Formation of curcumin nanoparticles via solution-enhanced dispersion by supercritical CO₂

Figures & data

Figure 1 Schematic diagram of the SEDS process.

Abbreviation: SEDS, solution-enhanced dispersion by supercritical carbon dioxide (CO₂); P, pressure; T, temperature; HPLC, high performance liquid chromatography.

Table 1 Experimental factors and levels

Symbols	Factors	Coded level
		−1	+1
A	Pressure (MPa)	10	20
B	Temperature (°C)	35	45
C	Flow rate of solution (mL·min^−1)	0.5	1
D	Concentration (%)	0.5	1

Notes: Precipitation pressure (A), precipitation temperature (B), flow rate of curcumin solution (C), concentration of curcumin solution (D).

Table 2 Experimental design and results of full factorial design

Run order	A	B	C	D	Mean size (nm)	SD
1	1	−1	−1	−1	389	61
2	1	−1	−1	−1	325	21
3	−1	1	−1	−1	694	64
4	1	1	−1	−1	337	12
5	−1	−1	1	−1	547	44
6	1	−1	1	−1	386	16
7	−1	1	1	−1	1,024	58
8	1	1	1	−1	370	4
9	−1	−1	−1	1	427	53
10	1	−1	−1	1	368	24
11	−1	1	−1	1	483	9
12	1	1	−1	1	372	53
13	−1	−1	1	1	374	19
14	1	−1	1	1	334	30
15	−1	1	1	1	899	163
16	1	1	1	1	692	118

Notes: Precipitation pressure (A), precipitation temperature (B), flow rate of curcumin solution (C), concentration of curcumin solution (D).

Figure 2 SEM micrograph of the original curcumin powders.

Abbreviation: SEM, scanning electron microscopy.

Figure 3 SEM micrographs of curcumin nanoparticles prepared by the SEDS process under different conditions (A) 0.5%-35°C-0.5 mL/min-20 Mpa; (B) 0.5%-45°C-1 mL/min-10 Mpa; (C) 0.5%-45°C-0.5 mL/min-10 Mpa; (D) 5%-45°C-0.5 mL/min-20 Mpa; (E) 0.5%-35°C-1 mL/min-10 Mpa; (F) 1%-45°C-0.5 mL/min-20 Mpa; (G) 1%-45°C-1 mL/min-20 Mpa; (H) 1%-35°C-1 mL/min-20 Mpa; (I) 0.5%-35°C-1 mL/min-20 Mpa.

Abbreviations: SEM, scanning electron microscopy; SEDS, solution-enhanced dispersion by supercritical carbon dioxide (CO₂).

Table 3 Estimated effects and coefficients for particle size (nm) (coded units)

Term	Effect	Coef	SE coef	T	P
Constant		0.5011	0.01552	32.29	0.000
Pressure (MPa)	−0.2064	−0.1032	0.01552	−6.65	0.000
Temperature (°C)	0.2152	0.1076	0.01552	6.93	0.000
Flow rate of solution (mL/min)	0.1539	0.0770	0.01552	4.96	0.000
Concentration (%)	−0.0152	−0.0076	0.01552	−0.49	0.631

Abbreviations: T, temperature; P, pressure; Coef, coefficient; SE coef, standard error coefficient.

Figure 4 Standardized effect of the factors on particle size.

Figure 5 Main effects plot for particle size.

Figure 5 Main effects plot for particle size.

Figure 6 FTIR spectra of original curcumin and curcumin nanoparticles prepared by the SEDS process under optimal conditions.

Abbreviations: FTIR, Fourier transform infrared; SEDS, solution-enhanced dispersion by supercritical carbon dioxide (CO₂).

Figure 7 XRPD pattern of original curcumin and curcumin nanoparticles prepared by the SEDS process under optimal conditions. Figure 7 inset is a partially enlarged view.

Abbreviations: XRPD, X-ray powder diffraction; SEDS, solution-enhanced dispersion by supercritical carbon dioxide (CO₂).

Figure 8 DSC curves of original curcumin and curcumin nanoparticles prepared by the SEDS process under optimal conditions.

Abbreviations: DSC, differential scanning calorimetry; SEDS, solution-enhanced dispersion by supercritical carbon dioxide (CO₂).

Figure 9 TG curves of original curcumin and curcumin nanoparticles prepared by the SEDS process under optimal conditions.

Abbreviations: TG, thermogravimetric; SEDS, solution-enhanced dispersion by supercritical carbon dioxide (CO₂).

Figure 10 Dissolution profiles of original curcumin and curcumin nanoparticles prepared by the SEDS process under optimal conditions.

Abbreviation: SEDS, solution-enhanced dispersion by supercritical carbon dioxide (CO₂).