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Vitaly Vodyanoy,1 Yasmine Daniels,2 Oleg Pustovyy,1 William A MacCrehan,2 Shin Muramoto,2 Gheorghe Stan21Department of Anatomy, Physiology and Pharmacology, Auburn University College of Veterinary Medicine, Auburn, AL, 2Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MA, USA Background: Small metal nanoparticles obtained from animal blood were observed to be toxic to cultured cancer cells, whereas noncancerous cells were much less affected. In this work, engineered zinc and copper metal nanoparticles were produced from bulk metal rods by an underwater high-voltage discharge method. The metal nanoparticles were characterized by atomic force microscopy and X-ray photoelectron spectroscopy. The metal nanoparticles, with estimated diameters of 1 nm–2 nm, were determined to be more than 85% nonoxidized. A cell viability assay and high-resolution light microscopy showed that exposure of RG2, cultured rat brain glioma cancer cells, to the zinc and copper nanoparticles resulted in cell morphological changes, including decreased cell adherence, shrinking/rounding, nuclear condensation, and budding from cell bodies. The metal-induced cell injuries were similar to the effects of staurosporine, an active apoptotic reagent. The viability experiments conducted for zinc and copper yielded values of dissociation constants of 0.22±0.08 nmol/L (standard error [SE]) and 0.12±0.02 nmol/L (SE), respectively. The noncancerous astrocytes were not affected at the same conditions. Because metal nanoparticles were lethal to the cancer cells at sub-nanomolar concentrations, they are potentially important as nanomedicine.Purpose: Lethal concentrations of synthetic metal nanoparticles reported in the literature are a few orders of magnitude higher than the natural, blood-isolated metal nanoparticles; therefore, in this work, engineered metal nanoparticles were examined to mimic the properties of endogenous m

Proof-in-concept biosensors were prepared for the rapid detection of Salmonella typhimurium in solution, based on affinity-selected filamentous phage prepared as probes physically adsorbed to piezoelectric transducers. Quantitative deposition studies indicated that ^3 x 10 to the 10th power phage particles per square cm could be irreversibly adsorbed for 1 h at room temperature to prepare working biosensors. The quality of phage deposition was monitored by fluorescent microscopy. Specific bacterial binding resulted in resonance frequency changes of prepared sensors, which were evaluated using linear regression analysis. Sensors possessed a rapid response time < 180 s, had a low detection limit of 100 cells/ml and were linear over a range of 10 to 10 to the 7th power cells/ml with a sensitivity of 10.9 Hz per order of magnitude of S. typhimurium concentration. Viscosity effects due to increasing bacterial concentration and non-specific binding were not significant to the piezoelectric platform as confirmed by dose-response analysis. Phage-bacterial binding was confirmed by fluorescence and scanning electron microscopy. Overall, phage may constitute effective bioreceptors for use with analytical platforms for detecting and monitoring bacterial agents, including use in food products and possibly biological warfare applications., Supported in part by DARPA (contract no. MDA972-00-1-0011); ARO/DARPA (contract no. DAAD19-01-1-0454); NIH (contract no. NIH-1-R21-AI055645); and USDA (contract no. 99-34394-7546).

Salmonella typhimurium is a leading cause of inadvertent gastrointestinal foodborne illness in the United States. Although few actual accounts of deliberate food contamination have been documented in the United States, the recent advent of biocrimes and terrorism in our country suggests that this trend will not continue, highlighting the importance of rapidly identifying biological agents, regardless of the contamination origin, as one part of a comprehensive strategic plan to secure the public food supply. There is an urgent need for deployable, real-time threat agent detectors to replace traditional methods of food safety analysis that are slower, labor-intensive, and cost-inefficient. Confirmation of presence in food products can take as long as 48 hours by conventional culture. Current rapid detection initiatives include biosensors that routinely incorporate antibodies as the biorecognition unit. Although sensitive and specific, antibodies are costly and may degrade under unfavorable environmental conditions. We believe that a stable, inexpensive substitute for antibodies is filamentous phage manipulated through phage display technique then affinity selected for specificity to S. typhimurium from billion-clone phage landscape libraries. Our results show that recombinant phage affinity selected against S. typhimurium can be 12,000- 22,000 times for more specific than controls and 10-1000 times more selective for S. typhimurium than other select enterobacteria. We anticipate that these highly specific, selective phage binders will build upon our current biosensor development initiatives for the rapid detection of biological agents such as S. typhimurium.