MXene- and MOF-Based Hydrogels: Emerging Platforms for Electrochemical Biosensing and Health Monitoring Kandaswamy Theyagarajan, Sairaman Saikrithika, Young-Joon Kim Micromachines, 2026 Smart healthcare is rapidly emerging as a transformative paradigm, enabling simultaneous health monitoring, therapeutic intervention, and early prediction of disease onset. In this context, electrochemical monitoring systems have attracted growing interest due to their cost-effectiveness, ease of operation, miniaturization and compatibility with wearable platforms. Accordingly, conductive hydrogel-based electrochemical (bio)sensors have gained significant attention for health monitoring owing to their soft mechanical properties, high water content, excellent biocompatibility, and ability to form intimate, conformal interfaces with biological tissues. Their three-dimensional polymeric networks facilitate efficient ion transport and mechanical flexibility, making them particularly suitable for wearable and noninvasive sensing and monitoring applications. However, the intrinsically limited conductivity and catalytic activity of pristine hydrogels often constrain their electrochemical performance. To overcome these limitations, functional nanomaterials such as metal–organic frameworks (MOFs) and MXene (MX) nanosheets have been increasingly integrated into hydrogel matrices to enhance conductivity and electrochemical activity. This review provides a comprehensive and critical comparison of recent advances in MOF- and MX-integrated conductive hydrogels for electrochemical health monitoring. In addition to material design strategies and sensing performance, emerging trends in data-driven sensing aimed at improving signal interpretation and multi-analyte discrimination are systematically discussed. Key challenges related to long-term stability, biocompatibility, scalability, and intelligent system integration are critically assessed, and the future potential of these platforms within closed-loop architectures is highlighted, paving the way for next-generation conductive hydrogel-based electrochemical sensors in smart healthcare applications.
Advances in MXene-Based Hybrids for Electrochemical Health Monitoring Kandaswamy Theyagarajan, Young-Joon Kim Chemosensors, 2026 The growing demand for advanced health-monitoring technologies has intensified the need for early diagnosis of incurable diseases and timely detection of life-threatening conditions. Among various detection modalities, electrochemical sensing has emerged as a particularly promising approach due to its simplicity, cost-effectiveness, high sensitivity, rapid response, ease of miniaturization, and compatibility with portable, wearable, and implantable platforms. The performance of electrochemical sensors is strongly governed by the morphology and physicochemical properties of electrode materials. In this context, MXenes, 2D transition-metal carbides, nitrides, and carbonitrides have attracted increasing attention for sensing applications owing to their high electrical conductivity, large surface area, hydrophilicity, and rich surface chemistry. However, their practical implementation is hindered by oxidation and environmental instability, while surface modification strategies, although improving stability, may compromise intrinsic electrochemical activity and biocompatibility. Notably, MXene-based hybrids consistently demonstrate enhanced sensing performance, underscoring their potential for flexible and wearable electrochemical devices. Despite rapid progress in this field, a comprehensive review addressing the significance of MXene hybrids, their structure–property–performance relationships, and their role in electrochemical detection remains limited. Therefore, this review summarizes recent advances in MXene-based hybrid materials for electrochemical sensing and biosensing of biologically relevant analytes, with an emphasis on design strategies, functional enhancements, and their prospects for next-generation health-monitoring technologies.
