The You Group focuses on the synthesis and characterization of novel multifunctional materials for a variety of applications, predominately in electronics and photonics. Challenges to be addressed include, for example, can a 10% solar cell be made through organic materials? Can single molecules serve as the fundamental unit for electronics and spintronics? Group members are working tirelessly to answer these questions by applying interdisciplinary approaches, including organic and polymer synthesis, surface chemistry, nano-patterning, device fabrication, and physical properties characterization using state-of-the-art instrumentation.
Research in the Alexanian Group focuses on the general areas of reaction development and chemical synthesis. Our studies are ultimately driven by the discovery of new and useful forms of chemical reactivity. A theme of these studies is an emphasis on catalytic transformations employing easily accessed substrates and common molecular functionality. We also use the wide array of unique architectures found in nature to challenge and inspire ourselves to develop creative solutions to current problems in complex molecule synthesis.
One current area of investigation is the utilization of simple hydroxamic acids to develop general, radical-mediated approaches to the metal-free difunctionalization of alkenes. We are also exploring novel approaches to the catalytic activation of alkyl electrophiles for the development of new carbon-carbon bond-forming processes, and the development of new complexity-generating multi-component cycloadditions for synthesis. Ultimately, we strive to apply these new processes to the efficient syntheses of bioactive natural and un-natural products.
The purpose of the NSF Graduate Research Fellowship Program, GRFP, is to help ensure the vitality and diversity of the scientific and engineering workforce of the United States. The program recognizes and supports outstanding graduate students who are pursuing research-based master's and doctoral degrees in science and engineering. The award provides three years of support for the graduate education of individuals who have demonstrated their potential for significant achievements in science and engineering. This year, the program received over 16,000 applications, and selected 2,000 recipients. Carolina Chemistry have eleven awardees, more than any previous year, representing 40% of UNC's total recipients.
From left to right:
Shannon McCullough – Cahoon Group, Desiree Matias-Lopez – Meek Group, Anginelle Alabanza – Forbes Group, Tyler Farnsworth – Warren Group, Rufai Ibrahim – Ashby Group, Tyler Motley – G. Meyer Group, Dillon Yost – Kanai Group, Wesley Swords – G. Meyer Group, David Hill – Cahoon Group, Adam Woomer – Warren Group, Alexandra Sullivan – Miller Group
Additive manufacturing processes such as 3D printing use time-consuming, stepwise layer-by-layer approaches to object fabrication. As published in Science, and becoming that issue's cover story, researchers in the DeSimone Group demonstrate the continuous generation of monolithic polymeric parts up to tens of centimeters in size with feature resolution below 100 micrometers.
Continuous liquid interface production is achieved with an oxygen-permeable window below the ultraviolet image projection plane, which creates a "dead zone," or persistent liquid interface, where photopolymerization is inhibited between the window and the polymerizing part. By delineating critical control parameters the researchers show that complex solid parts can be drawn out of the resin at rates of hundreds of millimeters per hour. These print speeds allow parts to be produced in minutes instead of hours, and have become "game changing" properties of this technology.
Researchers in the Schoenfisch Group, have published research in Acta Biomaterialia, where they describe how S-Nitrosothiol-modified chitosan oligosaccharides were synthesized by reaction with 2-iminothiolane hydrochloride and 3-acetamido-4,4-dimethylthietan-2-one, followed by thiol nitrosation. The resulting nitric oxide (NO)-releasing chitosan oligosaccharides stored approximately 0.3 micromol NO mg-1 chitosan. Both the chemical structure of the nitrosothiol, that is primary and tertiary, and the use of ascorbic acid as a trigger for NO donor decomposition were used to control the NO-release kinetics. With ascorbic acid, the S-nitrosothiol-modified chitosan oligosaccharides elicited a 4-log reduction in Pseudomonas aeruginosa viability.
