{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,12]],"date-time":"2026-09-12T19:03:41Z","timestamp":1789239821146,"version":"build-2803163510"},"reference-count":45,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2022,4,22]],"date-time":"2022-04-22T00:00:00Z","timestamp":1650585600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Ministry of Science and Technology Taiwan","award":["MOST111-2327-B-005-002 and MOST 110-2321-B-005-010"],"award-info":[{"award-number":["MOST111-2327-B-005-002 and MOST 110-2321-B-005-010"]}]},{"name":"Ministry of Education, Taiwan","award":["Higher Education Sprout Project"],"award-info":[{"award-number":["Higher Education Sprout Project"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biosensors"],"abstract":"<jats:p>The timely detecting of SARS-CoV-2 coronavirus antigens for infection validation is an urgent request for COVID-19 pandemic control. This study constructed label-free electrochemical impedance spectroscopy (EIS)-based immunosensors based on gold nanostructured screen-printed carbon electrodes (AuNS\/SPCEs) to detect the SARS-CoV-2 nucleocapsid protein (N-protein) in saliva. Using short-chain 3-mercaptopropionic acid (MPA) as a linker to covalently bond streptavidin (SA) and bovine serum albumin (BSA) for controlling the oriented immobilization of the biotinylated anti-N-protein antibody (BioAb) can offer a greater sensitivity, a lower limit of detection (LOD), and better reproducibility of immunosensors (defined as BioAb\/SA-BSA\/MPA\/AuNS\/SPCEs) than the antibody randomly immobilized immunosensors and the long-chain 11-mercaptoundecanoic acid (MUA)-modified immunosensors (BioAb\/SA-BSA\/MUA\/AuNS\/SPCEs). The BioAb\/SA-BSA\/MPA\/AuNS\/SPCE-based immunosensors presented good linearity from 0.01 ng\/mL to 100 ng\/mL and a low LOD of 6 pg\/mL in a phosphate buffer solution (PBS) and PBS-diluted saliva. Moreover, the immunosensor exhibited little cross-activity with other viral antigens such as MERS-CoV N-protein, influenza A N-protein, influenza B N-protein, and SARS-CoV-2 spike protein, indicating the high specificity of the immunosensors. The disposable label-free EIS-based immunosensors have promising potential in facilitating the rapid and sensitive tests of saliva-based COVID-19 diagnostics.<\/jats:p>","DOI":"10.3390\/bios12050265","type":"journal-article","created":{"date-parts":[[2022,4,23]],"date-time":"2022-04-23T08:14:06Z","timestamp":1650701646000},"page":"265","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":54,"title":["A Label-Free Electrochemical Impedimetric Immunosensor with Biotinylated-Antibody for SARS-CoV-2 Nucleoprotein Detection in Saliva"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8683-3796","authenticated-orcid":false,"given":"Ching-Chou","family":"Wu","sequence":"first","affiliation":[{"name":"Department of Bio-industrial Mechatronics Engineering, National Chung Hsing University, Taichung 402, Taiwan"},{"name":"Innovation and Development Center of Sustainable Agriculture, National Chung Hsing University, Taichung 402, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yu-Huan","family":"Chiang","sequence":"additional","affiliation":[{"name":"Department of Bio-industrial Mechatronics Engineering, National Chung Hsing University, Taichung 402, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hsin-Yu","family":"Chiang","sequence":"additional","affiliation":[{"name":"ACK Biotechnology Co., Ltd., Taichung 402, Taiwan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,4,22]]},"reference":[{"key":"ref_1","unstructured":"World Health Organization (2022, March 15). 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