The Lawrence Group works at the interface between organic synthesis and cell biology. In fact, half the group resides in Chemistry's Kenan Labs and the other half can be found in the newly opened multidisciplinary Genetic Medicine Building in the medical school complex. The lab focuses on the design, synthesis, characterization, and application of probes of intracellular chemistry. Research interests include new diagnostic strategies for cancer, sensors of signaling pathways, mitochondrial proteomics, the molecular basis of memory and learning, and the control of gene expression in living animals.
The Waters Group is an interdisciplinary group, focusing on problems of molecular and biomolecular recognition. Molecular recognition impacts a wide range of fields, including asymmetric catalysis, materials chemistry, and protein folding. Consider, for example, designing a drug to bind to the active site of an enzyme. What features other than shape might contribute to binding? What types of interactions will provide high affinity as well as high selectivity? These are general questions in the field of molecular recognition that the Waters Group investigates for applications to biosensing, drug delivery, and de novo protein design.
Chancellor's Eminent Professor of Chemistry Joseph DeSimone has been elected into the National Academy of Sciences, one of the highest honors that a U.S. scientist or engineer can receive.
DeSimone is one of 84 new members and 21 foreign associates from 14 countries elected into the academy. He is the 12th UNC-Chapel Hill faculty member to be elected to the academy, a private organization of scientists and engineers dedicated to advancing science and technology and their use for the public good.
New methods to direct the self-assembly of particles are highly sought after for multiple applications, including photonics, electronics, and drug delivery. Most techniques, however, are limited to chemical patterning on spherical particles, limiting the range of possible structures.
As published in JACS, the DeSimone Group, in collaboration with the Sheiko Group, has developed a lithographic technique for fabrication of chemically anisotropic rod-like particles in which both the size and shape of particles can be specified, while implementing multiple diverse materials to control interfacial interactions. Multiphase rod-like particles, including amphiphilic diblock, triblock, and multiblock were fabricated in the same template mold having a tunable hydrophilic/hydrophobic ratio. Self-assembly of diblock or triblock rods at a water/oil interface led to the formation of bilayer or ribbon-like structures.
The roles of nitric oxide, NO, in physiology and pathophysiology merit the use of NO as a therapeutic for certain biomedical applications. Unfortunately, limited NO payloads, too rapid NO release, and the lack of targeted NO delivery have hindered the clinical utility of NO gas and low molecular weight NO donor compounds.
A wide-variety of NO-releasing macromolecular scaffolds has thus been developed to improve NO's pharmacological potential. In a series of tutorial reviews from the Schoenfisch Group, published in Chemical Society Reviews, the initial article provides an overview of the most promising NO release scaffolds including protein, organic, inorganic, and hybrid organic-inorganic systems. The NO release vehicles selected for discussion were chosen based on their enhanced NO storage, tunable NO release characteristics, and potential as therapeutics.
Congratulations to all students who were recognized at this year's Chemistry Commencement ceremony. Chemistry is considered one of the most demanding degrees offered at Carolina.
Professor and Department Chair Matthew Redindo delivered the welcome address, after which followed the doctoral hooding ceremony, presided over by Professor Mark Schoenfisch, Director of Graduate Studies. Miss Eva Archer then delivered the undergraduate student commencement address.
Dr. Marcey Waters, Professor and Director of Undergraduate Studies presented the undergraduate student awards. Congratulations to all winners.
Francis P. Venable Medal
Matthew Detter
Sophie Liu
Emmett Gladstone Rand Premedical Scholarship
Ryan Gardner
Kathryn Magee
Garrick Talmadge
David L. Stern Scholarships in Chemistry
Xiaoling Zang
Merck Index Award
Stephen Barilovits IV
Srikar Bongu
Carrie Ann Largent Award
Sean Doris
Teresa Long
Hypercube Scholar Award
Hannah Gavin
The Schoenfisch Group describes in ACS Applied Materials & Interfaces, the synthesis of a tertiary thiol-bearing silane precursor, such as N-acetyl penicillamine propyltrimethoxysilane or NAPTMS, to enable enhanced NO storage stability at physiological temperature. The novel silane was co-condensed with alkoxy- or alkylalkoxysilanes under varied synthetic parameters, for example water to silane ratio, catalyst and solvent concentrations, and reaction time, to evaluate systematically the formation of stable xerogel films.
The resulting xerogels were subsequently nitrosated to yield tertiary RSNO-modified coatings. Total NO storage ranged from 0.87 to 1.78 µmol cm–2 depending on the NAPTMS concentration and xerogel coating thickness. Steric hindrance near the nitroso functionality necessitated the use of photolysis to liberate NO. The average NO flux for irradiated xerogels —20% NAPTMS balance TEOS xerogel film cast using 30 µL— in physiological buffer at 37 ℃ was ~23 pmol cm–2 s–1. The biomedical utility of the photoinitiated NO-releasing films was illustrated by their ability to both reduce Pseudomonas aeruginosa adhesion by 90% relative to control interfaces and eradicate the adhered bacteria.
Electrochemical detection with carbon-fiber microelectrodes has become an established method to monitor directly the release of dopamine from neurons and its uptake by the dopamine transporter. With constant potential amperometry (CPA), the measured current provides a real time view of the rapid concentration changes, but the method lacks chemical identification of the monitored species and markedly increases the difficulty of signal calibration. Monitoring with fast-scan cyclic voltammetry (FSCV) allows species identification and concentration measurements but often exhibits a delayed response time due to the time-dependent adsorption/desorption of electroactive species at the electrode.
Researchers in the Wightman Group, as published in ACS Chemical Neuroscience sought to improve the temporal resolution of FSCV to make it more comparable to CPA by increasing the waveform repetition rate from 10 to 60 Hz with uncoated carbon-fiber electrodes. The faster acquisition led to diminished time delays of the recordings that tracked more closely with CPA measurements. The measurements reveal that FSCV at 10 Hz underestimates the normal rate of dopamine uptake by about 18%. However, FSCV collection at 10 and 60 Hz provide identical results when a dopamine transporter (DAT) blocker such as cocaine is bath applied.
To further verify the utility of this method, the group used transgenic mice that overexpress DAT. After accounting for the slight adsorption delay time, FSCV at 60 Hz adequately monitored the increased uptake rate that arose from overexpression of DAT and, again, was similar to CPA results. Furthermore, the utility of collecting data at 60 Hz was verified in an anesthetized rat by using a higher scan rate (2400 V/s) to increase sensitivity and the overall signal.