Confocal microscopy indicated that the primary S-nitrosothiol-modified chitosan oligosaccharides associated more with the bacteria relative to the tertiary S-nitrosothiol system. The primary S-nitrosothiol-modified chitosan oligosaccharides elicited minimal toxicity towards L929 mouse fibroblast cells at the concentration necessary for a 4-log reduction in bacterial viability, further demonstrating the potential of S-nitrosothiol-modified chitosan oligosaccharides as NO-release therapeutics.
A unique event occurred at Carolina Chemistry on Tuesday, February 18th. We had three graduate students, all from the DeSimone Group, successfully defend their dissertations in the same day. Congratulations and all the best to Doctors Kevin Reuter, Dominica Wong, and Katie Moga!
We are very proud to announce that Kaitlyn Tsai has been selected as a Barry Goldwater Scholar. The Barry Goldwater Scholarship Program was established by Congress in 1986 to honor Senator Barry Goldwater, who served his country for 56 years as a soldier and statesman, including 30 years of service in the U.S. Senate. The purpose of the Foundation is to provide a continuing source of highly qualified scientists, mathematicians, and engineers by awarding scholarships to college students who intend to pursue research careers in these fields.
Kaitlyn Tsai is from Apex, North Carolina where she went to Apex High School. She feels that she came to the Department of Chemistry at Carolina, almost by accident since she came in with a lot of AP credit. Later, she has come to believe that choosing chemistry was one of the best decisions she could have made for her undergraduate studies. She claims that "between the amazing faculty and extensive opportunities for research," she has "become more inspired to pursue chemistry research." Her initial choice was to start as Chemistry B.S. major, but after taking genetics, she became more interested in the biological applications of chemistry and switched to the biochemistry track. Kaitlyn is currently conducting research in Dr. Marcey Waters' Bioorganic Chemistry lab, where she is part of a team investigating protein binding involved in histone methylation for epigenetic regulation. Dysregulation of histone methylation has been associated with certain types of cancers, and the eventual development of inhibitors molecules to correct for epigenetic malfunction is the end goal of this research. After graduation, Kaitlyn intends to enroll in a Ph.D. program in Chemistry, and hopes to continue epigenetic research. She would also like to stay in academia since it would give her the opportunity to teach and mentor. -Congratulations to the very prestigious award, Kaitlyn!
Protein quinary interactions organize the cellular interior and its metabolism. Although the interactions stabilizing secondary, tertiary, and quaternary protein structure are well defined, details about the protein–matrix contacts that compose quinary structure remain elusive. This gap exists because proteins function in the crowded cellular environment, but are traditionally studied in simple buffered solutions.
Researchers in the Pielak Group use NMR-detected H/D exchange to quantify quinary interactions between the B1 domain of protein G and the cytosol of Escherichia coli. In their work, published in PNAS, the group demonstrates that a surface mutation in this protein is 10-fold more destabilizing in cells than in buffer, a surprising result that firmly establishes the significance of quinary interactions. Remarkably, the energy involved in these interactions can be as large as the energies that stabilize specific protein complexes. These results will drive the critical task of implementing quinary structure into models for understanding the proteome.
Over the past decade, thermoplastics have been used as alternative substrates to glass and Si for microfluidic devices because of the diverse and robust fabrication protocols available for thermoplastics that can generate high production rates of the desired structures at low cost and with high replication fidelity, the extensive array of physiochemical properties they possess, and the simple surface activation strategies that can be employed to tune their surface chemistry appropriate for the intended application. While the advantages of polymer microfluidics are currently being realized, the evolution of thermoplastic-based nanofluidic devices is fraught with challenges. One challenge is assembly of the device, which consists of sealing a cover plate to the patterned fluidic substrate.
Typically, channel collapse or substrate dissolution occurs during assembly, making the device inoperable resulting in low process yield rates. Now, in an article published in Lab on a Chip as a "Hot Article," researchers in the Soper Group report a low temperature hybrid assembly approach for the generation of functional thermoplastic nanofluidic devices with high process yield rates, >90%, and with a short total assembly time of only sixteen minutes. The functionality of the assembled devices was demonstrated by studying the stretching and translocation dynamics of dsDNA in the enclosed thermoplastic nanofluidic channels.