with capacitance retention of 93.9% after 10,000 cycles in 6 M KOH electrolyte.

The concentration gradient of K+ across the cell membrane of a neuron determines its resting potential and cell excitability. During neurotransmission, the efflux of K+ from the cell via various channels will not only decrease the intracellular K+ content but also elevate the extracellular K+ concentration. However, it is not clear to what extent this change could be. In this study, we developed a multiple-parallel-connected silicon nanowire field-effect transistor (SiNW-FET) modified with K+-specific DNA-aptamers (aptamer/SiNW-FET) for the real-time detection of the K+ efflux from cultured cortical neurons. The aptamer/SiNW-FET showed an association constant of (2.18 ± 0.44) × 106 M–1 against K+ and an either less or negligible response to other alkali metal ions. The α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) stimulation induced an outward current and hyperpolarized the membrane potential in a whole-cell patched neuron under a Na+/K+-free buffer. When neurons were placed atop the aptame...

Hydrogen has been recognized as a future energy carrier that may allow a gradual transformation from a fossil fuel-based economy to a hydrogen economy. One of main obstacles to implement hydrogen economy is efficient storage of hydrogen. Up to present, none of proposed storage methods completely satisfy all department of energy (DOE) target criteria with gravimetric capacity ~5.5 wt% and loss rate 0.1 (g/h)/kg for hydrogen storage yet. Here we demonstrate high density of hydrogen nano-bubble (HNB) up to ~3.4±0.18 wt% can be efficiently generated and stored via an electron radiolysis assisted abstraction reaction (RAAR) in an encapsulated quasi-2D water reservoir containing organic molecules. The RAAR is a reaction between radiolytic water species and the surface groups of organic molecules. In our system, the long term stability of HNB comes from supersaturation of hydrogen molecules controllable by the electron dose rate and concentration of the organic molecule. The best gravimetric capacity and loss rate in our experiment are ~3.4±0.18 wt% and 0.18(g/h)/kg, respectively, in 25 °C and at 1 bar which fall closely to the DOE targets. A TEM equipped with a continuous flow holder with a quasi-2D water reservoir is utilized for in-situ generation and storage of HNB. The regeneration time for HNB formation is in the order of a few ten seconds. This process can be linked with the microbial electrolysis cell technology that converts hydrogen from wastewater containing abundant organics.

Two-dimensional (2D) molybdenum disulfide (MoS2) nanosheets were synthesized to anchor onto the surfaces of directly grown one-dimensional (1D) carbon nanotubes (CNTs) on fluorinated tin oxide (FTO) glass. This three-dimensional (3D) vertically aligned hybrid nanoarchitecture was used in Pt-free counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). The prepared 2D MoS2 nanosheets, with exposed layers, provided a great deal of edge-plane catalytically active sites for I3− reduction. The directly grown 1D CNTs provide an attractive template that offers a large surface area to promote the loading of 2D MoS2 nanosheets for enhancing electrochemical activity. The CNTs directly grown on the FTO substrate provided a high-speed pathway that promoted charge transport and transfer, resulting in a lower electron lifetime that increased the exchange current density and reduced the charge-transfer resistance. The DSSCs assembled with the 3D vertically aligned MoS2/CNT hybrid nanoarchitecture CE achieved a power conversion efficiency of 7.83%, 9.5% higher than that of a cell prepared with a Pt film CE (7.15%).

In this paper we propose a nano-shield mechanism via polystyrene beads (PSBs) to resist the chemical etching, simultaneously produce a highly selective etching ratio to create more hot-spots for Surface-enhanced Raman spectroscopy (SERS) enhancement of a Janus-Biosensor. In this paper reports an improved method for processing nona-pillar array structure characterized by High-Aspect-Ratio, which extend the third dimension of hot-spots distribution. After depositing gold, nano-pillar array produce more hot-spots for greater SERS enhancement around 10 times than original substrate, which sensor could be proposed as high sensitivity bio-sensing application purpose.With this SERS substrate, we can improve the sensitivity to distinguish clearly of the hybridization process by Raman spectrum in label-free way. With this method, we will have a widespread implication in DNA analysis. Especially detecting biomarkers in liquid biopsy field, to achieve the final purpose of early cancer screening.

