The mean particle size was approximated as the z-average diameter and the width of the distribution as the PDI. DLS measurements were performed at 25°C with a detection angle of
90°. All measurements were preformed in triplicate, and the results were reported as mean ± standard deviation. Fourier transform infrared spectroscopy Fourier transform infrared (FTIR) spectroscopy (Bruker, Ettlingen, Germany) was used to characterize bonding characteristics of the lyophilized ASNase II, CS, CSNPs, and ASNase II-CSNPs. Morphological observations Examinations of surface morphology and size distribution for CSNPs and ASNase II-loaded CSNPs were performed using a transmission electron microscope (TEM) (Philips CM30, Eindhoven, The Netherlands). About 5 μl of the nanoparticle solution was placed on a copper grid and stained with DihydrotestosteroneDHT in vitro 2% (w/v) phosphotungstic acid. In vitroASNase II release ASNase II release from the matrix complex was evaluated in three solutions of glycerol (5%)-phosphate-buffered saline (PBS) solution (pH 7.4), PBS solution (pH 7.4), and DDW containing 5% glycerol (pH 7.0). ASNase II-loaded CSNPs with the highest protein loading capacity were suspended in each of these solutions and incubated at 37°C. At predetermining time points, nanoparticles were collected with a centrifuge (25,000 × g, 30 min ��-Nicotinamide clinical trial and 25°C). The supernatant was removed for protein content assay. The percentage of leakage from the
nanoparticles Smoothened was calculated using the following equation: where %L represents the percentage of leakage, M o is the mass of ASNase II in the supernatant, and M e is the mass of entrapped ASNase II. Effect of pH on enzyme activity and stability The activities of the immobilized and free ASNase II were evaluated at different pH values in the range between pH 6.5 and 10 adjusted with Tris–HCl (0.1 M). In the case of pH stability experiment, the immobilized
and free enzymes were incubated for 24 h at 4°C ± 1°C at different pH values (pH 6 to 10) in the absence of the substrate, and the residual activity was determined. The percentage of residual activities was calculated based on the untreated control activity, which was taken as 100%. Effect of temperature on enzyme stability find more Thermostability studies were carried out by pre-incubating the immobilized and free ASNase II at different temperatures (37°C, 45°C, 50°C, 60°C, 70°C, 80°C, and 90°C) for 60 min, followed by cooling. The percentage of residual activities was determined and calculated based on the untreated control activity, which was taken as 100%. Half-life determination of the free and immobilized ASNase II The solutions of Tris–HCl (0.1 M, pH = 8.5), DDW-glycerol (5%), and PBS-glycerol (5%) were considered for measuring the half-life of the free and immobilized enzyme. Solutions of the immobilized and free enzyme were slowly homogenized and incubated at 37°C to measure the half-life of both.