Water-stable perovskite/metallic nanocomposites-based SERS aptasensor for detection of neuron-specific enolase.

Perovskite/metallic heterojunction-based surface enhanced Raman scattering (SERS) substrates have been proven to be capable of providing Raman enhancement. However, the inherent water instability and poor dispersibility of perovskite/metallic nanocomposites-based SERS substrates pose significant challenges to their application in aqueous environments. Herein, polydopamine (PDA)-encapsulated cesium lead bromide (CsPbBr) adsorbing gold nanoparticles (AuNPs), termed as CsPbBr@PDA@AuNPs, is prepared as SERS substrate, which exhibits excellent water stability and SERS activity. Dopamine as organic ligand not only passivates surface defects during the growth of perovskite nanocrystals, but also forms porous PDA protective layer, effectively preventing degradation of perovskite in aqueous medium. Meanwhile, PDA with abundant functional groups and conjugated π structure will adsorb AuNPs and promote electron flow between CsPbBr and AuNPs, resulting in strong SERS activity. Based on the results, a SERS aptasensor has been fabricated by conjugation between CsPbBr@PDA@AuNPs and double-stranded DNA (dsDNA), which is composed of neuron-specific enolase (NSE) aptamer and partial complementary signal-stranded DNA (ssDNA). The working strategy of as-fabricated SERS aptasensor is based on the conformational change (of ssDNA)-triggered Raman response for the detection of NSE. Upon the addition of NSE, the specific binding of NSE aptamers to NSE can convert rigid dsDNA into a flexible ssDNA, and the Cy5 signal molecule modified at the end of ssDNA will close to CsPbBr@PDA@AuNPs SERS substrate, generating significant Raman signals with the lower limit of detection (1.02 pg/mL) of NSE. The SERS aptasensor has broad application prospect in the field of life/medicine science fields (e.g. early diagnosis and screening of disease).