Aptamer-functionalized Au nanoparticles array as the effective SERS biosensor for label-free detection of interleukin-6 in serum

A label-free, highly sensitive, and selective biosensor for detection of interleukin-6 (IL-6), which is an important inflammatory and cancer progression cytokine, has been achieved by combining gold nanoparticles (NPs) array surface-enhanced Raman spectroscopy (SERS) substrate and DNA aptamer. The SERS substrate consisted of Au NPs array is functionalized with the aptamer which is composed of the IL-6 recognition sequence and the output signal reporter. Upon recognition of target IL-6 in serum, the aptamer changes its conformation, resulting in the corresponding change of the output Raman intensity ratio (I660/I736), with which the quantitative evaluation of IL-6 in 10-12-10-7 M range can be realized. This SERS approach was employed to detect IL-6 in mice serum for inspecting the effect of drug and bacterial infection, and particularly, the radiation injury in the treated animals. This work therefore exemplifies that the aptamer-based SERS biosensor can serve as a promising tool for quick and convenient medical diagnosis applications.