Grafting Sulfoammonium Zwitterionic Brushes onto Polycarbonateurethane Surface to Improve Hemocompatibility

Construction of antifouling zwitterionic membranes by facile multi-step integration method

Membrane fouling during the use of separation membrane has always been the main reason for the degradation of membrane performance. The traditional solution is complicated and inefficient, so we proposed multi-step integration method to prepare antifouling zwitterionic poly(aryl ether sulfone) (PAES-Z-x) ultrafiltration (UF) membrane with higher efficiency. We designed and synthesized a bisphenol precursor containing tertiary amine groups, which could provide reactive sites for grafting zwitterionic group. Afterwards, the zwitterionic modified UF membrane was prepared by graft copolymerization and non-solvent-induced phase separation (NIPS). The morphology, hydrophilicity, water flux and rejection of the PAES-Z-x membrane could be optimized by tuning zwitterion content. The hydration layer formed by zwitterions effectively reduced the adsorption of proteins and endowed the membrane good antifouling properties. The resulting membrane showed the pure water flux increased (up to 311 L m^-2h^-1 bar^-1), high bovine serum albumin (BSA) rejection (97%) and good water flux recovery ratio (FRR) (82.8%). Zwitterionic antifouling PAES UF membrane prepared by a simple and effective method provided a new direction for improving PAES UF membrane's antifouling performance.

Oscillating Magnetic Field Regulates Cell Adherence and Endothelialization Based on Magnetic Nanoparticle-Modified Bacterial Cellulose

Despite the widely explored biomaterial scaffolds in vascular tissue engineering applications lately, no ideal platform has been provided for small diameter synthetic vascular grafts mainly due to the thrombosis issue. Endothelium is the only known completely non-thrombogenic material; so, functional endothelialization onto vascular biomaterials is critical in maintaining the patency of vascular networks. Bacterial cellulose (BC) is a natural biomaterial with superior biocompatibility and appropriate hydrophilicity as potential vascular grafts. In previous studies, surface modification of active peptides such as Arg-Gly-Asp (RGD) sequences onto biomaterials has been proven to achieve accelerated and selective endothelial cell (EC) adhesion. In our study, we demonstrated a new strategy to remotely regulate the adhesion of endothelial cells based on an oscillating magnetic field and achieve successful endothelialization on the modified BC membranes. In details, we synthesized bacterial cellulose (BC), magnetic BC (MBC), and RGD peptide-grafted magnetic BC (RMBC), modified with the HOOC-PEG-COOH-coated iron oxide nanoparticles (PEG-IONs). The endothelial cells were cultured on the three materials under different frequencies of an oscillating magnetic field, including "stationary" (0 Hz), "slow" (0.1 Hz), and "fast" (2 Hz) groups. Compared to BC and MBC membranes, the cells on RMBC membranes generally show better adhesion and proliferation. Meanwhile, the "slow" frequency of a magnetic field promotes this phenomenon on RMBC and achieves endothelialization after culture for 4 days, whereas "fast" inhibits the cellular attachment. Overall, we demonstrate a non-invasive and convenient method to regulate the endothelialization process, with promising applications in vascular tissue engineering.

Surface modification and endothelialization of biomaterials as potential scaffolds for vascular tissue engineering applications

This review highlights the recent developments of surface modification and endothelialization of biomaterials in vascular tissue engineering applications.

Grafting of phosphorylcholine functional groups on polycarbonate urethane surface for resisting platelet adhesion

In order to improve the resistance of platelet adhesion on material surface, 2-methacryloyloxyethyl phosphorylcholine (MPC) was grafted onto polycarbonate urethane (PCU) surface via Michael reaction to create biomimetic structure. After introducing primary amine groups via coupling tris(2-aminoethyl)amine (TAEA) onto the polymer surface, the double bond of MPC reacted with the amino group to obtain MPC modified PCU. The modified surface was characterized by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The results verified that MPC was grafted onto PCU surface by Michael reaction method. The MPC grafted PCU surface had a low water contact angle and a high water uptake. This means that the hydrophilic PC functional groups improved the surface hydrophilicity significantly. In addition, surface morphology of MPC grafted PCU film was imaged by atomic force microscope (AFM). The results showed that the grafted surface was rougher than the blank PCU surface. In addition, platelet adhesion study was evaluated by scanning electron microscopy (SEM) observation. The PCU films after treated with platelet-rich plasma demonstrated that much fewer platelets adhered to the MPC-grafted PCU surface than to the blank PCU surface. The antithrombogenicity of the MPC-grafted PCU surface was determined by the activated partial thromboplastin time (APTT). The result suggested that the MPC modified PCU may have potential application as biomaterials in blood-contacting and some subcutaneously implanted devices.