Modulating the electronic structure of VS2via Ru decoration for an efficient pH-universal electrocatalytic hydrogen evolution reaction.

High-efficiency water electrolysis over a broad pH range is desirable but challenging. Herein, Ru-decorated VS2 on carbon cloth (Ru-VS2/CC) has been in situ synthesized, which features the regulated electronic structure of VS2 by introducing Ru. It is remarkable that the optimal Ru-VS2/CC displays excellent electrocatalytic hydrogen evolution activity with overpotentials of 89 and 87 mV at -10 mA cm-2 in 0.5 M H2SO4 and 1.0 M KOH, respectively. Theoretical calculations and electrocatalytic measurements have demonstrated that introducing Ru induces an enhanced charge density around the Fermi level, facilitating charge transfer and speeding up the electrocatalytic HER kinetics. The Gibbs free energy of the hydrogen intermediate (ΔGH*) of Ru-VS2/CC (0.23 eV) is much closer to zero than that of pure VS2 (0.51 eV) and Ru (-0.37 eV), demonstrating an easier hydrogen adsorption and desorption process for Ru-VS2/CC. The more favorable ΔGH*, differential charge density and the d-band center endow Ru-VS2 with enhanced intrinsic electrocatalytic activity. This study presents a feasible strategy for enhancing electrocatalytic HER activity by the regulation of the electronic structure and the rational integration of dual active components.

Interface engineering of 0D/2D Cu2O/BiOBr Z-scheme heterojunction for efficient degradation of sulfamethoxazole: Mechanism, degradation pathway, and DFT calculation.

Constructed heterojunction has been considered an efficient strategy to enhance the migration and transfer of photoinduced charge carriers. Herein, a Z-scheme Cu2O/BiOBr heterojunction with 0D/2D structure was fabricated by microwave hydrothermal method. It was found that the optimal composites photocatalyst showed excellent activity for sulfamethoxazole (SMZ) illumination, and the removal rate reached 90.7%, which was higher than pristine Cu2O (53.0%) and BiOBr (60.0%). Subsequently, the operational parameters such as catalyst dosage, concentrations of pollutants, and pH of solution were investigated. According to the ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRs), Mott-Schottky curve, and density functional theory (DFT) analysis, the Z-scheme degradation mechanism of Cu2O/BiOBr heterostructure was proposed. Among them, the interface structure of 0-dimensions/2-dimensions (0D/2D) can significantly increase the number of heterojunctions in the composite catalyst, and Z-scheme heterostructures can accelerate the generation and migration of photoinduced charge carriers, which has a facilitation effect on improving the decomposition activity of the photocatalyst. Moreover, three possible pathways for SMZ degradation were inferred. This study provides a promising strategy for constructing novel heterojunctions with high photocatalytic performance.

An Intelligent Sorting Method of Film in Cotton Combining Hyperspectral Imaging and the AlexNet-PCA Algorithm.

Long-staple cotton from Xinjiang is renowned for its exceptional quality. However, it is susceptible to contamination with plastic film during mechanical picking. To address the issue of tricky removal of film in seed cotton, a technique based on hyperspectral images and AlexNet-PCA is proposed to identify the colorless and transparent film of the seed cotton. The method consists of black and white correction of hyperspectral images, dimensionality reduction of hyperspectral data, and training and testing of convolutional neural network (CNN) models. The key technique is to find the optimal way to reduce the dimensionality of the hyperspectral data, thus reducing the computational cost. The biggest innovation of the paper is the combination of CNNs and dimensionality reduction methods to achieve high-precision intelligent recognition of transparent plastic films. Experiments with three dimensionality reduction methods and three CNN architectures are conducted to seek the optimal model for plastic film recognition. The results demonstrate that AlexNet-PCA-12 achieves the highest recognition accuracy and cost performance in dimensionality reduction. In the practical application sorting tests, the method proposed in this paper achieved a 97.02% removal rate of plastic film, which provides a modern theoretical model and effective method for high-precision identification of heteropolymers in seed cotton.

Intelligent identification of film on cotton based on hyperspectral imaging and convolutional neural network.

