Cellular Uptake and Cytotoxicity of β-Lactoglobulin Nanoparticles: The Effects of Particle Size and Surface Charge

It is necessary to understand the cellular uptake and cytotoxicity of food-grade delivery systems, such as beta-lactoglobulin (beta-1g) nanoparticles, for the application of bioactive compounds to functional foods. The objectives of this study were to investigate the relationships between the physicochemical properties of beta-Ig nanoparticles, such as particle size and zeta-potential value, and their cellular uptakes and cytotoxicity in Caco-2 cells. Physicochemical properties of beta-1g nanoparticles were evaluated using particle size analyzer. Flow cytometry and confocal laser scanning microscopy were used to investigate cellular uptake and cytotoxicity of beta-1g nanoparticles. The beta-Ig nanoparticles with various particle sizes (98 to 192 nm) and zeta-potential values (-14.8 to 17.6 mV) were successfully formed. A decrease in heating temperature from 70 degrees C to 60 degrees C resulted in a decrease in the particle size and an increase in the zeta-potential value of beta-Ig nanoparticles. Non-cytotoxicity was observed in Caco-2 cells treated with beta-1g nanoparticles. There was an increase in cellular uptake of beta-1g nanoparticles with a decrease in particle size and an increase in zeta-potential value. Cellular uptake beta-1g nanoparticles was negatively correlated with particle size and positively correlated with zeta-potential value. Therefore, these results suggest that the particle size and zeta-potential value of beta-1g nanoparticles play an important role in the cellular uptake. The beta-1g nanoparticles can be used as a delivery system in foods due to its high cellular uptake and non-cytotoxicity.