Controlled Cell Patterning on Bioactive Surfaces with Special Wettability

The ability to control cell patterning on artificial substrates with various physicochemical properties is of essence for important implications in cytology and biomedical fields. Despite extensive progress, the ability to control the cell-surface interaction is complicated by the complexity in the physiochemical features of bioactive surfaces. In particular, the manifesta- tion of special wettability rendered by the combination of surface roughness and surface chemistry further enriches the cell-surface interaction. Herein we investigated the cell adhesion behaviors of Circulating Tumor Cells （CTCs） on topog- raphically patterned but chemically homogeneous surfaces. Harnessing the distinctive cell adhesion on surfaces with different topography, we further explored the feasibility of controlled cell patterning using periodic lattices of alternative topographies. We envision that our method provides a designer＇s toolbox to manage the extracellular environment.

Acoustofluidics for cell patterning and tissue engineering

Acoustofluidics has been a promising approach using sound waves to manipulate particles and actuate fluids in biomedical applications.It usually generates acoustic radiation force and acoustic streaming to initiate diffraction,reflection and interference,building up a pressure distribution to facilitate accurate manipulation of micro-or nano-scale particles and fluids.Owing to its remarkable contact-free and biocompatible advantages,acoustoflu-idics has been used in high-throughput cell analysis,size-controllable organoid structures,and functional tissue mimics.We enumerate the basic concepts and the sufficient research of acoustofluidics in precise patterning and tissue engineering in this review,including the design and function of four typical acoustofluidic devices,var-ious forms of cell patterning and 3D tissue engineering.Meanwhile,we outlined current challenges and future directions of acoustofluidics in biomedicine and tissue engineering.

Rapid and mass manufacturing of soft hydrogel microstructures for cell patterns assisted by 3D printing

Micro-/nano-patterns on hydrogels are widely used in cell patterning.However,manufacturing molds with traditional lithography is time-consuming and expensive.In addition,the excessive demolding force can easily damage patterns since biocompatible hydrogels are ultra-soft or brittle.Here,we presented a novel method for rapid and mass fabrication of cell patterns.High-precision three-dimensional(3D)printing was used to manufacture a mold with a resolution of 2µm,and the gelatin-based hydrogel was cured by thermal–photo-crosslinking so that the low-concentration and low-substitutionrate hydrogel could be demolded successfully.We found that pre-cooling before illumination made gelatin-based hydrogels resilient due to the partial regain of triple-helix structures.With this method,arbitrarily customized hydrogel patterns with a feature size of 6–80µm can be fabricated stably and at low cost.When cardiomyocytes were seeded on ultra-soft hydrogels with parallel groove structures,a consistent and spontaneous beating with 216 beats per minute(BPM)could be observed,approaching the natural beating rate of rat hearts(300 BPM).Overall,this work provides a general scheme for manufacturing cell patterns which has great potential for cell ethology and tissue repair.

Demonstration of reversible retinal ganglion cell dysfunction in inflammatory optic neuropathies utilizing pattern electroretinography

Dear Editor,I am Dr.Austin Bach from Larkin Community Hospital in South Miami,Florida,USA.I am writing to you to present three cases of inflammatory optic neuritis that was followed to resolution using pattern electroretinography（PERG）.

Cell trapping and patterning using dielectric-structure-assisted negative dieletrophoresis

This paper reports a cell trapping and patterning method using dielectric-pattern-assisted negative dielectrophoresis (dnDEP) that can achieve high-density cell arrays and complicated cell patterns.The dnDEP device consists of two planar metal electrodes and a patterned dielectric layer sandwiched in-between.The dielectric patterns generate non-uniform electric fields when an ac voltage is applied on the two electrodes,and the interaction of polarizable cells and the non-uniform electric fields imposes negative DEP forces on the cells,pushing them to the patterns in the dielectric layer.Using this dnDEP device,human lymphoma cells were successfully patterned in high-density microwell arrays and stellate structures.Thanks to the three-dimensional configuration and the small distance between the electrodes,cell trapping and patterning can be implemented with a voltage of 10 V.This dnDEP device has the advantages of simple configuration,low actuating voltage,and the compatibility with high conductivity physiological media for cell culturing.