The identification of the film on cotton is of great significance for the improvement of cotton quality. Most of the existing technologies are dedicated to removing colored foreign fibers from cotton using photoelectric sorting methods. However, the current technologies are difficult to identify colorless transparent film, which becomes an obstacle for the harvest of high-quality cotton. In this paper, an intelligent identification method is proposed to identify the colorless and transparent film on cotton, based on short-wave near-infrared hyperspectral imaging and convolutional neural network (CNN). The algorithm includes black-and-white correction of hyperspectral images, hyperspectral data dimensionality reduction, CNN model training and testing. The key technology is that the features of the hyperspectral image data are degraded by the principal component analysis (PCA) to reduce the amount of computing time. The main innovation is that the colorless and transparent film on cotton can be accurately identified through a CNN with the performance of automatic feature extraction. The experimental results show that the proposed method can greatly improve the identification precision, compared with the traditional methods. After the simulation experiment, the method proposed in this paper has a recognition rate of 98.5% for film. After field testing, the selection rate of film is as high as 96.5%, which meets the actual production needs.

Cascaded filter deterministic lateral displacement microchips for isolation and molecular analysis of circulating tumor cells and fusion cells.

Precise isolation and analysis of circulating tumor cells (CTCs) from blood samples offer considerable potential for cancer research and personalized treatment. Currently, available CTC isolation approaches remain challenging in the quest for simple strategies to achieve cell isolation with both high separation efficiency and high purity, which limits the use of captured CTCs for downstream analyses. Here, we present a filter deterministic lateral displacement concept to achieve one-step and label-free CTC isolation with high throughput. Unlike conventional deterministic lateral displacement (DLD) devices, the proposed method uses a hydrodynamic cell sorting design by incorporating a filtration concept into a DLD structure, and enables high-throughput and clog-free isolation by a cascaded microfluidic design. The cascaded filter-DLD (CFD) design demonstrated enhanced performance for size-based cell separation, and achieved high separation efficiency (>96%), high cell purity (WBC removal rate 99.995%), high cell viability (>98%) and high processing rate (1 mL min-1). Samples from lung cancer patients were analyzed using the CFD-Chip, CTCs and tumor cell-leukocyte fusion cells were efficiently collected, and changes in CTC levels were used for treatment response monitoring. The CFD-Chip platform isolated CTCs with good viability, enabling direct downstream analysis with single-cell RNA sequencing. Transcriptome analysis of enriched CTCs identified new subtypes of CTCs such as tumor cell-leukocyte fusion cells, providing insights into cancer diagnostics and therapeutics.

Identifying the mean residence time of soil water for different vegetation types in a water source area of the Yuanyang Terrace, southwestern China.

The mean residence time of soil water (MRTsw) for forestland and shrubland in a water source area of Yuanyang Terrace, southwestern China, was estimated using stable isotope tracer tests and the sine-wave regression model. Stable isotope analyses from precipitation and soil water were performed in 2015. The δ2H/δ18O relationship of precipitation resulted in δ2H = 7.31δ18O + 1.49, which is nearly identical to the local meteoric water line in Kunming, southwestern, China. The MRTsw was simulated at five depth ranges (0-20, 20-40, 40-60, 60-80, 80-100 cm) of the two vegetation types by precipitation δ18O input data and soil water δ18O output data. The results showed that the MRTsw values of the forestland and shrubland both increased with soil depth. However, differences in the MRTsw of the forestland (between day 53 and 94) and of the shrubland (between day 76 and 142) were discussed. Regarding the physical properties of the soil profiles from the sample plots, non-capillary porosity decreased with soil depth in the forestland (from 48.5 to 20.5 %), and was clearly higher than that in the shrubland (from 38.8 to 18.7 %). Therefore, non-capillary porosity (macropores) could be a factor that shortens the mean residence time of soil water.

Integrated Microfluidic System for Gene Silencing and Cell Migration.

Metastasis involves the phenotype transition of cancer cells to gain invasiveness, and the following migration at the tumor site. Here an integrated microfluidic chip to study this process is presented by combining on-chip delivery of siRNA for gene silencing and cell migration assay. The major advantage of the integrated chip is the simple input of cells and gene transfection materials, and the ultimate output of migration ability. The reverse-fishbone structure and 0.7× phosphate-buffered saline solution are the optimized parameters for improved delivery efficiency. Using the chip, it is validated that cofilin plays an essential role in regulating cancer cell migration. The integrated chip may provide a simple and effective platform for biologists to easily check the role of specific genes in metastasis.

