Table 1.

Coded levels and actual values of the factors investigated in the factorial experiment

Coded variable	Actual variable	Coded levels of factors
		− 1	0	+ 1
		Actual values of factors
X HA	HA concentration (wt.%)	0.5	1	1.5
X MC	MC concentration (wt.%)	0.5	1	1.5
X NP	NP size (nm)	50	100	200