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

摘要

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/Cu_2O NPs. The CuO/Cu_2O 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-T_n-CuO/Cu_2O NPs exhibited intrinsic peroxidase-like activity for the H_2O_2-mediated oxidation of Amplex Red (AR) to fluorescent resorufin.The catalytic activity of thrombin binding aptamer-templated CuO/Cu_2O NPs (TBA-T_n-CuO/Cu_2O NPs) was significantly suppressed after the specific binding of thrombin to the aptamer units on the particles' surfaces. The H_2O_2/AR-TBA-T_n-CuO/Cu_2O NP probe provided a limit of detection (LOD) of thrombin in serum samples of 0.5 nM. Using Mucin1 binding aptamer-templated CuO/Cu_2O NPs (Apt_(MUC1)-T_(30)-CuO/Cu_2O 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/Cu_2O NPs for detection of proteins and labeling of tumor cells when using appropriate aptamers.