2.4. NEMs Preparation by Spray-Drying

Nanogels were mixed with aqueous solutions of trehalose or mannitol via mild shaking in order to achieve excipient:nanogel ratios of 10:1 to 20:1 (w/w). The final suspension concentrations ranged from 3.17 to 6.05 mg/mL and were subsequently spray-dried using a Büchi B-290 spray dryer (Flawil, Switzerland) equipped with a Büchi B-267 dehumidifier. The spray-drying parameters were varied with respect to feedstock composition, feed rate, and inlet and outlet temperature (Table 2). The drying air flow rate and atomizing air flow rate were kept constant at 22.5 m³/h and 450 L/h, respectively. The spray-dried powders were collected and stored in a desiccator at room temperature.

Effect of inlet temperatures on resulting (chitosan, sodium tri-penta phosphate (TPP) and alginate (sample CTA)) nano-embedded microparticle (NEM) properties. NEMs were spray-dried at different inlet temperatures. Particle size was measured after redispersion. MMAD: mass median aerodynamic diameter.