Nucleic acid sensor and fluid handling for detection of bacterial pathogens

An embedded controller with a keypad user interface was used to operate a nucleic acid sensor with fluid handling and real-time PCR capabilities. The sensor system consisted of pumps and valves for fluid transfer, a fluorometer composed of a light emitting diode, photodiode, and signal conditioning circuitry, a thermoelectric module for heating and cooling the reaction chamber, and power switching circuitry. The amplification and dissociation results of the SYBR Green real-time PCR test were downloaded to a PC for evaluation. Extracted Salmonella DNA in autoclaved water was automatically mixed with real-time PCR reagents and loaded into a glass reaction chamber. Alternating positive and negative control reactions were run, and the Salmonella sample carrying line was automatically cleaned with a combination of reagents following each reaction. Evaluation of amplification, dissociation, and agarose gel electrophoresis data indicated that DNA carry-over contamination and inhibition of PCR by the cleaning reagents were not significant problems, and therefore it was possible to reuse the same sample carrying line between runs. (C) 2008 Elsevier B.V. All rights reserved,