Optimizing supercritical antisolvent process parameters to minimize the particle size of paracetamol nanoencapsulated in L-polylactide

Figures & data

Table 1 Variable process parameters

Process parameters	Value
Pressure (bar)	80, 90, 100, 110, 120
Temperature (°C)	30, 35, 40, 45, 50, 55
Polymer concentration (mg/mL)	12, 16, 20, 24, 28

Table 2 Fixed process parameters

Process parameters	Value
CO2 flow rate (mL/min)	15
Feed flow rate (mL/min)	1.75
Feed delivery (mL)	20
Ratio of DCM/acetone	3.2
Paracetamol concentration (mg/mL)	0.5

Figure 1 Response surface plots for particle size as a function of (A) pressure and concentration, (B) temperature and concentration, and (C) temperature and pressure.

Figure 2 Scanning electron microscopic images of nanoencapsulated paracetamol inside L-polylactide at different process parameters.

Figure 3 Thermogravimetric analysis of pure paracetamol, pure L-polylactide, and encapsulated paracetamol inside L-polylactide.

Figure 4 Zeta potential distribution graph of nanoencapsulated paracetamol inside L-polylactide.

Notes: The nanoparticles had a large negative zeta potential (−33 ±3 mV) as shown in Figure 4 due to the presence of carboxyl end groups of the L-polylactide chain. Sustained release of paracetamol in phopshate-buffered saline was investigated over 4 weeks. The first burst happened after 1 week and the cumulative paracetamol release versus time are shown in Figure 5.

Figure 5 In vitro release profile of paracetamol encapsulated in L-polylactide based on the Korsmeyer–Peppas model.