586 Nanosensors: Physical, Chemical, and Biological
NPs have carved a niche for themselves. A few reasons explaining why gold
NPs have aroused interest are as follows: (i) Au NPs provide a stable sur-
face for the immobilization of biomolecules with retention of their biological
activities, probably due to enhanced orientational freedom. This percep-
tion is extremely useful when preparing biosensors. (ii) Moreover, gold NPs
allow direct electron transport between redox proteins and bulk electrode
materials. Thus, they permit ES to be performed without the need for elec-
tron-transfer mediators. (iii) Desirable characteristics of gold NPs, such as
their high surface-to-volume ratio, their large surface energy, their capabil-
ity to decrea ...