Biosynthesis of highly pure poly-[gamma]-glutamic acid for biomedical applications

• Published in: Journal of materials science. Materials in medicine Vol. 23; no. 7; p. 1583
• Main Authors: Pereira, Catarina Leite, Antunes, Joana Costa, Gonçalves, Raquel Madeira, Ferreira-da-silva, Frederico, Barbosa, Mário Adolfo
• Format: Journal Article
• Language: English
• Published: London Springer Nature B.V 01.07.2012
• Subjects: Biomedical materials; Biosynthesis; Materials science; Nanotechnology; Polymers
• ISSN: 0957-4530; 1573-4838
• DOI: 10.1007/s10856-012-4639-x

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.[PUBLICATION ABSTRACT]