A Comprehensive Review on Transition Metal-Based Catalysts for Water Electrolysis: Fundamentals, Recent Progress, and Future Perspectives Abdul Kareem, Kandaswamy Theyagarajan, Kathavarayan Thenmozhi, Sudhagar Pitchaimuthu, Sellappan Senthilkumar Advanced Sustainable Systems, 2025 Electrochemical water splitting would be a wise route for fetching greener fuel, since it produces clean hydrogen and oxygen by means of water electrolysis. However, it has always been a big challenge for researchers to develop a low‐cost electrocatalyst with high stability and conductivity, along with excellent activity toward bulk generation of hydrogen and oxygen. Even though noble metal‐based electrocatalysts show excellent activity, their limited availability, high cost, and low stability hinder their use in large‐scale applications. To address this issue, researchers have turned their focus toward transition metal (TM) based electrocatalysts, since they possess good stability even under harsh conditions, high conductivity, low cost, and ease of availability. In this perspective, this review focuses on various types of TM‐based electrocatalysts (sulphides, selenides, phosphides, nitrides, carbides, oxides, and layered double hydroxides), their challenges, research trends, and methods to improve the catalytic efficacy toward hydrogen evolution reaction and oxygen evolution reaction activities. Further, this review provides an insight into the fundamental mechanism involved in water electrolysis and important parameters associated, including overpotential, Tafel slope, iR drop, stability, exchange current density, turnover frequency, electrochemical surface area, and double‐layer capacitance, along with types of electrolytes, including electrodes and their importance in different electrolytes.
Demonstration of CMOS-compatible memristor-based electrochemical biosensor transducer with threshold-sensing functionality Young-Joon Kim, Youna Kwon, Youngwoo Yoo, Kandaswamy Theyagarajan, Sairaman Saikrithika, et al. Nature Communications, 2025 Many electrochemical biosensors operate based on a threshold-sensing (TS) method, which indicates the presence of a disease when the concentration of a biomarker exceeds a predetermined, disease-specific threshold. The TS in biosensor systems is often implemented using power-hungry signal processing (SP) modules or computers, which increases energy consumption and system complexity. Here, we propose a memristor-based bio-to-electrical transducer with built-in TS functionality, allowing TS to be performed directly within the transducer instead of relying on SP modules and computers. Fabricated resistive random-access memory-based TaO X /Ta 2 O 5 memristors meet the transducer requirements, such as a high on/off ratio greater than 30 while maintaining a long unit pulse width exceeding 10 μs. The intended operation of the proposed transducer was experimentally confirmed by the immediate change in resistance of the memristor (R M ) from high resistance state to low resistance state. Using this proposed transducer, a complete electrochemical biosensor system was implemented by integrating a sensor electrode for pH sensing, an SP module, and a display with the proposed transducer. The memristor-based system offers flexible control of the threshold pH point through a simple design, making it well-suited for point-of-care diagnostics, where portability is highly essential.
Metal Organic Frameworks Based Wearable and Point-of-Care Electrochemical Sensors for Healthcare Monitoring K Theyagarajan, Young-Joon Kim Biosensors, 2024 The modern healthcare system strives to provide patients with more comfortable and less invasive experiences, focusing on noninvasive and painless diagnostic and treatment methods. A key priority is the early diagnosis of life-threatening diseases, which can significantly improve patient outcomes by enabling treatment at earlier stages. While most patients must undergo diagnostic procedures before beginning treatment, many existing methods are invasive, time-consuming, and inconvenient. To address these challenges, electrochemical-based wearable and point-of-care (PoC) sensing devices have emerged, playing a crucial role in the noninvasive, continuous, periodic, and remote monitoring of key biomarkers. Due to their numerous advantages, several wearable and PoC devices have been developed. In this focused review, we explore the advancements in metal–organic frameworks (MOFs)-based wearable and PoC devices. MOFs are porous crystalline materials that are cost-effective, biocompatible, and can be synthesized sustainably on a large scale, making them promising candidates for sensor development. However, research on MOF-based wearable and PoC sensors remains limited, and no comprehensive review has yet to synthesize the existing knowledge in this area. This review aims to fill that gap by emphasizing the design of materials, fabrication methodologies, sensing mechanisms, device construction, and real-world applicability of these sensors. Additionally, we underscore the importance and potential of MOF-based wearable and PoC sensors for advancing healthcare technologies. In conclusion, this review sheds light on the current state of the art, the challenges faced, and the opportunities ahead in MOF-based wearable and PoC sensing technologies.
