Extending suitability of physisorption strategy in fluorescent platforms design: Surface passivation and covalent linkage on MOF nanosheets with enhanced OTC detection sensitivity

The physisorption strategy is an universal sensing principle in fluorescent platform design, which have realized the successful detection for various targets based on nanomaterial-enabled sensors. However, this type of ”turn-on” biosensor is still faced with the dilemma of low detection sensitivity, which was mostly caused by non-specific probe displacement and relative low desorption efficiency. As a result, the extensive suitability of physisorption strategy in “turn-on” fluorescent platform has been restricted. In this work, we have established covalent-linked 2D MOF-DNA nanosystem and employed FAM-labelled short-chain as signal reporter. To further improve the detection performance for oxytetracycline (OTC), we also screened a series of blocking agents to passivate the surface of MOF nanosheets and avoid the adsorption of DNA reporter. Compared with directly covalent-linked nanosensor, the nanosensor treated with short-chain DNA reporter and surface passivation has not only possessed intrinsic specificity as apasensor but also exhibited enhanced detection performance for OTC with a linear range of 0.50–5.00 μg/L and a LOD of 0.40 μg/L (3δ/s). The as-developed strategy has shown its great potentials in a variety of nanosheets-DNA sensing systems, especially favorable for those nanomaterials with poor affinity towards DNA.