Central composite design for two independent variables and observed responses.

Run	Coded value		Uncoded value		I (μA)		Predicted accuracy
	A	B	GO (mg mL−1)	AuNR (mL)	Predicted	Experimental
1	0	−1.414	3.75	3.96447	4.426	4.510	98.14%
2	−1.414	0	1.98223	7.5	5.789	5.900	98.12%
3	1.414	0	5.51777	7.5	4.413	4.447	99.24%
4	−1	1	2.5	10	6.571	6.480	98.60%
5	−1	−1	2.5	5	4.802	4.695	97.72%
6	0	0	3.75	7.5	5.739	5.687	99.09%
7	0	0	3.75	7.5	5.739	5.787	99.17%
8	0	1.414	3.75	11.0355	6.173	6.235	99.01%
9	1	1	5	10	5.065	5.028	99.26%
10	0	0	3.75	7.5	5.739	5.785	99.20%
11	1	−1	5	5	4.363	4.310	98.77%
12	0	0	3.75	7.5	5.739	5.649	98.41%
13	0	0	3.75	7.5	5.739	5.791	99.10%