Protein-stabilized gold nanoclusters for cancer theranostics

Abstract

A new branch of medicine, which represents a targeted therapy based on specific diagnostic tests, has emerged in recent years. It was named theranostics, combining the measures of diagnostics of the disease and its simultaneous treatment. The methods of nanomaterials science are used in theranostics to create multimodal platforms, which would allow several desired effects to be realized. Such theranostic platforms being applied in oncology would eliminate multi-step procedures, reduce delays in treatment and improve patient care. The combined approach offers various advantages besides the improved diagnosis such as tumor specific delivery of drugs, reduced toxic effects to normal tissues, etc. Here we present BSA-Au nanoclusters (NCs) as one of the theranostics platforms. Due to an ultrasmall size, unique molecule-like optical properties and facile synthesis, gold nanoclusters are considered as promising photoluminescent agents for biosensing, bioimaging and targeted therapy. Previous investigation on the intracellular uptake of BSA-Au NCs has shown that BSA-Au NCs accumulate in MCF-7 and MDA-MB-231 cells [1]. In this work, the photoluminescence measurements evidenced the capability of BSA-Au NCs to generate multiple reactive oxygen species upon light exposure in the presence of two molecular probes, while the observed sensitivity of the photoluminescence properties of NCs might be used to indicate photooxidative processes in the cell growth medium. The viability test performed on the cultures of cancerous cells after incubation with BSA-Au NCs and subsequent irradiation with the violet light revealed notable difference in induced phototoxicity between two selected cell lines, which was not the case after the corresponding treatment using the photosensitizer chlorin e6. Thus, BSA-Au NCs could be used not only as photoluminescent agents, but also as photosensitizing agents in the photodynamic therapy of cancer.