Composite Films for Modifying Evanescent Wave Characteristics in Long-Period Grating Biosensors

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dc.contributor.authorMartin, Jennifer E.en
dc.contributor.committeechairVelander, William H.en
dc.contributor.committeememberForsten-Williams, Kimberlyen
dc.contributor.committeememberDavis, Richey M.en
dc.contributor.departmentChemical Engineeringen
dc.date.accessioned2014-03-14T20:31:50Zen
dc.date.adate2001-02-17en
dc.date.available2014-03-14T20:31:50Zen
dc.date.issued2001-02-09en
dc.date.rdate2002-02-17en
dc.date.sdate2001-02-17en
dc.description.abstractBiosensors are detection devices that couple biological recognition elements to physiochemical transducers to generate quantifiable signals. Immunosensors are biosensors that use antibodies as the recognition element. The highly specific nature of antibody-antigen binding is exploited to create immunosensors that are sensitive to analytes in complex mixtures and demonstrate a rapid response. Fiber optical immunosensors based on long-period gratings have limited sensitivity at the refractive index of ordinary aqueous solutions (~1.33). A composite film was designed to raise the local refractive index of the sensor, thus increasing sensitivity. Titanium dioxide deposition raised the refractive index of the sensor to ~1.42. Bovine serum albumin was immobilized onto a dextran hydrogel and attached to the LPG element via reductive amination. The thickness of the hydrogel was estimated to be 500 nm using Environmental Scanning Electron Microscopy. The affinity film was probed by an evanescent wave to detect changes in refractive index due to the binding of anti-BSA IgG. Under these conditions, the sensor yielded a signal ratio of approximately 10-4 refractive index units per nm signal. Reproducible binding was shown over multiple exposures, with no cross reactivity for non-specific antibodies and other proteins. Anti-BSA IgG (20 µg/mL) in whole serum was recycled through the fiber holder with an accompanying peak wavelength shift that averaged 2 nm on an Optical Spectrum Analyzer with a noise level of 0.1 nm. The BSA affinity film was regenerated 50 times and showed a baseline shift of -1.3 nm.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-02172001-014116en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-02172001-014116/en
dc.identifier.urihttp://hdl.handle.net/10919/31253en
dc.publisherVirginia Techen
dc.relation.haspartJEMartinETD.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectbiosensoren
dc.subjectevanescent waveen
dc.subjectlong-period gratings (LPG)en
dc.subjectaffinity ligand filmen
dc.subjecttitanium dioxideen
dc.titleComposite Films for Modifying Evanescent Wave Characteristics in Long-Period Grating Biosensorsen
dc.typeThesisen
thesis.degree.disciplineChemical Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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