Detection of bacteria aided by immuno-nanoparticles

Magnetic immuno-nanorice particles were used for the capture and detection of Escherichia coli (E. coli) bacteria. The selectivity of the method was attained by attaching a specific anti-E. coli antibody on the surface of the nanorice, binding exclusively to E. coli. The antibody attachment to the nanorice (60% sorption efficiency) took place through protein-A molecules (82% uptake). Once E. coli was captured, the immuno-nanorice-bacteria complex was separated from the solution using the magnetic property of the nanorice. The detection of bacteria sorbed onto the immuno-nanorice was accomplished using the ultra-violet resonance Raman (UVRR) method, detecting single bacterial cells. Specific information concerning the aromatic residues tyrosine (Tyr), phenylalanine (Phe) and tryptophan (Trp) was derived. The discriminant function and cluster hierarchical analysis confirmed the specific and reliable bacteria-detection capabilities.