Construction of a 3D rigidified DNA nanodevice for anti-interference and reinforced biosensing by turning nuclease into a catalyst.

The practical application of DNA biosensors is impeded by numerous limitations in complicated physiological environments, particularly the susceptibility of common DNA components to nuclease degradation, which has been recognized as a major barrier in DNA nanotechnology. In contrast, the present study presents an anti-interference and reinforced biosensing strategy based on a 3D DNA-rigidified nanodevice (3D RND) by converting a nuclease into a catalyst. 3D RND is a well-known tetrahedral DNA scaffold containing four faces, four vertices, and six double-stranded edges. The scaffold was rebuilt to serve as a biosensor by embedding a recognition region and two palindromic tails on one edge. In the absence of a target, the rigidified nanodevice exhibited enhanced nuclease resistance, resulting in a low false-positive signal. 3D RNDs have been proven to be compatible with 10% serum for at least 8 h. Once exposed to the target miRNA, the system can be unlocked and converted into common DNAs from a high-defense state, followed by polymerase- and nuclease-co-driven conformational downgrading to achieve amplified and reinforced biosensing. The signal response can be improved by approximately 700% within 2 h at room temperature, and the limit of detection (LOD) is approximately 10-fold lower under biomimetic conditions. The final application to serum miRNA-mediated clinical diagnosis of colorectal cancer (CRC) patients revealed that 3D RND is a reliable approach to collecting clinical information for differentiating patients from healthy individuals. This study provides novel insights into the development of anti-interference and reinforced DNA biosensors.