%0 Journal Article
%T Amphiphilic Poly(3-hydroxy alkanoate)s: Potential Candidates for Medical Applications
%A Baki Hazer
%J International Journal of Polymer Science
%D 2010
%I Hindawi Publishing Corporation
%R 10.1155/2010/423460
%X Poly(3-hydroxy alkanoate)s, PHAs, have been very attractive as biomaterials due to their biodegradability and biocompatibility. These hydrophobic natural polyesters, PHAs, need to have hydrophilic character particularly for drug delivery systems. In this manner, poly(ethylene glycol) (PEG) and hydrophilic functional groups such as amine, hydroxyl, carboxyl, and sulfonic acid have been introduced into the PHAs in order to obtain amphiphilic polymers. This review involves in the synthesis and characterization of the amphiphilic PHAs. 1. Introduction Biomaterials have been widely used in medical applications, such as drug delivery, tissue engineering, device-based therapies, and medical imaging [1, 2]. Synthetic and naturally occurring polymers have played important role in the treatment of disease and the improvement of health care. Among them, PHAs are promising materials for biomedical applications in tissue engineering and drug delivery system because they are natural, renewable, biodegradable, and biocompatible thermoplastics. PHAs have been used to develop devices, including sutures, nerve repair devices, repair patches, slings, cardiovascular patches, orthopedic pins, adhesion barriers, stents, guided tissue repair/regeneration devices, articular cartilage repair devices, nerve guides, tendon repair devices, bone-marrow scaffolds, tissue engineered cardiovascular devices, and wound dressing. However the direct use of these polyesters has been hampered by their hydrophobic character and some physical shortcomings [3]. The key to biocompatibility of biomedical implantable materials is to render their surface in a way that minimizes hydrophobic interaction with the surrounding tissue. Therefore, hydrophilic groups have been introduced into the PHAs in order to obtain amphiphilic polymer. This review has been focused on the chemically modified PHAs with enhanced hydrophilic character as biomaterials for medical applications. 2. PHAs PHAs are accumulated as intracellular granules as a result of a metabolic stress upon imbalanced growth due to a limited supply of an essential nutrient and the presence of an excess of a carbon source. These novel biopolymers have material properties ranging from rigid and highly crystalline to flexible, rather amorphous and elastomeric. There have been many studies reported on the modification reactions to enhance mechanical and thermal properties to prepare new biomaterials for the medical applications [4¨C13]. PHAs can be classified into three groups based on the number of carbon atoms in the monomer units:
%U http://www.hindawi.com/journals/ijps/2010/423460/