Poly(hydroxy alkanoate)s in Medical Applications

Abstract

This review summarizes the state-of-the-art knowledge of the usage of poly(hydroxy alkanoate)s in medical and sanitary applications. Depending on the monomers incorporated into the polymers and copolymers, this class of polymers exhibits a broad range of (thermo-)plastic properties, enabling their processing by, e.g., solution casting or melt extrusion. In this review, strategies for the polymer analogous modification of these materials and their surfaces are highlighted and correlated with the potential applications of the corresponding materials and blends. While the commercial availability of purified PHAs is addressed in brief, special focus is put on the (bio-)degradability of these polymers and ways to influence the degradation mechanism and/or the duration of degradation.

Keywords: bio-degradation; medical application; poly(hydroxy alkanoate); polymer analogous modification; polymer processing.

Fig. 1

Generic structural formula of PHAs. The integer m typically has the value of 1 (with the exception of 4-hydroxy alkanoates such as 4-hydroxybutyrate), the integer n quantifies the degree of polymerization.

Fig. 2

Overlay of light and fluorescence micrographs showing cell adhesion on fibers composed of a PLA core and a coating of statistical copolymers of P(HB-HV). Reprinted from reference with permission from John Wiley and Sons.

Fig. 3

Top: Crosslinking of polymer chains with a bisazide (BA) under UV irradiation. Bottom: Multi-step photolithographic processes based on P(HB-HV). Reproduced in part from reference with permission of The Royal Society of Chemistry.

Fig. 4

SEM images of the morphology of PHA composites after 0, 60, and 120 days of degradation. A-C: pristine PHA, D-F: PHA crosslinked with cellulose actetate, G-I: PHA grafted on acrylic acid/cellulose acetate. Biodegradation by Acetobacter pasteurianus can be monitored by the erosion in the films. Reprinted from reference with permission from Elsevier.

Fig. 5

SEM micrographs showing the morphological features of electrospun fibers (left) and spincast films (right) of PHB blended with TiO₂. Reprinted from reference with permission from Hindawi Publishing Corporation.

Fig. 6

SEM images of composite scaffolds of P(HB-HHx) and mesoporous bioactive glass (MBG) at different magnifications (top and bottom). A: reference material poly(vinyl alcohol):MBG = 1:7; B: P(HB-HHx):MBG = 1:7; C: P(HB-HHx):MBG = 1:5; D: P(HB-HHx):MBG = 1:3. Reproduced in part from reference with permission of The Royal Society of Chemistry.