Uv 2600 spectrophotometer

After being cultured for 24 h, the earthworm coelomocyte fluid was centrifuged (3500 RPM, 5 min). The supernatant was poured out, and washed twice with normal saline under the same centrifugation conditions. The coelomocytes were treated with 20% amplitude ultrasound and centrifugated at 5000 RPM for 5 min at 4 °C. Then the supernatant was collected to determine the total SOD activity, CAT activity, GSH content, and MDA level. According to the kit instructions (Nanjing Jiancheng Biological Engineering Institute, Nanjing, China), the total SOD activity, GSH content, and MDA level were calculated by using a UV-2600 spectrophotometer (Shimadzu, Kyoto, Japan) to measure A₅₅₀, A₄₀₅ and A₅₃₂, respectively.
CAT activity was evaluated by measuring the absorbance change rate of H₂O₂ at 240 nm [21 (link)]. 300 μL supernatant was quickly mixed with 2.7 mL hydrogen peroxide (10 mM, diluted with normal saline), and then A₂₄₀ was recorded by using a UV-2600 spectrophotometer (Shimadzu, Kyoto, Japan). Using ultrapure water as a reference, the changes in A₂₄₀ were measured every 30 s within 3 min. After the measurement, the measured data were drawn as a scatter plot, and linear fitting was performed. The slope of the line was the change rate of H₂O₂ absorbance (the X axis was the measurement time, and the Y axis was the value of A₂₄₀ every 30 s).

Five milliliters of 0.01 M AgNO₃ was heated to boiling. To this solution, 0.5 ml of 1% trisodium citrate (pH 5.0) was added drop by drop. During the process, the solution was mixed vigorously and heated until the change in color was evident (brownish-yellow). Then, it was removed from the heating device and stirred until cooled to room temperature. After synthesis, the particles were washed with distilled water twice and suspended in 1× phosphate-buffered saline (PBS, pH 7.0) for storage and further experiments.
The citrate-coated AgNPs were characterized using SPR pattern under UV–vis spectra ranging from 300 to 700 nm using a Shimazu UV-2600 spectrophotometer. The average hydrodynamic diameter and stability of biogenic LAgNPs were determined using DLS and zeta potential studies by Microtrac's dynamic light scattering model Nanotrac.