Homogeneous Electrochemical Biosensor for Melamine Based on DNA Triplex Structure and Exonuclease III-Assisted Recycling Amplification

Electrochemiluminescence Biosensor Based on 3-D DNA Nanomachine Signal Probe Powered by Protein-Aptamer Binding Complex for Ultrasensitive Mucin 1 Detection

Herein, we fabricated a novel electrochemiluminescence (ECL) biosensor for ultrasensitive detection of mucin 1 (MUC1) based on a three-dimensional (3-D) DNA nanomachine signal probe powered by protein-aptamer binding complex. The assembly of 3-D DNA nanomachine signal probe achieved the cyclic reuse of target protein based on the protein-aptamer binding complex induced catalyzed hairpin assembly (CHA), which overcame the shortcoming of protein conversion with enzyme cleavage or polymerization in the traditional examination of protein. In addition, CoFe₂O₄, a mimic peroxidase, was used as the nanocarrier of the 3-D DNA nanomachine signal probe to catalyze the decomposition of coreactant H₂O₂ to generate numerous reactive hydroxyl radical OH^• as the efficient accelerator of N-(aminobutyl)-N-(ethylisoluminol) (ABEI) ECL reaction to amplify the luminescence signal. Simultaneously, the assembly of 3-D DNA nanomachine signal probe was executed in solution, which led to abundant luminophore ABEI be immobilized around the CoFe₂O₄ surface with amplified ECL signal output since the CHA reaction was occurred unencumberedly in all directions under homogeneous environment. The prepared ECL biosensor showed a favorable linear response for MUC1 detection with a relatively low detection limit of 0.62 fg mL^-1. With excellent sensitivity, the strategy may provide an efficient method for clinical application, especially in trace protein determination.