More Like this

1. Laser-Trimmed, Surface-Functionalized Four-Bore CFMs Enable Co-Detection of Neurochemicals and Toxic Metal Ions

   https://doi.org/10.3390/chemosensors13120423  

   Udawaththa, Navoda; Daninger, Ashley; Manring, Noel; Guillen, Valentina; Koifman, Gene; Pathirathna, Pavithra (December 2025, Chemosensors)

   Simultaneous detection of multiple neurochemicals and toxic metal ions in real time remains a major analytical challenge in neurochemistry and environmental sensing. In this study, we present a novel, biocompatible, laser-trimmed four-bore carbon fiber microelectrode (CFM) platform capable of ultra-fast, multi-analyte detection using fast-scan cyclic voltammetry (FSCV). Each of the four carbon fibers, spaced nanometers apart within a glass housing, was independently functionalized and addressed with a distinct waveform, allowing the selective and concurrent detection of four analytes without electrical crosstalk. To validate the system, we developed two electrochemical detection paradigms: (1) selective electrodeposition of gold nanoparticles (AuNPs) on one fiber for enhanced detection of cadmium (Cd²⁺), alongside dopamine (DA), arsenic (As³⁺), and copper (Cu²⁺); and (2) Nafion-modification of two diagonally opposing fibers for discriminating DA and serotonin (5-HT) from their interferents, ascorbic acid (AA) and 5-hydroxyindoleacetic acid (5-HIAA), respectively. Scanning electron microscopy and energy-dispersive X-ray spectroscopy analysis confirmed surface modifications and the spatial localization of electrodeposited materials. Electrochemical characterization in tris buffer, which mimics artificial cerebrospinal fluid, demonstrated enhanced analytical performance. Compared to single-bore CFMs, the four-bore design yielded a 28% increase in sensitivity for Cd²⁺ (147.62 to 190.02 nA µM⁻¹), 12% increase for DA (10.785 to 12.767 nA µM⁻¹), and enabled detection of As³⁺ with a sensitivity of 0.844 nA µM⁻¹, which was not possible with single-bore electrodes within the mixture of analytes. Limits of detection improved twofold for both DA (0.025 µM) and Cd²⁺ (0.005 µM), while As³⁺ was detectable down to 0.1 µM. In neurotransmitter-interference studies, sensitivity increased by 39% for DA and 33% for 5-HT with four-bore CFMs compared to single-bore CFMs, despite modest Nafion diffusion onto adjacent fibers. Overall, our four-bore CFM system enables rapid, selective, and multiplexed detection of chemically diverse analytes in a single scan, providing a highly promising platform for real-time neurochemical monitoring, envi-ronmental toxicology, and future integration with AI-based in vivo calibration models. 

   more » « less
2. Employing Conductive Metal-Organic Frameworks for Voltammetric Detection of Neurochemicals

   https://doi.org/10.1021/jacs.9b13402  

   Ko, Michael; Mendecki, Lukasz; Eagleton, Aileen M.; Durbin, Claudia G.; Stolz, Robert M.; Meng, Zheng; Mirica, Katherine A (March 2020, Journal of the American Chemical Society)

   This paper describes the first implementation of an array of two-dimensional (2D) layered conductive metal–organic frameworks (MOFs) as drop-casted film electrodes that facilitate voltammetric detection of redox active neurochemicals in a multi-analyte solution. The device configuration comprises a glassy carbon electrode modified with a film of conductive MOF (M3HXTP2; M = Ni, Cu; and X = NH, 2,3,6,7,10,11-hexaiminotriphenylene (HITP) or O, 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP)). The utility of 2D MOFs in voltammetric sensing is measured by the detection of ascorbic acid (AA), dopamine (DA), uric acid (UA), and serotonin (5-HT) in 0.1 M PBS (pH=7.4). In particular, Ni3HHTP2 MOF demonstrated nanomolar detection limits of 63 ± 11 nM for DA and 40 ± 17 nM for 5-HT through a wide concentration range (40 nM – 200 µM). The applicability in biologically-relevant detection was further demonstrated in simulated urine using Ni3HHTP2 MOFs for the detection of 5-HT with nanomolar detection limit of 63 ± 11 nM for 5-HT through a wide concentration range (63 nM – 200 µM) in the presence of constant background of DA. The implementation of conductive MOFs in voltammetric detection holds promise for further development of highly modular, sensitive, selective, and stable electroanalytical devices. 

   more » « less
3. Two-Dimensional Tellurium Nanosheets for the Efficient Nonenzymatic Electrochemical Detection of H2O2

   https://doi.org/10.3390/chemosensors12020017  

   Shringi, Amit Kumar; Kumar, Rajeev; Dennis, Netanya F.; Yan, Fei (February 2024, Chemosensors)

