Association and dissociation binding kinetics of ultrasmall gold nanoparticles with proteins

• Grant number: 21/01034-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2021
• End date: February 28, 2022
• Field of knowledge: Interdisciplinary Subjects
• Principal Investigator: Alioscka Augusto Sousa
• Grantee: André Ferreira Lima
• Host Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil

Abstract

Ultrasmall gold nanoparticles (AuNPs) (core diameter <3 nm) constitute an emerging and interesting class of nanomaterials. Due to their smaller sizes, these particles display special physico-chemical properties and distinct behavior in biological media compared to their larger counterparts (> 3 nm). Significantly, while protein interactions with larger AuNPs typically promote the formation of an irreversibly adsorbed layer of partially denatured proteins (hard corona), protein interactions with ultrasmall AuNPs are usually reversible and bear greater resemblance to classic biomolecular interactions (such as protein-protein interactions). In this context, a detailed biophysical characterization of the interactions between ultrasmall AuNPs and proteins is essential to understand how the particles can be designed as biomimetic structures capable of interacting with proteins in a controlled manner. Therefore, in this project, we will characterize the kinetics of association (kon) and dissociation (koff) of ultrasmall AuNPs with a model protein (trypsin). The kon and koff kinetic constants carry characteristic information about molecular mechanisms of interaction: knowledge about kon allows to identify intermediate reaction steps separated by energy barriers, while knowledge about koff allows to calculate the residence time of the final complex, which in turn is related to the stability of the binding interface. The techniques of surface plasmon resonance (Biacore system) and stopped-flow spectroscopy will be used in the kinetics characterization. In combination with other results, the kinetics data will be used to propose a mechanistic model of the interactions studied here. (AU)