Event
Bioengineering Seminar Series: Igor Medintz
Friday, November 21, 2014
9:00 a.m.
Pepco Room (1105), Jeong H. Kim Engineering Building
Associate Professor Ian White
ianwhite@umd.edu
Igor Medintz
Research Biologist IV
U.S. Naval Research Laboratory
Targeted Cellular Delivery of Quantum Dots for Biosensing Related Applications
Nanoparticles ranging from metallic nanocrystals to softer dendrimeric structures are being investigaged as novel platforms for decoration with proteins, peptides, nucleic acids, drugs, contrast agents, and the like, in pursuit of creating new functional biodevices along with nanomedicines and theranostic devices. Amongst these material, semiconductor quantum dots (QDs) are a potent prototypical nanoparticle due to their unique quantum confined properties including bright photoluminescence, photostability, non-trivial surface area and amenability to biosensing. In particular, we have been using QDs as a robust model platform for understanding the intricacies of nanoparticle cellular uptake. The most popular method for facilitating nanoparticle uptake into cells remains use of cell penetrating peptides. Despite their diverse sequences and structures, these peptides invariably take advantage of some type of endosomal uptake to accomplish cellular delivery where the QDs remain sequestered in this complex vesicular system. Preliminary screening of a peptide designed to deliver palmitoyl-protein thioesterase inhibitors to neurons indicated that it could potentially mediate endosomal escape of QDs in cultured cells. Detailed studies characterized properties relevant to the peptide’s ability to mediate cytosolic delivery of QDs to a wide range of cell-types, brain tissue culture and the developing neuronal system in a model chick embryo system in a remarkably non-toxic manner. An iterative structure-activity relationship analysis of the peptide was undertaken by discretely modifying key components including length, charge, fatty acid content and their order and this allowed us to define key motifs required for endosomal escape, to select more efficient escape sequences, along with unexpectedly identifying a sequence that specifically targeted QDs to cellular membranes. Finally, how this work and related efforts are leading to new QD bioapplications and addressing important issues related to this field in general will be discussed.
About the Speaker
Igor Medintz received his Ph.D. in molecular and cellular biology under Prof. Corinne Michels from the City University of New York in 1998. He carried out postdoctoral research on developing FRET-based genetic assays for diagnosing cancer under Prof. Richard A. Mathies in the College of Chemistry at the University of California, Berkeley. Since 2002 he has been at the Center for Bio/Molecular Science and Engineering of the U.S. Naval Research Laboratory in Washington, D.C. where he is currently head of the Laboratory for Bio/Nano Science and Technology. His research is focused on developing nanoscale energy transfer devices, understanding enzyme activity at nanoparticle interfaces, and designing biosensing hybrids that incorporate energy transfer for intracellular applications. He has published more than 150 papers, which have been cited approximately 18,000 times, and he is a co-inventor of 13 patents.
