In this paper, we report the fabrication of a miniaturized, inexpensive and battery-operated ultra-sensitive laser induced fluorescence (LIF) optical fibre sensor based on quenching of the LIF signal by gold nanoparticles to detect single base-mismatch DNA. Presence of the fluorescence signal indicates that the target DNA has been detected, and several pathogens could be monitored simultaneously. This nanotechnology-based method, which has yet to be fully optimized, is a few orders more selective than conventional methods. It can pinpoint single-base mismatches that are missed by conventional fluorescence technology. It is highly selective, capable of differentiating single-base mismatches and thereby reducing false positives. This portable sensor can be used to get better results in all categories important in DNA detection - sensitivity, selectivity, cost, ease of use and speed.
Detection of specific DNA sequences has important applications in clinical diagnosis, the food and drug industries, pathology, genetics and environmental monitoring. Looking into the future, we expect that this compact sensor will have important implications for the development of better biosensors and bioassays for applications in pathogen detection, clinical analysis and biomedical research. Our observations also point towards the exciting possibility of performing spatially-confined detection on arrayed biological recognition formats, for example RNA/DNA hybridization or antibody-antigen recognition. The null character of the measurement, high sensitivity of fluorescence detection, and the ability to work in complex mixtures of targets will allow us to use this powerful assay for multiple pathogen detection.