OBJECTIVE: To improve the existing manually-assembled cochlear implant electrode arrays, a thin film electrode array (TFEA) was micro-fabricated to have a maximum electrode density of 15 sites along an 8-mm length, with each site having a 75 × 1.8-μm (diameter × height) disk electrode. METHODS: The micro-fabrication method adopted a sequence of photoresist transferring, lift-off, two-step oxygen plasma etching, and fuming nitric acid release to reduce lift-off complexity, protect the metal layer, and increase the release efficiency. RESULTS: Systematic in vitro characterization showed that the TFEA’s bending stiffness was 6.40 × 10(−10) N·m(2) near the base and 1.26 × 10(−10) N·m(2) near the apex. On average, the TFEA electrode produced an impedance of 16 kΩ and a maximum current limit of 800 μA, measured with a 1-kHz sinusoidal current using monopolar stimulation in saline. A TFEA prototype was implanted in a cat cochlea to obtain in vivo measurements of electrically-evoked auditory brainstem and inferior colliculus responses to monopolar stimulation with 41-μs/phase, biphasic pulses. Both physiological responses produced a threshold of ~300 μA and a dynamic range of 5–8 dB above the threshold. Comparing with existing electrode arrays, the present TFEA had 10(4) times less bending stiffness, 97% less electrode area, and comparable physiological thresholds. CONCLUSION: Using a simplified structure and stable fabrication method, the present TEFA produced physical and physiological performance comparable to existing commercial devices. SIGNIFICANCE: The present TFEA and micro-fabrication method represent a step closer towards an automated process replacing the labor-intensive and expensive manual assembly of electrode arrays in most neural prostheses including the cochlear implant.

In this work, we synthesized metal (Au, Ag or Cu)–based nanoclusters (NCs) with different photoluminescence (PL) properties and investigated their application for the specific detection of heavy metal ions in water samples. Bovine serum albumin (BSA) and thiosalicylic acid (TSA) acted as protecting ligands for the synthesis of metallic NCs (MNCs). The as–prepared TSA/BSA–Au NCs, TSA/BSA–Ag NCs and TSA/BSA–Cu NCs exhibit PL emission at 700, 624, and 430 nm, with average lifetimes of 1540, 30.9, and 11.7 ns, respectively, when excited at 350 nm. MNCs has a metal core and metal–thiolate shell, where shell species are Au38–SR24, Ag9–SR7 and Cu3–14–SRm in the TSA/BSA–Au NCs, TSA/BSA–Ag NCs, and TSA/BSA–Cu NCs, respectively. PL quenching of MNCs induced through metallophilic interaction, metal–thiol complexation and/or inner filter effect, which enables the quantitation of Hg2+, As3+, and Cr6+ ions, with linear ranges of 1–350, 1–20, and 50–400 nM, and with limits of detection of 0.25, 0.34 and 3.54 nM, respectively. The TSA/BSA–Au NCs, TSA/BSA–Ag NCs, and TSA/BSA–Cu NCs probe systems exhibit the advantages of simplicity, rapidity, selectivity, sensitivity, and practicality for the quantitation of metal ions in water samples.

Fabrication of three-dimensional (3D) SU-8 (an epoxy-based negative photoresist from MicroChem) prisms as low-loss couplers for interconnection between optical components, particularly optical fibers and silicon-on-isolator waveguides (SOI WGs), which have mismatched mode sizes, has been investigated. With an interfacial structure formed by a 3D SU-8 prism partly overlaying an SOI WG end with a portion of buried oxide (BOX) removed under the interface, low-loss coupling is ensured and the transmission efficiency can reach 70%. To fabricate these 3D SU-8 prisms, a simple method with two photolithography steps was used for SU-8 hinges and CYTOP (an amorphous fluoropolymer from AGC Chemicals) prism windows, with mild soft and hard bakes, to define the prism profiles with diluted SU-8 filled in the CYTOP prism windows. A buffered oxide etchant is used to remove BOX parts under the interfaces. Some of the fabricated structures were tested, demonstrating the contribution of overlaying SU-8 prisms to the transmission efficiency of optical interconnections between fibers and SOI WGs.

This paper presents two facile methods to fabricate off-plane lenses made of SU-8, an epoxy-based negative photoresist from MicroChem, on glass for optical interconnection. The methods allow the fabrication of lenses with flexible spot size and focal length depending on SU-8 well size and SU-8 drop volume and viscosity. In the first method, SU-8 drops were applied directly into patterned SU-8 wells with Teflon-coated micropipettes, and were baked to become (a)-spherical lenses. The lens shape and size were mainly determined by SU-8 viscosity, ratio of drop volume to well volume, and baking temperature and time. In the second method, a glass substrate with SU-8 patterned wells was emerged in diluted SU-8, then drawn up and baked to form lenses. The lens shapes and sizes were mainly determined by SU-8 viscosity and well volume. By the two methods, SU-8 lenses were successfully fabricated with spot sizes varying in range from micrometers to hundred micrometers, and focal lengths varying in range of several millimeters, depending on the lens rim diameters and aspheric sag height. Besides, on-plane SU-8 lenses were fabricated by photolithography to work in conjunction with the off-plane SU-8 lenses. The cascaded lenses produced light spots reduced to several micrometers, and they can be applied as a coupler for light coupling from fiber/Light-emitting diode (LED) to microstructures and nanostructures. The results open up the path for fabricating novel optical microsystems for optical communication and optical sensing applications.