Microfluidic Mapping of Cancer Cell-Protein Binding Interaction.

The interaction between tumor cells and microenvironment during metastasis is mediated by the binding of cell surface receptors, such as integrins and selectins, with protein ligands. Delineation of their binding interaction and identification of key receptors may be particularly important both in understanding extracellular matrix (ECM) remodeling and in developing potential therapeutic targets. Here we present a microfluidic chip that allows qualitative and quantitative mapping of a large population cell-protein interactions. It was found that ß1 integrin showed stronger binding interaction with collagen than with other ECM proteins. The upregulated ß1 integrin in invasive cancer cells enhanced cell-ECM interaction and may promote ECM remodeling. Cancer cells also showed strong interaction with plasma fibrinogen, the elevated level of which may help cancer cells arrest on blood vessels. We also verified that the chip may provide a platform for drug discovery by targeting integrins and cytoskeletons.

Highly efficient genome editing of human hematopoietic stem cells via a nano-silicon-blade delivery approach.

Recently, the clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 bacterial immunity system has opened a promising avenue to treat genetic diseases that affect the human hematopoietic stem cells (HSCs). Therefore, finding a highly efficient delivery method capable of modifying the genome in the hard-to-transfect HSCs, combined with the advanced CRISPR-Cas9 system, may meet the challenges for dissecting the hematologic disease mechanisms and facilitate future clinical applications. Here, we developed an effective HSC-specified delivery microfluidic chip to disrupt the cell membrane transiently by inducing rapid mechanical deformation that allowed the delivery of biomaterials into the cytoplasm from the surrounding matrix. Compared with the previous designs, the new nano-silicon-blade structure was specifically optimized for HSCs. Using the silicon substrate, the sharpness and rigidity of the nano-blade constriction was largely enhanced to improve the biomaterials delivery efficiency. We achieved highly efficient delivery results by transporting various macro-molecules into the HSCs. Moreover, the treated HSCs possess high viability and maintain inherent pluripotency after the delivery via the Nano-Blade Chip (NB-Chip). Subsequently, we disrupted the p42 isoform in C/EBPα on the NB-Chip and induced HSCs into a myeloid proliferation behavior. In conclusion, the NB-Chip provides a harmless, rapid and high-throughput gene editing approach for the HSC study and therapeutics.

Cas9 Ribonucleoprotein Delivery via Microfluidic Cell-Deformation Chip for Human T-Cell Genome Editing and Immunotherapy.

This study reports a microfluidic cell deformation-based method to deliver the Cas9 ribonucleoprotein (RNP) complexes to different cell types for efficient genome editing, including hard-to-transfect human primary CD4+ T cells. The RNP based CRISPR-Cas9 system has great advantage in shortening reaction time and reducing off-target problems, which holds great potential in future gene therapy applications.

Microfluidic Cell Deformability Assay for Rapid and Efficient Kinase Screening with the CRISPR-Cas9 System.

Herein we report a CRISPR-Cas9-mediated loss-of-function kinase screen for cancer cell deformability and invasive potential in a high-throughput microfluidic chip. In this microfluidic cell separation platform, flexible cells with high deformability and metastatic propensity flowed out, while stiff cells remained trapped. Through deep sequencing, we found that loss of certain kinases resulted in cells becoming more deformable and invasive. High-ranking candidates identified included well-reported tumor suppressor kinases, such as chk2, IKK-α, p38 MAPKs, and DAPK2. A high-ranking candidate STK4 was chosen for functional validation and identified to play an important role in the regulation of cell deformability and tumor suppression. Collectively, we have demonstrated that CRISPR-based on-chip mechanical screening is a potentially powerful strategy to facilitate systematic genetic analyses.

Recent Progress of Microfluidics in Translational Applications.

