A smartphone-assisted ultrasensitive colorimetric aptasensor based on DNA-encoded porous MXene nanozyme for visual detection of okadaic acid.

The smartphone-assisted ultrasensitive colorimetric aptasensor based on DNA-encoded porous TiC nanozyme (Apt-P-TiC) was exploited for real-time detection of OA. Porous TiC (P-TiC) MXene with outstanding peroxidase-like activities were crafted using microwave combustion, facilitating the efficient catalysis of chromogenic substrate oxidation by HO. The integration of a considerable number of unsaturated Ti center edges and residual Mn within the single-layer porous TiC framework augmented the adsorption capacity of DNA aptamer, thereby yielding a heightened catalytic efficacy of P-TiC nanoparticles. The enhanced catalytic activity of P-TiC can be partially diminished through specific recognition of OA. Concurrently, a smartphone platform was integrated for signal reading based on the colorimetric sensing strategy. The smartphone-based biosensor exhibited a reliable and ultrasensitive capability for OA detection with the detection limit of 0.38 ng·mL. It is anticipated that the developed smartphone-based biosensing platform can provide a prospective ultrasensitive detection method for marine algal toxin in food analysis.