Efficacy of nanodiamond–doxorubicin complexes on human breast adenocarcinoma cell lines

Figures & data

Table 1. Detailed preparation of the drug delivery system under various treatment conditions.

Sample	Nanodiamond (mg/mL)	Doxorubicin (mg/mL)	Nanodiamond–doxorubicin (mg/mL)
1	5.0000000	1.0000000	3.000000
2	2.5000000	0.5000000	1.500000
3	1.2500000	0.2500000	0.750000
4	0.6250000	0.1250000	0.375000
5	0.3125000	0.0625000	0.187500
6	0.1562500	0.0312500	0.093750
7	0.0781250	0.0156250	0.046875
8	0.0390625	0.0078125	0.023438

Figure 1. Photos showing the drug delivery scheme from representative samples 1–5. (a) Nanodiamond–doxorubicin solution after the binding condition is adjusted to pH = 8.0. (b) Pelleting of nanodiamond–doxorubicin complexes after the centrifugation. (c) The resuspended solution after supernatant from part (b) is separated and replaced by an identical volume of a physiological buffer (5 min, 5000 rpm). The final colour is orange.

Figure 2. Representative absorbance of 1.0 mg/mL doxorubicin (DOX) before and after adsorption. About 0.2 mg/mL of the added 1.0 mg/mL DOX is remained in the supernatant after facilitating adsorption to nanodiamond–doxorubicin complexes. The absorbance peak of nanodiamond–doxorubicin is found at 495 nm.

Figure 3. Representative fluorescence intensity of 1.0 mg/mL doxorubicin (DOX) before and after adsorption. The fluorescence peak of nanodiamond–doxorubicin is found at 600 nm.

Figure 4. Fluorescence polarization as a function of concentration of nanodiamond–doxorubicin.

Figure 5. Doxorubicin (DOX) loading capacity and efficacy at various treatment conditions. NDX represents nanodiamond–doxorubicin complexes.

Figure 6. Representative fluorescent microscopy images of MCF-7 cells after 12 h exposure (a) and after 24 h exposure (b) to 3.0 mg/mL nanodiamond–doxorubicin conjugates. Green identifies the fluorescence due to Ethidium Bromide staining. All images are shown with 40× magnification.

Figure 7. Cytotoxicity of MCF-7 cells after exposure to a range of treatment concentrations. NDX represents nanodiamond–doxorubicin complexes. Dash line denotes IC-50 value.

Figure 8. Representative bright-field microscopy images of Vero as the normal cells after 24 h exposure with 5.0 mg/mL nanodiamond alone (a) and 1.0 mg/mL doxorubicin alone (b). The interaction of doxorubicin with Vero was much higher than that of nanodiamond. All images are shown with 40× magnification.

Data availability

All data used to support the findings of this study are included in the article.