Mediated by tea polypeptides: A green synthesis approach for selenium nanoparticles exhibiting potent antioxidant and antibacterial properties

Figures & data

Table 1. Independent variables and levels used in Box-Behnken design for TP preparation.

Symbol	Independent variable	Level
		−1	0	1
A	pH	6	7	8
B	Temperature (°C)	40	45	50
C	Time (h)	3	6	9
D	Enzyme (%)	2	3	4

Table 2. Independent variables and levels used in Box-Behnken design for TP-SeNPs preparation.

Symbol	Independent variable	Level
		−1	0	1
A	pH	3	4	5
B	Temperature (°C)	35	45	55
C	Time (h)	3	6	9
D	TP content (mg/mL)	3	4	5

Table 3. Response Surface Design and Results of the Tea Polypeptides Preparation.

Run	pH	Temperature (°C)	Time (h)	Enzyme (%)	TP Content (%)
1	6	40	3	2	23.37
2	6	50	3	2	16.58
3	7	45	6	3	12.53
4	8	50	9	2	16.74
5	8	50	9	4	20.62
6	7	45	6	4	11.75
7	7	45	3	3	17.05
8	6	40	3	2	13.83
9	7	45	9	3	20.19
10	8	45	6	3	13.6
11	7	45	6	2	23.78
12	6	45	6	3	12.04
13	8	50	3	4	16.63
14	8	40	3	4	12.98
15	6	50	9	4	15.75
16	8	40	3	2	10.4
17	7	45	6	2	21.55
18	6	50	3	4	28.12
19	7	50	6	3	15.75
20	6	45	6	3	9.32
21	6	40	3	4	10.29
22	6	50	9	2	16.78
23	6	40	9	4	23.91
24	8	40	9	4	8.32
25	8	40	9	2	13.56
26	7	40	6	3	10.31
27	8	40	6	3	15.35

Table 4. Response Surface Design and Results of the Tea peptide selenium nanoparticles Process.

Run	pH	Temperature(°C)	Time(h)	TP concentration (mg/mL)	Particle diameter(nm)
1	4	35	6	5	122
2	4	45	3	3	123
3	4	45	3	4	112
4	4	35	3	4	98
5	5	45	3	4	122
6	4	55	3	4	132
7	3	45	3	4	146
8	4	45	3	5	156
9	5	45	6	5	218
10	3	45	6	3	134
11	4	55	6	5	192
12	4	55	6	3	109
13	4	45	6	4	177
14	3	55	6	4	174
15	5	45	6	3	128
16	5	55	6	4	165
17	3	45	6	4	157
18	5	45	9	4	189
19	3	45	6	5	164
20	3	35	6	4	108
21	5	35	6	4	159
22	4	35	6	3	126
23	4	45	6	4	173
24	4	55	9	4	137
25	4	45	9	3	103
26	3	45	9	4	110
27	4	45	9	5	166

Figure 1. The characterization of TP, SeNPs, and TP-SeNPs. (a) UV spectrum, (b) EDS, (c) SEM image of TP, (d) SEM images of SeNPs, (e) TEM image of TP-SeNPs ,(f) SEM image of TP-SeNPs, (g) FT-IR spectra, (h) XRD spectra.

Figure 2. The antioxidant activity of TP, SeNPs and TP-SeNPs. (a) DPPH radical scavenging activity (b) ABTS radical scavenging activity (c) Hydroxyl radical scavenging activity (d) Ferric reducing antioxidant power.

Figure 3. The cell viability of TP-SeNPs.

*p<.05; ***p<.001

Table 5. Inhibitory effects of TP, SeNPs and TP-SeNPs against Escherichia coli and Bacillus subtilis.

Bacteria	Sample Concentration	Bacteria Sample concentration Size of bacteriostatic circle (mm)
		TP	SeNPs	TP-SeNPs
Escherichia coli	2%	0.57 ± 0.02^c	0.79 ± 0.02^b	0.96 ± 0.04^a
	4%	0.60 ± 0.13^c	0.80 ± 0.04^b	1.04 ± 0.08^a
	6%	0.70 ± 0.02^c	0.87 ± 0.01^b	1.30 ± 0.03^a
Bacillus subtilis	8%	0.73 ± 0.01^c	0.92 ± 0.02^b	1.48 ± 0.06^a
	10%	0.79 ± 0.03^c	0.92 ± 0.04^b	2.06 ± 0.06^a
	2%	0.42 ± 0.02^b	0.45 ± 0.04^b	0.64 ± 0.05^a
	4%	0.49 ± 0.06^b	0.61 ± 0.04^ab	0.72 ± 0.03^a
	6%	0.56 ± 0.06^b	0.60 ± 0.09^b	0.84 ± 0.10^a
	8%	0.65 ± 0.03^b	0.83 ± 0.05^b	1.22 ± 0.12^a
	10%	0.77 ± 0.04^c	0.95 ± 0.06^b	1.37 ± 0.05^a

Note: Different letters represent significant differences at P<.05 level; same letters represent no significant difference at P<.05 level.