Chemiluminescence Imaging for a Protein Assay via Proximity- Dependent DNAzyme Formation

ABSTRACT: An array-based chemiluminescence (CL) imag-ing method is presented for simple and high throughput detection of protein targets via the formation of a proximity-dependent DNAzyme to produce sensitive CL signal. The protein array is prepared by covalently immobilizing single-stranded guanine-rich nucleic acid 1-labeled antibody 1 (GDNA1-Ab1) or GDNA-thrombin aptamer subunit 1 (Apt-P1) as the capture probe on each sensing site on an aldehyde-functionalized disposable glass chip. In the presence of target protein, hemin, and another GDNA2-Ab2 or Apt-P2 probe, a sandwich complex among the protein and two probes can be formed to trigger the proximity assembly of GDNA1, hemin, and GDNA2, which leads to the formation of hemin-G-quadruplex DNAzyme. At different sensing sites, the DNAzyme-induced CL signals are simultaneously collected by a charge-coupled device for imaging readout of the sensing events. As a proof of concept, the proposed array-based CL imaging strategy is applied to detect carcinoembryonic antigen and thrombin and shows wide linear ranges over 4 and 5 orders of magnitude with the detection limits of 0.15 ng mL−1 and 0.49 pM, respectively. Benefiting from the one-step proximity-dependent DNAzyme formation, the assay method is extremely simple and can be carried out within 40 min