Nanosilver-embedded silicon nanowires as a SERS-active substrate for the ultrasensitive detection of monoamine neurotransmitters

Abstract

The trace detection of neurotransmitters is very useful in the diagnosis of severe neuropsychiatric diseases such as Parkinson's, Schizophrenia, and Depression. Surface enhanced Raman scattering (SERS) is a prospective technique for the sensitive detection of analyte with molecular information. Herein, a porous silicon (pSi) template (so-called silicon nanowires) was prepared using a metal-assisted chemical etching process, and the pSi template was successfully embedded with plenty of nanosilvers. The nanosilver-embedded pSi (pSi@Ag) was employed as a SERS-active substrate to detect dopamine (DA) and serotonin (ST) neurotransmitters at ultralow concentrations. The optimized pSi@Ag substrate produced an excellent dynamic linear range over six orders of magnitude (from 10−6 to 10−12 M), as well as showing the picomolar detection limit of ~10−13 M. The substrate exhibited the comparable performance to the current state-of-the-art researches, probably because the SERS signals were generated from larger number of analyte molecules adsorbed on the internal silver nanostructures with porous layer. Furthermore, the pSi@Ag substrate distinguished the individual component in the mixture (DA and ST at 10−8 M) without any labelling, corroborating the reliable pSi@Ag substrate for the application to the actual biological fluid.