{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T23:57:54Z","timestamp":1792799874083,"version":"4.5.0"},"reference-count":39,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2025,3,14]],"date-time":"2025-03-14T00:00:00Z","timestamp":1741910400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100005375","name":"Latvian Council of Science","doi-asserted-by":"publisher","award":["LZP-2021\/1-0584"],"award-info":[{"award-number":["LZP-2021\/1-0584"]}],"id":[{"id":"10.13039\/501100005375","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biosensors"],"abstract":"<jats:p>Indium tin oxide (ITO) is a transparent conducting material with exceptional electrical and optical properties, widely used in biosensing and bioelectronics. Functionalization of ITO with linker molecules enables covalent attachment of biomolecules, allowing for dual-mode optical and electrochemical detection. Carbonic anhydrase IX (CA IX), a transmembrane enzyme overexpressed in hypoxic tumors, is a promising biomarker for cancer diagnostics due to its restricted expression in normal tissues. However, conventional detection methods are time-intensive and unsuitable for point-of-care applications. In this study, ITO surfaces were functionalized using silane-based chemistry to immobilize CA IX-specific antibodies, creating a novel biosensing platform. The biosensor utilized a secondary horseradish peroxidase (HRP)-conjugated antibody to catalyze the oxidation of luminol in the presence of hydrogen peroxide, producing a chemiluminescent and electrochemical signal. Characterization of the biosensor via a dual-mode optical and electrochemical approach revealed efficient antibody immobilization. Due to the high variation observed in the optical approach, limit of detection (LOD) experiments were conducted exclusively with electrochemistry, yielding an LOD of 266.4 ng\/mL. These findings demonstrate the potential of ITO-based electrochemical biosensors for sensitive and selective CA IX detection, highlighting their applicability in cancer diagnostics and other biomedical fields.<\/jats:p>","DOI":"10.3390\/bios15030186","type":"journal-article","created":{"date-parts":[[2025,3,14]],"date-time":"2025-03-14T07:02:16Z","timestamp":1741935736000},"page":"186","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Surface Functionalization of ITO for Dual-Mode Hypoxia-Associated Cancer Biomarker Detection"],"prefix":"10.3390","volume":"15","author":[{"given":"Edmunds","family":"Zutis","sequence":"first","affiliation":[{"name":"Institute of Solid State Physics, University of Latvia, 8 Kengaraga Street, LV-1063 Riga, Latvia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gunita","family":"Paidere","sequence":"additional","affiliation":[{"name":"Institute of Solid State Physics, University of Latvia, 8 Kengaraga Street, LV-1063 Riga, Latvia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8652-2421","authenticated-orcid":false,"given":"Rihards","family":"Ruska","sequence":"additional","affiliation":[{"name":"Institute of Solid State Physics, University of Latvia, 8 Kengaraga Street, LV-1063 Riga, Latvia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Toms","family":"Freimanis","sequence":"additional","affiliation":[{"name":"Latvian Institute of Organic Synthesis, 21 Aizkraukles Street, LV-1006 Riga, Latvia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3538-8554","authenticated-orcid":false,"given":"Janis","family":"Cipa","sequence":"additional","affiliation":[{"name":"Institute of Solid State Physics, University of Latvia, 8 Kengaraga Street, LV-1063 Riga, Latvia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9471-1342","authenticated-orcid":false,"given":"Raivis","family":"Zalubovskis","sequence":"additional","affiliation":[{"name":"Latvian Institute of Organic Synthesis, 21 Aizkraukles Street, LV-1006 Riga, Latvia"},{"name":"Institute of Chemistry and Chemical Technology, Faculty of Natural Sciences and Technology, Riga Technical University, P. Valdena iela 3, LV-1048 Riga, Latvia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2999-3520","authenticated-orcid":false,"given":"Maira","family":"Elksne","sequence":"additional","affiliation":[{"name":"Institute of Solid State Physics, University of Latvia, 8 Kengaraga Street, LV-1063 Riga, Latvia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kaspars","family":"Tars","sequence":"additional","affiliation":[{"name":"Latvian Biomedical Research and Study Centre, 1 k-1 Ratsupites Street, LV-1067 Riga, Latvia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4964-0984","authenticated-orcid":false,"given":"Andris","family":"Kazaks","sequence":"additional","affiliation":[{"name":"Latvian Biomedical Research and Study Centre, 1 k-1 Ratsupites Street, LV-1067 Riga, Latvia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Janis","family":"Leitans","sequence":"additional","affiliation":[{"name":"Latvian Biomedical Research and Study Centre, 1 k-1 Ratsupites Street, LV-1067 Riga, Latvia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2568-4758","authenticated-orcid":false,"given":"Anatolijs","family":"Sarakovskis","sequence":"additional","affiliation":[{"name":"Institute of Solid State Physics, University of Latvia, 8 Kengaraga Street, LV-1063 Riga, Latvia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7174-175X","authenticated-orcid":false,"given":"Andris","family":"Anspoks","sequence":"additional","affiliation":[{"name":"Institute of Solid State Physics, University of Latvia, 8 Kengaraga Street, LV-1063 Riga, Latvia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,3,14]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Altay, D.N., Yagar, H., and Ozcan, H.M. 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