RUI: Characterizing the birth of a nanoparticle: toward molecular control over nanoparticle synthesis

San Francisco State University, San Francisco CA

Investigators

Abstract

Scientists are striving to gain precise control over the creation of nanoparticles and nanomaterials. If this goal is achieved, society will gain access to customizable nanomaterials that can be made-to-order for applications including targeted drug delivery, diagnostic imaging and chemical separations. However, while scientists understand how nanoparticles grow in size, it is still not clear how nanoparticles are born. Without understanding this very first step of nanoparticle formation, scientists cannot rationally design protocols that will deliver custom nanomaterials. In this project, Professor Krista Vikse of San Francisco State University conducts experiments to uncover the exact details of how the seed of a nanoparticle forms. At the same time, Professor Vikse is developing enhanced educational infrastructure for undergraduate students who are working in an active chemical research laboratory for the first time. Scannable Quick Response (QR) codes are being incorporated into the physical research space. Using their cell phones, student can scan these codes to link to relevant virtual training materials on-demand. In this way, Dr. Vikse is aiming to make STEM research more accessible and less intimidating for all students, with a particular focus on groups of students who are underrepresented in the field of chemistry. With funding from the Macromolecular, Supramolecular and Nanochemistry Program of the NSF Chemistry Division, Professor Krista Vikse of San Francisco State University is elucidating the atomically precise mechanism for the early reduction and nucleation events in gold citrate nanoparticle formation. The focus is on the first stage of formation as the clusters grow from 2 - 10 metal atoms. To this end, nanoparticle synthesis reaction mixtures are monitored in operando using pressurized sample infusion mass spectrometry (PSI-MS). Kinetic data are collected for all reactive species. Key intermediates are intercepted within the mass spectrometer and gas-phase ion-molecule reactions are conducted to probe the structure and inherent reactivity of each intermediate. Finally, Density Functional Theory (DFT) calculations elucidate detailed structure-activity relationships based on the experimentally collected gas-phase data. A complete molecular understanding of the formation of gold nanoparticles facilitates the rational design of metallic nanoparticle cores and also informs the field of metal cluster catalyzed reactions. As an integral part of this project, Dr. Vikse and her students develop and test educational infrastructure for undergraduate students who are working in an active research laboratory for the first time. Scannable Quick Response (QR) codes are placed in key locations around the laboratory giving students direct, on-demand access to virtual instructional materials using their cell phones. This allows for increased accessibility to standardized training and timely reminders of best practices in the laboratory. The goal is to improve student confidence in a STEM laboratory setting and ultimately attract students to the STEM profession. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.