Preparation and evaluation of mesoporous silica nanoparticles loaded quercetin against bacterial infections in Oreochromis niloticus

The present work investigated the potential use of mesoporous silica nanoparticles (MSN) to deliver quercetin in fish through oral route to protect the fish from infection caused by S. agalactiae and K. pneumoniae. The MSNs were synthesized by sol gel method. Polyethylene glycol (PEG)-coated MSNs (PMSNs) were synthesized employing a similar procedure by the addition of PEG and Quercetin conjugated PMSNs (QMSNs) were prepared by the co-precipitation process. These nanoparticles were characterized by UV–vis spectrum, FTIR, XRD, DLS and Zeta potential. The morphology and particle size measurements of the nanoparticles were studied by FE-SEM. The in vitro drug release profile was assessed at different pH, and pH 6.5 was found to be more efficient to release quercetin. The cytotoxicity of QMSNs nanoparticles was evaluated by MTT assay using tilapia gill (TG) cell line. The expression of immune related gene in gill, brain and liver were found to be increased significantly in fish (Oreochromis niloticus) fed with experimental feed when compared to the control fish fed with normal feed. The antibacterial effect of QMSNs against S. agalactiae and K. pneumoniae infection were analysed. The QMSNs produced strong antibacterial activity aganist both the pathogens. The results of this study indicate that quercetin can be easily delivered into fish by feeding with QMSNs for treatment against bacterial infections.