{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,17]],"date-time":"2026-10-17T20:54:46Z","timestamp":1792270486267,"version":"4.4.0"},"reference-count":41,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2026,2,17]],"date-time":"2026-02-17T00:00:00Z","timestamp":1771286400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003725","name":"National Research Foundation (NRF) of Korea","doi-asserted-by":"crossref","award":["2021R1I1A1A01049638"],"award-info":[{"award-number":["2021R1I1A1A01049638"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100003725","name":"National Research Foundation (NRF) of Korea","doi-asserted-by":"crossref","award":["RS-2023-NR076644"],"award-info":[{"award-number":["RS-2023-NR076644"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100003725","name":"National Research Foundation (NRF) of Korea","doi-asserted-by":"crossref","award":["RS-2022-NR075805"],"award-info":[{"award-number":["RS-2022-NR075805"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"crossref"}]},{"name":"Ministry of Education","award":["RS202300249778"],"award-info":[{"award-number":["RS202300249778"]}]},{"name":"Korean government","award":["RS-2021-NR060086"],"award-info":[{"award-number":["RS-2021-NR060086"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biosensors"],"abstract":"<jats:p>We report a highly sensitive and interference-free electrochemical sensor for dopamine (DA) detection in the presence of uric acid (UA) and ascorbic acid (AA), based on an in situ deposited graphitic carbon nitride (g-C3N4) and polymethyl thymol blue (PMTB) nanohybrid modified screen-printed carbon electrode (SPCE). The as-fabricated g-C3N4\/PMTB\/SPCE was thoroughly characterized using various physicochemical techniques. The electrochemical behavior of the modified electrode was systematically investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The g-C3N4\/PMTB\/SPCE exhibited excellent electrocatalytic activity toward the selective oxidation of DA under optimized experimental conditions, including pH and scan rate. Interference-free detection of DA in the presence of AA and UA was achieved using DPV and chronoamperometric methods, revealing a wide linear concentration range, an ultralow limit of detection, and high sensitivity. Furthermore, the practical applicability of the proposed sensor was validated by determining DA in artificial biofluid samples, including blood serum, and urine. The recovery results obtained good agreement with those obtained using high-performance liquid chromatography (HPLC), confirming the reliability and accuracy of the developed sensing platform.<\/jats:p>","DOI":"10.3390\/bios16020124","type":"journal-article","created":{"date-parts":[[2026,2,17]],"date-time":"2026-02-17T09:22:46Z","timestamp":1771320166000},"page":"124","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Metal-Free Electrochemical Dopamine Sensing Using a g-C3N4\/Polymethyl Thymol Blue Nanohybrid"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9554-2328","authenticated-orcid":false,"given":"Sankar","family":"Sekar","sequence":"first","affiliation":[{"name":"Division of System Semiconductor, Dongguk University-Seoul, Seoul 04620, Republic of Korea"},{"name":"Quantum-Functional Semiconductor Research Center, Dongguk University-Seoul, Seoul 04620, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4548-7436","authenticated-orcid":false,"given":"Sejoon","family":"Lee","sequence":"additional","affiliation":[{"name":"Division of System Semiconductor, Dongguk University-Seoul, Seoul 04620, Republic of Korea"},{"name":"Quantum-Functional Semiconductor Research Center, Dongguk University-Seoul, Seoul 04620, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sutha","family":"Sadhasivam","sequence":"additional","affiliation":[{"name":"Department of Chemistry, CMS College of Engineering, Namakkal 637003, Tamil Nadu, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kumar Sangeetha","family":"Selvan","sequence":"additional","affiliation":[{"name":"Department of Chemistry, VelTech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology, Avadi, Chennai 600062, Tamil Nadu, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Saravanan","family":"Sekar","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, K. Ramakrishnan College of Technology, Trichy 621112, Tamil Nadu, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8685-3033","authenticated-orcid":false,"given":"Youngmin","family":"Lee","sequence":"additional","affiliation":[{"name":"Division of System Semiconductor, Dongguk University-Seoul, Seoul 04620, Republic of Korea"},{"name":"Quantum-Functional Semiconductor Research Center, Dongguk University-Seoul, Seoul 04620, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pugazhendi","family":"Ilanchezhiyan","sequence":"additional","affiliation":[{"name":"Centre for Research and Development, Sri Manakula Vinayagar Engineering College, Madagadipet, Puducherry 605107, India"},{"name":"Department of Physics, Sri Manakula Vinayagar Engineering