Core/shell Ag@silicate nanoplatelets and poly(vinyl alcohol) spherical nanohybrids fabricated by coaxial electrospraying as highly sensitive SERS substrates

Abstract

A novel, flexible, freestanding, and large-scale substrate for surface-enhanced Raman spectroscopy (SERS) was successfully prepared by coaxial electrospraying. Nanohybrids of silver nanoparticles (AgNPs)/triblock copolymer surfactant (copolymer)/silicate nanoplatelets (Ag@silicate) were prepared by the in situ reduction of AgNO₃ in the presence of silicate platelets and a polymeric surfactant. Nonwoven mats of the hybrids were prepared via coaxial electrospraying, assembling Ag@silicate hybrids outside a poly(vinyl alcohol) (PVA) surface to form core–shell microstructures. Characterization showed that the core–shell Ag@silicate/PVA nanosphere substrate significantly enhanced the SERS signal intensity, with enhancement values approaching 5.1 × 10⁵ for adenine molecules from DNA. These core–shell nanosphere hybrids fabricated by electrospraying have great potential as SERS substrates in biosensor technology.