Understanding the nano-bio interactions using real-time surface plasmon resonance tool

Abstract Our current understanding of the biophysicochemical interactions at nano-bio interfaces is still very limited. Surface plasmon resonance (SPR) is a powerful tool for understanding the real-time kinetics of protein binding on the surface of nanoparticles (NPs) but has been least exploited for this purpose. In this study, we demonstrated the interaction of negatively charged poly lactic- co -glycolic acid (PLGA) NPs and positively charged chitosan oligosaccharide (COS)-coated PLGA NPs with two model proteins, namely bovine serum albumin (BSA) and hen egg white lysozyme (LYZ), at the physiological pH of 7.4. Various biophysical characterization techniques were employed to elucidate the influence of surface charge of NPs on protein interaction. SPR investigations revealed the binding affinity and binding kinetics involved in nanoparticle-protein interactions. These results confirmed that the affinity of both types of NPs towards positively charged LYZ was much greater than that for negatively charged BSA, which was also in accordance with the results of the adsorption studies. Our results demonstrate that the surface properties of the interacting species play a dominant role during protein-nanoparticle interactions, apart from the net charge on their individual surfaces. The information obtained from this study adds significant value to the biophysicochemical toolbox for characterization of nano-bio interactions.