Chromium hydroxide nanoparticles-based fluorescent aptameric sensing for sensitive patulin detection: The significance of nanocrystal and morphology modulation

The widespread of patulin (PAT) and its potential hazards to human health call for alternative rapid assays to monitor it in food and the environment. Herein, we prepared chromium hydroxide [Cr(OH)3] nanoparticles via a one-pot chemical precipitation strategy and used them to fabricate a turn-on fluorescent aptasensor employing a morphological effect for sensitive PAT detection. Three Cr(OH)3 nanoparticle structures were synthesized by changing the solvent, and their structures and physicochemical properties were investigated. Then, we evaluated the effects of morphological structures on the fluorescence quenching-recovery capability of Cr(OH)3 nanoparticles before and after incubation with PAT. We found that the Cr(OH)3-3 nanoparticles efficiently absorbed the fluorescence dye 6-carboxyfluorescein labeled aptamer (FAM-Apt) and quenched the fluorophore through photoinduced electron transfer. Under optimal experimental conditions, the turn-on fluorescent aptasensor for PAT determination displayed two linear ranges (0.01-10 ng/mL and 1-200 ng/mL) with a low detection limit of 7.3 pg/mL. Moreover, the proposed aptasensor had no cross-reactivity with interferents that usually coexist with PAT and can be used to detect PAT in apple juices accurately. The results of the as-fabricated method were not significantly different from the high-performance liquid chromatography. Hence, we demonstrated that different Cr(OH)3 nanoparticles can be prepared by changing reaction conditions, and provided a novel strategy to improve the detection performance of fluorescent aptasensor by changing the morphological structure and crystalline properties of nano-quenchers.