title: Ultra-high frequency piezoelectric aptasensor for the label-free detection of cocaine.
abstract: This paper describes a label-free and real-time piezoelectric aptasensor for the detection of cocaine. The acoustic wave sensing platform is a quartz substrate functionalized with an adlayer of S-(11-trichlorosilyl-undecanyl)-benzenethiosulfonate (BTS) cross-linker onto which the anti-cocaine MN4 DNA aptamer is next immobilized. Preparation of the sensor surface was monitored using X-ray photoelectron spectroscopy (XPS), while the binding of cocaine to surface-attached MN4 was evaluated using the electromagnetic piezoelectric acoustic sensor (EMPAS). The MN4 aptamer, unlike other cocaine aptamer variants, has its secondary structure preformed in the unbound state with only tertiary structure changes occurring during target binding. It is postulated that the highly sensitive EMPAS detected the binding of cocaine through target mass loading coupled to aptamer tertiary structure folding. The sensor achieved an apparent Kd of 45 ± 12 µM, and a limit of detection of 0.9 µM. Repeated regenerability of the sensor platform was also demonstrated. This work constitutes the first application of EMPAS technology in the field of aptasensors. Furthermore, it is so far one of the very few examples of a bulk acoustic wave aptasensor that is able to directly detect the binding interaction between an aptamer and a small molecule in a facile one-step protocol without the use of a complex assay or signal amplification step.
authors.affiliation: Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada M5S 3H6.
authors.forename: Miguel A D
authors.initials: MA
authors.lastname: Neves
authors.affiliation: Econous Systems Inc., 80 St. George Street, Toronto, Ontario, Canada M5S 3H6.
authors.forename: Christophe
authors.initials: C
authors.lastname: Blaszykowski
authors.affiliation: Institute for Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario, Canada M5S 3G9.
authors.forename: Sumra
authors.initials: S
authors.lastname: Bokhari
authors.affiliation: Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada M5S 3H6; Econous Systems Inc., 80 St. George Street, Toronto, Ontario, Canada M5S 3H6; Institute for Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario, Canada M5S 3G9. Electronic address: mikethom@chem.utoronto.ca.
authors.forename: Michael
authors.initials: M
authors.lastname: Thompson
mesh_terms: D000162:Acoustics / Q000295:instrumentation*; D000779:Anesthetics, Local / Q000032:analysis; D052157:Aptamers, Nucleotide / Q000737:chemistry*; D001483:Base Sequence; D015374:Biosensing Techniques / Q000295:instrumentation*; D003042:Cocaine / Q000032:analysis*; D018765:Dopamine Uptake Inhibitors / Q000032:analysis*; D055664:Electrochemical Techniques / Q000295:instrumentation*; D061925:Immobilized Nucleic Acids / Q000737:chemistry; D056951:Photoelectron Spectroscopy / Q000295:instrumentation; D012821:Silanes / Q000737:chemistry; D013016:Sound; D015813:Substance Abuse Detection / Q000295:instrumentation
chemical_list: D000779:Anesthetics, Local; D052157:Aptamers, Nucleotide; D018765:Dopamine Uptake Inhibitors; D061925:Immobilized Nucleic Acids; D012821:Silanes; D003042:Cocaine
keywords: Aptasensor; Biosensor; Cocaine aptamer; Electromagnetic piezoelectric acoustic sensor; Organosilane adlayer