Microfluidics, featuring microfabricated structures, is a technology for manipulating fluids at the micrometer scale. The small dimension and flexibility of microfluidic systems are ideal for mimicking molecular and cellular microenvironment, and show great potential in translational research and development. Here, the recent progress of microfluidics in biological and biomedical applications, including molecular analysis, cellular analysis, and chip-based material delivery and biomimetic design is presented. The potential future developments in the translational microfluidics field are also discussed.

CRISPR-Cas9 delivery to hard-to-transfect cells via membrane deformation.

The CRISPR (clustered regularly interspaced short palindromic repeats)-Cas (CRISPR-associated) nuclease system represents an efficient tool for genome editing and gene function analysis. It consists of two components: single-guide RNA (sgRNA) and the enzyme Cas9. Typical sgRNA and Cas9 intracellular delivery techniques are limited by their reliance on cell type and exogenous materials as well as their toxic effects on cells (for example, electroporation). We introduce and optimize a microfluidic membrane deformation method to deliver sgRNA and Cas9 into different cell types and achieve successful genome editing. This approach uses rapid cell mechanical deformation to generate transient membrane holes to enable delivery of biomaterials in the medium. We achieved high delivery efficiency of different macromolecules into different cell types, including hard-to-transfect lymphoma cells and embryonic stem cells, while maintaining high cell viability. With the advantages of broad applicability across different cell types, particularly hard-to-transfect cells, and flexibility of application, this method could potentially enable new avenues of biomedical research and gene targeting therapy such as mutation correction of disease genes through combination of the CRISPR-Cas9-mediated knockin system.

Microfluidic cytometric analysis of cancer cell transportability and invasiveness.

The extensive phenotypic and functional heterogeneity of cancer cells plays an important role in tumor progression and therapeutic resistance. Characterizing this heterogeneity and identifying invasive phenotype may provide possibility to improve chemotherapy treatment. By mimicking cancer cell perfusion through circulatory system in metastasis, we develop a unique microfluidic cytometry (MC) platform to separate cancer cells at high throughput, and further derive a physical parameter 'transportability' to characterize the ability to pass through micro-constrictions. The transportability is determined by cell stiffness and cell-surface frictional property, and can be used to probe tumor heterogeneity, discriminate more invasive phenotypes and correlate with biomarker expressions in breast cancer cells. Decreased cell stiffness and cell-surface frictional force leads to an increase in transportability and may be a feature of invasive cancer cells by promoting cell perfusion through narrow spaces in circulatory system. The MC-Chip provides a promising microfluidic platform for studying cell mechanics and transportability could be used as a novel marker for probing tumor heterogeneity and determining invasive phenotypes.

Retinal synaptic regeneration via microfluidic guiding channels.

In vitro culture of dissociated retinal neurons is an important model for investigating retinal synaptic regeneration (RSR) and exploring potentials in artificial retina. Here, retinal precursor cells were cultured in a microfluidic chip with multiple arrays of microchannels in order to reconstruct the retinal neuronal synapse. The cultured retinal cells were physically connected through microchannels. Activation of electric signal transduction by the cells through the microchannels was demonstrated by administration of glycinergic factors. In addition, an image-based analytical method was used to quantify the synaptic connections and to assess the kinetics of synaptic regeneration. The rate of RSR decreased significantly below 100 µM of inhibitor glycine and then approached to a relatively constant level at higher concentrations. Furthermore, RSR was enhanced by chemical stimulation with potassium chloride. Collectively, the microfluidic synaptic regeneration chip provides a novel tool for high-throughput investigation of RSR at the cellular level and may be useful in quality control of retinal precursor cell transplantation.

High throughput capture of circulating tumor cells using an integrated microfluidic system.

In this work, we introduced an integrated microfluidic system for fast and efficient circulating tumor cell (CTC) isolation and capture. In this microfluidic platform, a combination of microfluidic deterministic lateral displacement array and affinity-based cell capture architecture, allows for the high efficiency cancer cell enrichment and continuous high throughput and purity cancer cell capture. Using this device to isolate breast cancer cells from spiked blood samples, we achieved an enrichment factor of 1500×, and a high processing throughput of 9.6mL/min with 90% capture yield and more than 50% capture purity at cell concentration 10(2)cells/mL. This integrated platform offers a promising approach for CTC capture with high recovery rates, purity and stability, and exhibits potential capability in cancer cell culture and drug screening.

