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Research Highlights

Chemistry Department Research Highlights

Ma group and collaborators publish bio-inspired uranium nano-traps in Nature Communications

>> May 17, 2018

Bio-inspired Uranium Nano-traps.
Bio-inspired Uranium Nano-traps.

With nuclear power generation expected to increase over the coming decades to meet the increasing global energy demand, access to this unconventional reserve is a matter of energy security. Reserves of such non-renewable raw materials are often limited to a few countries. Uranium is one such “critical metal” and as estimated by the International Atomic Energy Agency (IAEA), the total identified conventional resources can only last for about a century. However, it is estimated that there is an astonishing 4 billion metric tons of uranium dissolved in the Earth’s oceans at a concentration of 3.3 ppb, which is approximately 1000 times more than is available from terrestrial ores, affording a near limitless supply of uranium. With this knowledge, technology development capable of sequestering uranium from seawater in an economic manner would afford a financial backstop, ensure resource accessibility to nations devoid of uranium reserves, and impede any dramatic fluctuations in the uranium supply chain. Given the extreme complexity and vast volume of seawater, as well as very low concentration of uranium in it, to attain this ambitious task demands the design of adsorbents with high affinity and fast kinetics.

The Ma group we developed an effective approach to regulate uranyl capture performance by creating bio-inspired nano-traps, illustrated by constructing chelating moieties into porous frameworks, where the binding motif’s coordinative interaction towards uranyl is enhanced by introducing an assistant group, reminiscent of biological systems. The porous framework bearing 2-aminobenzamidoxime is exceptional in sequestering high uranium concentrations with sufficient capacities (530 mg-1) and trace quantities, including uranium in real seawater (4.36 mg g-1, triple the benchmark).

Cai, Ma, and Van Der Vaart publish novel peptidomimetic architecture in JACS and the paper was selected for the cover of JACS

>> May 7, 2018

3D supramolecular network of dimer formed through self-assembly
3D supramolecular network of dimer formed through self-assembly

Dr. Jianfeng Cai, collaborated with Dr. Shengqian Ma and Dr. Arjan van der Vaart, reported a novel hydrogen-bonding-driven 3D assembly of artificial protein (a peptidomimetic zipper) for the first time by using an α/AApeptide zipper that assembles into a de novo lattice arrangement through hydrogen-bonded linker-directed interactions as well as intermolecular C‒Cl∙∙∙Cl‒C halogen bonding and hydrophobic interactions. The JACS communication paper titled “Hydrogen-Bonding-Driven 3D Supramolecular Assembly of Peptidomimetic Zipper” was published this May 2, and was selected as the cover. As the first example of an unnatural peptidic zipper, the dimensional augmentation of the zipper in this paper differs from metal-coordinated strategies, and may have general implications for the preparation of peptidic functional materials for a variety of future applications.

Woodcock group and collaborators publish paper on PETase in PNAS

>> April 23, 2018

A study published in PNAS by Dr. Woodcock (Associate Professor of Chemistry) and collaborators elucidates how PETase breaks down polyethylene teraphthalate (PET), the most commonly manufactured plastic material. This enzyme was isolated from a bacterium found in a Japanese recycling plant in 2016. After its discovery, researchers at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL), at the University of Portsmouth, and at the University of South, led a joint interdisciplinary effort to understand how PETase works. Additionally, during their investigation, they inadvertently improved the activity of PETase, and Dr. Woodcock and graduate students Fiona Kearns and Ben Pollard used computational techniques to understand this improved activity.

Woodcock group and collaborators publish paper on PETase in PNAS
PETase breaks down polyethylene teraphthalate (PET)

The study is particulary significant, giving the enormous accumulation of plastics in the environment: it is estimated that 5-13 million metric tons of plastic finds its way in the ocean every year, corresponding to 1-3 garbage trucks of plastic every minute.

Li group and collaborators publish emissive supramolecules in Nature Communications

>> February 8, 2018

Coordination-driven self-assembly has emerged as a powerful bottom-up approach to construct various supramolecular architectures with increasing complexity and functionality. Dr. Li and his collaborators constructed a series of supramolecular materials with precisely-controlled rosettes-like structures. Such supramolecules display tunable emissive properties with respect to different generations, particularly, pure white-light emission.

Li Group Nature Communications
Self-assembled supramolecules with rosette-like structures

Dr. Xiaopeng Li, Assistant Professor in the Chemistry Department at USF, reports the self-assembly of three generations of giant supramolecules with rosettes-like structures. Such supramolecules display tunable emissive properties with respect to different generations, particularly, pure white-light emission. His Nature Communications paper entitled "Self-assembly of emissive supramolecular rosettes with increasing complexity using multitopic terpyridine ligands" was published this February.

Most traditional fluorophores only exhibit emission in dilute solution but not in aggregation state due to aggregation caused quenching (ACQ) phenomenon. Dr. Li and his team introduced two levels of restrictions to minimize the intramolecular rotation through elaborate molecular design. They obtained strong emissive supramolecular materials in both solution and aggregation states. Another striking discovery is that G2 exhibited highly pure white light emission property under a wide range of good/poor solvents ratios. The single-component white light emitter is expected to exhibit superior performance improved stability, good reproducibility, and simple device fabrication procedure compared to those multi-component emitters. The team eventually named those structures as supramolecular rosettes, and hopefully, they can give out a bright light in both supramolecular chemistry and emissive materials community to inspire us to seek more complicated structures with tunable properties. The team was also invited by Nature Communications to write a story Behind the Paper.

Gelis group and collaborators publish ground-breaking paper on Hsp90 in Nature Communications

>> January 26, 2018

Dr. Ioannis Gelis, Assistant Professor in the Chemistry Department at USF, reports a ground-breaking study on the Hsp90 chaperone. His Nature Communications paper entitled "Phosphorylation induced cochaperone unfolding promotes kinase recruitment and client class-specific Hsp90 phosphorylation" was published this January. The study shows how phosphorylation controls the timely progression of the critical Hsp90 machinery through different steps of the chaperone cycle and resulted in a more complete understanding of its mechanism, which will aid cancer drug development.

Gelis group Nature Communications
Prof. Ioannis Gelis and graduate student Ashleigh Bachman

Hsp90 is important for cancer and helps other proteins fold. It needs the Cdc37 cochaperone to mediate folding of protein kinases, in a cycle regulated by phosphorylation. Using high field NMR, the Gelis lab showed that phosphorylation of Cdc37 results in partial unfolding of Cdc37. The unfolding did not affect Cdc37 association with the machinery, but revealed a SH2 domain binding motif, which recruited other kinases to subsequently phosphorylate Hsp90. The latter phosphorylation caused dissociation of Cdc37 from the Hsp90 complex, without affecting the interaction with other cochaperones. Aspects of the study were validated by cellular experiments in collaboration with Dr. Len Neckers' group from the National Cancer Institute at NIH, and computer simulations by Dr. Arjan van der Vaart's group in the Chemistry Department at USF.