Table S2.

Summary of central composite design (CCD) fitting parameters

Regression coefficient	Y1 (particle size, nm)		Y2 (PI)	Y3 (zeta potential, mV)
Estimate	p-level	Estimate	p-level
b0	535.338	0.006	N/A	14.644	0.152
b1	−101.260	0.005		−9.682	0.012
b2	−2.776	0.934		−0.952	0.0001
b3	−2.705	0.010		0.140	0.214
b4	7.661	0002		0.418	0.085
b5	0.018	0.423		0.002	0.621
b6	0.031	0.055		−0.001	0.269
b7	0.617	0.049		0.118	0.0001
b8	−0.027	0.768	0.003	0.168
b9	0.166	0.313		−0.036	0.091
F-value (p<0.0001)	148			79.9
R2	0.959			0.895