title: Preparation and properties of EDC/NHS mediated crosslinking poly (gamma-glutamic acid)/epsilon-polylysine hydrogels.
abstract: In this paper, a novel pH-sensitive poly (amino acid) hydrogel based on poly γ-glutamic acid (γ-PGA) and ε-polylysine (ε-PL) was prepared by carbodiimide (EDC) and N-hydroxysuccinimide (NHS) mediated polymerization. The influence of PGA/PL molar ratio and EDC/NHS concentration on the structure and properties was studied. Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) proved that hydrogels were crosslinked through amide bond linkage, and the conversion rate of a carboxyl group could reach 96%. Scanning electron microscopy (SEM) results showed a regularly porous structure with 20 μm pore size in average. The gelation time in the crosslink process of PGA/PL hydrogels was within less than 5 min. PGA/PL hydrogels had excellent optical performance that was evaluated by a novel optotype method. Furthermore, PGA/PL hydrogels were found to be pH-sensitive, which could be adjusted to the pH of swelling media intelligently. The terminal pH of swelling medium could be controlled at 5 ± 1 after equilibrium when the initial pH was within 3-11. The swelling kinetics was found to follow a Voigt model in deionized water but a pseudo-second-order model in normal saline and phosphate buffer solution, respectively. The differential swelling degrees were attributed to the swelling theory based on the different ratio of -COOH/-NH2 and pore size in hydrogels. The results of mechanical property indicated that PGA/PL hydrogels were soft and elastic. Moreover, PGA/PL hydrogels exhibited excellent biocompatibility by cell proliferation experiment. PGA/PL hydrogels could be degraded in PBS solution and the degradation rate was decreased with the increase of the molar ratio of PL. Considering the simple preparation process and pH-sensitive property, these PGA/PL hydrogels might have high potential for use in medical and clinical fields.
authors.affiliation: Key Laboratory of Advanced Textile Composites, Tianjin Polytechnic University, Ministry of Education, Tianjin 300387, China; School of Textiles, Tianjin Polytechnic University, Tianjin 300387, China.
authors.forename: Jiachuan
authors.initials: J
authors.lastname: Hua
authors.affiliation: Key Laboratory of Advanced Textile Composites, Tianjin Polytechnic University, Ministry of Education, Tianjin 300387, China; School of Textiles, Tianjin Polytechnic University, Tianjin 300387, China. Electronic address: lizheng_nx@163.com.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Li
authors.affiliation: Key Laboratory of Advanced Textile Composites, Tianjin Polytechnic University, Ministry of Education, Tianjin 300387, China; School of Textiles, Tianjin Polytechnic University, Tianjin 300387, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Xia
authors.affiliation: Key Laboratory of Advanced Textile Composites, Tianjin Polytechnic University, Ministry of Education, Tianjin 300387, China; School of Textiles, Tianjin Polytechnic University, Tianjin 300387, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Yang
authors.affiliation: Key Laboratory of Advanced Textile Composites, Tianjin Polytechnic University, Ministry of Education, Tianjin 300387, China; School of Textiles, Tianjin Polytechnic University, Tianjin 300387, China.
authors.forename: Jixian
authors.initials: J
authors.lastname: Gong
authors.affiliation: Key Laboratory of Advanced Textile Composites, Tianjin Polytechnic University, Ministry of Education, Tianjin 300387, China; School of Textiles, Tianjin Polytechnic University, Tianjin 300387, China. Electronic address: zhangjianfei1960@126.com.
authors.forename: Jianfei
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Industrial Microbiology, Tianjin University of Science and Technology, Ministry of Education, Tianjin 300457, China.
authors.forename: Changsheng
authors.initials: C
authors.lastname: Qiao
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D005022:Ethyldimethylaminopropyl Carbodiimide / Q000737:chemistry; D020100:Hydrogels / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D051379:Mice; D008855:Microscopy, Electron, Scanning; D056951:Photoelectron Spectroscopy; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D011107:Polylysine / Q000737:chemistry*; D016062:Porosity; D017550:Spectroscopy, Fourier Transform Infrared; D013388:Succinimides / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; D020100:Hydrogels; D013388:Succinimides; C511775:poly(gamma-glutamic acid); D011107:Polylysine; D011099:Polyglutamic Acid; C001426:N-hydroxysuccinimide; D005022:Ethyldimethylaminopropyl Carbodiimide
keywords: Biocompatibility; Hydrogel; Poly γ-glutamic acid; Swelling kinetics; ε-Polylysine