Polyhydroxyalkanoates as biomaterials

Abstract

Polyhydroxyalkanoates (PHAs) are biopolymers synthesized by bacteria under unbalanced growth conditions. These biopolymers are considered as potential biomaterials for future applications because they are biocompatible, biodegradable, and easy to produce and functionalize with strong mechanical strength. Currently, PHAs are being extensively innovated for biomedical applications due to their prerequisite properties. The wide range of biomedical applications includes drug delivery systems, implants, tissue engineering, scaffolds, artificial organ constructs, etc. In this article we review the utility of PHAs in various forms (bulk/nano) for biomedical applications so as to bring about the future vision for PHAs as biomaterials for the advancement of research and technology.

Fig. 1. Various applications of polyhydroxyalkanoates.

Fig. 2. In vitro cytotoxicity tests of ellipticine loaded PHBV-12 nanoparticles at different concentrations for A549 cell line [(a–c) Student–Newman–Keuls test (P < 0.05)] (reprinted with permission from Masood et al., 2013, J. Mater. Sci.: Mater. Med.).

Fig. 3. Appearance of a three-dimensional PHBHHx scaffold. (a) Surface of the scaffold, scale bar: 1 mm. (b) Cross-section of the scaffold by SEM, scale bar: 1 mm. (c) Porous structure in the middle of the cross section by SEM, scale bar: 100 μm. (d) Edge of the scaffold by SEM, scale bar: 100 μm. (e) Side view of the scaffold, scale bar: 1 mm. (f) Radial section of the scaffold by SEM, scale bar: 1 mm. (g) Porous structure in the middle of the radial section by SEM, scale bar: 100 μm. (h) Protuberant part from the side of the scaffold by SEM, scale bar: 100 μm (reprinted with permission from Wang et al., 2008, Biomaterials).

Fig. 4. Co-culture of Celltracker™ labelled fibroblasts (green) and hESMPs (red) on bilayer membranes of PHBV–PLA. After 7 days (A) fibroblasts (green) are confined to the PLA face with no sign of hESMPs (red). (B) On the opposite face of PHBV, hESMPs are grown without growth of fibroblast. (C) A cross section of a PHBV–PLA membrane shows each cell type on its respective side. (D) Scanning electron micrographs (SEMs) of an electrospun scaffold (cross section) of PHBV–PLA. The PHBV region on the left side is dense while the PLA region has a more open structure (reprinted with permission from Bye et al., 2013, Biomaterials Science).

Fig. 5. Microscopic image of the wound contracture over time for (A1) 1 week and (A2) 2 weeks using PHBV fibers, (B1) 1 week and (B2) 2 weeks using R-Spondin 1 and (C1) 1 week and (C2) 2 weeks using PHBV fibers loaded with R-Spondin 1 (reprinted with permission from Kuppan et al., 2011, Biomacromolecules).

Bhagyashri S. Thorat Gadgil

Naresh Killi

GVN Rathna