College, Madagadipet, Puducherry 605107, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2333-9424","authenticated-orcid":false,"given":"Seung-Cheol","family":"Chang","sequence":"additional","affiliation":[{"name":"Department of Cogno-Mechatronics Engineering, College of Nanoscience and Nanotechnology, Pusan National University, Busan 46241, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1947-9715","authenticated-orcid":false,"given":"Ramalingam","family":"Manikandan","sequence":"additional","affiliation":[{"name":"Department of Cogno-Mechatronics Engineering, College of Nanoscience and Nanotechnology, Pusan National University, Busan 46241, Republic of Korea"},{"name":"Engineering Research Center for Color-Modulated Extra-Sensory Perception Technology, Pusan National University, Busan 46241, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,2,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"9730467","DOI":"10.1155\/2016\/9730467","article-title":"The Role of Dopamine and Its Dysfunction as a Consequence of Oxidative Stress","volume":"2016","year":"2016","journal-title":"Oxidative Med. Cell. Longev."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"112115","DOI":"10.1016\/j.isci.2025.112115","article-title":"Spatiotemporal proteomic and transcriptomic landscape of DAT+ dopaminergic neurons development and function","volume":"28","author":"Zhao","year":"2025","journal-title":"iScience"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"7529","DOI":"10.1038\/s41467-025-62280-1","article-title":"Tonic dopamine and biases in value learning linked through a biologically inspired reinforcement learning model","volume":"16","author":"Uchida","year":"2025","journal-title":"Nat. Commun."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"118992","DOI":"10.1016\/j.jelechem.2025.118992","article-title":"Simultaneous determination of serotonin, dopamine, and ascorbic acid at a glassy carbon electrode modified with chitosan-alginate hydrogel and reduced graphene oxide","volume":"980","year":"2025","journal-title":"J. Electroanal. Chem."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"118275","DOI":"10.1016\/j.carbon.2023.118275","article-title":"Dispersant-free supra single-walled carbon nanotubes for simultaneous and highly sensitive biomolecule sensing in ex vivo mouse tissues","volume":"213","author":"Manikandan","year":"2023","journal-title":"Carbon"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"114813","DOI":"10.1016\/j.inoche.2025.114813","article-title":"Microelectrochemical biosensor utilizing in-situ coated PANI@Fe3O4 on disposable laser-induced graphene electrodes for dopamine detection","volume":"179","author":"Jang","year":"2025","journal-title":"Inorg. Chem. Commun."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"e5513","DOI":"10.1002\/bmc.5513","article-title":"Rapid and sensitive HPLC\u2013MS\/MS method for the quantification of dopamine, GABA, serotonin, glutamine and glutamate in rat brain regions after exposure to tobacco cigarettes","volume":"37","author":"Alhusban","year":"2023","journal-title":"Biomed. Chromatogr."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"528","DOI":"10.1080\/22297928.2022.2121662","article-title":"Characterization and HPLC Method Validation for Determination of Dopamine Hydrochloride in Prepared Nano Particles and Pharmacokinetic Application","volume":"12","author":"Neha","year":"2022","journal-title":"Anal. Chem. Lett."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Sekar, S., Arumugasamy, S.K., Lee, S., Sekar, S., Sadhasivam, S., Vaithilingam, S., Srinivasan, N., Krishnan, E., Chang, S.-C., and Manikandan, R. (2025). Magnetosome-Based Immunosensors for Foodborne Pathogen Detection. Chemosensors, 13.","DOI":"10.3390\/chemosensors13090355"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"216261","DOI":"10.1016\/j.ccr.2024.216261","article-title":"Nano-engineered paper-based electrochemical biosensors: Versatile diagnostic tools for biomarker detection","volume":"523","author":"Manikandan","year":"2025","journal-title":"Coord. Chem. Rev."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"215487","DOI":"10.1016\/j.ccr.2023.215487","article-title":"Recent advances in miniaturized electrochemical analyzers for hazardous heavy metal sensing in environmental samples","volume":"499","author":"Manikandan","year":"2024","journal-title":"Coord. Chem. Rev."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"136483","DOI":"10.1016\/j.foodchem.2023.136483","article-title":"Fabrication of S and O-incorporated graphitic carbon nitride linked poly(1,3,4-thiadiazole-2,5-dithiol) film for selective sensing of Hg2+ ions in water, fish, and crab samples","volume":"425","author":"Manikandan","year":"2023","journal-title":"Food Chem."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"116808","DOI":"10.1016\/j.bios.2024.116808","article-title":"Non-enzymatic g-C3N4 supported CuO derived-biochar based electrochemical sensors for trace level detection of malathion","volume":"267","author":"Devi","year":"2025","journal-title":"Biosens. Bioelectron."