title: Tunable detection sensitivity of opiates in urine via a label-free porous silicon competitive inhibition immunosensor.
abstract: Currently, there is need for laboratory-based high-throughput and reliable point-of-care drug screening methodologies. We demonstrate here a chip-based label-free porous silicon (PSi) photonic sensor for detecting opiates in urine. This technique provides a cost-effective alternative to conventional labeled drug screening immunoassays with potential for translation to multiplexed analysis. Important effects of surface chemistry and competitive binding assay protocol on the sensitivity of opiate detection are revealed. Capability to tune sensitivity and detection range over approximately 3 orders of magnitude (18.0 nM to 10.8 muM) was achieved by varying the applied urine specimen volume (100-5 muL), which results in systematic shifts in the competitive binding response curve. A detection range (0.36-4.02 muM) of morphine in urine (15 muL) was designed to span the current positive cutoff value (1.05 muM morphine) in medical opiate urine screening. Desirable high cross-reactivity to oxycodone, in addition to other common opiates, morphine, morphine-3-glucuronide, 6-acetyl morphine, demonstrates an advantage over current commercial screening assays, while low interference with cocaine metabolite was maintained. This study uniquely displays PSi sensor technology as an inexpensive, rapid, and reliable drug screening technology. Furthermore, the versatile surface chemistry developed can be implemented on a range of solid-supported sensors to conduct competitive inhibition assays.
authors.affiliation: Department of Dermatology, University of Rochester Medical Center, 601 Elmwood Avenue, Box 697, Rochester, New York 14642, USA.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Bonanno
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Delouise
mesh_terms: D000906:Antibodies / Q000276:immunology / Q000378:metabolism; D001667:Binding, Competitive; D015374:Biosensing Techniques / Q000379:methods*; D003042:Cocaine / Q000652:urine; D056656:Lab-On-A-Chip Devices; D009020:Morphine / Q000652:urine; D009022:Morphine Derivatives / Q000652:urine; D009294:Narcotics / Q000652:urine*; D010098:Oxycodone / Q000652:urine; D016062:Porosity; D012825:Silicon / Q000737:chemistry*; D015813:Substance Abuse Detection / Q000379:methods*
chemical_list: D000906:Antibodies; D009022:Morphine Derivatives; D009294:Narcotics; D009020:Morphine; D010098:Oxycodone; D003042:Cocaine; C018108:morphine-3-glucuronide; D012825:Silicon