{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,24]],"date-time":"2026-02-24T10:51:52Z","timestamp":1771930312501,"version":"3.50.1"},"reference-count":30,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2015,1,27]],"date-time":"2015-01-27T00:00:00Z","timestamp":1422316800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biosensors"],"abstract":"<jats:p>Direct, small-molecule determination of the antiepileptic drug, valproic acid, was investigated by a label-free, nanomechanical biosensor. Valproic acid has long been used as an antiepileptic medication, which is administered through therapeutic drug monitoring and has a narrow therapeutic dosage range of 50\u2013100 \u03bcg\u00b7mL\u22121 in blood or serum. Unlike labeled and clinically-used measurement techniques, the label-free, electrical detection microcantilever biosensor can be miniaturized and simplified for use in portable or hand-held point-of-care platforms or personal diagnostic tools. A micromachined microcantilever sensor was packaged into the micro-channel of a fluidic system. The measurement of the antiepileptic drug, valproic acid, in phosphate-buffered saline and serum used a single free-standing, piezoresistive microcantilever biosensor in a thermally-controlled system. The measured surface stresses showed a profile over a concentration range of 50\u2013500 \u03bcg\u00b7mL\u22121, which covered the clinically therapeutic range of 50\u2013100 \u03bcg\u00b7mL\u22121. The estimated limit of detection (LOD) was calculated to be 45 \u03bcg\u00b7mL\u22121, and the binding affinity between the drug and the antibody was measured at around 90 \u00b1 21 \u03bcg\u00b7mL\u22121. Lastly, the results of the proposed device showed a similar profile in valproic acid drug detection with those of the clinically-used fluorescence polarization immunoassay.<\/jats:p>","DOI":"10.3390\/bios5010037","type":"journal-article","created":{"date-parts":[[2015,1,27]],"date-time":"2015-01-27T09:57:28Z","timestamp":1422352648000},"page":"37-50","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["Direct Determination of a Small-Molecule Drug, Valproic Acid, by an Electrically-Detected Microcantilever Biosensor for Personalized Diagnostics"],"prefix":"10.3390","volume":"5","author":[{"given":"Long-Sun","family":"Huang","sequence":"first","affiliation":[{"name":"Institute of Applied Mechanics, National Taiwan University, Taipei 10617, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Christian","family":"Gunawan","sequence":"additional","affiliation":[{"name":"Institute of Applied Mechanics, National Taiwan University, Taipei 10617, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yi-Kuang","family":"Yen","sequence":"additional","affiliation":[{"name":"Institute of Applied Mechanics, National Taiwan University, Taipei 10617, Taiwan"},{"name":"Department of Chemical Physics, Weizmann Institute of Science, 234 Herzl Street,  Rehovot 7610001, Israel"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kai-Fung","family":"Chang","sequence":"additional","affiliation":[{"name":"Institute of Applied Mechanics, National Taiwan University, Taipei 10617, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2015,1,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1539","DOI":"10.1039\/c0an01007c","article-title":"Microcantilever biosensors for chemicals and bioorganisms","volume":"136","author":"Buchapudi","year":"2011","journal-title":"Analyst"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"316","DOI":"10.1126\/science.288.5464.316","article-title":"Translating biomolecularrecognition into nanomechanics","volume":"288","author":"Fritz","year":"2000","journal-title":"Science"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"8400","DOI":"10.1021\/la0511687","article-title":"Nanomechanicalsensing of DNA sequences using piezoresistivecantilevers","volume":"21","author":"Mukhopadhyay","year":"2005","journal-title":"Langmuir"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"856","DOI":"10.1038\/nbt0901-856","article-title":"Bioassay of prostate-specific antigen (PSA) using microcantilevers","volume":"19","author":"Wu","year":"2001","journal-title":"Nat. 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