Chitosan-based Nanoparticles for Drug Delivery

Chitosan-based nanoparticles including blank CS NPs, SF-loaded chitosan nanoparticles (SF-CS NPs), and Tween 80-coated SF-loaded CS-NPs (T- SF-CS NPs) were prepared using essentially a TPP ionic gelation method with some modification [25 (link)]. In brief, low molecular weight CS was dissolved in an acetic acid solution with magnetic stirring overnight. After pH adjustment to 4.7-4.8 with 20% NaOH, the CS solution was filtered using a 0.45 μm nylon syringe filter. A cold-filtered TPP solution (3 mL) was added to the CS solution (10 mL) in a water bath at 60°C under magnetic stirring for about 10 min and the formed blank SF-CS NPs were separated. To adjust the physical properties of plain CS-NPs, particularly, the particle size and size distribution, a series of preliminary trials based on the preparation of NPs by changing the experimental variables one at a time while keeping other variables constant was undertaken. The variables included the concentration of CS and TPP solutions (0.5 mg/mL vs. 2 mg/mL), the temperature of the CS solution during TPP addition (25°C vs. 60°C) as well and the method of separation of the formed CS NPs (low-speed centrifugation at 3000 rpm for 10 min at ambient temperature vs probe sonication for 10 and 20 min).
SF-CS-NPs were prepared by dissolving SF (2 mg/mL) in the CS solution as reported earlier for berberine-loaded CS NPs [26 (link)], and the procedure was completed as described above. For the preparation of T-SF-CS-NPs, freshly prepared SF-CS NPs were resuspended in 1% Tween 80 solution and sonicated for 20 min in a water bath sonicator [27 (link)].