An optical sensing platform based on hexacyanoferrate intercalated layered double hydroxide nanozyme for determination of chromium in water.

In this work, hexacyanoferrate intercalated Ni/Al LDH (Ni/Al-Fe(CN) ₆ LDH) nanozyme was synthesized by one-pot co-precipitation method and used for determination of chromium in water samples by employing its peroxidase mimicking activity. The synthesized nanozyme can effectively catalyze the oxidation of fluorometric peroxidase substrate terephthalic acid by H ₂ O ₂ to produce a highly fluorescent product. It was found that Cr(VI) promotes the peroxidase-like activity of Ni/Al-Fe(CN) ₆ LDH and this effect was intensified by increasing the Cr(VI) concentration. Several variables affecting the fluorescence intensity including the concentration of nanoparticles and reagents as well as reaction time were investigated and optimized. Under the optimal conditions, good linearity was observed in the range of 0.067-10 μM Cr(VI), and limit of detection and quantification were found to be 0.039 and 0.131 μM, respectively. Furthermore, the developed method showed good applicability for the determination of total Cr based on the oxidation of Cr (III) to Cr (VI). The applicability of the proposed method was demonstrated by analyzing various environmental water samples. The presented nanozyme displayed superior benefits in terms of reusability, repeatability, cost and environment-friendly features. The present work aims to expand LDHs based enzyme mimics to optical sensor fields.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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