Alladi Ramakrishnan Hall

Mixed Self-Assembled Monolayers on Gold Nanoparticles: A Molecular dynamic study

V. Vasumathi

Department of Chemistry and Biochemistry, University of Porto, Porto, Portugal

Gold nanoparticles (AuNPs) coated with self-assembled monolayers (SAMs) of thiolates provide many unique properties of high reactivity to the living cells, stability over high temperatures, exceptional optical properties and translocation into the cells, etc., those that make them attractive in multiple potential applications, including sensing, catalysis, drug delivery, electron transfer efficiency, electrochemical charging, and molecular recognition. In fact, SAMs serve as a linker between the AuNPs and the environment, providing important properties to the material such as stability and solubility. AuNPs properties can be fine-tuned by grafting ligands onto them such that the physicochemical properties of their surfaces are controlled by the structure and chemistry of the anchored ligands. Therefore, understanding the structure of thiolate self-assembled monolayers (SAMs) on AuNPs has been an active area of research. In this talk, I start discussing, what are the possible ways to functionalize the gold nanoparticle and survey of studies on functionalized gold nanoparticle. Later on I will discuss the structural properties of mixed SAMs on gold(111) surface at three different arrangements and inspect their surface hydrophilicity. To understand the surface curvature effect on the properties of SAMs at three different arrangements, I present a detailed simulation study of the structural properties of hydrophobic-hydrophilic mixed SAMs on AuNPs at three different arrangements. The outcome of the above study concludes that the bending of longer thiols over shorter ones clearly depends on the thiols’ arrangements and chemical nature of their terminal groups. Next interesting question is: what is the optimum stripe thickness for thiols to be absorbed onto AuNPs without bending? Therefore, I discuss the effect of stripe thickness on structural morphology and hydration of SAMs. Later on, I will discuss the formation of Janus nanoparticles when droplets of different thiols are sprayed/dispersed in an extremely bad solvent that contains the gold nanoparticles. Finally, I will discuss about the binding nature of cytochromeC on AuNPs for the application of biosensors.