title: Direct determination of a small-molecule drug, valproic Acid, by an electrically-detected microcantilever biosensor for personalized diagnostics.
abstract: 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 50-100 μg·mL-1 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 50-500 μg·mL-1, which covered the clinically therapeutic range of 50-100 μg·mL-1. The estimated limit of detection (LOD) was calculated to be 45 μg·mL-1, and the binding affinity between the drug and the antibody was measured at around 90 ± 21 μg·mL-1. 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.
authors: Institute of Applied Mechanics, National Taiwan University, Taipei 10617, Taiwan. lshuang@ntu.edu.tw.
authors: Long-Sun
authors: LS
authors: Huang
authors: Institute of Applied Mechanics, National Taiwan University, Taipei 10617, Taiwan. cgwu@ntumems.net.
authors: Christian
authors: C
authors: Gunawan
authors: Institute of Applied Mechanics, National Taiwan University, Taipei 10617, Taiwan. yi-kuang.yen@weizmann.ac.il.
authors: Yi-Kuang
authors: YK
authors: Yen
authors: Institute of Applied Mechanics, National Taiwan University, Taipei 10617, Taiwan. kfjhang@ntumems.net.
authors: Kai-Fung
authors: KF
authors: Chang
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