Other nanomaterials such as nano-Au and QDs have also
been used. Nano-Au was used to detect pesticides at ppb
levels in a colorimetric assay (Lisha et al., 2009); modified
nano-Au was shown to detect Hg2þ and CH3Hgþ rapidly with
high sensitivity and selectivity (Lin and Tseng, 2010). QD
modified TiO2 nanotubes lowered the detection limits of PAHs
to the level of pica-mole per liter based on fluorescence
resonance energy transfer (Yang et al., 2010a). A nanosensor
based on CoTe QDs immobilized on a glassy carbon electrode
surface was reported to detect Bisphenol A in water at concentrations
as low as w10 nM within 5 s (Yin et al., 2010).