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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
These authors contributed equally to this work.
* Author to whom correspondence should be addressed.
Received: 2 July 2012; in revised form: 3 September 2012 / Accepted: 4 September 2012 / Published: 10 September 2012
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.
Onen O, Ahmad AA, Guldiken R, Gallant ND. Surface Modification on Acoustic Wave Biosensors for Enhanced Specificity. Sensors. 2012; 12(9):12317-12328.
Onen, Onursal; Ahmad, Asad A.; Guldiken, Rasim; Gallant, Nathan D. 2012. "Surface Modification on Acoustic Wave Biosensors for Enhanced Specificity." Sensors 12, no. 9: 12317-12328.