Single-cell electroporation is a powerful technique to understand cellular behavior with heterogeneity, which might be impossible based on bulk measurements of millions of cells together. In this study, a dielectric passivation layer was deposited on top of an indium-tin oxide micro-electrode-based transparent chip surface using a plasma enhanced chemical vapour deposition technique. We theoretically and experimentally investigated the key effects of the dielectric passivation layer on localized single-cell electroporation for different cancer cells, which were randomly distributed with a high density throughout the chip surface as a monolayer. The passivation layer not only prevented the conventional or bulk electroporation with bubble and ion generation, but also provide an intense electric field in-between electrode gap for localized single-cell electroporation with high cell viability. Thus, devices with dielectric passivation layers are potentially applicable for single-cell studies.

A diffractive method using a visible laser to directly monitor colloids trapped at an air/water interface under isothermal compression is discussed. Upon merely measuring the ratio of first- and second-order diffractions on the screen, the center-to-center distance of adjacent colloids can be determined. Complicated instruments such as advanced optical microscopy, geometries of the apparatus and particle tracking analysis are not necessarily required. The equation of estimation is established based on the theory of Ewald sphere construction. Fabricating and precise monitoring of a colloidal monolayer can be achieved in parallel by this noninvasive method.

The depletion of shallow-buried reserves has been driving the exploitation activities into the deeper crust, and the rising lithostatic stress thus poses substantial challenges to dynamic rock breakage. In this paper, we present new mechanistic insights into the effects of in-situ stresses on blast responses of intact rocks via integrated analytical and numerical analyses. An elastodynamic framework was first developed to characterize the blast wave propagation in pre-stressed rocks. The analytical solution suggests that the rock pressure can essentially promote dynamic compaction by diverting the explosive loading path and suppress fracturing by imposing circumferential compression. Such effects are more pronounced in the minor principal stress (σ3) direction of anisotropic stress fields. The rock responses under the coupled static-dynamic loadings were then simulated using a constitutive framework that was proven valid in this study for broad spectrums of pressures and strain rates. Image processing of the breakage patterns shows that the crushed zone contracts as the rock pressure rises. The crushed zone becomes elliptic in anisotropic stress fields, and its major axis coincides with the major principal stress (σ1) direction and declines more slowly than the minor axis aligned with σ3. The orientation distribution shows quantitatively that fractures get increasingly more clustered around σ1 as stress anisotropy rises, and the fracture density decreases more rapidly in equibiaxial conditions with greater vertical stresses. The consistent insights of the analytical and numerical studies can improve the mechanistic understanding of the evolution of dynamic rock behavior in different in-situ stress conditions.

Closed-loop artificial pancreas systems have recently been proposed as a solution for treating stage I diabetes by reproducing the function of the pancreas. However, there are many unresolved issues associated with their development, including monitoring and controlling oxygen, immune responses and the optimization of glucose. All of which need to be monitored and controlled to produce an efficient and viable artificial organ, that can become integrated in the patient and maintain homeostasis. This research focused on monitoring oxygen concentration, specifically achieving this kinetically as the oxygen gradient in an artificial pancreas made of alginate spheres containing islet cells. Functional Nanoparticle (NP) for measuring the oxygen gradient in different hydrogel cellular environments using fluorescence-based (F) microscopy were developed and tested. By ester bond, a linker Pluronic F127 was conjugated with a carboxylic acid modified polystyrene Nanoparticle (510 nm). A hydrophilic/ hydrophobic interaction between the commercially available oxygen sensitive fluorophore with F127 results in Fluorescence-based Nano oxygen particle (FNOP). The in-house synthesized FNOP was calibrated inside electro sprayed alginate filled hydrogels and demonstrated a good broad Dynamic Range (2.73-22.23) mg/L as well as a Resolution of -0.01 mg/L with an accuracy of ± 4%. The calibrated FNOP was utilised for continuous measuring of oxygen concentration gradient for cell lines RIN-m5F / HeLa for more than five days in alginate hydrogel spheres in vitro.

