Formulation and Evaluation of Niosomes
Span 20-based niosome was prepared by lipid film hydration technique and loaded with Newcastle disease vaccine. Three batches with Span 20, cholesterol and dicetyl phosphate in micro molar ratios of 10:10:1; 15:15:1 and 20:20:1 were prepared and evaluated for encapsulation efficiency using haemagglutination test. The morphology of the vesicles was studied by means of transmission electron microscopy. Particle size, zeta potential and polydispersity index were determined by photon correlation spectroscopy using a nanosizer. Adjuvanticity was assessed using haemagglutination inhibition test. The vesicles of Span 20-based niosomes were distinct, near spherical large unilamellar vesicles. The vesicles were of varied sizes (<1000 nm) with the entrapped Newcastle disease vaccine in the core of the vaccine. The zeta potential had a peak at -50 mV. The polydispersity index was 0.68. Haemagglutination inhibition test showed a 71% increment in immune response over that of the marketed La Sota® vaccine which had a 60% increment in immune response. The niosomal vaccine did not alter but rather enhanced the immunogenicity of the Newcastle disease vaccine.