Size-controlled fabrication of egg-like protein nanoparticles: thermodynamic characterization of the interaction between zein nanoparticles and serum albumin

Abstract

In this study, an improved antisolvent nanoprecipitation method was developed for preparation of size-controlled zein nanoparticles, and the effects of various factors, such as zein solution concentration, water to zein solution ratio, stirrer speed and pH values of zein solution in zein nanoparticles formation were investigated. The use of optimal conditions produced spherical nanoparticles of 57.64 nm and a zeta potential of +35.7 mV. To the best of the authors’ knowledge, it is the smallest size ever reported for zein nanoparticles which is measured by the dynamic light scattering method. The interaction between zein nanoparticles and bovine serum albumin was investigated using fluorescence quenching and calorimetric techniques. Serum albumin adsorbs to the surface of the zein nanoparticles by hydrophobic interaction and reduces their isoelectric point that provide increased physical stability in high ionic strength solutions and biological environments. The results from thermodynamic studies suggest that the zein nanoparticles have a strong binding affinity (KSV 4.88 × 105 M−1) with serum albumin and the adsorption process is exothermic (ΔH −7.46 kJ mol−1) and spontaneous (ΔG −32.06 kJ mol−1) in nature. Stabilizing zein nanoparticles in serum albumin is considered a major advantage for further evaluation of the immune response and drug delivery applications.