Biosensor platform for testing active pharmaceutical ingredients K. Theyagarajan, Vadakke Purakkal Sruthi, Devarasu Mohanapriya, Kathavarayan Thenmozhi, Sellappan Senthilkumar Health and Environmental Applications of Biosensing Technologies Clinical and Allied Health Science Perspective, 2023
Real-Time On-Body Sweat Sensing: Electrochemical Insights, Progress, and Prospects S Saikrithika, L Zahra, K Theyagarajan, YJ Kim TrAC Trends in Analytical Chemistry, 118882 , 2026 2026
Advances in the design and fabrication of flexible, wearable, and implantable electrochemical neurotransmitter sensors K Theyagarajan, L Zahra, YJ Kim Coordination Chemistry Reviews 549, 217287 , 2026 2026 Citations: 8
MXene-and MOF-Based Hydrogels: Emerging Platforms for Electrochemical Biosensing and Health Monitoring K Theyagarajan, S Saikrithika, YJ Kim Micromachines 17, 267 , 2026 2026 Citations: 2
Advances in MXene-Based hybrids for electrochemical health monitoring K Theyagarajan, YJ Kim Chemosensors 14, 6 , 2026 2026 Citations: 2
Demonstration of CMOS-compatible memristor-based electrochemical biosensor transducer with threshold-sensing functionality YJ Kim, Y Kwon, Y Yoo, K Theyagarajan, S Saikrithika, A Lee, NH Bae, ... Nature Communications 16 (1), 10851 , 2025 2025 Citations: 9
A Comprehensive Review on Transition Metal‐Based Catalysts for Water Electrolysis: Fundamentals, Recent Progress, and Future Perspectives A Kareem, K Theyagarajan, K Thenmozhi, S Pitchaimuthu, ... Advanced Sustainable Systems 9 (12), e01270 , 2025 2025 Citations: 11
Bio-capped ZnO nanoparticles formulated from Prosopis juliflora gum: Phytochemical characterization and therapeutic potential N Thanjavur, BA Lakshmi, L Bugude, K Theyagarajan, YJ Kim International Journal of Biological Macromolecules, 149092 , 2025 2025 Citations: 1
Enzymeless detection and real-time analysis of intracellular hydrogen peroxide released from cancer cells using gold nanoparticles embedded bimetallic metal organic framework K Theyagarajan, BA Lakshmi, YJ Kim Colloids and Surfaces B: Biointerfaces 245, 114209 , 2025 2025 Citations: 13
Materials and design strategies for the electrochemical detection of antineoplastic drugs: Progress and perspectives K Theyagarajan, VP Sruthi, J Satija, S Senthilkumar, YJ Kim Materials Science and Engineering: R: Reports 161, 100840 , 2024 2024 Citations: 24
Metal organic frameworks based wearable and point-of-care electrochemical sensors for healthcare monitoring K Theyagarajan, YJ Kim Biosensors 14 (10), 492 , 2024 2024 Citations: 25
A nanohybrid-based smartphone-compatible high performance electrochemical glucose sensor K Theyagarajan, BA Lakshmi, C Kim, YJ Kim Materials Today Chemistry 41, 102282 , 2024 2024 Citations: 13
Electrochemical sensing of acetaminophen in biofluids, pharmaceutical and environmental samples using cobalt hexacyanoferrate decorated iron terephthalate metal organic framework K Theyagarajan, BA Lakshmi, YJ Kim Electrochimica Acta 488, 144229 , 2024 2024 Citations: 16
Biosensor platform for testing active pharmaceutical ingredients K Theyagarajan, VP Sruthi, D Mohanapriya, K Thenmozhi, ... Health and Environmental Applications of Biosensing Technologies, 129-152 , 2024 2024 Citations: 3
Highly efficient electrocatalytic hydrogen generation in neutral water by a nanostructured cobalt catalyst derived in-situ from ionic liquid tagged cobalt terpyridine M Benjamin1, D Manoj1, K Theyagarajan1, K Thenmozhi, ... International Journal of Hydrogen Energy , 2023 2023 Citations: 5
