Biochemistry

Controlling Selectivity Using Electro-Photochemical Biocatalysis
 

Ava Kwan
Baylor University
 

Organic synthesis is vital to numerous industries and is a growing field. Researchers are concerned with controlling stereoselectivity, regioselectivity, and enantioselectivity. Current methods produce large amounts of waste and toxins while having low product yields. Electrochemistry reduces or eliminates the need for toxic solvents. Electrocatalysis, biocatalysis, and photoexcitation are utilized to develop a sustainable and effective method for producing organic compounds while controlling stereoselectivity. This research will utilize ‘ene’-reductase enzymes to understand their stereoselectivity and efficiency in hydrogen atom transfer reactions. This research will require the expression and purification of the ‘ene’-reductase, as well as electrochemical experiments using cyclic voltammetry methods. Due to the qualities of the enzyme, a reductive mediator is used to bring electrons from the electrode to the enzyme, allowing for bio-electrocatalysis to occur. Light photons will photoexcite the ‘ene’-reductase’s cofactor, thereby increasing reaction efficiency. The results showed increased catalysis in the presence of ‘ene’-reductase and with the addition of light. The increased catalysis was assessed by analyzing the current response from the cyclic voltammetry experiments. These findings will help researchers manipulate stereoselectivity, regioselectivity, and enantioselectivity to increase product yield. Overall, a sustainable technique will be developed to produce organic substances that could be used in pharmaceutical, agricultural, and energy industries. 
I would like to acknowledge Baylor University for its opportunities, the Chemistry and Biochemistry Department for support, the McNair Scholars Program for guidance, the Welch Foundation for funding, Dr. Dylan Boucher for mentorship, and Anne Gaudard Corrêa Rangel for including me as part of her research.

Expansion of Direct Quantum Yield Measurement for Complex Ligand-to-Metal Charge Transfer Photocatalysts Using Cyclic Voltammetry

Weitong Gao
Baylor University

Organic radicals are highly reactive intermediates that play a critical role in modern organic synthesis. However, their selective generation and controlled utilization remain challenging due to competing side reactions. Investigating the ligand-to-metal charge-transfer kinetics of organometallic catalysts can provide critical insight into developing a generalizable framework for controlled radical generation. The integration of electrocatalytic and photochemical methodologies enables highly reducing and oxidizing reactions, which can be examined using electroanalytical techniques such as cyclic voltammetry. In this work, bond homolysis complex ligand-to-metal charge-transfer catalytic systems, specifically cobalt tetraphenylporphyrin and copper chloride, are investigated under electrophotocatalytic conditions. The reaction mechanism is probed by varying substrate concentration, voltammetric scan rates, and irradiation intensity. Electrochemical analysis of these ligand-to-metal charge-transfer catalyst systems provides evidence of photoinduced bond homolysis under combined electrochemical and photochemical activation while establishing direct quantum yield measurements across different catalytic systems. Further studies will expand the investigation to additional ligand-to-metal charge-transfer catalytic systems to establish parameters for a direct quantum yield measurement method applicable to inorganic, organic, and biological systems.

The Discovery of Lymphatic Loss during Blood Vessel Growth
 

Natalie Luna1
Florida International University

Investigating blood and lymphatic vessel growth is important for developing regenerative therapies, inflammation management, and understanding diseased environments. Blood and lymphatic vasculature work together to maintain proper fluid balance and regulate inflammation. For this reason, both vessels are assumed to grow at the same time. However, few studies have determined when, how, and if lymphatic vessels grow during angiogenesis, the growth of new blood vessels.  The objective of this study was to quantify the presence of lymphatic vessels during cancer angiogenesis. Human lung carcinoma cells were transplanted onto adult male WISTAR rat mesentery tissues. The tissues were harvested 3 and 5 days post transplantation.  PECAM and LYVE-1 labeling were used to identify blood and lymphatic vessels. Lymphatic vessel length was quantified for tissue regions without blood vessels (avascular) and angiogenic vascular regions. Significant decreases in lymphatic length for both region types were found across tissues from unstimulated Day 0 to angiogenic time points Day 3 and Day 5. A decrease in lymphatic length was also found within Day 5 tissues from the avascular to vascular regions. The results indicate that lymphatic loss occurs during angiogenesis, suggesting a new paradigm for understanding the relationships between angiogenesis and lymphangiogenesis.