An ultrasensitive and specific fluorescence split-aptasensor for D-VP detection based on target-induced self-propelled 3D DNA walkers coupled with CRISPR-Cas12a

In this work, we present an ultrasensitive, specific, and high-signal-to-background ratio fluorescence split-aptasensor for D-vasopressin (D-VP) detection. This sensor is based on target-induced self-propelled 3D DNA walkers in conjunction with CRISPR-Cas12a technology. Two split probes (SDA 1 and SDA 2) were designed to undergo structural recombination and function as a walking chain (SDA) under the induction of D-VP. Simultaneously, an intact Mg 2+ -dependent DNAzyme domain was formed at the tail of SDA and subsequently activated. The activated Mg 2+ -dependent DNAzyme continuously propelled the 3D DNA walker, enabling the generation of signal strand DNA (activator DNA). The activator DNA can subsequently trigger the activation of the Cas12a protein, enabling it to cleave the FAM-ssDNA-BHQ1 substrate. This process leads to signal amplification and the specific detection of D-VP. Under optimal conditions, the designed split-aptasensor exhibits excellent linearity across a concentration range of 5 ng/mL to 1215 ng/mL, with a detection limit (LOD) as low as 0.22 ng/mL. This split-aptasensor were employed to identify D-VP in human serum and urine samples, yielding highly satisfactory results. This unique design acts as a proof of concept and illustrates considerable promise for the detection of a wide range of analytes.