A chemiluminescent biosensor for ultrasensitive detection of adenosine based on target-responsive DNA hydrogel with Au@HKUST-1 encapsulation

Abstract

In this work, target-responsive DNA hydrogel with high loading and good biocompatibility was used to construct chemiluminescent biosensor for specific detection of adenosine. Acrydite-modified adenosine aptamer (Acry-A-Apt), acrydite-modified single-strand DNA (Acry-ssDNA) and hemin aptamer (H-Apt) were used to prepared the DNA hydrogel, and the three single-strand DNA were partially complementary to each other. Thus, the DNA hydrogel only dissolved when adenosine and hemin were present simultaneously. HKUST-1 is a Cu-based MOFs with peroxidase-like activity. Au NPs were coated into cavities of HKUST-1 to obtain Au@HKUST-1, and the Au@HKUST-1 had a stronger peroxidase-like activity than HKUST-1. Au@HKUST-1 was coated in the DNA hydrogel. When only hemin was present, hemin bound to the H-Apt to form the G-quadruplex/hemin and the DNA hydrogel remained in the gel state. Therefore, the G-quadruplex/hemin was formed in the hydrogel and the excess hemin can be removed, avoiding background signal interference. Adenosine was then added and the preferential interaction between adenosine and adenosine aptamer resulted in complete dissolution of the DNA hydrogel. Subsequently, G-quadruplex/hemin and Au@HKUST-1 were released simultaneously, enabling dual signal amplification of chemiluminescent biosensor, yielding a “signal on” readout. As a result, the biosensor could quantify adenosine from 4 × 10−13 – 1.5 × 10-10 mol/L with a detection limit as low as 1.04 × 10−13 mol/L. The DNA hydrogel system provides a simple, sensitive and biocompatible method for the detection of adenosine which is useful in the field of biotechnology.