Nanodiamond s (ND) possess a unique set of properties for drug delivery that include:
- Rapid transmembrane transport
- High drug loading capacity based on high surface to volume ratio
- Tunable surface chemistry enabling efficient binding and sustainable release of drugs.
There are a few examples of ND uses as drug carriers.
Chemotherapy, the most common treatment for many forms of cancer, usually results in deleterious side effects. In addition, most of cancer stem cells (CSCs) initiating tumor growth are chemoresistant and escape the treatment, accounting for failure in treating metastatic cancer1. During standard chemotherapy the drugs are readily uptaken by tumor cells. However, they are quickly pumped out by the P-glycoprotein, which is overexpressed in cancer cells.
Chemotherapeutic drugs conjugated with ND are not recognized by P-glycoprotein and evade the efflux. The intracellular concentration of the drug increases following sustained release from the carrier, inducing apoptosis and eradicating the tumor 2. Thus, ND carriers significantly enhance the activity of chemotherapeutic drugs, while reducing or preventing their harmful side effects.
Doxorubicin (Dox), a standard treatment for cancer, was conjugated with ND and tested on mice cancer models 3. The authors reported that
- ND-Dox complex did not induce chemoresistance.
- A nearly 4-fold increase in tumor apoptosis was observed in mice treated with ND-Dox compared to the uncoupled drug.
- Elimination or significant reduction in deleterious side effects.
Chemical grafting of a tumor marker to the nanodiamond drug complex enables localization of the drug release in the tumor highly increasing in the effectiveness of cancer treatment.
Unique properties of diamond enable efficient detection of ND in tissues and cells, which makes nanodiamonds an ideal platform for theranostic applications, combining therapeutic and diagnostic functions.
The photothermal effect is achieved by conversion of light energy to heat using nanomaterials. High temperatures develop locally, leading to cell death. Nanodiamond-metal hybrid particles can be highly efficient for photothermal ablation of tumors. The photothermal particles are localized by ND intrinsic fluorescence 4. Particles localized in the tumor are then selectively destroyed by laser treatment.
- L.N. Abdullah, E.K.-H. Chow, Mechanisms of chemoresistance in cancer stem cells, Clin. Transl. Med. 2 (2013) 3.
- K. Cho, et al., Therapeutic nanoparticles for drug delivery in cancer, Clin. Cancer Res. 14 (5) (2008) 1310–1316.
- E.K. Chow, et al., Nanodiamond therapeutic delivery agents mediate enhanced chemoresistant tumor treatment, Sci. Transl. Med. 3 (73) (2011) 73ra21.
- Gong J, Steinsultz N and Ouyang M 2016 Nanodiamond based nanostructures for coupling nitrogen-vacancy centresto metal nanoparticles and semiconductor quantum dots Nat. Commun. 7 11820