Aptamer-based SERS assay of ATP and lysozyme by using primer self-generation.

A simple bifunctional surface-enhanced Raman scattering (SERS) assay based on primer self-generation strand-displacement polymerization (PS-SDP) is developed to detect small molecules or proteins in parallel. Triphosphate (ATP) and lysozyme are used as the models of small molecules and proteins. Compared to traditional bifunctional methods, the method possesses some remarkable features as follows: 1) by virtue of the simple PS-SDP reaction, a bifunctional aptamer assembly binding of trigger 1 and trigger 2 was used as a functional structure for the simultaneous sensing of ATP or lysozyme. 2) The concept of isothermal amplification bifunctional detection has been first introduced into SERS biosensing applications as a signal-amplification tool. 3) The problem of high background induced by excess bio-barcodes is circumvented by using magnetic beads (MBs) as the carrier of signal-output products and massive of hairpin DNA binding with SERS active bio-barcodes relied on Au nanoparticles (Au NPs), SERS signal is significantly enhanced. Overall, with multiple amplification steps and one magnetic-separation procedure, this flexible biosensing system exhibited not only high sensitivity and specificity, with the detection limits of ATP and lysozyme of 0.05 nM and 10 fM, respectively.