Noble metal nanoparticles have emerged to open new opportunities
for many applications including colorimetric sensors, e.g.
gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) which
are used as optical sensing materials due to their cost-effective and
high molar extinction coefficients of their surface plasmon resonance
(SPR) absorption band: 108 M1
cm1 [6] and 1010 M1
cm1
[7], respectively. Because of their lower cost compared with AuNPs,
the use of AgNPs in colorimetric sensor has become more popular
[8,9]. Furthermore, AgNPs with the 100-fold greater molar extinction
coefficient has a potential to provide better sensitivity [10].
The colorimetric sensor based on AgNPs is now obtaining increasing
attention.
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