The biocompatibility of nanodiamonds and their application in drug delivery systems

Abstract

Nanodiamonds (NDs), as a new member of the carbon nanoparticles family, have attracted more and more attention in biomedicine recently due to their excellent physical and chemical properties. This paper summarizes the main results from the in vitro and in vivo safety assessments of NDs and reports the application of NDs in the development of drug delivery systems. In view of the NDs' characteristics of easy formation of a porous cluster structure in solution, an adsorption model for a variety of functional molecules on the ND clusters is proposed, which provides new ideas for developing a novel smart drug with various features such as sustained-release, targeting, and fluorescence imaging.

Keywords: Nanodiamonds (NDs); adsorption model; biocompatibility; drug delivery system; versatility..

Figure 1

Cytotoxicity evaluation after 24 h of incubation with various nanocarbons showing differential toxicities on (A) neuroblastoma cells or (B) macrophages. Values that are significantly different from the control (p<0.05) are denoted with asterisks (*). [Reprinted from ref. 11 with permission].

Figure 2

Coronal sections of PET images acquired 120 min after injection of four different ND preparations. Images show animals injected with ¹⁸F-NDs dorsal (A) to ventral (B), with filtered ¹⁸F-NDs dorsal (C) to ventral (D), with ¹⁸F-NDs + Tween 80 dorsal (E) to ventral (F), and finally with ¹⁸F-NDs + PEG₈₀₀₀ dorsal (G) to ventral (H). Organs that exhibited an elevated uptake of the radiolabeled compound are labeled with numbers for easy identification. [Reprinted from ref. 33 with permission].

Figure 3

Schematic drawing of the ND-nanofilm formation and the drug incorporation into the film. [Reprinted from ref. 44 with permission].

Figure 4

ND delivery of Dox inhibits tumor growth in murine liver tumor models and mammary carcinoma model. (A) Images of livers/tumors from PBS, Dox, ND, or NDX treated LT2-Myc liver tumor bearing mice. (B) Representative images of excised tumors from PBS, Dox, or NDX treated 4T1 mammary tumor bearing mice. (C) Kaplan-Meier survival plot for LT2-Myc mice treated with PBS (n = 5), Dox (100 mg) (n = 8), or NDX (100 mg of Dox equivalent) (n = 7) by tail vein injection every 7 d. *P < 0.03; **P < 0.06. (D) Kaplan-Meier survival plot for 4T1 mice treated with PBS (n = 7), Dox (100 mg) (n = 10), NDX (100 mg of Dox equivalent) (n = 10), Dox (200 mg) (n = 5), or NDX (200 mg of Dox equivalent) (n = 5) by tail vein injection every 6 d. *P < 0.003. [Reprinted from ref. 47 with permission].

Figure 5

Schematic illustration showing the different loading of different functional molecules on NDs.