Impact of heat treatment on size, structure, and bioactivity of elemental selenium nanoparticles

Figures & data

Figure 1 Heat treatment changes the size and the structure of 80 nm selenium nanoparticles. (A) Unheated precursor selenium nanoparticles. (B) Precursor selenium nanoparticle solution after heating at 90°C for one hour.

Note: The bar in A and B represents 170 nm.

Figure 2 Heat treatment reduces bioavailability of 80 nm selenium nanoparticles at a nutritional level. Selenium-deficient mice were orally administered with saline as a control, or 80 nm selenium nanoparticles, either unheated or heated, at a selenium dose of 100 μg/kg for 7 days.

Notes Compared with the controls, *P < 0.05; **P < 0.01; ***P < 0.001.

Abbreviations: GPx, glutathione peroxidase; TxR, thioredoxin reductase.

Figure 3 Heat treatment reduces the bioactivity of 80 nm selenium nanoparticles at a supranutritional level. Selenium-deficient mice were orally administered with saline as a control, or 80 nm selenium nanoparticles, either unheated or heated, at selenium dose of 2000 μg/kg for 7 days.

Note: Compared with the controls, ***P < 0.001.

Abbreviations: GST, glutathione; GPx, glutathione peroxidase.

Figure 4 Heat treatment changes the morphology of 40 nm selenium nanoparticles. (A) and (C) Unheated precursor selenium nanoparticles. (B) and (D) Precursor selenium nanoparticle solution after heating at 90°C for one hour.

Note: The bar in A and B represents 170 nm, and in C and D represents 80 nm.

Table 1 Comparison of bioactivity of selenium nanoparticles with different sizes in vitro and in vivo at nutritional levels (small 5–15 nm, medium 20–60 nm, large 80–200 nm)

In vitro and in vivo models	Size effects	Reference
In vitro models by ESR spectra detection
Scavenging AAPH-generated radical	S > M > L	^Citation48
Scavenging DPPH radical	S > M > L	^Citation48
Scavenging superoxide radical	S > M = L	^Citation48
Scavenging singlet oxygen	M > L	^Citation48
Attenuating Cu^2+-induced DNA damage	S > M > L	^Citation48
HepG2 cells
Increasing GPx activity	S = M = L	^Citation47
Increasing PHGPx activity	S = M = L	^Citation47
Increasing TrxR activity	S = M = L	^Citation47
Selenium-deficient mice
Increasing hepatic selenium	S = M = L	^Citation47
Increasing hepatic GPx activity	S = M = L	^Citation47
Increasing hepatic TrxR activity	S = M = L	^Citation47

Abbreviations: ESR, electron spin resonance; AAPH, 2,2′-azo-bis-(2- amidinopropane) hydrochloride; DPPH, 1,1-diphenyl-2-picryhydrazyl; GPx, glutathione peroxidase; PHGPx, phospholipid hydroperoxide glutathione peroxidase; TrxR, thioredoxin reductase; S, small; M, medium; L, large.

Table 2 Comparison of bioactivity of 36 nm and 90 nm selenium nanoparticles at supranutritional levels

Oral selenium nanoparticle doses in mice	Size effects in term of increase	Reference
0.5 mg/kg for 7 days	Blood selenium 36 nm > 90 nm	^Citation40
0.5 mg/kg for 7 days	Hepatic GST activity 36 nm > 90 nm	^Citation40
2 mg/kg for 7 days	Blood selenium 36 nm > 90 nm	^Citation40
2 mg/kg for 7 days	Hepatic selenium 36 nm > 90 nm	^Citation40
2 mg/kg for 7 days	Hepatic GST activity 36 nm > 90 nm	^Citation40
5 or 10 mg/kg once, monitored at 24 or 72 hours	Blood selenium 36 nm > 90 nm	^Citation40
5 or 10 mg/kg once, monitored at 24 or 72 hours	Hepatic selenium 36 nm > 90 nm	^Citation40
5 or 10 mg/kg once, monitored at 72 hours	Hepatic GST activity 36 nm > 90 nm	^Citation40

Abbreviation: GST, glutathione.

Figure S1. Impact of heat treatment on size and structure of 31 nm selenium nanoparticles. (A) Unheated precursor selenium nanoparticles. (B) Precursor selenium nanoparticle solution after heating at 60°C for 40 minutes. (C) Size before and after heat treatment.

Note: Data are presented as the mean ± standard deviation (n = 70).

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