Plenty more room on the glass bottom： Surface functionalization and nanobiotechnology for cell isolation

Surface functionalization is a widely adopted technique for surface modification which allows researchers to customize surfaces to integrate with their research. Surface functionalization has been used recently to adapt surfaces to integrate with biological materials specifically to isolate cells or mimic biological tissues through cell patterning. Cell isolation and cell patterning both can be integrated with extant techniques or surfaces to customize the research to whatever needs to be tested. Substrates such as metals, biologically mimicking surfaces, environmental responsive surfaces, and even three-dimensional surfaces such as hydrogels have all been adapted to allow for functionalization for both patterning and isolation. In this review we have described both the advantages and disadvantages of these techniques and the related chemistries to better understand these tools and how best to apply them in the hope that we can further expand upon the research in the field.

Histological and Ultrastructural Observation Reveals Significant Cellular Differences between Agrobacterium Transformed Embryogenic and Non-embryogenic Calli of Cotton

Over the past few decades genetic engineering has been applied to improve cotton breeding. Agrobacterium medicated transformation is nowadays widely used as an efficient approach to introduce exogenous genes into cotton for genetically modified organisms. However, it still needs to be improved for better transformation efficiency and higher embryogenic callus induction ratios. To research further the difference of mechanisms for morphogenesis between embryogenic callus and non-embryogenic callus, we carried out a systematical study on the histological and cellular ultrastructure of Agrobacterium transformed calli. Results showed that the embryogenic callus developed nodule-like structures, which were formed by small, tightly packed, hemispherical cells. The surface of some embryogenic callus was covered with a fibrilar-like structure named extracellular matrix. The cells of embryogenic calli had similar morphological characteristics. Organelles of embryogenic callus cells were located near the nucleus, and chloroplasts degraded to proplastid-like structures with some starch grains. In contrast, the non-embryogenic calli were covered by oval or sphere cells or small clusters of cells. It was observed that cells had vacuolation of cytoplasm and plastids with a well organized endomembrane system. This study aims to understand the mechanisms of embryogenic callus morphogenesis and to improve the efficiency of cotton transformation in future.

Efficient fully laser-patterned flexible perovskite modules and solar cells based on low-temperature solution-processed SnO2/mesoporous-TiO2 electron transport layers

Efficient flexible perovskite solar cells and modules were developed using a combination of SnO2 and mesoporous-TiO2 as a fully solution-processed electron transport layer （ETL）. Cells using such ETLs delivered a maximum power conversion efficiency （PCE） of 14.8%, which was 30% higher than the PCE of cells with only SnO2 as the ETL. The presence of a mesoporous TiO2 scaffold layer over SnO2 led to higher rectification ratios, lower series resistances, and higher shunt resistances. The cells were also evaluated under 200 and 400 lx artificial indoor illumination and found to deliver maximum power densities of 9.77 μW/cm^2 （estimated PCE of 12.8%） and 19.2 μW/cm^2 （estimated PCE of 13.3%）, respectively, representing the highest values among flexible photovoltaic technologies reported so far. Furthermore, for the first time, a fully laser-patterned flexible perovskite module was fabricated using a complete three-step laser scribing procedure （P1, P2, P3） with a PCE of 8.8% over an active area of 12 cm^2 under an illumination of 1 sun.

Functional non-homologous end joining patterns triggered by CRISPR/Cas9 in human cells

CRISPR/Cas9-mediated genome engineering technologies are now widely applied in various organisms,including mouse and human cells（Cong et al.,2013;Mali et al.,2013;Yang et al.,2013;Hsu et al.,2014）.The most widely used customized CRISPR/Cas9（Sp Cas9）is derived from Streptococcus pyogenes（Cong et al.,2013）.

Facile and robust strategy to antireflective photo-curing coating through self-wrinkling

We reported a facile and bio-inspired strategy for obtaining antireflective （AR） coating through polymerization-induced self-wrinkling. Upon irradiation of light, the complex wrinkle micro-patterns with different morphologies were generated spontaneously on the surface of coating during photo-cross- linking, which enables the photo-curing coating can decrease reflection. The resulting photo-curing coating exhibits a high transmittance over 90% and low reflection below 5% ～ 8%, with an efficiency anti- reflection of 4% ～ 7%; compared to the flat blank coating. The successful application of these AR coatings with wrinkles pattern to encapsulate the thin film solar cells results in appreciable photovoltaic performance improvement of more than 4% ～ 8%, which benefits from the decrease of the light reflection and increase of optical paths in the photoactive layer by the introduction of wrinkling pattern. Furthermore, the efficiency improvements of the solar cells are more obvious, with a remarkable increase of 8.5%, at oblique light incident angle than that with vertical light incident angle