Nano Archive

Toward Automatic Label-Free Whispering Gallery Modes Biodetection with a Quantum Dot-Coated Microsphere Population

Charlebois, M. and Paquet, A. and Verret, L. S. and Boissinot, K. and Boissinot, M. and Bergeron, M. G. and Allen, C. Nì. (2010) Toward Automatic Label-Free Whispering Gallery Modes Biodetection with a Quantum Dot-Coated Microsphere Population. NANOSCALE RESEARCH LETTERS, 5 (3). pp. 524-532. ISSN 1931-7573 (Print) 1556-276X (Online)

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Official URL: http://www.springerlink.com/content/r1121452551253...

Abstract

We explore a new calibration-free approach to biodetection based on whispering gallery modes (WGMs) without a reference measure and relative shifts. Thus, the requirement to keep track of the sensor position is removed, and a freely moving population of fluorophore-doped polystyrene microspheres can now fulfill this role of sensing resonator. Breaking free from fixed surface-based biosensing promotes adhesion between the microsphere sensors and the analytes since both can now be thoroughly mixed. The 70-nm-wide spectrum of green fluorescent microbeads allows us to monitor over 20 WGMs simultaneously without needing evanescent light coupling into the microspheres, hence enabling remote sensing. Since the exact radius of each microsphere is unknown a priori, it requires algorithmic analyses to obtain a reliable result for the refractive index of a solution. We first test our approach with different solutions of alcohol in water obtaining 3 × 10−4 precision on the refractive index at lower concentrations. Then, the solutions of bacterial spores in water yield clear evidence of biodetection in the statistical analysis of WGMs from 50 microspheres. To extend the fluorescence spectral range of our WGM sensors, we present preliminary results on coating microspheres with CdSe/ZnS quantum dots.

Item Type:Article
Subjects:Biomedical Science > Nanobiotechnology
ID Code:8774
Deposited By:M T V
Deposited On:21 Apr 2010 15:28
Last Modified:21 Apr 2010 15:28

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