Detection, identification and characterization of single nanoparticles based on plamonic visualization of their electrochemical dissolution

• Applicant: Professor Dr. Vladimir M. Mirsky
• Subject Area: Analytical Chemistry
• Term: since 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 399234637

There is still a lack of highly sensitive analytical technique for routine analysis of nanoparticles. In the same time, a permanently increasing industrial production and application of nanoparticles increase a risk of human exposure to these potentially hazardous materials. The goal of the project is the development of a highly sensitive analytical method for detection, characterization and identification of nanoparticles in liquid media. The detection of nanoparticles will be performed using wide field surface plasmon microscopy - this technology allows one to detect single nanoparticles adsorbed on the gold surface. The measurements are performed on the electrodes of macroscopic size, this provides high sensitivity (below 100 nanoparticles per µL), high dynamic range (each nanoparticle from up to hundreds thousands is detected and analyzed individually) and the possibility to make reliable statistical analysis. Dependence of optical signals of nanoparticles on their size and composition provides a possibility to study electrochemical behavior of each individual nanoparticle without direct measurements of electrical current. Depending on the type of nanoparticles, their electrochemical conversions or electrocatalytical activity will be analyzed. For example, electrochemical dissolution of adsorbed nanoparticles, detected as the disappearance of their images (obtained by surface plasmon microscopy) at defined electrical potential applied to the gold layer, gives information on the chemical composition of each adsorbed nanoparticle. A small shift of the dissolution potential relative its thermodynamic value provides information on the size of nanoparticle. Kinetic limitations of electrochemical conversions of nanoparticles are expected to give information on the thickness of dielectric coating of nanoparticles. The first work package of the proposal is focused on optimization of experimental conditions for fast and complete electrochemical dissolution of a possibly wide range of metal nanoparticles. The results will be used in the second work package focused on the investigation of these processes using surface plasmon microscopy. High throughput analysis of optical data characterizing simultaneous electrochemical reactions on each from many thousands of nanoparticles requires a development and programming of sophisticated algorithms for image analysis, this is the main goal of the third work package. In the fourth work package the results will be extended to practically relevant oxide nanoparticles, non-aqueous electrolytes will be used to extend potential window. Finally (the fifth work package), the method will be applied for analysis of multicomponent systems containing nanoparticles of various composition, size and shape and for analysis of real samples containing nanoparticles in complex media.

• DFG Programme: Research Grants