Wheat germ agglutinin and Lens culinaris agglutinin sensitized anisotropic silver nanoparticles in detection of bacteria: A simple photometric assay.

Efficacy of anisotropic silver nanoparticles sensitized with wheat germ agglutinin (WGA) and Lens culinaris agglutinin (LCA) was studied for detection of Staphylococcus aureus and Escherichia coli. It was demonstrated that interaction of these nanoparticles with bacteria stabilizes them and prevents their aggregation upon addition of sodium chloride; such stabilization depends on bacteria concentration. High concentration of bacteria results in higher stabilization whereas low concentration leads to aggregation of nanoparticles. Optical changes as a result of aggregation correlate with bacteria concentration. The developed approach allows the detection of Gram-positive bacteria (S.aureus) with the lowest detectable concentration of 103 cells/mL and Gram-negative bacteria (E. coli) with the lowest detectable concentration of 3 × 103 cells/mL using WGA-sensitized nanoparticles. In the case of LCA-sensitized nanoparticles the lowest detection was 5 × 103 cells/mL for S. aureus and 5 × 104 cells/mL for E. coli.