Table 1.
Central composite design (CCD) using selected independent variables X1 and X2
| Exp. no. | X1* | X2* | Y1 (nm) | Y2# (%) |
|---|---|---|---|---|
| 1 | 0.50 (− 1) | 1.44 (0) | 336 | 61.8 ± 0.43 |
| 2 | 2.75 (0) | 1.44 (0) | 290 | 72.5 ± 0.52 |
| 3 | 0.50 (− 1) | 0.38 (− 1) | 338.2 | 59.6 ± 0.34 |
| 4 | 2.75 (0) | 0.38 (− 1) | 390 | 74.3 ± 0.42 |
| 5 | 2.75 (0) | 1.44 (0) | 230 | 75.3 ± 0.56 |
| 6 | 5.00 (1) | 1.44 (0) | 573.1 | 66.4 ± 0.74 |
| 7 | 5.00 (1) | 0.38 (− 1) | 601 | 49.5 ± 0.83 |
| 8 | 2.75 (0) | 1.44 (0) | 335 | 75.7 ± 0.14 |
| 9 | 0.50 (− 1) | 2.50 (1) | 302 | 54.0 ± 0.64 |
| 10 | 5.00 (1) | 2.50 (1) | 550.6 | 72.3 ± 0.44 |
| 11 | 2.75 (0) | 1.44 (0) | 220 | 70 ± 0.49 |
| 12 | 2.75(0) | 1.44(0) | 236 | 73.4 ± 0.64 |
| 13 | 2.75 (0) | 2.50 (1) | 332.8 | 72.0 ± 0.44 |
X1 values 5 = (5/1), 2.75 = 3/1.09, 0.5 = 1/2; X2 values 2.5 = 5/2, 1.44 = 3.25/2.26, 0.38 = 1.5/4
X1, ratio of Compritol® 888 ATO/P 90H; X2, ratio of P 188/PEG 400; Y1, particle size; Y2, % entrapment efficiency; 1, 0, and − 1 represent the highest, middle, and lowest concentration levels of each independent variable, respectively
*Values in bracket indicate the coded levels, i.e., + 1 (highest), 0 (middle/center point), and − 1 (lowest level)
#Response was determined on three different occasions (n = 3) and is represented as mean ± SD (standard deviation)