Document Detail


Integration of microsphere resonators with bioassay fluidics for whispering gallery mode imaging.
MedLine Citation:
PMID:  23615457     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Whispering gallery mode resonators are small, radially symmetric dielectrics that trap light through continuous total internal reflection. The resonant condition at which light is efficiently confined within the structure is linked with refractive index, which has led to the development of sensitive label-free sensing schemes based on whispering gallery mode resonators. One resonator design uses inexpensive high index glass microspheres that offer intrinsically superior optical characteristics, but have proven difficult to multiplex and integrate with the fluidics for sample delivery and fluid exchange necessary for assay development. Recently, we introduced a fluorescence imaging approach that enables large scale multiplexing with microsphere resonators, thus removing one obstacle for assay development. Here we report an approach for microsphere immobilization that overcomes limitations arising from their integration with fluidic delivery. The approach is an adaptation of a calcium-assisted glass bonding method originally developed for microfluidic glass chip fabrication. Microspheres bonded to glass using this technique are shown to be stable with respect to fluid flow and show no detectable loss in optical performance. Measured Q-factors, for example, remain unchanged following sphere bonding to the substrate. The stability of the immobilized resonators is further demonstrated by transferring lipid films onto the immobilized spheres using the Langmuir-Blodgett technique. Bilayers of DOPC doped with GM1 were transferred onto immobilized resonators to detect the binding of cholera toxin to GM1. Binding curves generated from shifts in the whispering gallery mode resonance result in a measured Kd of 1.5 × 10(-11) with a limit of detection of 3.3 pM. These results are discussed in terms of future assay development using microsphere resonators.
Authors:
Daniel C Kim; Kevin P Armendariz; Robert C Dunn
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  The Analyst     Volume:  138     ISSN:  1364-5528     ISO Abbreviation:  Analyst     Publication Date:  2013 Jun 
Date Detail:
Created Date:  2013-05-07     Completed Date:  2013-12-27     Revised Date:  2014-06-10    
Medline Journal Info:
Nlm Unique ID:  0372652     Medline TA:  Analyst     Country:  England    
Other Details:
Languages:  eng     Pagination:  3189-95     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Barium Compounds / chemistry
Biological Assay / instrumentation,  methods*
Limit of Detection
Microfluidic Analytical Techniques
Microspheres*
Molecular Imaging / instrumentation,  methods*
Spectrometry, Fluorescence
Titanium / chemistry
Grant Support
ID/Acronym/Agency:
T32 GM008545/GM/NIGMS NIH HHS; T32 GM08545/GM/NIGMS NIH HHS
Chemical
Reg. No./Substance:
0/Barium Compounds; 12047-27-7/barium titanate(IV); D1JT611TNE/Titanium
Comments/Corrections

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