With this award, the Chemical Measurement and Imaging Program in the Division of Chemistry is supporting Professor Steven Eppell at Case Western Reserve University and Professor Fredy Zypman at Yeshiva University to develop a scanning probe-based technique to map charge onto the surfaces of nanoparticles and molecules with sub-10 nm resolution. Studying charge distributions is an old problem for which fundamental understanding of the process is still lacking. Gaining insight into those fundamentals is expected have broader scientific impact in areas such as self-assembly at interfaces and macromolecular interactions. The project will also provide training opportunities for graduate and undergraduate students through both research activities and the development of a new interdisciplinary lab/theory course on "SFM (Scanned Force Microscopy) Use in Basic Science". Both PIs actively recruit and engage talented junior students, especially those from underrepresented groups.
The proposed research uses high speed digitization of passive sensors coupled with a theory that reliably converts sensor position into force curves and maps charge onto surfaces of nanoparticles and molecules submerged in electrolytes with sub-10 nm resolution. The proposed research objectives are (1) to develop a measurement process that converts experimental scanned force microscope force-distance curves into charge density measurements on an object of interest with sub-10 nm spatial resolution; (2) to calibrate the system using known charged nanospheres; and (3) to demonstrate the proposed approach to study the self-assembly and mechanics of collagen nanofibrils, the formation of nanochains and the creation of rechargeable heavy metal cation chelators using magnetic nanoparticles. The technical approach being developed has the potential to impact the discovery process for new materials by allowing existing theories to be matched with experimental measurements of charge distribution, and by allowing synthetic chemists to identify sub-populations of desired products existing within a larger group of otherwise undesired byproducts.