To provide uniform mixture of methanol vapor, steam and oxygen in a methanol reformer, the present study investigates the boiling heat transfer performance and two-phase flow of methanol and 50 wt% hydrogen peroxide mixture in an microchannel evaporator with V-shaped micro diffusers for the entrance region and 52 parallel diverging channels. The decomposition of hydrogen peroxide may produce oxygen and significant amount of heat making the convective boiling of the mixture extraordinary. Experiments of three volume ratios (C) of hydrogen peroxide to methanol of 1/2, 1/3, 1/4 and three flow rates, 0.18, 0.36, and 0.54 ml/min are conducted and analyzed. The experimental results reveal that the addition of hydrogen peroxide can significantly enhance boiling heat transfer as well as the critical heat flux possibly due to the Marangoni convection caused by concentration gradient, but the enhancement is limited by the introduction of decomposition heat internally in the working fluid. The oxygen and enhanced evaporation due to decomposition may make the boiling two-phase flow unstable and deteriorate the heat transfer. Consequently, the mixture with C = 1/3 showing the best heat transfer coefficient may be the optimized working fluid for a microchannel evaporator to serve the purpose of this study.

A sensitivity silicon p-n diodes for detecting backscattering electrons in SEM was proposed and fabricated. The multi-annular configuration enables to provide higher sensitivity of Z-contrast and better surface topography contrast of BSE image. In this study, the multi-annular backscattered electron detector (BSED) can provide enhancement of surface topography contrast and image contrast with 105% and 42% as compared with commercial BSED which with the multi-fan configuration. We also designed a high sensitivity to low energy electrons detector which with lateral p-n junctions and Al metal grids.

In recent years, Surface Enhanced Raman Scattering (SERS) has been widely applied to many different areas, including chemical analysis, biomolecule detection, bioagent diagnostics, DNA sequence, and environmental monitor, due to its capabilities of unlabeled fingerprint identification, high sensitivity, and rapid detection. In biomicrofluidic systems, it is also very powerful to integrate SERS based devices with specified micro-fluid flow fields to further focusing/enhancing/multiplexing SERS signals through molecule registration, concentration/accumulation, and allocation. In this review, after a brief introduction of the mechanism of SERS detection on proteins, we will first focus on the effectiveness of different nanostructures for SERS enhancement and light-to-heat conversion in trace protein analysis. Various protein molecule accumulation schemes by either (bio-)chemical or physical ways, such as immuno, electrochemical, Tip-enhanced Raman spectroscopy, and magnetic, will then be reviewed for further SERS signal amplification. The analytical and repeatability/stability issues of SERS detection on proteins will also be brought up for possible solutions. Then, the comparison about various ways employing microfluidic systems to register, concentrate, and enhance the signals of SERS and reduce the background noise by active or passive means to manipulate SERS nanostructures and protein molecules will be elaborated. Finally, we will carry on the discussion on the challenges and opportunities by introducing SERS into biomicrofluidic systems and their potential solutions.

Present work lies in the fact that we have demonstrated that highly stable oxygen Nano bubbles (NBs) could be generated and stabilized in a liquid environmental transmission electron microscope (LETEM), using an in house fabricated quasi-2D system. The size of the stabilized NBs varies in the range from 10 to 50 nm, its formation occurred via decomposition of 0.025% hydrogen peroxide on Platinum/CNT nanocomposite. The characterization of growth and long-term stability of NBs has been successfully carried out. In our system, the long-term stability of oxygen NB comes from supersaturation of oxygen molecules and compact arranged of NB. We have also developed the theoretical model derived from Henry's law by which we can predict the stability stage of NBs.

A novel method for desalination of saline water through manipulation of electric-double-layer (EDL) in the anodic aluminum oxide (AAO) nanochannels to form the ion depletion boundary as virtual ionic filter was reported for the first time. The higher the bias was applied on the electrode, the stronger the EDLs overlapping effect can be achieved. Furthermore, a continuous desalination flow by connecting two chambers together with a pumping system whose flow rate is controllable was demonstrated. Desalination efficiency and power consumption were measured and estimated, compared with that of multi-stage flash (MSF), reversal osmosis (RO), and electrodialysis (ED), providing a more convenient way to generate pure water from saline water and has a significant interest in commercialization for demand of the desalination of saline water with highly efficient, affordable, and sustainable merits.

