Novel photopolymerizable biodegradable triblock polymers for tissue engineering scaffolds: synthesis and characterization

For use in micro-patterned scaffolds in tissue engineering, novel diacrylated triblock macromers (PLA-b-PCL-b-PLA, PGA-b-PCL-b-PGA and PCL-b-PEO-b-PCL) were synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC). All diacrylated polymers were designed as triblock copolymers and involved biodegradable blocks of relatively non-polar epsilon-caprolactone (CL) and polar monomers such as glycolide (GA), lactide (LA) or ethylene oxide (EO). All triblock polymers were prepared in molecular weights of a few kilo daltons via the anionic ring-opening polymerization (ROP) of the corresponding lactide, glycolide or caprolactone using stannous octoate [Sn(Oct)(2)] as catalyst. The polymers had low polydispersity indices, ranging from 1.23 to 1.56. Biodegradable polymeric networks were prepared with conversions of 72-84% via photopolymerization of the triblock diacrylated polymers with 2,2-dimethoxy-2-phenylacetophenone (DMPA) as photoinitiator. PLA-b-PCL-b-PLA copolymers crumbled easily and were not suitable for micro-patterning. PGA-b-PCL-b-PGA copolymers had higher water contact angles than PCL-b-PEO-b-PCL and were also cytocompatible with Fibroblasts 3T3.     

A Robust Method to Generate Mechanically Anisotropic Vascular Smooth Muscle Cell Sheets for Vascular Tissue Engineering

In arterial tissue engineering, mimicking native structure and mechanical properties is essential because compliance mismatch can lead to graft failure and further disease. With bottom‐up tissue engineering approaches, designing tissue components with proper microscale mechanical properties is crucial to achieve the necessary macroscale properties in the final implant. This study develops a thermoresponsive cell culture platform for growing aligned vascular smooth muscle cell (VSMC) sheets by photografting N‐isopropylacrylamide (NIPAAm) onto micropatterned poly(dimethysiloxane) (PDMS). The grafting process is experimentally and computationally optimized to produce PNIPAAm–PDMS substrates optimal for VSMC attachment. To allow long‐term VSMC sheet culture and increase the rate of VSMC sheet formation, PNIPAAm–PDMS surfaces were further modified with 3‐aminopropyltriethoxysilane yielding a robust, thermoresponsive cell culture platform for culturing VSMC sheets. VSMC cell sheets cultured on patterned thermoresponsive substrates exhibit cellular and collagen alignment in the direction of the micropattern. Mechanical characterization of patterned, single‐layer VSMC sheets reveals increased stiffness in the aligned direction compared to the perpendicular direction whereas nonpatterned cell sheets exhibit no directional dependence. Structural and mechanical anisotropy of aligned, single‐layer VSMC sheets makes this platform an attractive microstructural building block for engineering a vascular graft to match the in vivo mechanical properties of native arterial tissue.

     

Fouling Mitigation by Surface-Patterned Polymeric Membranes in Water Treatment: A Review of Recent Advancements in Fabrication Techniques

The world is constantly challenged regarding managing environmental and ecological contamination due to human and industrial activities. This is because of the constant threat posed by pollution. Nowadays, membrane-based technology is a growing field, making practically all the separation of foulant from wastewater possible. The membrane fouling resulting from the interaction between the foulant and the membrane surface presents a challenge for the technology in maintaining performance over extended periods of operation. As a result, there is a rising interest in research focusing mainly on creating patterned membrane surfaces that reduce fouling and effectively enhance the surface area. This article comprehensively overviews the most recent and cutting-edge techniques that can be applied to modify and construct high-performance patterned membranes suitable for ultrafiltration, microfiltration, nanofiltration, and reverse osmosis (UF, MF, NF, and RO) water purification processes. In this study, recent developments in membrane material are dissected, focusing on methods for improving surface chemistry, structure, and hydrodynamics, as well as the consequences of these characteristics on filtering performance.     

铂纳米颗粒自组装膜的微图像化

从硝基重氮树脂(NDR)与包裹巯基乙酸的铂纳米颗粒(MA-PtNP)的静电自组装,制备了感光性的自组装多层超薄膜.经选择性紫外曝光和十二烷基硫酸钠(SDS)水溶液显影,光照部分的膜,因层与层之间的离子键转变为共价键,不再被SDS水溶液洗脱而留下来;未光照部分的膜,层与层之间仍是离子键,在显影时被除去,从而形成图像.用AFM和SEM对形成的图像进行了表征.     

Synthesis and Microcontact Printing of Dual End‐Functionalized Mucin‐like Glycopolymers for Microarray Applications

Click to view : Glycopolymers can be used to display glycans on microarrays in native‐like architectures. The structurally uniform alkyne‐terminated mucin mimetic glycopolymers (see picture; TR=fluorophore) were printed on azide‐functionalized chips by microcontact printing in the presence of a copper catalyst. The surface‐bound glycopolymers bind lectins in a ligand‐specific manner.

     

Photodegradable Hydrogels for Capture,Detection, and Release of Live Cells

Cells may be captured and released using a photodegradable hydrogel (photogel) functionalized with antibodies. Photogel substrates were used to first isolate human CD4 or CD8 T‐cells from a heterogeneous cell suspension and then to release desired cells or groups of cells by UV‐induced photodegradation. Flow cytometry analysis of the retrieved cells revealed approximately 95 % purity of CD4 and CD8 T‐cells, suggesting that this substrate had excellent specificity. To demonstrate the possibility of sorting cells according to their function, photogel substrates that were functionalized with anti‐CD4 and anti‐TNF‐α antibodies were prepared. Single cells captured and stimulated on such substrates were identified by the fluorescence “halo” after immunofluorescent staining and could be retrieved by site‐specific exposure to UV light through a microscope objective. Overall, it was demonstrated that functional photodegradable hydrogels enable the capture, analysis, and sorting of live cells.