Temperature dependent human serum albumin Corona formation: A case study on gold nanorods and nanospheres

Protein molecules interact with nanoparticles to form a protein layer on the surface called the protein corona. Corona formation can be affected by the temperature and shape of the nanoparticles thereby impacting the fate of the nanoparticles inside physiological systems. We have investigated the human serum albumin (HSA) corona formation and its interactions with gold nanospheres and nanorods at different temperatures (18-42 °C). UV-Vis, fluorescence, isothermal titration calorimetry (ITC), x-ray photoelectron spectroscopy (XPS) and circular dichroism (CD) experiments have been performed to determine the changes due to the shape and temperature. UV-Vis spectra show a greater propensity of corona induced aggregation in the nanorods compared to the nanospheres. The Stern-Volmer plot indicates that static quenching is predominant in the HSA-AuNP interactions with higher quenching efficiency for nanorods than nanospheres. ITC analyses show that HSA-nanorods are involved in more favorable interactions compared to HSA-nanospheres. XPS studies indicate a more electron rich environment on the AuNRs surface and higher AuS interactions in AuNSs. CD spectra show higher secondary structural changes with temperature in case of HSA-AuNR interactions compared to HSA-AuNS interactions. The changes in the protein corona due to nanoparticle shape and variable temperature have been investigated through protein adsorption and composition, types of interactions and protein conformation.