Rapid isolation of cancer cells using microfluidic deterministic lateral displacement structure.

This work reports a microfluidic device with deterministic lateral displacement (DLD) arrays allowing rapid and label-free cancer cell separation and enrichment from diluted peripheral whole blood, by exploiting the size-dependent hydrodynamic forces. Experiment data and theoretical simulation are presented to evaluate the isolation efficiency of various types of cancer cells in the microfluidic DLD structure. We also demonstrated the use of both circular and triangular post arrays for cancer cell separation in cell solution and blood samples. The device was able to achieve high cancer cell isolation efficiency and enrichment factor with our optimized design. Therefore, this platform with DLD structure shows great potential on fundamental and clinical studies of circulating tumor cells.

Covalently immobilized biomolecule gradient on hydrogel surface using a gradient generating microfluidic device for a quantitative mesenchymal stem cell study.

Precisely controlling the spatial distribution of biomolecules on biomaterial surface is important for directing cellular activities in the controlled cell microenvironment. This paper describes a polydimethylsiloxane (PDMS) gradient-generating microfluidic device to immobilize the gradient of cellular adhesive Arg-Gly-Asp (RGD) peptide on poly (ethylene glycol) (PEG) hydrogel. Hydrogels are formed by exposing the mixture of PEG diacrylate (PEGDA), acryloyl-PEG-RGD, and photo-initiator with ultraviolet light. The microfluidic chip was simulated by a fluid dynamic model for the biomolecule diffusion process and gradient generation. PEG hydrogel covalently immobilized with RGD peptide gradient was fabricated in this microfluidic device by photo-polymerization. Bone marrow derived rat mesenchymal stem cells (MSCs) were then cultured on the surface of RGD gradient PEG hydrogel. Cell adhesion of rat MSCs on PEG hydrogel with various RGD gradients were then qualitatively and quantitatively analyzed by immunostaining method. MSCs cultured on PEG hydrogel surface with RGD gradient showed a grated fashion for cell adhesion and spreading that was proportional to RGD concentration. It was also found that 0.107-0.143 mM was the critical RGD concentration range for MSCs maximum adhesion on PEG hydrogel.

Nanoporous membrane-based cell chip for the study of anti-cancer drug effect of retinoic acid with impedance spectroscopy.

This paper presents a novel microchip with nanoporous anodic alumina membrane for the study of anti-cancer drug effect of retinoic acid (RA) on human esophageal squamous epithelial KYSE30 cancer cells in vitro with impedance spectroscopy. The impedance experiments with 0.01 M retinoic acid (RA) were explored for the study of anti-cancer drug effects on KYSE30 cancer cells. The impedance was monitored in the time domain at 0.1 Hz. After addition of 0.01 M RA to the cell chip, the impedance magnitude decreased with time from the value with confluent cell layer and returned to the initial base line after around 12h. The fluorescence experiments testified that this impedance decrease was due to the cell morphology change induced by RA.

BSA-modified polyethersulfone membrane: preparation, characterization and biocompatibility.

A polyethersulfone (PES) membrane was modified by blending with a co-polymer of acrylic acid (AA) and N-vinyl pyrrolidone (VP), followed by immobilization of bovine serum albumin (BSA) onto the surface. The scanning electron microscopy results showed that PES had good miscibility with the co-polymer. X-ray photoelectron spectroscopy confirmed the existence of P(VP-AA) co-polymer on the surface of the blended membrane and the existence of BSA after the immobilization process. The amount of BSA immobilized on the surface of the membranes was determined. It was found that the protein adsorption amounts from BSA, human plasma fibrinogen and diluted human plasma solutions decreased significantly after modification. According to the circular dichroism results, the proteins kept more alpha-helix conformation in the modified membranes than in the pure PES membrane. The number of the adhered platelets was reduced, and the morphology change for the adherent platelets was also suppressed by the modification with BSA. The SEM morphological observation of the cells and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay demonstrated that the BSA-modified PES membrane surface promoted endothelial cell adhesion and proliferation.