Recent developments in the design and fabrication of electrochemical biosensors using functional materials and molecules K Theyagarajan, YJ Kim Biosensors 13 (4), 424 , 2023 2023 Citations: 74
Novel biomass-derived porous-graphitic carbon coated iron oxide nanocomposite as an efficient electrocatalyst for the sensitive detection of rutin (vitamin P) in food and … M Elancheziyan1, S Ganesan1, K Theyagarajan1, M Duraisamy, ... Environmental Research 211, 113012 , 2022 2022 Citations: 38
Anthraquinone Functionalized Ionic Liquid Based Disposable Electrochemical Sensor for the Enzyme-Free Detection of Hydrogen Peroxide M Prathapaneni1, K Theyagarajan1, E Mari, H Shankar, T Kathavarayan, ... ECS Sensors Plus , 2022 2022 Citations: 60
Porous graphene oxide based disposable non-enzymatic electrochemical sensor for the determination of nicotinamide adenine dinucleotide M Elancheziyan1, K Theyagarajan1, VK Ponnusamy, K Thenmozhi, ... Micro and Nano Engineering 15, 100133 , 2022 2022 Citations: 15
Quantum Dots-based Disposable Sensors K Theyagarajan, PS Aayushi, A Devadoss, K Thenmozhi, S Senthilkumar Disposable Electrochemical Sensors for Healthcare Monitoring: Material … , 2021 2021 Citations: 1
Metal oxide-graphene nanocomposite modified electrochemical sensors for toxic chemicals K Theyagarajan, K Thenmozhi, S Senthilkumar Metal Oxides in Nanocomposite-Based Electrochemical Sensors for Toxic … , 2021 2021 Citations: 2
MOST CITED SCHOLAR PUBLICATIONS
Highly sensitive electrochemical detection of E. coli O157:H7 using conductive carbon dot/ZnO nanorod/PANI composite electrode A Pangajam, K Theyagarajan, K Dinakaran Sensing and Bio-Sensing Research 29, 100317 , 2020 2020 Citations: 89
Recent developments in the design and fabrication of electrochemical biosensors using functional materials and molecules K Theyagarajan, YJ Kim Biosensors 13 (4), 424 , 2023 2023 Citations: 74
Aldehyde functionalized ionic liquid on electrochemically reduced graphene oxide as a versatile platform for covalent immobilization of biomolecules and biosensing K Theyagarajan, D Manoj, D Saravanakumar, S Senthilkumar, ... Biosensors and Bioelectronics 103, 104-112 , 2018 2018 Citations: 74
Anthraquinone Functionalized Ionic Liquid Based Disposable Electrochemical Sensor for the Enzyme-Free Detection of Hydrogen Peroxide M Prathapaneni1, K Theyagarajan1, E Mari, H Shankar, T Kathavarayan, ... ECS Sensors Plus , 2022 2022 Citations: 60
Electrochemical biosensor for the detection of hydrogen peroxide using cytochrome c covalently immobilized on carboxyl functionalized ionic liquid/multiwalled carbon nanotube … M Murphy, K Theyagarajan, P Ganesan, S Senthilkumar, K Thenmozhi Applied Surface Science 492, 718-725 , 2019 2019 Citations: 57
Novel biomass-derived porous-graphitic carbon coated iron oxide nanocomposite as an efficient electrocatalyst for the sensitive detection of rutin (vitamin P) in food and … M Elancheziyan1, S Ganesan1, K Theyagarajan1, M Duraisamy, ... Environmental Research 211, 113012 , 2022 2022 Citations: 38
Viologen-terminated polyamidoamine (PAMAM) dendrimer encapsulated with gold nanoparticles for nonenzymatic determination of hydrogen peroxide M Elancheziyan, K Theyagarajan, D Saravanakumar, K Thenmozhi, ... Materials Today Chemistry 16, 100274 , 2020 2020 Citations: 30
