Pharmacokinetics, tissue distribution, and excretion of zinc oxide nanoparticles

Figures & data

Table 1 Particle size and zeta potential of ZnO nanoparticles

	Measured particle size (nm)a		Zeta potential (mV)
	Pristine	Citrate-modified	Pristineb	Citrate-modified
20 nm	20 ± 9	21 ± 6	22.0	−28.1
70 nm	67 ± 12	71 ± 19	19.6	−33.3

Notes:

a Average particle size was measured by randomly selecting 500 particles from transmission electron micrographs;

b zeta potential was measured in distilled water (pH 7.0).

Figure 1 SEM (A and C) and TEM (B and D) images of 20 nm and 70 nm ZnO nanoparticles, respectively. XRD patterns (E) for pristine 20 nm (A), pristine 70 nm (B), citrate-modified 20 nm (C), and citrate-modified 70 nm (D) nanoparticles.

Figure 2 Body weight gain in male (A and C) and female (B and D) rats treated with 20 nm and 70 nm ZnO nanoparticles, respectively.

Note: The data show no significant difference from the control group (P < 0.05).

Figure 3 Plasma concentrations of ZnO nanoparticles after single-dose oral administration in male (A and C) and female (B and D) rats.

Notes: ZnO nanoparticle levels were measured by ICP-AES. The data are presented as increased zinc levels after subtraction of the basal zinc level in the control group. Insert: higher magnification of plasma concentration-time curve for the 50 mg/kg dose.

Table 2 Pharmacokinetic parameters of different-sized ZnO nanoparticles in rats

	50 mg/kg				300 mg/kg				2000 mg/kg
	20 nm		70 nm		20 nm		70 nm		20 nm		70 nm
	Male	Female	Male	Female	Male	Female	Male	Female	Male	Female	Male	Female
Cmax (μg/mL)	34.28 ± 17.50^a	27.97 ± 5.44^ab	35.17 ± 6.99^a	12.85 ± 0.97^b	94.544 ± 17.16^a	91.56 ± 3.18^a	84.19 ± 4.92^ab	65.79 ± 13.08^b	179.53 ± 12.62^a	159.43 ± 15.54^a	180.91 ± 17.37^a	155.21 ± 36.82^a
Tmax (h)	1	1	1	1	6	6	6	6	24	24	24	24
AUC (h · g/mL)	105.32 ± 16.26^a	59.01 ± 10.11^b	93.7 ± 9.14^a	29.20 ± 4.61^c	1063.13 ± 313.15^a	917.50 ± 60.40^a	769.62 ± 28.33^ab	558.35 ± 91.11^b	7981.06 ± 653.69^a	6645.12 ± 473.98^b	6934.87 ± 664.07^ab	5883.28 ± 848.58^b
MRT (h)	7.16 ± 3.04^a	2.04 ± 0.46^b	3.34 ± 0.24^b	1.86 ± 0.21^b	11.91 ± 1.27^a	7.88 ± 0.96^c	9.60 ± 0.19^b	7.67 ± 0.29^c	39.19 ± 0.73^a	36.53 ± 0.56^b	32.30 ± 0.81^c	32.01 ± 2.20^c
T1/2 (h)	5.06 ± 2.00^a	1.21 ± 0.40^b	1.84 ± 0.16^b	0.86 ± 0.22^b	8.11 ± 1.31^a	6.77 ± 0.53^b	7.16 ± 0.04^ab	6.91 ± 0.21^ab	30.28 ± 0.00^a	26.17 ± 0.76^b	26.99 ± 0.52^b	14.72 ± 0.32^c

Note: Statistical analysis was performed between four groups administered with the same dose.

Abbreviations: AUC, area under the concentration-time curve; MRT, mean residence time; T_1/2, elimination half-life; C_max, maximum concentration; T_max, time to peak plasma concentration.

Table 3 Absorption of different-sized ZnO nanoparticles in rats

	50 mg/kg				300 mg/kg				2000 mg/kg
	20 nm		70 nm		20 nm		70 nm		20 nm		70 nm
	Male	Female	Male	Female	Male	Female	Male	Female	Male	Female	Male	Female
Absorption (%)*	17.55	11.35	15.62	5.62	29.53	29.41	21.38	17.90	33.25	31.95	28.90	28.29

Note:

* Absorption was calculated based on AUC values.

Figure 4 Tissue distribution of ZnO nanoparticles in rats after single-dose oral administration of 2000 mg/kg 20 nm and 70 nm in male (A and C) and female (B and D) rats, respectively.

