A Needle-Like MOFzyme with High Aspect Ratio and Extended pH/Temperature Working Ranges for Total Antioxidant...

A needle-like MOFzyme with high aspect ratio and extended pH/temperature working ranges was developed for quantification of total antioxidant capacity (TAC) and oxidant-/light-free dye degradation. The MOFzyme showed a length, width, and high aspect ratio of 17 ± 8 µm, 1.5 ± 0.6 µm, and 11.33, respectively. A superb oxidase-like activity, an enhanced V_max of 0.14 nM s^-1, an improved K_m of 0.12 mM, a wide pH range of 3.0-8.0, and an extended thermal range of 25-70°C were obtained, revealing their practical applicability for developing pH- and temperature-independent protocols. The MOFzyme was then utilized for the determination of TAC using trolox as a model antioxidant, providing a linear range of 0.0-200.0 μM, and a very low detection limit of 1.0 μM was obtained for TAC quantification. The selectivity studies showed that other coexisting materials cannot interfere with sensor response. The intra-day and inter-day reproducibility assays showed a %RSD as low as 1.7% and 2.36% for the sensor. The dye degradation was performed using rhodamine B as a model molecule, revealing 99.7% degradation within 40.0 min without any oxidant/light irradiation and 10 cycles of reusability. The applicability of the MOFzyme for real food and sustainable environmental applications was proved.