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Proceedings Paper

Label-free optical detection of bacteria on a 1-D photonic crystal of porous silicon
Author(s): Chia-Chen Wu; Sara D. Alvarez; Camilla U. Rang; Lin Chao; Michael J. Sailor
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Paper Abstract

The construction of a specific, label-free, bacteria biosensor using porous silicon 1-D photonic crystals will be described. Bacteria resident on the surface of porous silicon act as scattering centers for light resonant with the photonic crystal; the diffusely scattered light possesses the optical spectrum of the underlying photonic crystal. Using a spectrometer fitted to a light microscope, the bacteria are imaged without using exogenous dyes or labels and are quantified by measuring the intensity of scattered light. In order to selectively bind and identify bacteria using porous Si, we use surface modifications to reduce nonspecific binding to the surface and to engineer bacteria specificity onto the surface. Bovine serum albumin (BSA) was adsorbed to the porous Si surface to reduce nonspecific binding of bacteria. The coatings were then chemically activated to immobilize polyclonal antibodies specific to Escherichia coli. Two E. coli strains were used in our study, E. coli DH5α and non-pathogenic enterohemorrhagic Escherichia coli (EHEC) strain. The nonpathogenic Vibrio cholerae O1 strain was used to test for antibody specificity. Successful attachment of antibodies was measured using fluorescence microscopy and the scattering method was used to test for bacteria binding specificity.

Paper Details

Date Published: 19 February 2009
PDF: 10 pages
Proc. SPIE 7167, Frontiers in Pathogen Detection: From Nanosensors to Systems, 71670Z (19 February 2009); doi: 10.1117/12.809338
Show Author Affiliations
Chia-Chen Wu, Univ. of California, San Diego (United States)
Sara D. Alvarez, Univ. of California, San Diego (United States)
Camilla U. Rang, Univ. of California, San Diego (United States)
Lin Chao, Univ. of California, San Diego (United States)
Michael J. Sailor, Univ. of California, San Diego (United States)


Published in SPIE Proceedings Vol. 7167:
Frontiers in Pathogen Detection: From Nanosensors to Systems
Philippe M. Fauchet, Editor(s)

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