An Staphylococcus aureus biosensor was described
based on paramagnetic beads (micron dimension) modified
with gold nanoparticles with immobilized anti-S. aureus
antibodies (Sung et al., 2013). The inclusion of gold nanoparticles
on the larger paramagnetic bead was thought to
enhance the capture efficacy of S. aureus from the milk matrix.
The captured cells were concentrated by placing under
a magnet then passing through a micro-filter that retains
bound beads with unbound passing through. The fluorescence
of the gold particles were used to quantify the number of cells captured. Although rapid (40 min assay
time) the sensor exhibited poor sensitivity with a lower
detection limit of 5 log cfu/ml