Uv vis 1200 spectrophotometer

Pierce™ 660 nm protein quantification assay (Thermo Fisher Scientific, Waltham, MA, USA) was used to determine the amount of XRN1 covalently attached to the microfluidic channel containing micropillars. Absorbance of XRN1 solutions at 660 nm were measured (UV-VIS 1200 spectrophotometer, Shimadzu, Kyoto, Japan) before and after introduction into the IMER with attached enzyme. The calibration plot and a schematic of the experimental procedure used for protein quantification can be found in Supplementary Figure S2 in the SI.

The antioxidant activity was performed through 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical scavenging activity. Various concentrations of test compound were used and mixed with 0.5 ml of 1 μM/L of 2,2-diphenyl-1-picrylhydrazyl (DPPH) solution in methanol. All the compound solutions were incubated at room temperature (in darkness) for 30 minutes and then subjected to analysis by using an ultraviolet spectrophotometer (Shimadzu UV-VIS 1200 spectrophotometer (Shimadzu Corp., Kyoto, Japan)) at 517 nm [23 (link)]. Ascorbic acid was used as standard. The scavenging activity was determined through the formula given as follows: $\begin{array}{c}\text{effect\hspace{0.17em}of\hspace{0.17em}scavenging}\left(\text{\%}\right)=\frac{1-\text{\hspace{0.17em}sample}\left(517\text{nm}\right)}{\text{\hspace{0.17em}control}\left(517\text{nm}\right)}\times 100\text{.}\end{array}$