[CCoE Notice] PhD Defense - Eliedonna Cacao

[Khator, Suresh]

Ph.D. Defense Announcement

Eliedonna Cacao
Friday, July 22, 2011, 10:00 AM, Mechanical Engineering Large Conference Room (Room 202)
Advisors: Dr. R. Willson & Dr. Paul Ruchhoeft
ENZYMATIC DARKENING AND SILVER STAINING:
Application in microfluidic micro-retroreflector-based heterogeneous immunoassays

Micro-fabricated retroreflectors, which reflect light directly back to its source, potentially represent an attractive and economical new form of read-out for immunoassays. They are readily detectable, their signals can be easily measured with simple cheap optics, they are fabricated in vast numbers using scalable, inexpensive lithographic techniques, and they are well-suited for automated analysis.

One implementation of retroreflectors in bioassays is to modulate their brightness using light scatterers that accumulate in the presence of analyte. For this work, enzymatic darkening and silver staining were adapted to alter micro-retroreflector brightness by depositing insoluble precipitates. In enzymatic darkening, alkaline phosphatase (AP) and bromochloroindolyl-phosphate-nitroblue-tetrazolium were used, while three silver staining systems, gold nanoparticle-nucleated, horseradish peroxidase-mediated and AP-mediated, were investigated.

Two distinct retroreflecting geometries were investigated, one consisting of four discrete reflectors (tetrads) and the other consisting of long, linear reflectors embedded in a planar polymer. To use the tetrad structures, a unique helium ion beam passivation step was developed that left only one retroreflecting surface active while passivating the remaining surfaces with extremely high contrast. Results using these retroreflectors showed the selective deposition of chromophore and silver particles at sites where enzymes or gold nanoparticles were present, and allowed for the detection of Norwalk virus-like particles and Escherichia coli (E. coli) bacteria from solution. The linear retroreflectors were developed to overcome fluid-flow challenges around the three-dimensional tetrad reflectors and allow for the detection of analyte over much large surface areas. An automated silver staining assay, integrated into a microfluidic system, was developed for the detection of individual E. coli bacteria.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://Bug.EGR.UH.EDU/pipermail/engi-dist/attachments/20110714/27bcebf6/attachment.html