Graduate Student

Title: Electrodeposition of Nickel-Iron Nanoclusters onto Glassy Carbon for Low-Cost Detection of Organic Pollutants

Department of Chemical and Biomolecular Engineering

Email: bahrola@clarkson.edu

Advisor: Elizabeth Podlaha-Murphy

Abstract: Methylene blue (MB) is a redox-active molecule, which is used for biochemical studies as a redox indicator, and as a comparable model for pyocyanin, a bacteria metabolite. In this study, a low-cost approach was used to develop a novel Ni–Fe/glassy carbon (GC) composite electrode to detect methylene blue. Ni-Fe microstructures were deposited from a sulfate-boric acid electrolyte at a pH of 3 by a pulse galvanostatic method. The adsorption behaviors of MB were characterized with chronoamperometry and the results were confirmed by electrochemical impedance spectroscopy (EIS) in 10 mM phosphate buffer solution (PBS) with variable µM amounts of MB.

The electrodeposition results showed interesting morphology and composition that impacted the MB electrochemistry. The average composition of Ni-Fe clusters with a 2 s deposition time and without rotation was Ni-rich, and the morphology of the microscale clusters was composed of nanoscale nuclei in a circular shape with a hole in its center. The average composition of Ni-Fe clusters with a 6 s deposition time and 400 rpm rotation rate had a contrasting composition, Fe-rich, and the morphology demonstrated microscale clusters with crack. The Ni-Fe clusters impacted MB chronoamperometry, enhancing the response particularly for low concentrations of MB. Deviations from linearity in a plot of it1/2 vs. t indicated that the response at times below 100 s is a combination of capacitive and diffusion effects, where the Ni-Fe/GC composite electrode had a significantly larger current signal, but with diffusion behavior observed at long times. The results show that the time constant for enhanced electrochemical detection of MB with the Ni-Fe clusters is an important factor and adsorption plays a role in the overall capacitance.

Graduate Student

Title: Electrochemically stimulated molecule release associated with interfacial pH changes

Department of Chemistry & Biomolecular Science

Email: bellarm@clarkson.edu

Advisors: Artem Melman and Evgeny Katz

Abstract: Stimuli responsive materials are extremely important in many applications in biomedical and biotechnological field. Over past several decades, a large number of materials/systems which respond to the various activating/deactivating signals have been proposed and developed. External stimuli controlled release of therapeutic agents is one among such systems. In this field a large variety of stimuli such as pH, temperature, light, magnetic field and many more have been exploited to achieve signal stimulated release of drugs/biomolecules. Electrochemically triggered release of (bio)molecules is gaining attention due to the simplicity and easy integration of those systems with sophisticated electronic devices. These methods take advantage of some common phenomenon such as formation/cleavage of redox bonds (for example; disulfide linkages), electrostatic association/dissociation, and entrapping/releasing the (bio)molecules from the (bio)polymer gels for achieving immobilization and electrochemically stimulated release. While these methods are powerful, they have their own limitations (for example, reduction of disulfide bonds is significantly complicated in presence of other redox species). Hence to design an universal approach for electrochemically triggered release of (bio)molecules, we investigated the development of a hydrolysable linker at mild basic (pH 8-10) conditions. Herein we report a new linker with a hydrolysable phenolic ester bond at basic pH (~8-10) for electrode modification. Basic pH locally produced at the electrode surface upon electrochemical reduction of oxygen resulted in the hydrolytic cleavage of the phenolic ester bond and release of the immobilized fluorescent dye used as a model compound.

Research Associate

Title: Wide Bandgap III-Nitride Semiconductors for Electronics and Optoelectronics Applications

Department of Electrical and Computer Engineering

Email: dborovac@clarkson.edu

Phone: 315-268-6511

Advisor: Chee-Keong Tan

Abstract: The advances in III-nitride semiconductor technologies over the last few decades have propelled this class of semiconductors and attracted a significant amount of research activities globally. As the demand for efficient solid-state lighting and high-power applications increases, the search for innovative material and design approaches are becoming more valuable. In this talk a brief overview of dilute-anion and III-nitride semiconductors will be given, with the emphasis on recent findings pertaining their optoelectronic properties and potential applications of these material systems. Additionally, experimental works on the synthesis of the AlInN semiconductor via metalorganic chemical vapor deposition and its use for power applications will be discussed.

Graduate Student

Title: Electrochemical control of catalytic activity of immobilized enzymes

Department of Chemistry & Biomolecular Science

Email: kadambvk@clarkson.edu

Advisors: Artem Melman and Evgeny Katz

Abstract: Enzymatic networks utilizing concerted work of multiple enzymes are the central part of cellular machinery. Selective switching and tuning of catalytic activity of enzymes in these networks is the key property of living systems allowing detection and amplification of external signals, keeping cellular homeostasis, and controlling every aspect of their functioning. Natural processes in living cells are carefully orchestrated through entangled regulation of a large number of enzymes using allosteric regulation, covalent modification of enzymes, protein-protein interactions, and controlled gene expression. Hence it is important to control the enzyme activities for various applications such as biomimetic artificial systems involving enzymes, where in various chemical/biochemical reactions are needed to be controlled. Herein we report the regulation of the catalytic activity of enzymes immobilized on carbon nanotube electrodes, achieved by changing their local pH by using electrochemical reactions. Reduction of oxygen was used to increase the interfacial pH while the oxidation of ascorbate was used to decrease the interfacial pH, hence allowing changing rates of enzymatic reactions of electrode immobilized amyloglycosidase and trypsin enzymes over wide pH range.

Graduate Student

Title: Sensing Interfaces for Stimulated Biomolecule Release

Department of Chemistry & Biomolecular Science

Email: masim@clarkson.edu

Advisor: Evgeny Katz

Abstract: Signal-stimulated (bio)molecular release has been extensively studied and reported in numerous research papers, reviews and books(1), being motivated by various biomedical and biotechnological applications. Among many other molecular, biomolecular and nano-size species, DNA molecules have been studied for the signal-controlled release, being highly important for gene delivery therapy, biosensors, biochips, unconventional biocomputing, and for many other applications. Various signals triggering DNA release have been used including application of altering electromagnetic field, photochemical capture and release of DNA, thermally stimulated release of DNA, etc. Electrochemically triggered DNA release is particularly attractive due to its simple realization and versatility. Specifically, these developed systems are designed for different release processes triggered by various signals (electrical, biomolecular, illumination, etc.), thus representing a general interfacial platform for controlled release of different biomolecules and nano-size species(2).

Herein, we report on the DNA releasing system controlled by local/interfacial pH changes triggered by a very small potential applied to reduce oxygen bioelectrocatalytically with the help of immobilized bilirubin oxidase (BOx). Notably, the DNA release was only a convenient model, while the developed approach can be adapted to the electrically stimulated release of any negatively charged (bio)molecules or nano-species(3).

1. Li, X.; Jasti, B. R. Design of Controlled Release Drug Delivery Systems, McGraw-Hill Education, New York, 2005.

2. Masi, M., Bollella, P. and Katz, E., 2020. Biomolecular Release Stimulated by Electrochemical Signals at a Very Small Potential Applied. Electroanalysis, 32(1), pp.95-103.

3. Masi, Madeline, Paolo Bollella, and Evgeny Katz. ""DNA Release from a Modified Electrode Triggered by a Bioelectrocatalytic Process."" ACS Applied Materials & Interfaces 11, no. 50 (2019): 47625-47634.