Abstract:
There is growing interest in the development of new biomaterials and nano-sized drug delivery systems. Alkyds produced from palm kernel oil (PKO) show significant promise in this respect since they are produced entirely from bio-sourced starting materials that have an established record of safety as excipients in the manufacture of cosmetics and pharmaceuticals. A family of alkyd resins was synthesised using step-wise polymerisation. The physicochemical characteristics of the alkyds were probed using end-group analysis, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Results showed that the alkyds have acid value 5-6 mgKOH/g and hydroxyl value of 241-352 mgKOH/g. FTIR and NMR confirmed the functional groups of alkyd structures. Thermal analysis showed that the alkyds possess good thermal stability with degradation occurring only above 200°C, probably due to dehydration and cross-linking reactions involving hydroxyl groups. The biocompatibility of the alkyds was investigated by assessing cytotoxicity on a 3T3 fibroblast cell line using the cell viability assay. The data collectively indicated that the alkyds were biocompatible with no measurable cytotoxicity when cells were exposed to concentrations of 3-100 μg/mL for time periods up to 72 hours. Thus PKO-based alkyds have significant potential for biomedical and pharmaceutical applications. Nanoemulsions were prepared from alkyds (oil phase), Tween 80 (surfactant) and ultrapure water. The droplet size of the emulsions ranged from 10-100 nm depending on the composition of the nanoemulsion. Alkyd nanoemulsions in general were found to be stable at room temperature for three months. However, only nanoemulsions prepared from short oil length alkyds were stable at 45°C for 3 months indicating their potential as drug carriers for various applications including wound healing. The phenytoin was loaded into alkyd nanoemulsions and their physico-chemical properties were further investigated. The reverse phase high performance liquid chromatography method was developed and validated in order to identify and quantify the phenytoin in alkyd nanoemulsions. The phenytoin loaded alkyd nanoemulsions were found non-toxic and suitable to human skin cell line, HaCaT. The wound scratch study of phenytoin loaded alkyd nanoemulsions showed pronounced wound healing effects. In conclusion, the findings suggested that novel alkyd nanoemulsions are suitable for topical applications and could be formulated with phenytoin for promoting wound healing.
