Uv 1900

The kinetics of drug release was estimated using beet juice, as immersion fluid [35 (link)]. Firstly, a standard curve of beet juice concentration versus absorbance at 520 nm (Shimadzu UV-1900) [35 (link)] was obtained by measuring various dilutions (0.1, 0.3, 0.5, 0.7, 1, and 1.5%). The obtained curve had the following equation: y = 0.3644x + 0.0007 and an R² of 0.9996.
For the actual drug release assay, BCd and BCm (32.5 × 16.25 mm) membranes were loaded with concentrated beet juice overnight. The membranes, thus, prepared were immersed in 20 mL distillated water and a 2 mL solution was taken at precise time intervals (30 min; 1, 2, 3, 6, 24, 48, and 72 h), and their absorbance was measured at 520 nm (Shimadzu UV-1900) to determine the beet juice release [35 (link)]. After removing aliquots of 2 mL from each sample for analysis, the same volume of fresh distillated water was added [36 (link)]. UV absorbance was measured to determine the concentration of released beet juice at each time point [37 (link)]. The drug half-release time was obtained by plotting the released beet juice by time and computing the duration in which the pellicles release half of their total uptake [34 (link)]. All the measurements and computations were done in triplicate, and the results were expressed as mean ± SD.

Soluble sugars were extracted using the method of Fairbairn [40 (link)] with slight modifications. Leaves (0.2 g) were put into a test tube, to which 10 mL of distilled water was added and mixed. After 30 min in a water bath at 100 °C, the supernatant was collected, and distilled water was added to a volume of 25 mL. The soluble sugar content was determined with the sulfuric acid anthrone method at a wavelength of 620 nm using a UV spectrophotometer (UV-1900, Shimadzu, Tokyo, Japan).
Leaves (0.2 g) were placed in a mortar, flash frozen with liquid nitrogen, and ground to a powder. Phosphate buffer (5 mL; 50 mM, pH 7.0) was added, and the homogenate was centrifuged at 12,000 rpm for 4 min at 4 °C. The supernatant was used for determination of soluble protein content according to the method of Bradford [41 (link)], using 0.1 mL of the supernatant and 4.9 mL of Coomassie Brilliant Blue G-250 (0.1 g·L⁻¹). After 2 min, the absorbance was measured at 595 nm using a UV spectrophotometer (UV-1900, Shimadzu, Tokyo, Japan), and the soluble protein content was calculated using a standard curve (bovine serum albumin was used to make the standard curve).

For drug loading experiments, sample punches (6 mm diameter) were dissolved in 2 mL of AA. After filtering the samples through 0.22 µm syringe filters, the samples were measured using UV-Vis spectrophotometry (Shimadzu UV-1900, Kyoto, Japan) at 354 nm. Drug-free samples were used as a control, and all experiments were carried out in triplicate. Drug release experiments were carried out on sample punches (6 mm diameter), which were placed in a 24-well plate in 2 mL water at 37 °C. The samples were shaken at 200 rpm (neoMix thermoshaker, neoLab, Heidelberg, Germany) for the duration of the experiments. At different time points (0 min, 5 min, 10 min, 20 min, 30 min, 1 h, 3 h, 24 h and 48 h), 1 mL was removed from the well plates and replaced with 1 mL fresh 37 °C Milli-Q water. The removed samples were filtered through a 0.22 μm syringe filter and analyzed by UV-Vis spectrophotometry (Shimadzu UV-1900, Kyoto, Japan) at 354 nm. Drug-free samples were used as controls, and measurements were conducted in triplicate.