Self-templated formation of aptamer-functionalized copper oxide nanorods with intrinsic peroxidase catalytic activity for protein and tumor cell detection

Abstract

We have synthesized aptamer-functionalized copper nanoparticles (Apt-Cu NPs) using simple ascorbate-mediated reduction of Cu(II) ions in Apt-T-n templates comprising an aptamer (Apt) sequence with a poly(dT) motif at both the 3' and 5'-termini. The as-prepared Apt-Cu NPs underwent rapid oxidation to Apt-T-n-CuO/Cu2O NPs. The CuO/Cu2O NPs tended to have rod-like shapes when the Apt-T-n templates had long poly(dT) units (n > 30). Interestingly, the as-formed Apt-Tn-CuO/Cu2O NPs exhibited intrinsic peroxidase-like activity for the H2O2-mediated oxidation of Amplex Red (AR) to fluorescent resorufin. The catalytic activity of thrombin binding aptamer-templated CuO/Cu2O NPs (TBA-T-n-CuO/Cu2O NPs) was significantly suppressed after the specific binding of thrombin to the aptamer units on the particles' surfaces. The H2O2/AR TBA-Tn CuO/Cu2O NP probe provided a limit of detection (LOD) of thrombin in serum samples of 0.5 nM. Using Mucinl binding aptamer-templated CuO/Cu2O NPs (Aptmuci-T3O-CuO/Cu2O NPs), we applied this sensing platform to the detection of Mucinl-overexpressing tumor cells (LOD:ca.100 cells). This study suggests that the Apt-T-n can be used as a universal template for preparation of enzyme-like CuO/Cu2O NPs for detection of proteins and labeling of tumor cells when using appropriate aptamers. (C) 2015 Elsevier B.V. All rights reserved.