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Bioconjugation Strategies for Microtoroidal Optical Resonators

Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089, USA
Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
Ming Hsieh Department of Electrical Engineering-Electrophysics, University of Southern California, Los Angeles, CA 90089, USA
Author to whom correspondence should be addressed.
Sensors 2010, 10(10), 9317-9336;
Received: 14 September 2010 / Revised: 8 October 2010 / Accepted: 14 October 2010 / Published: 18 October 2010
(This article belongs to the Special Issue Optical Resonant Microsensors)
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The development of label-free biosensors with high sensitivity and specificity is of significant interest for medical diagnostics and environmental monitoring, where rapid and real-time detection of antigens, bacteria, viruses, etc., is necessary. Optical resonant devices, which have very high sensitivity resulting from their low optical loss, are uniquely suited to sensing applications. However, previous research efforts in this area have focused on the development of the sensor itself. While device sensitivity is an important feature of a sensor, specificity is an equally, if not more, important performance parameter. Therefore, it is crucial to develop a covalent surface functionalization process, which also maintains the device’s sensing capabilities or optical qualities. Here, we demonstrate a facile method to impart specificity to optical microcavities, without adversely impacting their optical performance. In this approach, we selectively functionalize the surface of the silica microtoroids with biotin, using amine-terminated silane coupling agents as linkers. The surface chemistry of these devices is demonstrated using X-ray photoelectron spectroscopy, and fluorescent and optical microscopy. The quality factors of the surface functionalized devices are also characterized to determine the impact of the chemistry methods on the device sensitivity. The resulting devices show uniform surface coverage, with no microstructural damage. This work represents one of the first examples of non-physisorption-based bioconjugation of microtoroidal optical resonators. View Full-Text
Keywords: bioconjugation; optical resonators; sensors; high quality factor bioconjugation; optical resonators; sensors; high quality factor

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This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

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Hunt, H.K.; Soteropulos, C.; Armani, A.M. Bioconjugation Strategies for Microtoroidal Optical Resonators. Sensors 2010, 10, 9317-9336.

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