Biomolecular and cellular interactions of ultrasmall gold nanoparticles

Abstract

Ultrasmall gold nanoparticles (usGNPs) with core diameters below 3 nm constitute an emerging, special class of nanomaterials owing to their distinctive physicochemical properties and unique biological behaviors. These particles support a wide array of biomedical and basic science applications, including enzyme function regulation, biosensing applications, antimicrobial applications, cancer diagnosis and therapy, among others. However, despite all the progress so far, we are still far from understanding fundamental aspects of the biointeractions of usGNPs at the molecular and cellular levels. Therefore, here we propose to undertake a set of biochemical, biophysical and cell biology studies to advance our fundamental knowledge of the nano-bio interactions of usGNPs, with a special focus on the molecular aspects. The overall project consists of three main areas of investigation, which are currently under study in our laboratory. Subprojects 1 and 2 deal with the molecular biointeractions of the usGNPs, addressing mechanisms of interaction and regulation of protein function, while Subproject 3 deals with the cellular biointeractions of the usGNPs, focusing on the process of endocytosis. Subproject 1: The association and dissociation kinetics of usGNP-protein complexation will be characterized by stopped-flow spectroscopy. A mechanistic interaction model will be proposed based on a quantitative analysis of the kinetic data. Subproject 2: The impact of usGNPs on the structure and function of enzymes will be assessed by a combination of biophysical and enzyme activity measurements. The investigations will focus on the allosteric regulation of thrombin activity through the modulation of the active-site conformation upon usGNP binding. Subproject 3: The uptake of fluorescent usGNPs by wild-type and mutant (surface glycosaminoglycan-deficient) CHO cell lines will be studied by flow cytometry. The aim here will be to understand the particular influence of the highly anionic glycosaminoglycans on usGNP cellular internalization. (AU)