CURRENT GROUP MEMBERS

ASSISTANT RESEARCH PROFESSOR
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Vignesh Sundaresan

vsundare@nd.edu

Ph.D., Temple University

B.Tech., Central Electrochemical Research Institute

My research focuses on understanding the reactivity of individual enzyme cofactors, enzymes, and bacteria using coupled optical and electrochemical techniques. I am particularly interested in exploring the potential-/controlled redox environment-dependent fluorescence dynamics of the fluorogenic flavin based entities, starting from its molecular state (flavin mononucleotide and flavin adenine dinucleotide) to its state as a cofactor or electron carrier in flavoenzyme (monomeric sarcosine oxidase) or bacteria (M. Xanthus) respectively. These studies help us to understand the contribution of individual molecules behavior to the ensemble average behavior and to elucidate the metabolic pathways in microbes.

POSTDOCTORAL ASSOCIATE

Seol Baek

sbaek3@nd.edu

M.S., Seoul National University
B.S., Seoul National University

With the availability of highly sophisticated nanofabrication, recently more challenging and elaborate studies for electron transfer reactions have been conducted using nanotechnologies. The investigation of electron transfer events in single biological redox enzyme is one of the important topics in low dimensional electrochemistry area. My research focuses on understanding the relationship between the condition of individual redox enzymes and the macroscopic phenomenon coming from an ensemble or bulk collection of the same enzyme molecules, with anticipation of distinguished individual behavior of molecules over their average properties. For observing electron transfer events in single enzyme molecule, electrochemical zero-mode wave guide (ZMW) structures in nanoscale are fabricated, where recessed duel-ring electrodes are employed for redox cycling to amplify faradaic currents. Combining electrochemistry with spectroscopy, electrochemical ZMW devices enable not
only the control of potential in environmentally confined nanopore structures, but also in situ measurement of the potential-dependent fluorescence dynamics of single enzyme molecules.

GRADUATE STUDENTS

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Allison Cutri

acutri@nd.edu

B.S., Temple University

Psuedomonas aeruginosa is an opportunistic pathogen responsible for many hospital-acquired infections, and its ability to form biofilms contributes to its high antibiotic resistance, making these infections difficult to treat. While many studies have been performed on P.aeruginosa biofilms and bulk colonies, not much research has been done on the behavior of single P. aeruginosa bacteria. My work focuses on designing micropore electrode devices to be able to trap single bacteria and study their behavior upon changes to the surrounding environment through spectroscopic and electrochemical techniques.

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Meredith Lee

mlee46@nd.edu

B.S., University of Alabama

Fentanyl is a highly addictive synthetic opioid that is commonly used in acute analgesia and chronic pain management. Due to its high potency in minute quantities(~2mg), illicitly manufactured fentanyl analogs have been progressively used as an adulterant and frequently associated with the alarming increase in opioid related drug overdose death, commonly referred to as the “Opioid Overdose Crisis” by the National Institute on Drug abuse. Hidden in less potent drugs like heroin and morphine, fentanyl presents a threat to unsuspecting users, emphasizing the demand for field-deployable testing on par with lab setting discrimination. While there are efforts to develop more low-cost field deployable handheld detection devices, most still fail in the need to quantify concentrations of fentanyl. In addition, gold standard detection methods like mass spectroscopy still undergo challenges in miniaturization and ease of use for quantitative analysis. 

My research aims to utilize the sensitivity and inherent miniaturization of electrochemistry and translate electrochemical signals to more simple optical intensities that can be quantified using electrochromic materials. This research will focus on optimization of signal amplification due to self-induced redox cycling inherent in closed bipolar electrochemistry through electrolyte and electrode surface modifications.

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Jarek Metro

jmetro2@nd.edu

B.S., Penn State University

Many biological entities are present in low concentrations and require high sensitivity and low limits of detection to effectively study analytes. Digital counting using Single Molecule Arrays (Simoa) is currently the method of choice for detection as it uses a fluorescence response from a femtoliter sized well containing one analyte, but it does not allow potential or redox control of the environment. My research focuses on adapting Simoa to create a method that allows single molecules to be probed in a potential or redox controlled environment.

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Christiana Oh
coh@nd.edu

B.E., The City College of New York

Cytokines are small (6-70 kDa), soluble proteins produced by many cells in the immune system that regulate responses to external pathogens such as cell-cell communication and inflammatory responses. Because cytokines are pervasive components of inflammatory-based disease, nearly every type of disease has involvement of cytokines as potential biomarkers; accordingly, these are widely used as biomarkers for diagnosis, tracking of disease progression as well as therapeutic monitoring. The aim of my research is to combine the advantages presented by electrochemical sensing, optical sensing and micro- and nanoscale architectures or materials to develop enhanced biosensing strategies for these protein biomarkers. I am studying a range of sensor structures, configurations, and transduction methods to achieve sensitive and reliable immunoassaying with an emphasis towards point-of-care (POC) applications. The strategies developed in this research focus on several approaches: separation of biorecognition and transduction schemes, signal amplification by improved geometric efficiency, improved sensor stability and resistance to biofouling (i.e. electrode passivation by adsorption of nontarget biomolecules), and enhanced analyte delivery via improved fluidic transport.

Julius Reitemeier

jreiteme@nd.edu

M.S., Heidelberg University
B.S., Heidelberg University 

From recent advances in nanofabrication methods, a new generation of smart devices emerged, reducing their critical dimension down from the micro- to the nanoscale and enabling ultrasensitive detection even on the single-molecule level. Employing nano-confinements in an electrochemical cell provides multiple benefits, including enhanced mass transport by dominant radial diffusion, decreased charging currents and reduced ohmic losses. Combining electron transfer events of various biomolecules with a nano-confined electrode geometry enables an attractive approach for ultrafast, real-time sensing “lab-on-chip” devices.

Amid the SARS-CoV-2 pandemic, rapid screening and identification of biomolecules is of utmost importance. Recent work within our group demonstrated the ability of detecting biomolecules by electron transfer events using nano electrode arrays (NEA), interdigitated electrode arrays (IDEA) or closed-bipolar electrodes (CBE). The achieved real-time response and ultrahigh sensitivity pave the way to electrochemical screen single-entity events, thus, my research focuses on fabricating and designing novel electrode low-volume nano-chips for rapid and cost-efficient diagnostics, minimizing the use of expensive and limited analytical equipment.

Rebecca Corrente

Laboratory Support Coordinator

rcorrent@nd.edu

 

325 Stinson-Remick Hall

Notre Dame, IN 46556

Phone: (574) 631-1260