Silica nanoparticles tailored with a molecularly imprinted copolymer layer as a highly selective biorecognition element

Abstract

Molecularly imprinted silica nanoparticles (SP-MIP) are synthesized for the real-time optical detection of low-molecular-weight compounds. Azo-initiator-modified silica beads are functionalized through reversible addition-fragmentation chain transfer (RAFT) polymerization, which leads to efficient control of the grafted layer. The copolymerization of methacrylic acid (MAA) and ethylene glycol dimethacrylate (EDMA) on azo initiator-coated silica particles (≈100 nm) using chain transfer agent (2-phenylprop-2-yl-dithiobenzoate) is carried out in the presence of a target analyte molecule ($_L$-Boc-phenylalanine anilide, $_L$-BFA). The chemical and morphological properties of SP-MIP are characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller surface analysis, and thermogravimetric analysis. Finally, SP-MIP is located on the gold surface to be used as a biorecognition layer on the surface plasmon resonance spectrometer (SPR). The sensitivity, response time, and selectivity of SP-MIP are investigated by three similar analogous molecules ($_L$-Boc-Tryptophan, $_L$-Boc-Tyrosine, and $_L$-Boc-Phenylalanine) and the imprinted particle surface showed excellent relative selectivity toward $_L$-Boc-Phenylalanine ($_L$-BFA) (k = 61), while the sensitivity is recorded as limit of detection = 1.72 × 10⁻⁴ m.