The use of QDs as fluorescent labels is emerging as a novel
and promising class of fluorescent biosensors. For detection of
S. typhimurium in chicken carcass wash water, Yang and Li [31]
separated the bacteria from wash water using anti-Salmonellaantibody-
coated magnetic beads and allowed them to react
with secondary biotin-labeled anti-Salmonella antibody to
facilitate reaction of biotin with streptavidin-coated QDs and
measure fluorescence intensity. The linear response between
logarithm of bacterial cell number and fluorescence intensity
was in the range of 103e107 CFU/mL with the detection limit
obtained being 103 CFU/mL [31]. Earlier to the aforementioned
sensors for Salmonella, Weeks et al [32] developed a silicon
nitride cantilever for detection of Salmonella enterica cells as
low as 25 by monitoring the cantilever's surface bending,
which was directly proportional to the amount of bacteria
bound on cantilever.