A new approach to virus detection in an aqueous environment has been developed using the electrophoretic deposition of protein and viruses on a charged surface for in situ infrared characterization and identification. In this study, a potential was applied across a germanium ATR crystal, which acted as the anode, and an indium tin oxide (ITO) plate, which acted as the cathode in the electrodeposition setup. Sample aqueous solutions were placed between the germanium and the ITO with different concentrations of the protein bovine serum albumin (BSA) and the virus MS2, in tap water. The pH of the tap water was above the isoelectric point of the virus and the protein, resulting in a net negative charge for both. The negatively charged protein and virus were then driven to the surface of the positively charged germanium ATR crystal, once a potential was applied to the system. FTIR/ATR was used before and throughout electrodeposition to enable the in situ observation of the deposition with time. In this study, we evaluate the capture efficiency, compared to control experiments with no applied voltage, and the feasibility of using this approach for the collection and quantification of proteins and viruses from water samples. This technique resulted in the successful deposition of BSA, and MS2 with an applied voltage of only 1.1V. Furthermore, based on the analysis of the ATR spectra, distinct spectral features were identified for the protein and virus showing the potential for identification and characterization of biological molecules in an aqueous environment.
A new family of Tellurium based glasses from the Ge-Te-I ternary system has been investigated for use in bio-sensing
applications. A systematic series of compositions have been synthesized in order to explore the ternary phase diagram in
an attempt to optimize the glass composition for the fiber drawing process. The characteristic temperatures Tg, the glass
transition temperature, and Tx, the onset crystallization temperature, were measured in order to obtain &Dgr;T, the
difference between Tg and Tx, which must be maximized for optimum fiber drawing ability. The resulting glass
transition temperature range lies between 139oC and 174oC, with &Dgr;T values between 64oC and 124oC. The mechanical
properties of a selected number of glass compositions were also investigated, including hardness and Young's Modulus.
The Ge-Te-I glasses have an effective transmission window between 2-27 microns, encompassing the region of interest
for the identification of biologically relevant species such as carbon dioxide. Furthermore, the fibering potential of the
Ge-Te-I glasses makes them an interesting candidate for use in fiber evanescent wave spectroscopy (FEWS) and other
An optical bio-sensor is built based on an infrared chalcogenide fiber coated with live cells. The fiber is immersed in an aqueous media appropriate for cell viability. The response of the cells to small quantities of toxicant can be monitored spectroscopically. The properties of chalcogenide fibers used for cell-based biosensors are investigated. The chemical stability of Te-As-Se fibers in aqueous media is shown to depend on the previous storage time of the fiber. Older fibers are shown to generate an oxide layer during extended exposure to air. This layer readily dissolves in aqueous solution and causes the release of As in the cell environment. The release of As during dissolution of the oxide layer is measured with ICP-MS and is shown to be complete after a couple hours. Fresh fibers do not show any detectable oxide layer and show excellent stability in aqueous solution. The surface roughness of old and fresh fibers is investigated with AFM before and after dissolution in aqueous media. Old fibers immersed in solution show sizable roughness due to the oxide surface layer dissolution. Fresh fibers do not show any detectable changes even after extended immersion in aqueous solution. The toxicity of As to various types of vertebrate cells is quantified using a colorimetric assay. Old fibers are shown to be notably toxic due to As released during dissolution. The fiber toxicity is shown to decrease when the fibers are previously washed in solution. The toxicity of the resulting wash water is then shown to increase due to the increase in As concentration.