Preparation and properties of hydrogels loaded with phage endolysin Lys84 / 生物工程学报

This study investigated the application of poly(N-isopropylacrylamide)-based interpenetrating network temperature-sensitive hydrogels (notation: IPNT) as the delivery vehicle for phage endolysin Lys84 and the potential of drug-loaded hydrogels as antimicrobial materials. Interpenetrating network temperature-sensitive hydrogels were prepared by free radical polymerization of sodium alginate and N-isopropylacrylamide. Drug-loaded hydrogels (IPNT-Lys84) were obtained by dry soaking method with the endolysin Lys84 of Staphylococcus aureus phage. The physical properties of the hydrogels with and without drug loading were characterized by infrared spectroscopy, scanning electron microscopy, and differential scanning calorimetry. The swelling and deswelling of the hydrogels as well as the release of endolysin Lys84 were investigated. Moreover, the antibacterial properties of IPNT-Lys84 hydrogels at different temperatures and concentrations of the drug solution were studied. The results showed that IPNT-Lys84 hydrogel had uniform pores and a low critical solubility temperature (LCST) of 32 ℃. The equilibrium swelling of the hydrogel was 30 g/g, and the water loss rate was 88% upon deswelling. The release rate of endolysin reached more than 70% within 6 h at 37 ℃. The bactericidal rate of IPNT-Lys84 hydrogel was over 99.9%. The research results showed the feasibility of using IPNT to deliver the endolysin Lys84, and IPNT-Lys84 hydrogel might be an effective antimicrobial material against multi-drug resistant Staphylococcus aureus.

Effects of the amphiphilic peptides on membrane permeability of Acinetobacter baumannii / 重庆医学

Objective To investigate effects of the amphiphilic peptides on membrane permeability of acinetobacter bauman-nii .Methods The LysAB3 and LysAB3-D (lack of amphiphilic peptides structure gene) was synthesized and inserted into the vec-tor pET28a(+ ) to construct the recombinant expression plasmid (pET28a-LysAB3 ,pET28a-LysAB3-D) .After expression in E . coli BL21(DE3) and purification with Ni2+-NTA Sepharose .Acinetobacter baumannii was observed by scanning electron microsco-py and fluorescence microscope ,pretreated with LysAB3 and LysAB3-D respectively .Results Under scanning electron microscopy , LysAB3-treated acinetobacter baumannii exhibited not only significant abnormalities ,including deep roughening of the cell surface , but also FITC readily accumulated in bacteria .It was different from LysAB3-D-treated .Conclusion These results indicate that the amphiphilic peptides structure increase membrane permeability of acinetobacter baumannii ,which helps LysAB3 degrade bacteria .