THE USE OF BIOMATERIALS IN ARTIFICIAL SEED AND DRUG DELIVERY APPLICATIONS

Abstract

The potential of biomaterials, namely chitosan, alginate and poly(lactic acid) in two vastly different applications, biotechnology and biomedical technology, have been investigated. Chitosan and alginate have been demonstrated to form viable seed coat materials for the fabrication of artificial seeds for biotechnology application. Survival of secondary embryoids of winter oilseed rape (Brassica napus ssp. oleifera cv. Primor) has been used as an assay for the development of artificial seeds involving complex coacervation of alginate (polyanion) with chitosan (polycation). Two methods of encapsulation, either a chitosan solution dropping into an alginate solution or vice versa, were attempted. Germination frequency of 100% was achieved for encapsulated embryoids only when alginate formed the inner matrix and chitosan the outer layer. When the matrix makeup was reversed, there was no germination of embryoids. The artificial seeds produced were hardened in dilute alkaline solutions of NaOH and Ca(OH)2. An optimum setting time could be selected based on a quantitative measurement of resistance of hardened capsules to compression and the germination frequency of the encapsulated embryoids. A preliminary study to fabricate a controlled release drug delivery system for the treatment of prosthetic valve endocarditis (PVE) forms the potential biomedical application. The approach is unique in targeting the therapeutic agent (gentamicin) on surgical felt (known as a pledget) commonly used in surgical procedures to protect tissue from tearing during suturing compared to the conventional approach of drug impregnation onto sewing rings of prosthetic heart valves. Implanted at the site of potential infection, effective localised prophylaxis is feasible. The biodegradable drug delivery system was fabricated by nonsolvent coacervation of poly(lactic acid) to physically entrap a broad spectrum antibiotic, gentamicin, onto the pledget. In vitro dissolution studies were performed by timed sampling of incubation medium to evaluate the drug release profiles under different conditions of drug loading. The effects of polymer concentration and molecular weight on the performance of the delivery system were investigated. The results demonstrate that controlled drug delivery is feasible for the desired time frame for preventive treatment of PVE.