Fluorescent nanoparticles present in Coca-Cola and Pepsi-Cola: physiochemical properties, cytotoxicity, biodistribution and digestion studies

Figures & data

Figure 1. TEM images of NPs from (a) Coke and (b) Pepsi (scale bars 20 nm); insets are HRTEM images (scale bars 2 nm). Histograms of the size distributions of NPs from (c) Coke and (d) Pepsi. Insets are the photographs of Coke and Pepsi cans. UV–Vis absorption and fluorescent (FL) emission spectra of NPs in aqueous solution (0.05 mg mL⁻¹) from (e) Coke and (f) Pepsi. Insets show the photographs of NPs in aqueous solution under UV light.

Figure 2. (a) ¹H-NMR, (b) ¹³C-NMR spectra of fluorescent NPs extracted from Coke, and (c) ¹H-NMR, (d) ¹³C-NMR spectra of NPs extracted from Pepsi.

Figure 3. Bright field and fluorescence microscope images of malignant melanoma cells incubated with Coke NPs and Pepsi NPs for 24 h. Exposure time was 400 ms. Control cells were incubated without NPs. Scale bar = 20 µm.

Table 1. Body and major organ weight of mice after oral administration of NPs, glucose CDs and 0.9% NaCl.

	Wet weight (g)				Percentage of body (%)
Items mice	0.9% NaCl	Glucose CDs	Coke NPs	Pepsi NPs	0.9% NaCl	Glucose CDs	Coke NPs	Pepsi NPs
Whole body
Female	20.54 ± 0.19	20.48 ± 1.16	21.08 ± 0.29	20.7 ± 0.31	100%	100%	100%	100%
Male	20.48 ± 0.16	20.04 ± 0.54	20.97 ± 0.27	20.82 ± 0.17	100%	100%	100%	100%
Liver
Female	1.02 ± 0.02	1.01 ± 0.08	1.10 ± 0.04	1.02 ± 0.03	4.98 ± 0.21	4.92 ± 0.31	5.21 ± 0.49	4.94 ± 0.25
Male	1.02 ± 0.03	1.00 ± 0.07	0.97 ± 0.02	1.00 ± 0.04	4.99 ± 0.16	5.01 ± 0.21	4.64 ± 0.06	4.80 ± 0.16
Kidney
Female	0.27 ± 0.02	0.26 ± 0.02	0.29 ± 0.01	0.23 ± 0.03	1.30 ± 0.07	1.27 ± 0.12	1.37 ± 0.04	1.11 ± 0.11
Male	0.25 ± 0.00	0.26 ± 0.01	0.25 ± 0.01	0.27 ± 0.01	1.23 ± 0.02	1.28 ± 0.05	1.22 ± 0.03	1.27 ± 0.04
Thymus
Female	0.08 ± 0.02	0.08 ± 0.01	0.08 ± 0.01	0.14 ± 0.03	0.40 ± 0.09	0.38 ± 0.05	0.37 ± 0.07	0.68 ± 0.15
Male	0.08 ± 0.01	0.08 ± 0.01	0.08 ± 0.01	0.07 ± 0.01	0.40 ± 0.05	0.41 ± 0.05	0.40 ± 0.04	0.34 ± 0.06
Spleen
Female	0.09 ± 0.00	0.08 ± 0.01	0.09 ± 0.01	0.10 ± 0.01	0.42 ± 0.02	0.39 ± 0.05	0.40 ± 0.03	0.47 ± 0.07
Male	0.09 ± 0.00	0.08 ± 0.01	0.09 ± 0.00	0.09 ± 0.01	0.42 ± 0.02	0.40 ± 0.53	0.41 ± 0.01	0.44 ± 0.03
Heart
Female	0.15 ± 0.01	0.15 ± 0.01	0.15 ± 0.01	0.14 ± 0.01	0.73 ± 0.09	0.73 ± 0.08	0.76 ± 0.07	0.75 ± 0.06
Male	0.15 ± 0.01	0.15 ± 0.01	0.16 ± 0.01	0.15 ± 0.01	0.78 ± 0.09	0.77 ± 0.06	0.77 ± 0.11	0.79 ± 0.11
Brain
Female	0.55 ± 0.04	0.57 ± 0.05	0.57 ± 0.06	0.54 ± 0.05	2.73 ± 0.35	2.78 ± 0.29	2.88 ± 0.24	2.81 ± 0.27
Male	0.56 ± 0.05	0.59 ± 0.04	0.55 ± 0.06	0.55 ± 0.04	2.90 ± 0.350	2.94 ± 0.23	2.72 ± 0.50	2.82 ± 0.30
Lung
Female	0.14 ± 0.02	0.15 ± 0.01	0.15 ± 0.01	0.15 ± 0.01	0.76 ± 0.09	0.72 ± 0.05	0.78 ± 0.08	0.8 ± 0.06
Male	0.15 ± 0.01	0.15 ± 0.01	0.15 ± 0.01	0.16 ± 0.01	0.80 ± 0.14	0.76 ± 0.07	0.76 ± 0.07	0.81 ± 0.11
Ovarian/testis
Female	0.02 ± 0.00	0.02 ± 0.00	0.02 ± 0.00	0.02 ± 0.00	0.11 ± 0.00	0.10 ± 0.02	0.11 ± 0.01	0.11 ± 0.00
Male	0.15 ± 0.01	0.15 ± 0.01	0.13 ± 0.01	0.13 ± 0.01	0.74 ± 0.02	0.76 ± 0.07	0.64 ± 0.05	0.65 ± 0.04