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Yin, C., Liu, Y., Hu, T., and Chen, X. (2025). Graphitic Carbon Nitride Nanomaterials-Based Electrochemical Sensing Interfaces for Monitoring Heavy Metal Ions in Aqueous Environments. Nanomaterials, 15.","DOI":"10.3390\/nano15070564"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"5599894","DOI":"10.1155\/er\/5599894","article-title":"Tailoring Graphitic Carbon Nitride (g-C3N4) for Multifunctional Applications: Strategies for Overcoming Challenges in Catalysis and Energy Conversion","volume":"2025","author":"Nabeel","year":"2025","journal-title":"Int. J. Energy Res."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2416946","DOI":"10.1002\/adfm.202416946","article-title":"Multifunctional Roles of Ionic Microenvironments in the Preparation, Modification, and Application of g-C3N4","volume":"35","author":"Qian","year":"2025","journal-title":"Adv. Funct. Mater."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1007\/s00604-018-3178-7","article-title":"A nanocomposite consisting of porous graphitic carbon nitride nanosheets and oxidized multiwalled carbon nanotubes for simultaneous stripping voltammetric determination of cadmium(II), mercury(II), lead(II) and zinc(II)","volume":"186","author":"Ramalingam","year":"2019","journal-title":"Microchim. Acta"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"17481","DOI":"10.1007\/s11356-019-05494-3","article-title":"Electrochemical determination of 4-nitrophenol in environmental water samples using porous graphitic carbon nitride-coated screen-printed electrode","volume":"27","author":"Ramalingam","year":"2020","journal-title":"Environ. Sci. Pollut. Res."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"113764","DOI":"10.1016\/j.inoche.2024.113764","article-title":"Fabrication of thymol blue film modified electrode and its synergetic effects for simultaneous and interference free detection of toxic dihydroxybenzene isomers: An experimental and theoretical approach","volume":"172","author":"Ganesh","year":"2025","journal-title":"Inorg. Chem. Commun."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"998","DOI":"10.1007\/s11270-025-08671-y","article-title":"Thymol\u2013Menthol-Based Deep Eutectic Solvents for Efficient Rhodamine B Remediation: Molecular Interactions, Economic Feasibility, and Environmental Assessment","volume":"236","author":"Zheng","year":"2025","journal-title":"Water Air Soil Pollut."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"3567","DOI":"10.1007\/s10008-017-3604-5","article-title":"Fabrication and characterization of poly 2-napthol orange film modified electrode and its application to selective detection of dopamine","volume":"21","author":"Manikandan","year":"2017","journal-title":"J. Solid State Electrochem."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1475","DOI":"10.1007\/s11581-019-03279-9","article-title":"Simultaneous electrochemical determination of adenine and guanine using poly 2-naphthol orange film\u2013modified electrode","volume":"26","author":"Manikandan","year":"2020","journal-title":"Ionics"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"609","DOI":"10.1002\/elan.201600368","article-title":"Differential Pulse Anodic Stripping Voltammetric Determination of Lead (II) Using Poly Xylenol Orange Modified Electrode","volume":"29","author":"Manikandan","year":"2017","journal-title":"Electroanalysis"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1387","DOI":"10.1007\/s11581-018-2704-2","article-title":"Anodic stripping voltammetric determination of Hg(II) using poly xylenol orange film modified electrode","volume":"25","author":"Manikandan","year":"2019","journal-title":"Ionics"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"117075","DOI":"10.1016\/j.bios.2024.117075","article-title":"Fabrication of bio-mimic nanozyme based on Mxene@AuNPs and molecular imprinted poly(thionine) films for creatinine detection","volume":"271","author":"Manikandan","year":"2025","journal-title":"Biosens. Bioelectron."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"117293","DOI":"10.1016\/j.envres.2023.117293","article-title":"Metal-free electrocatalytic nanocomposites of poly azovan blue-decorated graphitic carbon nitride for simultaneously sensing paracetamol and 4-aminophenol","volume":"239","author":"Sekar","year":"2023","journal-title":"Environ. Res."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"349","DOI":"10.1016\/j.cclet.2009.10.008","article-title":"A selective voltammetric detection for dopamine using poly (gallic acid) film modified electrode","volume":"21","author":"Song","year":"2010","journal-title":"Chin. Chem. Lett."