Sensors 2012, 12(9), 12317-12328; doi:10.3390/s120912317
Surface Modification on Acoustic Wave Biosensors for Enhanced Specificity
Department of Mechanical Engineering, University of South Florida, 4202 E Fowler Ave, ENB 118, Tampa, FL 33620, USA
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These authors contributed equally to this work.
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Received: 2 July 2012 / Revised: 3 September 2012 / Accepted: 4 September 2012 / Published: 10 September 2012
(This article belongs to the Special Issue BioMEMS and Advanced Analytical Sensors for Biological Applications)
Abstract
Changes in mass loading on the surface of acoustic biosensors result in output frequency shifts which provide precise measurements of analytes. Therefore, to detect a particular biomarker, the sensor delay path must be judiciously designed to maximize sensitivity and specificity. B-cell lymphoma 2 protein (Bcl-2) found in urine is under investigation as a biomarker for non-invasive early detection of ovarian cancer. In this study, surface chemistry and biofunctionalization approaches were evaluated for their effectiveness in presenting antibodies for Bcl-2 capture while minimizing non-specific protein adsorption. The optimal combination of sequentially adsorbing protein A/G, anti-Bcl-2 IgG and Pluronic F127 onto a hydrophobic surface provided the greatest signal-to-noise ratio and enabled the reliable detection of Bcl-2 concentrations below that previously identified for early stage ovarian cancer as characterized by a modified ELISA method. Finally, the optimal surface modification was applied to a prototype acoustic device and the frequency shift for a range of Bcl-2 concentration was quantified to demonstrate the effectiveness in surface acoustic wave (SAW)-based detection applications. The surface functionalization approaches demonstrated here to specifically and sensitively detect Bcl-2 in a working ultrasonic MEMS biosensor prototype can easily be modified to detect additional biomarkers and enhance other acoustic biosensors.Keywords:
bioconjugation; microelectromechanical systems (MEMS); point-of-care; sensor; early detection; ovarian cancer; Bcl-2; surface acoustic wave (SAW); self-assembled monolayer (SAM); polyethylene glycol (PEG)
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MDPI and ACS Style
Onen, O.; Ahmad, A.A.; Guldiken, R.; Gallant, N.D. Surface Modification on Acoustic Wave Biosensors for Enhanced Specificity. Sensors 2012, 12, 12317-12328.