The spectroscopy of the drug carrier human serum albumin (HSA) was studied in physiological conditions using fluorescein (FL) as a probe ligand. The quenching effect of FL on the fluorescence intensity of W214 (the sole tryptophan in HSA) indicates that FL occupies the warfarin drug-binding site in the protein which is known to bind most hydrophobic drugs. This was confirmed by site-competitive displacement experiments using ibuprofen and warfarin as site markers. Modification of the system was performed by coating selected gold nanoparticles (AuNPs) with the HSA-FL complex. The results indicate a complex formation in which HSA is adsorbed on the AuNPs surface. This was further confirmed using dynamic light scattering and transmission electron microscopy measurements. Significant quenching of the W214 fluorescence was observed in the HSA-AuNP complex which is attributed to the surface plasmon effect on the protein, thereby, implying an efficient energy transfer from HSA to the AuNPs. The absorbance change of the AuNPs was also quantified as a function of the HSA and FL concentration in order to understand the mechanism of interaction with the NPs. Optimization of the complex formation between the AuNPs and the HAS-FL complex will be discussed in the light of the different spectroscopic signatures in both frequency and time domains.

Comparative study of gold nanoparticles coated with human serum albumin as drug carriers

251st National Meeting (2016)

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