Metal organic frameworks based wearable and point-of-care electrochemical sensors for healthcare monitoring K Theyagarajan, YJ Kim Biosensors 14 (10), 492 , 2024 2024 Citations: 25
Materials and design strategies for the electrochemical detection of antineoplastic drugs: Progress and perspectives K Theyagarajan, VP Sruthi, J Satija, S Senthilkumar, YJ Kim Materials Science and Engineering: R: Reports 161, 100840 , 2024 2024 Citations: 24
Gold nanoparticle-redox ionic liquid based nanoconjugated matrix as a novel multifunctional biosensing interface K Theyagarajan, S Yadav, J Satija, K Thenmozhi, S Senthilkumar ACS Biomaterials Science & Engineering 6 (11), 6076-6085 , 2020 2020 Citations: 23
Direct electrochemistry of covalently immobilized hemoglobin on a naphthylimidazolium butyric acid ionic liquid/MWCNT matrix M Murphy, K Theyagarajan, K Thenmozhi, S Senthilkumar Colloids and Surfaces B: Biointerfaces 199, 111540 , 2021 2021 Citations: 22
Facile strategy for immobilizing horseradish peroxidase on a novel acetate functionalized ionic liquid/MWCNT matrix for electrochemical biosensing K Theyagarajan, M Elancheziyan, PS Aayushi, K Thenmozhi International Journal of Biological Macromolecules 163 (15), 358-365 , 2020 2020 Citations: 20
Rationally designed naphthyl substituted amine functionalized ionic liquid platform for covalent immobilization and direct electrochemistry of hemoglobin K Theyagarajan, D Saravanakumar, S Senthilkumar, K Thenmozhi Scientific reports 9 (1), 10428 , 2019 2019 Citations: 18
Quaternary Ammonium Based Carboxyl Functionalized Ionic Liquid for Covalent Immobilization of Horseradish Peroxidase and Development of Electrochemical Hydrogen Peroxide Biosensor M Manoharan, K Theyagarajan, T Kathavarayan, S Sellappan Electroanalysis , 2020 2020 Citations: 17
Electrochemical sensing of acetaminophen in biofluids, pharmaceutical and environmental samples using cobalt hexacyanoferrate decorated iron terephthalate metal organic framework K Theyagarajan, BA Lakshmi, YJ Kim Electrochimica Acta 488, 144229 , 2024 2024 Citations: 16
Porous graphene oxide based disposable non-enzymatic electrochemical sensor for the determination of nicotinamide adenine dinucleotide M Elancheziyan1, K Theyagarajan1, VK Ponnusamy, K Thenmozhi, ... Micro and Nano Engineering 15, 100133 , 2022 2022 Citations: 15
Enzymeless detection and real-time analysis of intracellular hydrogen peroxide released from cancer cells using gold nanoparticles embedded bimetallic metal organic framework K Theyagarajan, BA Lakshmi, YJ Kim Colloids and Surfaces B: Biointerfaces 245, 114209 , 2025 2025 Citations: 13
A nanohybrid-based smartphone-compatible high performance electrochemical glucose sensor K Theyagarajan, BA Lakshmi, C Kim, YJ Kim Materials Today Chemistry 41, 102282 , 2024 2024 Citations: 13
A Comprehensive Review on Transition Metal‐Based Catalysts for Water Electrolysis: Fundamentals, Recent Progress, and Future Perspectives A Kareem, K Theyagarajan, K Thenmozhi, S Pitchaimuthu, ... Advanced Sustainable Systems 9 (12), e01270 , 2025 2025 Citations: 11
Demonstration of CMOS-compatible memristor-based electrochemical biosensor transducer with threshold-sensing functionality YJ Kim, Y Kwon, Y Yoo, K Theyagarajan, S Saikrithika, A Lee, NH Bae, ... Nature Communications 16 (1), 10851 , 2025 2025 Citations: 9