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"92","DOI":"10.1016\/j.aca.2007.05.064","article-title":"Poly(3,4-ethylenedioxythiophene-co-(5-amino-2-naphthalenesulfonic acid)) (PEDOT-PANS) film modified glassy carbon electrode for selective detection of dopamine in the presence of ascorbic acid and uric acid","volume":"596","author":"Balamurugan","year":"2007","journal-title":"Anal. Chim. Acta"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"258","DOI":"10.1016\/j.bioelechem.2006.03.040","article-title":"Ion-exchange voltammetry of dopamine at Nafion-coated glassy carbon electrodes: Quantitative features of ion-exchange partition and reassessment on the oxidation mechanism of dopamine in the presence of excess ascorbic acid","volume":"69","author":"Rocha","year":"2006","journal-title":"Bioelectrochemistry"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"120507","DOI":"10.1016\/j.talanta.2019.120507","article-title":"Molybdenum oxide-based metal-organic framework\/polypyrrole nanocomposites for enhancing electrochemical detection of dopamine","volume":"209","author":"Zhou","year":"2020","journal-title":"Talanta"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"619","DOI":"10.1016\/j.apt.2021.01.011","article-title":"A novel preparation of water-dispersed graphene and their application to electrochemical detection of dopamine","volume":"32","author":"Tian","year":"2021","journal-title":"Adv. Powder Technol."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"138088","DOI":"10.1016\/j.cplett.2020.138088","article-title":"Nickel decorated graphite oxide and carbon nanofiber surface for electrochemical detection of dopamine","volume":"761","author":"Aryal","year":"2020","journal-title":"Chem. Phys. Lett."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"115133","DOI":"10.1016\/j.jelechem.2021.115133","article-title":"Construction of polydopamine-coated three-dimensional graphene-based conductive network platform for amperometric detection of dopamine","volume":"886","author":"Xue","year":"2021","journal-title":"J. Electroanal. Chem."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"107012","DOI":"10.1016\/j.elecom.2021.107012","article-title":"NO2-functionalized metal\u2013organic framework incorporating bimetallic alloy nanoparticles as a sensor for efficient electrochemical detection of dopamine","volume":"125","author":"Hira","year":"2021","journal-title":"Electrochem. Commun."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"106432","DOI":"10.1016\/j.microc.2021.106432","article-title":"The construction of CoP nanoparticles coated with carbon layers derived from core-shell bimetallic MOF for electrochemical detection of dopamine","volume":"168","author":"Xiao","year":"2021","journal-title":"Microchem. J."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1016\/j.bioelechem.2008.01.009","article-title":"Simultaneous determination of dopamine, ascorbic acid and uric acid at poly (Evans Blue) modified glassy carbon electrode","volume":"73","author":"Lin","year":"2008","journal-title":"Bioelectrochemistry"},{"key":"ref_37","first-page":"100737","article-title":"Ultrasensitive and selective dopamine detection using zirconia-decorated reduced graphene oxide nanocomposite via differential pulse voltammetry","volume":"28","author":"Parihar","year":"2026","journal-title":"Biosens. Bioelectron. X"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"139517","DOI":"10.1016\/j.snb.2026.139517","article-title":"Built-in cross-validation strategy for dopamine sensing: A Cu-MIL-88B(Fe)-based electrochemical\/colorimetric dual-mode platform","volume":"453","author":"Ma","year":"2026","journal-title":"Sens. Actuators B Chem."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"111199","DOI":"10.1016\/j.msec.2020.111199","article-title":"Application of cold plasma corona discharge in preparation of laccase-based biosensors for dopamine determination","volume":"116","author":"Wardak","year":"2020","journal-title":"Mater. Sci. Eng. C"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"105945","DOI":"10.1016\/j.microc.2021.105945","article-title":"Lemon juice-assisted synthesis of LaMnO3 perovskite nanoparticles for electrochemical detection of dopamine","volume":"164","author":"Shafi","year":"2021","journal-title":"Microchem. J."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"126267","DOI":"10.1016\/j.jhazmat.2021.126267","article-title":"Novel nano-engineered environmental sensor based on polymelamine\/graphitic-carbon nitride nanohybrid material for sensitive and simultaneous monitoring of toxic heavy metals","volume":"418","author":"Eswaran","year":"2021","journal-title":"J. Hazard. Mater."}],"container-title":["Biosensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-6374\/16\/2\/124\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,2,19]],"date-time":"2026-02-19T05:16:09Z","timestamp":1771478169000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-6374\/16\/2\/124"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,2,17]]},"references-count":41,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2026,2]]}},"alternative-id":["bios16020124"],"URL":"https:\/\/doi.org\/10.3390\/bios16020124","relation":{},"ISSN":["2079-6374"],"issn-type":[{"value":"2079-6374","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,2,17]]}}}