The values obtained in the central composite model for synthesizing Cu NPs (MG).

Regression coefficients	Absorbance	SPR, nm	p-Value of αi and αii
			Absorbance	SPR
α 0	1.168	598.6
α 1	0.077	−1.1	0.025	0.020
α 2	0.116	−2.4	0.003	< 0.001
α 11	−0.293	3.4	< 0.001	< 0.001
α 22	−0.406	5.0	< 0.001	< 0.001
R 2	0.970	0.967