Lets congratulate Ryan Hefti for his recent publication, "Long-Range Correlated Fluorescence Blinking in CdSe/ZnS Quantum Dots" in J . Phys. Chem. C (online pre print, DOI: 10.1021/jp3084343). Ryan is advised by Dr. Pat Moyer (Physics and Optical Science) and this work was in collaboration with Dr. Marcus Jones (chemistry).
University of South Carolina, Department of Chemistry and Biochemistry
“INTERFACIAL CHEMISTRY OF SEMICONDUCTOR NANOCRYSTALS”
Colloidal semiconductor nanocrystals – a type of quantum dot (QD) – are well-known as bright, highly photostable inorganic fluorophores that can be well-suited to imaging applications in biology. Additionally, the delocalized electronic states present in nanoscale semiconductors should offer distinctive ways to interact with and report on the biological environment. Such applications require good control of the interfacial chemistry of inorganic nanoparticles: in particular, to guide the formation of core/shell heterostructures to optimize brightness, and to introduce a surface coating that can enable the particles to function properly in the biological environment while limiting hydrodynamic size and avoiding quenching of the QD excited state.
Significant progress has been made in identifying specific examples that comprise these features, especially for the case of metal chalcogenide semiconductors, but there remains only a limited understanding of the reaction mechanisms and thermodynamics associated with the elaboration of the surfaces of such particles with inorganic and organic layers.
I will describe recent work at USC in which we have investigated the formation of CdS shells on CdSe nanocrystals under alternating layer addition conditions to evaluate the proposed selective ionic layer adhesion and reaction (SILAR) mechanism of shell growth, and ongoing work to directly measure the thermodynamics of ligand exchange reactions as part of a long-term effort to negotiate the trade-offs of binding strength against other properties such as fluorescence in the design of molecular monolayer coatings for biological applications of QDs.
Monday, October 15, 2012 @ 4:00 PM in Burson 115. Refreshments served at 3:45 PM
East Carolina University, Department of Pharmacology & Toxicology, Brody School of Medicine
“UNDERSTANDING MAST CELL ACTIVATION IN THE DEVELOPMENT OF SAFE NANOTECHNOLOGIES”
Concern about the use of engineered nanomaterials (ENMs) has increased significantly in recent years due to potentially hazardous impacts on human health. Mast cells are critical for innate and adaptive immune responses, often modulating allergic and pathogenic conditions. Mast cells act in response to environmental danger signals such as IL-33 and the IL-1 like receptor ST2. We have examined the involvement of mast cells and the IL-33/ST2 axis in adverse responses to ENMs. Mice with normal mast cell populations exhibit significant ENM directed systemic and pulmonary inflammation, fibrosis, altered lung function and exacerbated cardiac IR injury. In contrast, these toxicological effects of ENMs were not observed in mice deficient in mast cells or mice with mast cells unable to respond to IL-33. Lastly, we have established that certain ENMs are capable of inducing mast cell activation in vitro. Our findings establish for the first time that mast cells orchestrate adverse immune effects to ENMs giving insight into a previously unknown mechanism of toxicity and thereby providing a realistic therapeutic target. Lastly, the use of mast cells and the IL-33/ST2 axis as a screening tool for ENM safety and in the preclinical development of nanomedicines will be presented.
Thursday, October 11, 2012 @ 3:30 PM in Burson 115. Refreshments served at 3:15 PM