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1. DNA-Templated Silver Nanoclusters as Dual-Mode Sensitive Probes for Self-Powered Biosensor Fueled by Glucose

   https://doi.org/10.3390/nano13081299  

   Gupta, Akhilesh Kumar; Krasnoslobodtsev, Alexey V. (April 2023, Nanomaterials)

   Nanomaterials have been extensively explored in developing sensors due to their unique properties, contributing to the development of reliable sensor designs with improved sensitivity and specificity. Herein, we propose the construction of a fluorescent/electrochemical dual-mode self-powered biosensor for advanced biosensing using DNA-templated silver nanoclusters (AgNCs@DNA). AgNC@DNA, due to its small size, exhibits advantageous characteristics as an optical probe. We investigated the sensing efficacy of AgNCs@DNA as a fluorescent probe for glucose detection. Fluorescence emitted by AgNCs@DNA served as the readout signal as a response to more H2O2 being generated by glucose oxidase for increasing glucose levels. The second readout signal of this dual-mode biosensor was utilized via the electrochemical route, where AgNCs served as charge mediators between the glucose oxidase (GOx) enzyme and carbon working electrode during the oxidation process of glucose catalyzed by GOx. The developed biosensor features low-level limits of detection (LODs), ~23 μM for optical and ~29 μM for electrochemical readout, which are much lower than the typical glucose concentrations found in body fluids, including blood, urine, tears, and sweat. The low LODs, simultaneous utilization of different readout strategies, and self-powered design demonstrated in this study open new prospects for developing next-generation biosensor devices. 

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2. Stretchable Nanofiber-Based Felt as a String Electrode for Potential Use in Wearable Glucose Biosensors

   https://doi.org/10.3390/s24041283  

   Seufert, Bianca; Thomas, Sylvia; Takshi, Arash (February 2024, Sensors)

   Nanofiber technology is leading the revolution of wearable technology and provides a unique capability to fabricate smart textiles. With the novel fabrication technique of electrospinning, nanofibers can be fabricated and then manufactured into a durable conductive string for the application of smart textiles. This paper presents an electrospun nanofiber mesh-based (NF-Felt) string electrode with a conducting polymer coating for an electrochemical enzymatic glucose sensor. The surface area of a nanofiber matrix is a key physical property for enhanced glucose oxidase (GOx) enzyme binding for the development of an electrochemical biosensor. A morphological characterization of the NF-Felt string electrode was performed using scanning electron microscopy (SEM) and compared with a commercially available cotton–polyester (Cot-Pol) string coated with the same conducting polymer. The results from stress–strain testing demonstrated high stretchability of the NF-Felt string. Also, the electrochemical characterization results showed that the NF-Felt string electrode was able to detect a glucose concentration in the range between 0.0 mM and 30.0 mM with a sensitivity of 37.4 μA/mM·g and a detection limit of 3.31 mM. Overall, with better electrochemical performance and incredible flexibility, the NF-Felt-based string electrode is potentially more suitable for designing wearable biosensors for the detection of glucose in sweat. 

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3. An Automated Electrochemistry Platform for Accelerating the Characterization of Enzymatic Electrochemistry

   https://doi.org/10.1021/acselectrochem.6c00095  

   Pence, Michael A; Nguyen, Zachary A; Kays, Luke G; Boucher, Dylan G; Rodríguez-López, Joaquín; Minteer, Shelley D (April 2026, ACS Electrochemistry)

   Enzymatic electrochemistry harnesses the selectivity of enzymes to enable electrochemical applications spanning sensing, synthesis, and energy conversion. However, the sequential nature of electroanalytical experiments limits throughput, restricting the scale at which enzyme-electrode systems can be screened. Here we demonstrate the capabilities of an automated electrochemistry platform, eLab, to increase the throughput of enzymatic electrochemistry investigations. We used the eLab to collect over 10,000 cyclic voltammograms across a large parameter space consisting of two enzyme variants (promiscuous and wild-type glucose oxidase), 20 saccharide substrates, 21 concentrations, and four scan rates, with measurements being made all in triplicate. The expansive dataset enabled rapid identification of apparent outlier behavior of wild-type glucose oxidase toward glucose, which was confirmed to arise from oxygen sensitivity through targeted manual experiments. The promiscuous variant showed negligible oxygen sensitivity, a critical advantage for applications, such as enzymatic sensors, bioelectrosynthesis, and biofuel cells. Overall, this work demonstrates how automation can be applied to accelerate discovery in bioelectrochemistry. 

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4. A general Ca-MOM platform with enhanced acid-base stability for enzyme biocatalysis

   https://doi.org/https://doi.org/10.1016/j.checat.2021.03.001  

   Pan, Y.; Li, Q.; Li, H.; Farmakes, J.; Ugrinov, A.; Zhu, X.; Lai, Z.; Chen, B.; Yang, Z. (April 2021, Chem catalysis)

   null (Ed.)

   Co-precipitation of enzymes in metal-organic frameworks is a unique enzyme-immobilization strategy but is challenged by weak acid-base stability. To overcome this drawback, we discovered that Ca2+ can co-precipitate with carboxylate ligands and enzymes under ambient aqueous conditions and form enzyme@metal-organic material composites stable under a wide range of pHs (3.7–9.5). We proved this strategy on four enzymes with varied isoelectric points, molecular weights, and substrate sizes—lysozyme, lipase, glucose oxidase (GOx), and horseradish peroxidase (HRP)—as well as the cluster of HRP and GOx. Interestingly, the catalytic efficiency of the studied enzymes was found to depend on the ligand, probing the origins of which resulted in a correlation among enzyme backbone dynamics, ligand selection, and catalytic efficiency. Our approach resolved the long-lasting stability issue of aqueous-phase co-precipitation and can be generalized to biocatalysis with other enzymes to benefit both research and industry. 

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5. Electrochemical Fabrication of 2D CuO Nanosheets on Pt Foil as a Highly Sensitive Non‐Enzymatic Glucose Sensor

   https://doi.org/10.1002/slct.202300104  

   Bhangoji, Jagdish C.; Barile, Christopher J.; Shendage, Suresh S. (July 2023, ChemistrySelect)

   Abstract A simple and environmentally‐friendly approach was developed to synthesize 2D CuO nanosheets using electrochemical deposition. The formed 2D CuO nanosheets (NSs) exhibit numerous advantageous properties such as no toxicity, high electrical conductivity, large active surface area, and a p‐type semiconducting nature with a band gap of 1.2 eV. A sensitive electrochemical sensor was constructed for the amperometric detection of glucose to take advantage of these characteristics. The fabricated sensor displayed an excellent sensitivity of 2710 μA mM⁻¹ cm⁻²along with a wide linear range of 0.001–1.0 mM and a lower limit of detection of 0.8 μM (S/N=3). Additionally, the modified electrode possesses high selectivity and good stability. The outstanding electrocatalytic performance of the electrode is attributed to a large active surface area, unique structural morphology, and the high conductivity of the 2D CuO nanosheets. 

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