Table 4 Tissue distribution of different-sized ZnO nanoparticles

	Control		50 mg/kg				300 mg/kg				2000 mg/kg
	Male	Female	20 nm		70 nm		20 nm		70 nm		20 nm		70 nm
			Male	Female	Male	Female	Male	Female	Male	Female	Male	Female	Male	Female
Brain	57.32 ± 2.79	56.79 ± 4.79	56.00 ± 4.40	55.28 ± 3.74	60.02 ± 4.95	52.32 ± 3.33	56.16 ± 7.84	56.23 ± 2.89	61.97 ± 8.72	55.22 ± 5.96	57.84 ± 4.45	56.10 ± 8.54	65.59 ± 13.91	58.60 ± 5.16
Kidney	75.12 ± 12.51	75.69 ± 11.72	81.18 ± 4.81	84.09 ± 5.68	87.53 ± 10.36	86.61 ± 8.81	93.71 ± 7.01	96.36 ± 11.22	105.90 ± 27.55	93.02 ± 12.61	136.36 ± 21.69*	129.61 ± 25.03*	174.68 ± 30.05*	148.25 ± 38.12*
Liver	127.67 ± 10.08	142.99 ± 10.31	156.96 ± 25.47	150.27 ± 16.93	125.23 ± 19.57	148.09 ± 11.66	172.30 ± 22.67*	170.95 ± 35.26	155.10 ± 14.57	172.94 ± 16.96	248.46 ± 68.51*	256.22 ± 62.78*	297.24 ± 44.55*	280.11 ± 62.13*
Lung	77.71 ± 7.62	68.37 ± 8.27	99.21 ± 10.35*	66.03 ± 14.38	85.71 ± 17.65	68.40 ± 9.91	110.82 ± 18.16*	91.32 ± 22.82	177.15 ± 73.40	114.33 ± 48.59	136.87 ± 35.71*	114.80 ± 22.70*	538.88 ± 248.02*	562.33 ± 305.75*
Spleen	96.43 ± 6.62	90.12 ± 9.77	85.14 ± 14.16	85.54 ± 13.63	92.74 ± 11.43	81.46 ± 16.63	94.43 ± 19.22	92.79 ± 15.79	101.03 ± 10.32	104.74 ± 14.18	104.39 ± 16.15	96.75 ± 13.33	114.65 ± 14.38	96.22 ± 20.90
Ovary/testis	94.83 ± 3.65	88.06 ± 13.95	100.89 ± 5.31	95.11 ± 13.08	95.65 ± 9.19	95.00 ± 20.08	99.19 ± 7.77	99.02 ± 18.75	94.99 ± 6.34	115.81 ± 41.80	104.41 ± 12.16	117.65 ± 14.85	113.91 ± 14.36	119.12 ± 36.11
Total	529.08 ± 43.99	522.02 ± 58.81	579.37 ± 64.50	536.33 ± 67.44	544.87 ± 73.15	531.89 ± 70.43	626.61 ± 82.67	606.67 ± 106.73	696.14 ± 140.90	656.06 ± 140.10	788.34 ± 158.67	771.13 ± 147.24	1304.94 ± 365.27	1264.62 ± 468.18

Note:

* Significant difference from the control group (P < 0.05).

Figure 5 TEM images of the liver and kidney collected 24 hours after oral administration with two different-sized ZnO nanoparticles.

Figure 6 Fourier transform XAS spectra (radial distribution function) for 20 nm ZnO nanoparticles before oral administration (A), and liver (B), kidney (C), and spleen (D) at 24 hours after oral administration.

Figure 7 Excretion profile of 20 and 70 nm ZnO nanoparticles via urine and feces; 20 nm and 70 nm ZnO nanoparticles in urine in male (A and C) and female (B and D) rats, respectively; 20 nm and 70 nm ZnO nanoparticles in feces in male (E and G) and female (F and H), respectively.

Table 5 Excretion values of different-sized ZnO nanoparticles via urine and feces in rats

	50 mg/kg				300 mg/kg				2000 mg/kg
	20 nm		70 nm		20 nm		70 nm		20 nm		70 nm
	Male	Female	Male	Female	Male	Female	Male	Female	Male	Female	Male	Female
Excretion via urine (%)	1.13	0.98	1.47	1.36	0.78	0.61	0.71	0.61	0.49	0.32	0.50	0.34
Excretion amount via urine (mg)	0.07	0.05	0.09	0.07	0.28	0.19	0.26	0.19	1.18	0.67	1.20	0.71
Excretion via feces (%)	59.75	48.55	58.67	51.66	78.54	68.07	76.85	72.95	94.67	96.91	95.85	97.12
Excretion amount via feces (mg)	3.59	2.52	3.52	2.69	28.27	21.24	27.67	22.76	227.21	201.57	230.04	202.01

Figure S1. Tissue distribution of ZnO nanoparticles in rats after single dose oral administration of 50 mg/kg and 300 mg/kg. 50 mg/kg and 300 mg of 20 nm in male (A and B) and female (C and D). 50 mg/kg and 300 mg of 70 nm in male (E and F) and female (G and H) rats, respectively.

Figure S2. Solubility diagram of zinc cations in aqueous solution with respect to pH.