Table 2 Factor levels and observed responses for central composite design.

No.	Levels of independent factors			Responses
No.	X₁ (mg)	X₂	X₃ (mg)	Y₁(nm)	Y₂	Y₃(mV)	Y₄(%)
1	150	0.50	127	43.37 ± 0.87	0.18 ± 0.02	−14.4 ± 0.32	90.87 ± 1.23
2	170	0.32	90	99.74 ± 2.32	0.13 ± 0.01	−20.4 ± 0.56	84.11 ± 0.78
3	170	0.68	164	41.61 ± 1.78	0.19 ± 0.00	−8.01 ± 0.21	88.79 ± 2.03
4	170	0.68	90	49.59 ± 2.78	0.14 ± 0.01	−22.90 ± 0.45	88.96 ± 1.15
5	170	0.32	164	52.30 ± 3.48	0.22 ± 0.03	−17.64 ± 0.67	83.21 ± 1.59
6	200	0.50	190	39.53 ± 2.54	0.19 ± 0.02	−12.20 ± 0.28	97.19 ± 3.03
7	200	0.80	127	57.77 ± 1.56	0.17 ± 0.01	−16.93 ± 0.33	83.93 ± 1.45
8	200	0.50	127	56.56 ± 3.87	0.09 ± 0.01	−13.62 ± 0.71	87.79 ± 0.54
9	200	0.50	64	110.14 ± 5.02	0.17 ± 0.03	−22.76 ± 0.68	88.57 ± 1.02
10	200	0.50	127	57.87 ± 1.69	0.10 ± 0.00	−13.18 ± 0.15	88.31 ± 0.44
11	200	0.20	127	157.23 ± 6.18	0.21 ± 0.01	−20.63 ± 0.37	48.9 ± 1.67
12	200	0.50	127	52.36 ± 1.34	0.09 ± 0.02	−13.51 ± 0.43	87.74 ± 0.60
13	200	0.50	127	58.47 ± 2.77	0.10 ± 0.01	−12.93 ± 0.28	85.21 ± 0.39
14	200	0.50	127	53.28 ± 0.99	0.09 ± 0.03	−13.47 ± 0.22	85.44 ± 1.59
15	200	0.50	127	49.74 ± 3.11	0.10 ± 0.02	−14.15 ± 0.41	88.93 ± 1.65
16	230	0.68	164	46.96 ± 2.55	0.14 ± 0.03	−13.43 ± 0.18	85.20 ± 0.74
17	230	0.32	90	192.52 ± 4.03	0.21 ± 0.01	−12.12 ± 0.35	38.93 ± 0.70
18	230	0.32	164	91.65 ± 3.87	0.21 ± 0.04	−16.75 ± 0.17	65.87 ± 0.83
19	230	0.68	90	91.97 ± 1.21	0.15 ± 0.02	−21.21 ± 0.09	59.70 ± 1.22
20	250	0.50	127	89.03 ± 0.85	0.18 ± 0.01	−8.88 ± 0.06	53.89 ± 0.99

Factors—X₁: the total mass of medium chain triglyceride (MCT) and glyceryl monostearate (GMS); X₂: GMS/MCT mass ratio; and X₃: the amount of Solutol HS15. Responses—Y₁: the mean particle size (PS); Y₂: polydispersity index (PI); Y₃: zeta potential (ZP); and Y₄: entrapment efficiency (EE).

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