The number of animals in each group is five (n = 5).

Table 2. Comparison of serum GPT, GOT, urea and creatinine of mice orally administrated NPs from Coke and Pepsi with control mice with glucose CDs and 0.9% NaCl.

Gender	Biochemical index	0.9% NaCl (n = 5)	Glucose CDs (n = 5)	Coke NPs (n = 5)	Pepsi NPs (n = 5)	F-value	p value
Female	GPT	31.80 ± 7.12	36.00 ± 6.75	31.00 ± 6.56	32.20 ± 5.97	0.57	.66
	GOT (U L^−1)	101.40 ± 10.92	108.00 ± 21.24	99.40 ± 12.44	98.00 ± 18.40	0.37	.78
	Urea (mg dL^−1)	8.25 ± 1.64	7.91 ± 1.06	7.50 ± 1.14	8.24 ± 1.05	0.40	.76
	Creatinine (mg dL^−1)	45.60 ± 5.81	52.80 ± 11.82	49.80 ± 9.20	52.80 ± 11.37	0.60	.62
Male	GPT (U L^−1)	36.80 ± 3.27	31.00 ± 6.78	35.00 ± 6.12	34.80 ± 5.02	1.00	.42
	GOT (U L^−1)	122.40 ± 12.34	102.60 ± 20.53	107.20 ± 20.69	99.20 ± 12.52	1.81	.19
	Urea (mg dL^−1)	7.84 ± 0.70	7.48 ± 1.18	8.07 ± 0.93	8.00 ± 1.18	0.33	.80
	Creatinine (mg dL^−1)	57.00 ± 18.48	49.40 ± 9.37	53.00 ± 6.75	53.20 ± 7.79	0.36	.78

Values in table are mean ± standard deviation.

Values with the p value >.05 are not significantly different.

Figure 4. Representative H&E stained images of major organs, including liver, kidney, thymus, spleen, heart, brain, lung, stomach, small intestine, large intestine, testis and ovary for mice treated with NPs from Coke and Pepsi at a dose of 2 g kg⁻¹ body weight at 24 h. The control group mice were orally administrated 400 µL of a 0.9% NaCl and artificially synthesized glucose CDs (2 g kg⁻¹ body weight) aqueous solution. Scale bar =100 μm.

Figure 5. Biodistribution of the NPs from Coke and Pepsi in major organs. (a) Ex vivo imaging of digestive apparatus and major organs of the Balb/c mice orally administrated with NPs from Coke and Pepsi at a dose of 2 g kg⁻¹ body weight at 0, 1/4, 2, 6 and 24 h. 1, stomach; 2, small intestine; 3, vermiform appendix; 4, colorectum; 5 brain, 6 lung; 7 liver; 8 kidneys; 9 heart; 10 spleen; 11, muscle. (b) Relative fluorescence intensity of major organs of the mice treated with NPs from Coke and Pepsi at a dose of 2 g kg⁻¹ body weight at 0, 1/4, 2, 6 and 24 h. The control mice were sacrificed after oral administration of 0.9% NaCl aqueous solution.

Figure 6. (a) Fluorescence histological analysis of major organs for the mice treated with NPs from Coke and Pepsi at a dose of 2 g kg⁻¹ body weight at 1/4, 2, 6 and 24 h. (b) Relative fluorescence intensity of major organs of the mice treated with NPs from Coke and Pepsi at a dose of 2 g kg⁻¹ body weight at 1/4, 2, 6 and 24 h. Scale bar =200 µm.

Figure 7. (a) Schematic presentation of the in vitro digestion procedure of NPs. (b) Fluorescence quenching of Coke and Pepsi NPs when they are added into saliva juice, gastric juice and duodenal bile juice to simulate the mouth, stomach and intestine digestion.