   This study reports, for the first time, the utilization of two-dimensional (2D) tellurium (Te) nanosheets for the efficient nonenzymatic detection of hydrogen peroxide (H2O2). H2O2 acts as a pivotal biomarker with widespread applications across environmental, biological, industrial, and food processing domains. However, an excessive accumulation of H2O2 in the body poses a severe threat to human life. Consequently, the imperative need for a selective, sensitive, and cost-effective sensing platform for H2O2 detection has gained paramount significance. Employing a low-cost and straightforward hydrothermal method, Te nanosheets were synthesized to address the escalating demand for a reliable detection platform. The as-synthesized Te nanosheets are characterized through Raman spectroscopy and atomic force microscopy techniques. The electrochemical performance of the Te nanosheets integrated onto a glassy carbon (Te-GC) electrode was thoroughly investigated using cyclic voltammetry, differential pulse voltammetry, and chronoamperometry. The experiments were designed to evaluate the response of the Te-GC electrode in the presence and absence of H2O2, alongside its performance in the detection of other pertinent interfering analytes. The sensor shows a limit of detection of 0.47 µM and a sensitivity of 27.2 µA µM−1 cm−2 towards H2O2. The outcomes of this study demonstrate the efficacy of Te nanosheets as a promising material for nonenzymatic H2O2 detection in urine samples. The simplicity and cost-effectiveness of the hydrothermal synthesis process, coupled with the notable electrochemical performance of the Te/GC electrode, highlight the potential of Te nanosheets in the development of a robust sensing platform. This research contributes to the ongoing efforts to enhance our capabilities in monitoring and detecting H2O2, fostering advancements in environmental, biomedical, and industrial applications. 

   more » « less
4. Advances and opportunities in point-of-care detection of toxic metals: a review of electrochemical and non-electrochemical approaches

   https://doi.org/10.1039/D6AN00248J  

   Udawaththa, Navoda; Zubak, Olga; Daninger, Ashley; Page, Ralph; Strini, Miriam; Romero, Brianna; Pathirathna, Pavithra (April 2026, The Analyst)

   Heavy metal contamination remains a persistent global threat to human health and the environment, driving the urgent need for rapid, portable, and sensitive detection technologies. Recent advances in point-of-care (POC) platforms have enabled real-time monitoring of toxic metals in diverse matrices, including soil, water, food, and biological fluids. Electrochemical approaches, particularly screen-printed electrode systems, have emerged as highly adaptable tools. These systems achieve ultralow detection limits through nanomaterial modifications and enable multiplexed detection using techniques such as square-wave anodic stripping voltammetry and differential pulse voltammetry. Complementary paper-based analytical devices provide low-cost, disposable, and environmentally friendly sensing formats. These platforms integrate electrochemical, fluorescent, and colorimetric strategies, often coupled with smartphone-based readouts for real-time field deployment. Smartphone-integrated systems further enhance accessibility by combining miniaturized sensing with wireless connectivity, cloud-based data sharing, and machine learning algorithms that improve signal analysis and enable predictive monitoring. Portable optical spectroscopy kits extend sensitivity to trace metals in clinical, environmental, and food matrices, while wearable sensors, including textiles, wristbands, patches, and gloves, allow for noninvasive, continuous assessment of biofluids and environmental exposures. Importantly, emerging ultrafast electrochemical techniques, such as fast-scan cyclic voltammetry at carbon fiber microelectrodes, hold the potential to detect metal speciation with unprecedented temporal resolution. When coupled with artificial intelligence (AI), these approaches can deconvolute overlapping signals, enhance selectivity, and provide actionable insights into exposure dynamics. Collectively, these POC platforms represent a trajectory toward miniaturized, intelligent, and multiplexed sensing systems, offering scalable, real-world solutions for environmental monitoring, occupational safety, and personalized healthcare. The integration of advanced electrochemical methods, wearable technologies, and AI-driven analytics highlights the transformative potential of next-generation POC devices for comprehensive heavy metal surveillance. 

   more » « less
5. Adsorption Kinetic Model Predicts and Improves Reliability of Electrochemical Serotonin Detection

   https://doi.org/10.3390/mps6010006  

   Chapin, Ashley Augustiny; Han, Jinjing; Ghodssi, Reza (February 2023, Methods and Protocols)

   Serotonin (5-HT) is a neurotransmitter involved in many biophysiological processes in the brain and in the gastrointestinal tract. Electrochemical methods are commonly used to quantify 5-HT, but their reliability may suffer due to the time-dependent nature of adsorption-limited 5-HT detection, as well as electrode fouling over repeated measurements. Mathematical characterization and modeling of adsorption-based electrochemical signal generation would improve reliability of 5-HT measurement. Here, a model was developed to track 5-HT electrode adsorption and resulting current output by combining Langmuir adsorption kinetic equations and adsorption-limited electrochemical equations. 5-HT adsorption binding parameters were experimentally determined at a carbon-nanotube coated Au electrode: KD = 7 × 10−7 M, kon = 130 M−1 s−1, koff = 9.1 × 10−5 s−1. A computational model of 5-HT adsorption was then constructed, which could effectively predict 5-HT fouling over 50 measurements (R2 = 0.9947), as well as predict electrode responses over varying concentrations and measurement times. The model aided in optimizing the measurement of 5-HT secreted from a model enterochromaffin cell line—RIN14B—minimizing measurement time. The presented model simplified and improved the characterization of 5-HT detection at the selected electrode. This could be applied to many other adsorption-limited electrochemical analytes and electrode types, contributing to the improvement of application-specific modeling and optimization processes. 

   more » « less