Medium entropy-derived flower-like FeCeCu nanozyme with excellent oxidase-like activity for on-site and visual detection of carbosulfan.

BACKGROUND

Carbosulfan residues in environment is very harmful to human health. The rapid and high sensitive detection of carbosulfan residues is particularly important to guarantee human health and safety. The conventional chromatographic techniques and enzyme inhibition strategies cannot realize on-site and visual detection of carbosulfan. It is clear that a novel nanozyme-based method was need, which exhibited advantages in low-cost, rapidity, and portability with easy-to-use operation.

RESULTS

A medium entropy-derived flower-like FeCeCu nanozyme (FeCeCuzyme) were prepared via the metal-organic coordination method with "Ostwal ripening" growth process. FeCeCuzyme exhibited an excellent oxidase-like activity due to an abundant active sites in the flower-like structure. Carbosulfan can produce the sulfide compound by hydrolysis reaction under acidic condition, which could easily form sulfide-metal bonds with FeCeCuzyme, thereby significantly quenching their oxidase-like activity and hindering nanozyme-mediated chromogenic reaction. Given this phenomenon, the FeCeCuzyme were used as a colourimetric sensor for highly-specific carbosulfan detection without using acetylcholinesterase and HO. The FeCeCuzyme colourimetric sensor showed a wide linear range from 0.15 to 50.00 μM (R = 0.9970) with low detection limit of 0.13 μM. Meanwhile, FeCeCuzyme sensor was integrated with smartphone to design a portable detection platform, which realizes the on-site and rapid detection of carbosulfan with easy-to-operation. A low detection limit of 0.14 μM was obtained in the linear relation of 0.15-50.00 μM. The satisfactory recoveries (91.17%-108.00 %) from the spiking method were highly agreed with HPLC technique, and which further verified the feasibility of FeCeCuzyme-based strategies in real samples.

SIGNIFICANCE AND NOVELTY

This work provides a pioneer new avenue for design of novel nanozymes, and offers an efficient alternative to the conventional methods for specifical, fast, and on-sites detection of carbosulfan in environment.