Silica nanotube surface modification for multiplex detection of pathogenic bacteria.

This study described the prospect of silica nanotube surface modification in simultaneous detection of pathogenic bacteria by coupling cation exchange magnetic separation with quantum dot labeling. The outer surface of magnetic nanoparticles embedded long silica nanotube (capturing SNT) was modified with poly-L-lysine to serve as a cation exchange magnetic nano-complex to capture and isolate Escherichia coli (E. coli) O157:H7 and Salmonella enteritis typhimurium (S. typhimurium) in aqueous phase. Antibody conjugated quantum dot-embedded short SNT (reporting SNT) was used to simultaneously detect both bacteria, giving a high intensity and photo-stable fluorescent image that can detect single leveled bacterium binding on the capturing SNT. The fluorescent intensity generated from the capturing of both bacteria at different concentration was in the range of 10(2)-10(5) CFU/ml for both E. coli and S. typhimurium.