Most of the available DNA sequence-detecting assays rely
on PCR followed by electrophoretic visualization of PCR
products. However, the PCR-based assays require high reagent
and instrument costs as well as subsequent analysis by restriction
fragment length polymorphism for authentication of
specific sequences in PCR products [11e14]. In addition, the
complicated synthetic chemistry required to modify the DNA,
substrates, or nanoparticles and for hybridization on surfaces
could impose serious steric constraints, making the analysis
of PCR products both expensive and time consuming because
of low and inefficient binding of probe and target [11,14]. For
many years, the distinct optical property (SPR) exhibited by
colloidal GNPs has been studied for sensing specific oligonucleotide
sequences in several fields including biodiagnostics,
genetics, and food analysis [11e14]. Nevertheless, all these
studies based on cross-linking mechanism require surface