title: Shape Changes and Interaction Mechanism of Escherichia coli Cells Treated with Sericin and Use of a Sericin-Based Hydrogel for Wound Healing.
abstract: To verify the interaction mechanism between sericin and Escherichia coli, especially the morphological and structural changes in the bacterial cells, the antimicrobial activity of sericin against E. coli as a model for Gram-negative bacteria was investigated. The antibacterial activity of sericin on E. coli and the interaction mechanism were investigated in this study by analyzing the growth, integrity, and morphology of the bacterial cells following treatment with sericin. The changes in morphology and cellular compositions of bacterial cells treated with sericin were observed by an inverted fluorescence microscope, scanning electron microscopy, and transmission electron microscopy. Changes in electrical conductivity, total sugar concentration of the broth for the bacteria, and protein expression of the bacteria were determined to investigate the permeability of the cell membrane. A sericin-based hydrogel was prepared for an in vivo study of wound dressing. The results showed that the antibacterial activity of the hydrogel increased with the increase in the concentration of sericin from 10 g/liter to 40 g/liter. The introduction of sericin induces membrane blebbing of E. coli cells caused by antibiotic action on the cell membrane. The cytoplasm shrinkage phenomenon was accompanied by blurring of the membrane wall boundaries. When E. coli cells were treated with sericin, release of intracellular components quickly increased. The electrical conductivity assay indicated that the charged ions are reduced after exposure to sericin so that the integrity of the cell membrane is weakened and metabolism is blocked. In addition, sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated that sericin hinders the expression of bacterial protein. Sericin may damage the integrity of the bacterial cell membrane, thereby eventually inhibiting the growth and reproduction of E. coli Compared to sterile gauze, the sericin-based hydrogel promoted fibroblast cell proliferation and accelerated the formation of granulation tissues and neovessels.
  
  
  
  The specific relationship and interaction mechanism between sericin and E. coli cells were investigated and elucidated. The results show that after 12 h of treatment, sericin molecules induce membrane blebbing of E. coli cells, and the bacteria show decreases in liquidity and permeability of biological membrane, resulting in alterations in the conductivity of the culture medium and the integrity of the outer membrane. The subsequent in vivo results demonstrate that the sericin-poly(N-isopropylacrylamide-N,N'-methylene-bis-acrylamide [NIPAm-MBA]) hydrogel accelerated wound healing compared to that with sterile gauze, which is a beneficial result for future applications in clinical medicine and the textile, food, and coating industries.
authors.affiliation: School of Materials Science and Engineering, State Key Laboratory of Separation Membranes and Membrane Processes, Tianjin Polytechnic University, Tianjin, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Xue
authors.affiliation: School of Materials Science and Engineering, State Key Laboratory of Separation Membranes and Membrane Processes, Tianjin Polytechnic University, Tianjin, China.
authors.forename: Yalong
authors.initials: Y
authors.lastname: Liu
authors.affiliation: School of Materials Science and Engineering, State Key Laboratory of Separation Membranes and Membrane Processes, Tianjin Polytechnic University, Tianjin, China weiyen@tsinghua.edu.cn.|Department of Chemistry, Tsinghua University, Beijing, China.
authors.forename: Qingsong
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: School of Materials Science and Engineering, State Key Laboratory of Separation Membranes and Membrane Processes, Tianjin Polytechnic University, Tianjin, China.
authors.forename: Congcong
authors.initials: C
authors.lastname: Liang
authors.affiliation: School of Materials Science and Engineering, State Key Laboratory of Separation Membranes and Membrane Processes, Tianjin Polytechnic University, Tianjin, China.
authors.forename: Huazhen
authors.initials: H
authors.lastname: Qin
authors.affiliation: School of Computer Science and Software Engineering, Tianjin Polytechnic University, Tianjin, China.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Liu
authors.affiliation: Department of Chemistry, Tsinghua University, Beijing, China.
authors.forename: Ke
authors.initials: K
authors.lastname: Wang
authors.affiliation: Department of Chemistry, Tsinghua University, Beijing, China.
authors.forename: Xiaoyong
authors.initials: X
authors.lastname: Zhang
authors.affiliation: School of Materials Science and Engineering, State Key Laboratory of Separation Membranes and Membrane Processes, Tianjin Polytechnic University, Tianjin, China.
authors.forename: Li
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of Chemistry, Tsinghua University, Beijing, China weiyen@tsinghua.edu.cn.
authors.forename: Yen
authors.initials: Y
authors.lastname: Wei
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects* / Q000502:physiology; D004927:Escherichia coli Infections / Q000382:microbiology* / Q000503:physiopathology; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry / Q000494:pharmacology; D008297:Male; D008826:Microbial Sensitivity Tests; D051381:Rats; D017207:Rats, Sprague-Dawley / Q000276:immunology; D047030:Sericins / Q000737:chemistry / Q000494:pharmacology*; D014945:Wound Healing / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D047030:Sericins; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate