Multibranched gold-mesoporous silica nanoparticles coated with a molecularly imprinted polymer for label-free antibiotic surface-enhanced raman scattering analysis

Abstract

We describe the preparation of multibranchedgold−silica−molecularly imprinted polymer (bAu@mSiO2@MIP) core−shell nanoparticles, with their specific ability torecognize enrofloxacin (ENRO), and their application as label-free nanosensors for the specific detection of the antimicrobialby surface-enhanced Raman scattering. The use of thesenanocomposites results in a large enhancement of the Ramanscattering of ENRO upon binding of an antibiotic to theselective recognition sites in the MIP. These are in theproximity of the gold core branches that act as intrinsic hotspots providing highly localized and strongly enhancedelectromagneticfields caused by plasmon resonance. Theeffect of the multibranched morphology of the gold cores (bAu) on the optical spectroscopic response of the bAu@mSiO2@MIPnanosensors is investigated with the aim of improving ENRO detection. The optimized nanostructures allowed us to achieve adetection limit of 1.5 nM for ENRO, which is 2 orders of magnitude lower than those for previously reported Au@MIPnanosensors, additionally providing negligible cross-reactivity toward other potential interfering species.