Prof. Aryeh Frimer, of the Department of Chemistry and member of the Nano MedicineCenter at the Institute of Nanotechnology and Advanced Materials (BINA), is improving light-activated chemotherapy by fine-tuning the positioning of nano-particles within the cellular membrane.
Frimer and his team explore the chemistry of Active Oxygen Species (AOS) within lipid bilayers, and attempt to determine the depth at which AOS and other intercalants penetrate the cellular membrane.
Free radicals are molecular fragments with unpaired electrons. Despite the pivotal role of free radical processes in nature, free radical damage presents a serious and constant threat to living organisms.
One of the clearest sources of radicals in the body is superoxide anion radical [O2-], which is formed in many biologically important reactions in both enzymic and non-enzymic processes.
Using KO2/crown ether complex as their source of O2– in aprotic solvents, Frimer’s lab has been studying the organic chemistry of this species with vitamin C derivatives, steroids and flavones. They have also initiated a study of the reactions of O2– , hydroxy and hydroxyalkyl radicals, and singlet oxygen with organic substrates intercalated in the lipid bilayer of liposomes, biological membranes and erythrocyte ghosts, in the hope of understanding the action of these active oxygen species within cell membranes.
Decades of research have elucidated the fundamental role played by the cell membrane in regulating the transport of chemicals and nutrients into and out of the cell. Increasingly, the focus has moved from the aqueous areas of the cell to the lipophilic membrane itself.
Using both chemical and spectral techniques (NMR, ESR and fluorescence), Frimer proposes to develop chemical probes and a “molecular ruler” to measure the angstrom depth of intercalants and active oxygen species within the lipid bilayer of liposomes and biological membranes. His ultimate goal will be to demonstrate a correlation between the location/orientation of the substrate/intercalant within the bilayer and its reactivity.
High-performance, low-density polyimides and polymer-matrix composites (PMCs) are finding increasing application in various industries (including transportation, communication, construction and aerospace), in part as metal replacements.
Much time, money and effort continue to be invested in attempts to improve the long-term thermal-oxidative stability (TOS) of these important polyimides. Frimer’s team uses modern synthetic, spectroscopic and thermo-analytical techniques in order to gain further insight into the chemical changes that occur during the high temperature degradation and oxidation of polyimides, and relates these changes to the concomitant macroscopic changes. Most recently they have explored PMR-polyimides endcapped with 7-hydroxy, 7-fluoro and 7,7-difluoro nadic endcaps.
Frimer and his research team are primarily interested in the organic chemistry of Active Oxygen Species, e.g. singlet and triplet molecular oxygen, superoxide anion radical, and peroxides, and their role in metabolism, aging and cancer.
They are also interested in investigating the thermal-oxidative stability of aerospace polyimides, as well as stabilization and neutralization of high energy compounds.