HfO2/porous nickel silicide (NiSi) hierarchical structures fabricated by metal-assisted chemical etching (MACE) followed by a silicidation process and deposition of HfO2 by atomic layer deposition (ALD) have been. The as-formed porous structures are systematically investigated using etching solutions of various HF/H2O2 ratios and the manipulation of electrical double-layer (EDL) overlapping, leading to electrical charge-induced selective ion penetration in HfO2/porous NiSi hierarchical structures. Its desalination ability was examined, in which the ionic concentration of saline water can be reduced by 21% when a bias of 2 V was applied. In addition, the mechanical property of the as-formed porous NiSi membrane was estimated to have a flexural strength of 124.04 MPa. These porous NiSi membranes can be continuously operated for 18 h without loss of its deionization ability.

We present a method to directly observe three-dimensional (3D) distribution of aggregated gold nanoparticles (Au NPs) in live cells using dark-field sectional optical microscopy with chromatographic analysis. The scattering images of clustered Au NPs were transformed from RGB regular coordinate to hue, saturation, and value (HSV) cylindrical coordinate. The hue distinguished Au NPs from scattering images of cellular organelles. The saturation eliminated the interference from the defocused spots. The value, which indicated the scattering intensity, defined the 3D locations of Au NPs. The V/H ratio showed a linear relation with the Au NP number in the cluster. It was applied to estimate the numbers of aggregated nanoparticles in endosome vesicles. Using the chromatographic analysis, the calculated nanoparticle numbers were in good agreement with mass spectroscopic measurement. Compared to conventional methods, the chromatographic approach provides a simple observation of 3D distribution of Au NPs and their aggregation states in living cells.

We introduce a localized single-cell membrane nano-electroporation with controllable sequential molecular delivery by millisecond to nanosecond electrical pulses. An intense electrical field was generated by a pair of transparent indium tin oxide (ITO)-based nano-electrodes, which was confined to a narrow region of the single-cell membrane surface near the nano-electrode edges (approximately 2 μm × 50 nm area), whereas the remaining area of the membrane was unaffected. Moreover, a 250 nm SiO2 passivation layer on top of the nano-electrode reduced not only the thermal effect on the cell membrane surface, but it also avoided the generation of ions during the experiment, resulting in the reduction of cell toxicity and a significant enhancement of cell viability. Our approach precisely delivers dyes, Quantum Dots (QDs) and plasmids, through a localized region of single HeLa cells by considerably enhanced electrophoresis and diffusion effects with different duration of the pulsing process. The smaller molecules took less time to deliver into a single cell with a single pulse, whereas larger biomolecules took longer time even for multiple numbers of long lasting pulses. The system not only generates sequential well-controlled nano-pores allowing for the rapid recovery of cell membranes, but it also provides spatial, temporal and qualitative dosage control to deliver biomolecules into localized single-cell levels, which can be potentially beneficial for single cell studies and therapeutic applications.

Artificial guidance for cellular alignment is a hot topic in the field of tissue engineering. Most of the previous research has investigated single strain-induced cellular alignment on a cell-laden hydrogel by using complex experimental processes and mass controlling systems, which are usually associated with contamination issues. Thus, in this article, we propose a simple approach to building a gradient static strain using a fluidic chip with a plastic PDMS cover and a UV transparent glass substrate for the stimulation of cellular behavior in a 3D hydrogel. Overloading photo-patternable cell prepolymer in the fluidic chamber can generate a convex curved PDMS membrane on the cover. After UV crosslinking, through a concentric circular micropattern under the curved PDMS membrane, and buffer washing, a microenvironment for investigating cell behaviors under a variety of gradient strains is self-established in a single fluidic chip, without external instruments. NIH3T3 cells were demonstrated after observing the change in the cellular alignment trend under geometry guidance, in cooperation with strain stimulation, which varied from 15 - 65% on hydrogels. After a 3-day incubation, the hydrogel geometry dominated the cell alignment under low compressive strain, where cells aligned along the hydrogel elongation direction under high compressive strain. Between these, the cells showed random alignment due to the dissipation of the radical guidance of hydrogel elongation and the geometry guidance of the patterned hydrogel.

Immunofluorescence is widely used in detection and characterization of circulating tumor cells (CTCs). The process of immunofluorescence staining on cells needs centrifugal force to wash residual fluorescence, which is not only time consuming but also cells harmful. To speed up the staining process, a three-dimensional (3D) microfluidic device is employed in this work. This study also reports the rapid selection of identified live CTCs from whole blood on SACA chip for further characterization by automatic imaging and in-situ cell capturing process. The whole process takes 120 minutes for examining 4 ml whole blood sample and the recognition sensitivity can approach 1/108 by using the integrated chip and automatic image system. All cells are remained highly viable after the rapid selection process for further applications.