Biofouling resulting from the attachment of microorganisms communities to the membrane surface is the major obstacle for the widespread application of membrane technology. This work develops a feasible approach to prepare an anti-biofouling poly(vinylidene fluoride) (PVDF) membrane. A copolymer that possessed oppositely charged groups was first synthesized via radical copolymerization with methyl methacrylate, 2-methacryloxy ethyltrimethyl ammonium chloride and 2-acrylamide-2-methyl propane sulphonic acid as monomers. The copolymer was blended with the PVDF powder to prepare the antifouling membrane via the immersed phase inversion method. The antifouling properties of the modified PVDF membrane were studied by X-ray photoelectron spectroscopy, field emission scanning electron microscopy, water contact angle measurement, zeta-potential measurement, protein adsorption, microbial adhesion and filtration experiments. The modified PVDF membrane showed limited adsorption and adhesion of protein bovine serum albumin and microbes (Escherichia coli and Saccharomyces cerevisiae) with increasing copolymer concentration in the casting solution. The modified PVDF membrane exhibited excellent antibiofouling properties.

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The chemistry and topography of the material surfaces have an important effect on cell behaviors. In this study, we reported the preparation of thermoresponsive micropatterned surfaces (TS) and galactosylated TS for modulating the adhesion/detachment of cells. A thickness of 1 μm of poly(N-isopropylacrylamide) grafted layer was fabricated on the polystyrene surface with microgrooves using ultraviolet-induced copolymerization. The thick grafted layer was in favor of the interactions between cells and materials. The following immobilization of galactose ligand with specific affinity to hepatocyte onto TS promoted the adhesion of human hepatocyte line (HL-7702 cells). The microgrooves structure could facilitate cell adhesion and regulate the oriented growth of cells. Moreover, narrow grooves accelerated the spontaneous detachment of cells only by reducing temperature. Thus, micropatterned biofunctional designs with controlled geometrical features presented in this study have sufficient biofunctional activities in facilitating cell sheet engineering and regenerative medicine.

A novel polystyrene (PS) substrate with microscale porous structure was facilely fabricated by crystalline-controlled casting method using mixed solvent [N,N-dimethylformamide and ethyl alcohol (v/v)] based on the nonsolvent induced phase separation process. The substrate surfaces exhibited a bi-continuous microscale porous morphology with high porosity, large pore size and pore-pore connection structure. Moreover, behaviors of the normal human liver cell line (HL-7702) seeded on this substrate surface were carefully investigated. The results indicated that the cell adhesion, spread and cell-cell connection on the surface with subcellular pore size (∼ 10 μm) were similar to the cells proliferated on the flat PS surface. However, the number of HL-7702 cells proliferated on the PS microscale porous surface was higher than cells on the conventional PS flat surface, suggesting that the pore-pore structure was conducive to HL-7702 cell proliferation. Furthermore, hematoxylin and eosin staining and micronucleus test were performed. The results showed that fewer damages for nuclear and cytoplasm and less cell genotoxicity were caused by the microscale porous structure within the scope of pore size (∼ 10 μm) than that of the flat surface.