Aptamer-functionalized biomimetic supramolecular nanozyme constructed by dipeptide, glutaraldehyde and hemin and its excellent sensing performances for tetrodotoxin

Bioinspired nanozymes hold promise for simulating natural processes and creating optimized functional systems, but their application is hindered by limited catalytic activity and selectivity. These challenges can be addressed by reconstructing enzymatic active sites to enhance catalytic efficiency and integrating biological recognition units for specificity. In this work, we developed a peroxidase-mimicking nanozyme by stabilizing hemin on a supramolecular scaffold of diphenylalanine (FF) and glutaraldehyde (GA). To enable specific recognition, we conjugated a tetrodotoxin (TTX) aptamer, yielding the He@FF/GA-Apt composite nanozyme. This nanozyme demonstrated robust catalytic activity in 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation. The TTX aptamer conferred specific TTX recognition, with the aptamer-TTX complex blocking the nanozyme active site and reducing its activity. Based on this mechanism, we created a dual-mode TTX detection method using UV–vis spectroscopy and smartphone RGB analysis. The UV–vis mode achieved a linear range of 1.0–40.0 ng mL −1 and a limit of detection (LOD) of 0.61 ng mL −1 , while the smartphone mode had a LOD of 1.43 ng mL −1 in a linear range of 2.0–40.0 ng mL −1 . Both methods performed well in real samples, with recoveries of 96.29 %–102.57 % (UV–vis mode) and 92.07 %–109.46 % (RGB mode). In comparation, the UV–vis mode offers high sensitivity but requires lab equipment, whereas smartphone RGB mode enables rapid on-site detection despite a little lower sensitivity. This work provides a promising approach for developing target-specific nanozyme sensors.