title: Synthesis of poly(glutamic acid)-tyramine hydrogel by enzyme-mediated gelation for controlled release of proteins.
abstract: An in situ-formed hydrogel was synthesized by enzymatic cross-linking of poly(γ-glutamic acid)-tyramine conjugates (PGA-Tyr) using horseradish peroxidase (HRP) and hydrogen peroxide (H2O2). The gelation time ranged from 25 s to 5 min was accomplished by tuning the concentration of HRP, H2O2/Tyr molar ratio and the degree of substitution (DS) of Tyr groups. The storage modulus (G'), cross-link density, and mesh size can be tailored by controlling the H2O2/Tyr ratio and DS. The rheological analysis indicated that the storage modulus (G') can be tailored from approximately 40 to over 1100 Pa with the increasing H2O2/Tyr ratio and DS. The bovine serum albumin (BSA) was used as model protein and encapsulated into the hydrogel during the enzyme-mediated cross-linking reaction. Controlled release of BSA in vitro from the PGA-Tyr hydrogel was obtained. The release rate and cumulative release amount of encapsulated BSA were manipulated by controlling the H2O2/Tyr ratio and DS. More than 90% of encapsulated BSA was released from the hydrogel with low cross-link density and lager mesh size in 60 h, while only 68% of BSA was released from the hydrogel with high cross-link density and small mesh size. The results indicated that the PGA-Tyr hydrogel is a promising material for the controlled release of therapeutic protein or peptides.
authors.affiliation: a School of Materials Science and Engineering , Nanchang University , Nanchang 330031 , China.
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Peng
authors.forename: Yingqi
authors.initials: Y
authors.lastname: She
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
mesh_terms: D000818:Animals; D002417:Cattle; D003692:Delayed-Action Preparations / Q000138:chemical synthesis* / Q000737:chemistry; D006735:Horseradish Peroxidase / Q000737:chemistry; D020100:Hydrogels / Q000138:chemical synthesis* / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D008422:Materials Testing; D015394:Molecular Structure; D008970:Molecular Weight; D011099:Polyglutamic Acid / Q000138:chemical synthesis* / Q000737:chemistry; D066244:Proton Magnetic Resonance Spectroscopy; D012212:Rheology; D012710:Serum Albumin, Bovine / Q000737:chemistry; D013997:Time Factors; D014439:Tyramine / Q000138:chemical synthesis* / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D003692:Delayed-Action Preparations; D020100:Hydrogels; D014867:Water; D011099:Polyglutamic Acid; D012710:Serum Albumin, Bovine; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase; D014439:Tyramine
keywords: controlled release of protein; enzymatic cross-linking; horseradish peroxidase; hydrogel; poly(glutamic acid)