Effects of DHLA-capped CdSe/ZnS quantum dots on the fibrillation of human serum albumin.

Nanoparticles (NPs) are extremely small in size and possess very large surface areas, which gives them unique properties and applications distinct from those of bulk systems. When exposed to biological fluid, these NPs may become coated with proteins and other biomolecules given their dynamic nature. Hence, there is a significant possibility of an enhanced rate of protein fibrillation by utilizing the NPs as nucleation centers and, thus, promoting fibril formation. Protein fibrillation is closely associated with many fatal human diseases, including neurodegenerative diseases and a variety of systemic amyloidoses. This topic of protein-NP interaction brings about many key issues and concerns, especially with respect to the potential risks to human health and the environment. Herein, we demonstrate the effects of specific NPs, semiconductor quantum dots (QDs), in the process of protein fibril formation from samples of human serum albumin (HSA). The protein-NP systems are analyzed by time-lapse Thioflavin T spectroscopy, Congo red binding assays, circular dichroism (CD), protein fluorescence spectroscopy, and transmission electron microscopy (TEM). Our experimental results illustrate that an increased rate of fibrillation occurs following a thermally activated mechanism in conjunction with the addition of NPs into the protein system. These results give rise to the understanding and possibility of controlling biological self-assembly processes for use in nanobiotechnology and nanomedicine.