title: Biosynthesis of highly pure poly-γ-glutamic acid for biomedical applications.
abstract: The remarkable properties of poly-aminoacids, mainly their biocompatibility and biodegradability, have prompted an increasing interest in these polymers for biomedical applications. Poly-γ-glutamic acid (γ-PGA) is one of the most interesting poly-aminoacids with potential applications as a biomaterial. Here we describe the production and characterization of γ-PGA by Bacillus subtilis natto. The γ-PGA was produced with low molecular weight (10-50 kDa), high purity grade (>99 %) and a D: -/L: -glutamate ratio of 50-60/50-40 %. To evaluate the feasibility of using this γ-PGA as a biomaterial, chitosan (Ch)/γ-PGA nanoparticles were prepared by the coacervation method at pH ranging from 3.0 to 5.0, with dimensions in the interval 214-221 nm with a poly-dispersion index of ca. 0.2. The high purity of γ-PGA produced by this method, which is firstly described here, renders this biopolymer suitable for biomedical applications. Moreover, the Ch/γ-PGA nanocomplexes developed in this investigation can be combined with biologically active substances for their delivery in the organism. The fact that the assembly between Ch and γ-PGA relies on electrostatic interactions enables addition of other molecules that can be released into the medium through changes from acidic to physiological pH, without loss in biological activity.
authors.affiliation: INEB-Instituto de Engenharia Biomédica, Universidade do Porto, Rua do Campo Alegre, 823, 4150-180, Porto, Portugal. Catarina.pereira@ineb.up.pt
authors.forename: Catarina Leite
authors.initials: CL
authors.lastname: Pereira
authors.forename: Joana Costa
authors.initials: JC
authors.lastname: Antunes
authors.forename: Raquel Madeira
authors.initials: RM
authors.lastname: Gonçalves
authors.forename: Frederico
authors.initials: F
authors.lastname: Ferreira-da-Silva
authors.forename: Mário Adolfo
authors.initials: MA
authors.lastname: Barbosa
mesh_terms: D001412:Bacillus subtilis / Q000378:metabolism; D001672:Biocompatible Materials; D002942:Circular Dichroism; D004591:Electrophoresis, Polyacrylamide Gel; D008970:Molecular Weight; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared; D013237:Stereoisomerism
chemical_list: D001672:Biocompatible Materials; C511775:poly(gamma-glutamic acid); D011099:Polyglutamic Acid