Fluorescent Aptasensor Based on Fe3O4@PPy

Abstract

Abstract In this work, nanomaterial polypyrrole-coated magnetite nanoparticles (Fe3O4@PPy) was synthesized and combined with label free nucleic acid probe for aptasensing. Two kinds of nucleic acid probes were applied, including blue emissive 1,1,2,2-tetrakis [4-(2-bromo-ethoxy) phenyl] ethene (TTAPE) and red emissive malachite green. The two probes can be interacted with the aptamer to form aptasensor by label free strategy. Fe3O4@PPy not only adsorbed aptamer by electrostatic interaction as well as the π–π bonding and hydrogen bonding (between PPy coating and the phosphate backbone of DNA), but also quenched the fluorescence of fluorescent probes. Upon addition of target compounds, the aptasensor was away from Fe3O4@PPy and magnetic separated thus lower background noise was obtained. The turned-on photoluminescence (PL) emission intensity was recorded and showed linearity to the concentrations of targets. The aptasensor was applied to detect metal ions, small molecular acetamiprid, and thrombin protein by changing different aptamers. The robustness of method was proved by application in real samples including vegetables (for detection of acetamiprid, LODs 0.02 and 0.04 ng/L), serum samples (for detection of thrombin, LODs 5.5 and 4.3 nM) and water samples (for detection of Pb, LOD 0.17 nM). The recoveries ranged from 81 to 105%, with RSDs ranged from 4.3 to 9.2%. Given its high selectivity and sensitivity, this technique can be used as a general detection platform for clinical and environmental applications.