Chitosan-polymer based nanovaccine as promising immersion vaccine against Aeromonas veronii challenge in red tilapia (Oreochromis sp.).

Red tilapia (Oreochromis sp.), one of the important freshwater fish species in fish farming in Thailand, has for long been suffering from a serious bacterial disease named epizootic ulcerative syndrome and hemorrhagic septicemia. The disease is mainly caused by Aeromonas veronii. Vaccine is proposed to be a major impact tool for sustainable control and prevention strategies. Vaccination by immersion has many benefits over injection. However, the conventional immersion method suffers from a low potency due to the inefficient uptake of antigens across mucosal tissue. Here, we developed a chitosan-polymer based nanovaccine together with an efficient delivery vehicle to enhance the immunogenicity of immersion vaccination, increasing bioavailability and inducing local immune responses during transit to mucosal inductive immune sites. The physiochemical properties of nanovaccine, which was modified on surface particle by using a mucoadhesive polymer, were assessed for size, zeta potential, and particle distribution. Our study demonstrated by SEM image and microscopic fluorescence image that nanovaccine greatly increased the binding and penetrating ability into gills when compared with formalin killed vaccine. The nano-sized particles were well dispersed in water and trapped in core nanoparticle as confirmed by TEM image. The efficacy of vaccine was performed by immersion challenge with virulent A.veronii after 30 days post vaccination in tilapia. The result revealed a high level of mortality in the control, empty-polymeric nanovaccine and formalin killed bacterin vaccine groups. A high relative percentage survival (RPS) of vaccinated fish was noted with chitosan-polymer based nanovaccine. Our studies indicated that this chitosan-polymer based nanovaccine derived from cell fragments and supernatant was the improved version of the conventional formalin killed vaccine. The chitosan polymer based particle could increase the efficacy of nanovaccine toward the target mucosal membrane and enhance protection against A. veronii infection in red tilapia.

Self-calcifying lipid nanocarrier for bone tissue engineering.

BACKGROUND: A nanoemulsion with specific surface properties (such as charge and functional groups) can initiate the deposition of calcium phosphate (CaP) on its surface, leading to formation of CaP nanoparticles with a lipid core. The lipid core can carry lipophilic compounds based on the function of the nanoemulsion. Therefore, a dual purpose nanoemulsion of lipid nanoparticles (LNPs) exhibiting self-calcifying and carrier abilities can be developed. METHODS: We employed an emulsification process to formulate LNPs with a specific charged surface. The LNPs were tested for their ability to calcify in simulated body fluid and encapsulate cholecalciferol (a model of active compound). The self-calcifying LNP was successfully fabricated using the emulsification process and stabilized using a mixture of polysorbate 80 and polysorbate 20. RESULTS: The LNPs incubated in simulated body fluid bound to calcium and phosphate, subsequently forming CaP on the particle surface and resulting in approximately 180-nm CaP spheres with a lipid core. The LNPs facilitated calcium phosphate deposition in the collagen scaffolds. In addition, LNPs can be used as carriers of lipophilic compounds without impeding the self-calcifying ability.