Figure 1.

The scheme of a gold-nanoparticle (AU NP)-amplified microcantilever array biosensor for detection of foodborne bacteria. The six pairs of ssDNA probes (ssDNA₁ + ssDNA₂ complementary to the target gene) derived from the sequence analysis of the specific gene of the bacteria were developed and validated. The probes of ssDNA₁ were modified with -S-(CH₂)₆ at the 5′-end and ready to immobilize on the self-assembled monolayers (SAMs) of the sensing cantilevers in the array and couple with Au NPs, while the reference cantilevers were modified with 6-mercapto-1-hexanol SAMs to eliminate the interferences from the environment by detecting the deflection induced by non-specific interactions. For multianalyte sensing, the ssDNA₂ (partial complementary to the target gene) labeling on the Au NPs captured the target gene sequence in the solution, and then the Au NPs-ssDNA₂-target complex was hybridized with ssNDA1 fixed on the beam of the cantilever sensor resulting in secondary cascade amplification effect. The deflection of microcantilevers was positively correlated with the concentration of the target in the solution.