A New Interfacial Cross Linking Technique: Preparation, Characterization and Evaluation of Calcium alginate Nanoparticles as a Protein Delivery System.

摘要

Nanoparticles prove to be excellent carriers for site specific and/or time controlled delivery of small or large molecular weight drugs and other bioactive agents. The use of biopolymers as a natural carrier system not only makes the formulation easy but provides an additional advantage of being non toxic and easily degradable within the body, thereby making them safer for use. Alginate which is a polysaccharide polymer is particularly versatile in encapsulation of unstable and water soluble molecules such as proteins. In the presence of a divalent ion, alginates form bead like structures which can be used as carriers in drug delivery. The purpose of this research was to develop a new technique for synthesizing calcium alginate nanoparticles and to evaluate its potential as a protein delivery system. Two template w/o microemulsions were prepared using DOSS as surfactant and cyclohexane as the organic phase respectively. Various proportions of these mixtures were tested for their ability to form stable microemulsions using ternary phase diagrams. Based on the results, suitable mixtures containing 0.5% to 1% of aqueous sodium alginate dispersion in 0.2 M DOSS/cyclohexane and 0.5% to 1% aqueous calcium chloride in 0.2 M DOSS/cyclohexane were selected for nanoparticle preparation. Nanoparticle characterization studies indicated formation of calcium alginate nanoparticles in the size range 200-500nm.. Bovine Serum Albumin (BSA) loaded nanoparticles were prepared in the same way and characterized using dynamic light scattering, transmission electron microscopy, zeta potential, and differential scanning calorimetry. In vitro drug release studies showed that 90% of entrapped BSA was released within first 8 hrs followed by a slow release pattern. All entrapped protein was released within 30 hours. The presence of protein within the matrix system was investigated using FITC -BSA as a model via confocal laser scanning microscopy(CLSM). Zeta potential and CLSM results support the idea that BSA was partially adsorbed on the nanoparticle surface and the rest was encapsulated within the matrix. As an effort to increase the efficacy of these nanoparticles for protein delivery, chitosan was investigated as a cationic polymer to coat them. Zeta potential analysis and CLSM of nanoparticles subjected to coating with chitosan demonstrated deposition of the cationic polymer on the surface of the nanoparticle. Calcium alginate nanoparticles were successfully prepared via a novel interfacial cross linking method developed in our laboratory. Results obtained from various physico-chemical properties indicate that the nanoparticles possess characteristics suitable for use as a protein drug delivery system.