Impact of nanogold morphology on interactions with human serum

Gold nanoparticles (AuNPs) of differing shapes are of great interest to researchers due to their unique optical properties, making them potentially powerful theranostic tools. The synthesis of AuNPs is performed frequently, however the assessment of biological activity for each nanoparticle is not always commonplace. While it is thought that physicochemical parameters such as shape may play an important role in dictating the outcomes of interactions which take place at the nano-bio interface, a systematic approach to the assessment of nanomaterials has not been widely adopted. In this study, the interaction between human serum albumin (HSA) and four similar sized but different shaped AuNPs (spherical, rod shaped, prismatic and cubic) synthesised using a common chemical surfactant (CTAB), is presented. Using fluorescence spectroscopy it is shown that all AuNPs exhibit static binding with HSA, however the shape affects both the affinity and strength of the binding. Rod shaped nanoparticles were found to have the highest binding strength and affinity. Conversely, shapes with large flat planar surfaces such as prisms and cubes were shown to have reduced accessibility to the site of the fluorophore within the structure of HSA. The differences observed help to provide a better understanding of the effect of shape on AuNP-protein interactions - knowledge which may be applied to the development of AuNPs for future biological applications.