Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Development of Biosensor Materials for Sensitive Detection of Viral RNA and Foodborne Pathogen" By Seonah Jin Purdue MSE Ph.D. Final Exam Advisor: Professor Lia A. Stanciu ABSTRACT Pathogen detection for clinical diagnosis, vector surveillance and control is one of the important issues for public health and safety. Biosensing is considered as one of the promising techniques for pathogen detection due to its potential for rapid, simple, and relatively inexpensive detection. However, many biosensors still have limitations for commercialization. Development of materials and new detection methods are the ways to overcome these limitations. This study aims to develop rapid and sensitive material platforms for detection of the dengue viral RNA (Part I and II) and the foodborne pathogen Escherichia coli O157:H7 (Part III). The first part of the presentation will demonstrate the enhanced sensitivity of functionalized graphene oxide wrapped SiO2 particle composite (SiO2@APTES-GO) after primer immobilization for dengue DNA and RNA detection and determines selectivity and a limit of detection (LOD) below 1fM. The enhanced sensitivity is due to the increased surface area resulting from the wrapped structure of the graphene oxide (GO) layer on the silica particles, while maintaining good electrochemical properties. The second part will propose a new method for acceleration of nucleic acid hybridization. The oligonucleotide probe was neutralized by the sodium acetate treatment, which accelerated the hybridization speed and decreased the electrode incubation time from 5 hr to 30 min in low ionic strength solution. The last part of the presentation will demonstrate the sensitivities of gold-polystyrene particles (Au-PS) conjugated to antibodies. The sensitivity depended on the surface coverage and core particle size. Among all investigated conditions, the Au-PS with 0.46 µm diameter core PS, and 10% Au surface coverage showed the best sensitivity, of 5x102 CFU·mL-1 as the LOD for E. coli O157:H7 in both phosphate buffer solution and real food samples including apple juice and ground beef. This optimized surface coverage with gold nanoparticles on the submicron sized particles was the key factor for the sensitivity enhancement of lateral flow strip detection. Date: Friday, November 17, 2017 Time: 1:00 P.M. Place: HAMP 1113