Preparation and properties of SBS-g-DMAEMA copolymer membrane by ultraviolet radiation

Superelastic, Breathable, and High-Barrier Nanofibrous Membranes with Biomimetic ECM Structure for Toxic Chemical Protection

As the last line of protection for humans, chemical protective suits provided safe and effective protection where chemical warfare agents (CWAs) or chemical reagents leaked; however, the existing chemical protective clothing had poor wearing pressure comfort due to the limitation of inherent materials. Herein, we reported a scalable strategy to fabricate chemical protective fabric (CPF) with a biomimetic extracellular matrix (ECM) barrier layer composed of an elastic fiber framework based on the cross-linked nanofiber membrane and the styrene-butadiene-styrene block copolymer (SBS)/acticarbon matrix. The construction of the reliable and strategical biomimetic ECM structure succeeded in fulfilling hazardous chemical barrier properties, recoverable deformation, and thermal comfort improvement. The resulting CPF exhibited waterproofness with exceeding 200 kPa hydrostatic pressure and exceptional WVT of 550.96 g m^-2 d^-1, rapid elastic recovery from a strain of 80%, high-cycle fatigue resistance, superior barrier performance against toxic chemicals, and keeping CEES resistance after 100 tensile loading cycles. The successful preparation of the fascinating biomimetic nanofibrous membrane may provide a particular research foundation for developing chemical protective clothing in the future.

pH Sensitive Vinyl Copolymers as Vectors for Gene Therapy

A series of pH-sensitive vinyl (co)polymers was synthesised to investigate whether the buffering capacity is a crucial factor in determining the transfection efficiency of synthetic vectors in gene therapy. The polymers containing side groups with different pKa were prepared by radical polymerization. All cationic polymers were able to condense DNA, yielding rather small and homogeneous particles, as determined by dynamic light scattering. The effect of pH, temperature and serum albumin on complex formation was also investigated. The results from the titration studies showed that copolymers of (2-dimethylaminoethyl) methacrylate and 4-methyl-5-imidazoyl methyl methacrylate or methacrylic acid have a buffering effect over a broader pH range compared to poly(2-dimethylaminoethyl methacrylate). Introduction of N-(2-hydroxyethyl) nicotinamide methacrylate had no significant effect on the buffering range.

Modification of HTPB-based polyurethane with temperature-sensitive poly(N-isopropyl acrylamide) for biomaterial usage

Hydroxyl-terminated polybutadiene (HTPB)-based polyurethane with dimethyol propionic acid (DPA) as chain extender was synthesized by solution polymerization. The HTPB-based polyurethane was modified by UV radiation with N-isopropyl acrylamide monomer to get poly(N-isopropyl acrylamide)-modified polyurethane (PUDPANIPAAm). The cohesive energy (E(coh)), molar volume (V), solubility parameter (delta), molecular weight (W(M)), volume per gram (V(g)), and the density (1/V(g)) of PUDPANIPAAm were calculated by group contribution methods. To evaluate the application of PUDPANIPAAm for wound dressing and transplantation of cell sheet, the measurement of water content, water vapor transmission rate, and gas permeation on the PUDPANIPAAm membrane was evaluated. The biocompatibility of these membranes, cell adhesion, and proliferation assay were conducted in the cell culture. The effect of thermosensitivity of poly(N-isopropyl acrylamide) on cell detachment was also evaluated in the primary study. The results showed that these PUDPANIPAAm membranes are thermosensitive. The modification of PU with poly(N-isopropyl acrylamide) reduced the water vapor transmission rate and permeability of gas through PUDPANIPAAm membrane. PUDPANIPAAm membranes could support cell adhesion and growth. Owing to the thermosensitive nature of poly(N-isopropyl acrylamide), the relative cell numbers detached from PUDPANIPAAm membranes were larger than those detached from the polystyrene dish.

Preparation of poly(acrylic acid) modified polyurethane membrane for biomaterial by UV radiation without degassing

Poly(acrylic acid) modified polyurethane (AA/PU) membranes were prepared by UV radiation without degassing. The chemical composition of the AA/PU membrane was studied by IR spectroscopy. In addition to those absorption peaks associated with pure PU, the absorption peak at 2400 cm-1 of poly(AA) was also found. The morphology of AA/PU membrane was studied by optical polarizing microscopy. We also measured the glass transition temperature and the decomposition temperature of the AA/PU membrane by differential scanning calorimetry and thermogravimetric analysis. A significant domain was found in the AA/PU membrane, which resulted in different glass transition temperature and decomposition temperature between AA/PU and pure PU membrane. The effect of AA content on the contact angle and water absorption of the AA/PU membrane was determined. It was found that the water content of AA/PU membrane increased with increasing AA content, whereas the contact angle decreased. By using Kaeble's equation and the contact angle data, the surface free energy of AA/PU membrane was determined. The increase of surface free energy resulted from the increase of the dispersion (gammad) term and polar (gammap) term. In order to evaluate the biocompatibility of these membranes, a cytotoxicity test and a cell adhesion and proliferation assay were conducted in cell culture. Immortal cells and primary lymphocytes were both used in this study. The results showed that these AA/PU membranes exhibited very low cytotoxicity and could support cell adhesion and growth. An animal primary test was also done in this study. It was found that the AA/PU membrane could possibly be employed in the treatment of bowel defect.

Preparation and characterization of heparin-containing SBS-g-DMAEMA copolymer membrane

The grafting of dimethyl amino ethyl methacrylate (DMAEMA) onto styrene-butadiene-styrene triblock copolymer (SBS) membrane was subsequently conducted by UV-radiation induced graft copolymerization without degassing to obtain the SBS-g-DMAEMA copolymer membrane. The substituted amino groups on the SBS-g-DMAEMA graft copolymer membrane were quaternized with iodomethane, and then the membrane was treated with heparin to prepare the heparin-containing SBS-g-DMAEMA copolymer membrane (SBS-g-DMAEMA-HEP). The graft copolymer membrane (SBS-g-DMAEMA) and the heparin-containing SBS-g-DMAEMA copolymer membrane (SBS-g-DMAEMA-HEP) were characterized by FTIR spectroscopy. The heparin content was determined by toluidine blue heparin assay. Contact angle, water content, and protein adsorption of fibrinogen and albumin experiments were also performed to evaluate the effect of graft amount and heparin content on the biocompatibility of SBS-g-DMAEMA and SBS-g-DMAEMA-HEP graft copolymer membranes. By using Kaelble's equation, the surface tension of SBS-g-DMAEMA and SBS-g-DMAEMA-HEP were determined. It was found that with increasing grafting amount and the heparin content, the surface tension and water content of SBS-g-DMAEMA membrane increased, whereas the contact angle decreased. The amount of the adsorption of albumin and fibrinogen decreased with increasing graft amount and heparin content. However, there was a minimum for adsorption of proteins in the SBS-g-DMAEMA and SBS-g-DMAEMA-HEP membranes.