Magnetic and fluorescent nanohybrids with surface imprinting silica as a dual-functional sensing platform for ratiometric fluorescence detection of phycoerythrin

Abstract

In this work we prepared novel magnetic and fluorescent dual-functional nanohybrids that consisted of Fe₃O₄ nanoparticles (NPs) as the substrate, blue-emitting carbon dots (B-CDs) combined on the surface of Fe₃O₄ NPs, and phycoerythrin (PE) imprinted silica grown on the surface of an Fe₃O₄ NP/B-CD complex. Under optimal conditions, Fe₃O₄/B-CD/PE-imprinted SiO₂ nanohybrids (MIP-based nanohybrids) were prepared and their fluorescence (FL) properties were researched. The addition of PE induced an FL decrease of B-CDs, together with an FL increase of PE. The changes were due to FRET from B-CDs to PE, because there is a large overlap between the UV-vis absorption spectrum of PE and the FL emission spectrum of B-CDs. Meanwhile, the PE-induced inner filter effect of B-CDs also led to FL quenching of B-CDs. PE was captured into specific cavity sites of PE-imprinted SiO₂ shell layers on MIP-based nanohybrids to generate MIP-PE nanohybrids. Therefore, PE contacted B-CDs or was spatially close to B-CDs. There is a well-plotted linear relationship between FL peak intensity ratios (I_PE/I_B-CDs and I₆₀₅/I₄₅₀) and PE concentrations in the range of 5–200 ng mL⁻¹, with a low limit of detection of 1.5 ng mL⁻¹. This developed sensor showed selective and sensitive responses towards PE, over other interferents. In real samples, this sensor had excellent capacity for PE determination and superior detection performances.