A portable membrane-based analysis system for rapid and sensitive detection of bacteria

In this paper, we report a membrane filter-based detection system of bacteria using streptavidin functionalized quantum dots (SA-QDs) as a fluorescent probe. The aimed E. coli cells were marked by quantum dots through immuno-recognition, and then the marked bacteria were enriched by a low-fluorescence optical aluminium oxide membrane. A portable system was prepared for measurement of fluorescence on the membrane, which was correlation with the quantity of the marked bacteria. The whole testing time including sample pretreatment could be completed within 30 minutes. Comparing with the traditional plate count method, bacteria could be detected specifically and rapidly without time consuming cultivation. Our results showed that the output of instrument had a good correlation with total bacteria count in the range of 10²~10⁴ CFU/mL. The advantages of simple and efficient testing make this method potential attractive for in site detection of bacteria.