Herein, improving the antibacterial activity of a hydrogel system of sodium alginate (SA) and basic chitosan (CS) using sodium hydrogen carbonate by adding AgNPs was investigated. SA-coated AgNPs produced by ascorbic acid or microwave heating were evaluated for their antimicrobial activity. Unlike ascorbic acid, the microwave-assisted method produced uniform and stable SA-AgNPs with an optimal reaction time of 8 min. Transmission electron microscopy (TEM) confirmed the formation of SA-AgNPs with an average particle size of 9 ± 2 nm. Moreover, UV-vis spectroscopy confirmed the optimal conditions for SA-AgNP synthesis (0.5% SA, 50 mM AgNO₃, and pH 9 at 80 °C). Fourier transform infrared (FTIR) spectroscopy confirmed that the –COO⁻ group of SA electrostatically interacted with either the Ag⁺ or –NH₃⁺ of CS. Adding glucono-δ-lactone (GDL) to the mixture of SA-AgNPs/CS resulted in a low pH (below the pKa of CS). An SA-AgNPs/CS gel was formed successfully and retained its shape. This hydrogel exhibited 25 ± 2 mm and 21 ± 1 mm inhibition zones against E. coli and B. subtilis and showed low cytotoxicity. Additionally, the SA-AgNP/CS gel showed higher mechanical strength than SA/CS gels, possibly due to the higher crosslink density. In this work, a novel antibacterial hydrogel system was synthesized via 8 min of microwave heating.

To modify the surface properties of segmented polyurethane (SPU), effects of the molecular architecture of the 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers on the performance of the SPU/MPC polymer membrane were investigated. We combined the random-type, block-type, and graft-type of the MPC polymers with a typical SPU, Tecoflex^® using double solution casting procedure. The graft-type MPC polymers composed of a poly(MPC) main chain and poly(2-ethylhexyl methacrylate (EHMA)) side chains were synthesized through the combination of two different living radical polymerization techniques to regulate the density and chain length of the side chains. The SPU membranes modified with the MPC polymers were characterized using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The results revealed that the MPC units were located on the SPU surface. Although the breaking strength of the SPU membranes modified with block-type poly(MPC-block-EHMA) and graft-type poly(MPC-graft-EHMA) was lower than that of SPU membranes modified with random-type poly(MPC-random-EHMA), their breaking strengths were adequate for manufacturing medical devices. On the other hand, better stability was observed in the MPC polymer layer on the SPU membrane after immersion in an aqueous medium, wherein the SPU membrane had been modified with the poly(MPC-graft-EHMA). This was because of the intermixing of the hydrophobic poly(EHMA) segments in the domain of the hard segments in the SPU membrane. After this modification, each SPU/MPC polymer membrane showed hydrophilic nature based on the MPC polymers and a dramatic suppression of protein adsorption. From these results, we concluded that the SPU membrane modified with the poly(MPC-graft-EHMA) was one of the promising polymeric biomaterials for making blood-contacting medical devices.

In this study, oligo-prolines, (Pro)_n (n = 6 and 9) inspired by the backbone structure of collagen, were evaluated as a novel non-ionic anti-fouling peptide.