Dendrimer-assisted Signal Amplification for High Sensitivity DNA Detection

Although many small transducers have been demonstrated in the laboratory for detection of DNA high sensitivity detection generally requires amplification of the target using a method such as PCR. A detector that combines molecular recognition with signalamplification would dramatically minimize sample preparation, reduce analysis time, and lower cost and logistical burden. Equally important the risk of sample contamination is reduced by minimizing sample handling.Echo Technologies, Inc. has completed a Phase I program to develop and demonstrate a new technique for DNA detection and signal amplification that does not require PCR. Metal nanoparticles have been demonstrated for colorimetric detection ofpolynucleotides. Dendrimers have been used for templating and stabilization of metal colloids. The Phase I approach represents an integration of these technologies that will make the method more sensitive, robust and commercially viable.In Phase I sensitive and selective detection of B. anthracis DNA was demonstrated in the fmole range. ETI proposes a Phase II development effort to further validate the technique, optimize the reagents and related parameters, and demonstrate detection ofadditional BW or infectious pathogens. An integrated Portable DNA Detection System will be designed, fabricated and evaluated in the laboratory, and demonstrated at an extramural facility.Direct detection of DNA without the need for lengthy laboratory preparation would provide a sophisticated field tool for identifying pathogenic organisms of many types in air, water, food and soil. Military use includes rapid identification allowingprotection and decontamination measures to be initiated in a more timely manner. There is also a stated need to assure the safety of source waters as required by the Join Service Agent Water Monitor program. Specific civilian and commercial applicationsinclude the identification of enterotoxin producing bacteria in potable and recreational water supplies, respiratory pathogens such as Legionella in cooling towers, and food pathogens such as E. coli, Listeria, and Salmonella. The simplicity of the opticsand associated electronics suggest that the system could be manufactured at low cost for application in point-of-care medical diagnostics.