Considerable amount. of research is being conducted at present in developing biodegradable polymers and composites because of the environmental problems caused by petroleum-based non-degradable materials that are currently being used
Biodegradable polymers have been used in biomedical applications as sutures and more recently as drug delivery systems. Drug delivery systems use amphiphilic (non-polar part) block copolymers that self assemble into micelles above their critical. micellar concentration
Such block copolymers typically use copolymers of lactic acid and glycolic acid as the hydrophobic part, and polyethylene glycol as the hydrophilic part of the amphiphileas the polar part
These amphiphiles are capable of solubilizing hydrophobic drugs in aqueous media, thereby preventing premature drug degradation and premature drug precipitation. However, drug loading capabilities of such amphiphilic copolymers is limited due to the lack of functionalities on the main chain of the polymer.
. Other renewable polymers of cellulose resources reproduced from melt polycondensation of 5-hydroxylevulinic acid) the, poly (5-hydroxylevulinic acid) (PHLA), was synthesized and characterized with the in vitro degradation behaviors in phosphate-buffered saline and in deionized water were also found to be excellent and possesses unordinary high glass transition temperature as high as 120 oC. PHLA readily degraded hydrolytically in aqueous media.
Most commonly, the polymers for the controlled release of gene delivery systems are also biodegradable polymers manufactured as nanoparticles, microspheres,
implantable matrixes and scaffolds. The recent developments in the polymers used for the controlled release of gene delivery systems, with emphasis on their applications in gene therapy and tissue engineering, have had a wide pace in modern technology. These natural polymers and their derivatives are obtained from natural resources such as collagen, atelocollagen, gelatin, fibrin, glycosaminoglycans, chitosan, alginate, and agarose, Synthetic polymers include poly(lactide-co-glycolide), poly(lactic acid), functionalized poly(lactic acid), poly(orthoester)s, poly(?-amino ester)s, poly-anhydrides, polyurethanes and poly(ethylene-co-vinylacetate). Thus the exquisite adjusting of the chemical and physical .characteristics of the polymers and optimally engineered properties, may gain greater control over gene delivery and cell growth.
The crystallization, thermal behavior biodegradability has been extensively studied in recent years. The physical properties, such as the mechanical thermal properties, and of a semi-crystalline polymer generally is of great importance in the industry of manufacture of these polymers
Issues surrounding waste management of traditional and biodegradable polymers are discussed in the context of reducing environmental pressures and carbon footprints. Many literature citations address the development of plant-based biodegradable polymers. Plants naturally produce numerous polymers, including rubber, starch, cellulose and storage proteins, all of which have been exploited for biodegradable plastic production. Bacterial bioreactors fed with renewable resources from plants - so-called white biotechnology.' - have also been successful in producing biodegradable polymers and have the potential to become viable alternatives to petroleum-based plastics and an environmentally benign and carbon-neutral source of polymers.
In brief, the market of real-life-applications and science technology, both in medicine and the environment require a high demand for the affordability and easy access to biodegradable polymers instead of the petroleum-based artificial polymers of non-degradable materials that are currently being used which constitute a health hazard globally.