Detection of Light Scattering for Lab-On-A-Chip Immunoassays Using Optical Fibers

Persistent Link:
http://hdl.handle.net/10150/193897
Title:
Detection of Light Scattering for Lab-On-A-Chip Immunoassays Using Optical Fibers
Author:
Lucas, Lonnie J.
Issue Date:
2007
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
This dissertation develops technology for microfluidic point-of-care immunoassay devices. This research (2004–2007) improved microfluidic immunoassay performance by reducing reagent consumption, decreasing analysis time, increasing sensitivity, and integrating processes using a lab-on-a-chip. Estimates show that typical hospital laboratories can save $1.0 million per year by using microfluidic chips. Our first objective was to enhance mixing in a microfluidic channel, which had been one of the main barriers to using these devices. Another goal of our studies was to simplify immunoassays by eliminating surfactants. Manufacturers of latex immunoassays add surfactants to prevent non-specific aggregation of microspheres. However, these same surfactants can cause false positives (and negatives) during diagnostic testing. This work, published in Appendix A (© 2006 Elsevier) shows that highly carboxylated polystyrene (HCPS) microspheres can replace surfactants and induce rapid mixing via diffusion in microfluidic devices. Our second objective was to develop a microfluidic device using fiber optics to detect static light scattering (SLS) of microspheres in Appendix B (© 2007 Elsevier). Fiber optics were used to deliver light emitting diode (LED) or laser light. A miniature spectrometer was used to measure 45° forward light scattering collected by optical fiber. Latex microspheres coated with PR3 proteins were used to test for the vasculitis marker, anti-PR3. No false negatives or positives were observed. A limit of detection (LOD) of 50 ng mL⁻¹ was demonstrated. This optical detection system works without fluorescence or chemiluminescence markers. It is cost effective, small, and re-usable with simple rinsing. The final objective in this dissertation, published in Appendix C (© 2007 Elsevier), developed a multiplex immunoassay. A lab-on-a-chip was used to detect multiple antibodies using microsphere light scattering and quantum dot (QD) emission. We conjugated QDs onto microspheres and named this configuration “nano-on-micro” or “NOM”. Upon radiation with UV light, strong light scattering is observed. Since QDs also provide fluorescent emission, we are able to use increased light scattering for detecting antigen-antibody reactions, and decreased QD emission to identify which antibody is present.
Type:
text; Electronic Dissertation
Keywords:
multiplex assay; immunoagglutination; static light scattering; on-chip detection; quantum dots; microfluidic device
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Agricultural & Biosystems Engineering; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Yoon, Jeong-Yeol
Committee Chair:
Yoon, Jeong-Yeol

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleDetection of Light Scattering for Lab-On-A-Chip Immunoassays Using Optical Fibersen_US
dc.creatorLucas, Lonnie J.en_US
dc.contributor.authorLucas, Lonnie J.en_US
dc.date.issued2007en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThis dissertation develops technology for microfluidic point-of-care immunoassay devices. This research (2004–2007) improved microfluidic immunoassay performance by reducing reagent consumption, decreasing analysis time, increasing sensitivity, and integrating processes using a lab-on-a-chip. Estimates show that typical hospital laboratories can save $1.0 million per year by using microfluidic chips. Our first objective was to enhance mixing in a microfluidic channel, which had been one of the main barriers to using these devices. Another goal of our studies was to simplify immunoassays by eliminating surfactants. Manufacturers of latex immunoassays add surfactants to prevent non-specific aggregation of microspheres. However, these same surfactants can cause false positives (and negatives) during diagnostic testing. This work, published in Appendix A (© 2006 Elsevier) shows that highly carboxylated polystyrene (HCPS) microspheres can replace surfactants and induce rapid mixing via diffusion in microfluidic devices. Our second objective was to develop a microfluidic device using fiber optics to detect static light scattering (SLS) of microspheres in Appendix B (© 2007 Elsevier). Fiber optics were used to deliver light emitting diode (LED) or laser light. A miniature spectrometer was used to measure 45° forward light scattering collected by optical fiber. Latex microspheres coated with PR3 proteins were used to test for the vasculitis marker, anti-PR3. No false negatives or positives were observed. A limit of detection (LOD) of 50 ng mL⁻¹ was demonstrated. This optical detection system works without fluorescence or chemiluminescence markers. It is cost effective, small, and re-usable with simple rinsing. The final objective in this dissertation, published in Appendix C (© 2007 Elsevier), developed a multiplex immunoassay. A lab-on-a-chip was used to detect multiple antibodies using microsphere light scattering and quantum dot (QD) emission. We conjugated QDs onto microspheres and named this configuration “nano-on-micro” or “NOM”. Upon radiation with UV light, strong light scattering is observed. Since QDs also provide fluorescent emission, we are able to use increased light scattering for detecting antigen-antibody reactions, and decreased QD emission to identify which antibody is present.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectmultiplex assayen_US
dc.subjectimmunoagglutinationen_US
dc.subjectstatic light scatteringen_US
dc.subjecton-chip detectionen_US
dc.subjectquantum dotsen_US
dc.subjectmicrofluidic deviceen_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineAgricultural & Biosystems Engineeringen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorYoon, Jeong-Yeolen_US
dc.contributor.chairYoon, Jeong-Yeolen_US
dc.contributor.committeememberRiley, Marken_US
dc.contributor.committeememberSlack, Donalden_US
dc.contributor.committeememberChoi, Christopheren_US
dc.contributor.committeememberCuello, Joelen_US
dc.identifier.proquest2257en_US
dc.identifier.oclc659748095en_US
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