Functionalization of Nanodiamond Surfaces with Metal β-Diketonato Complexes with Possible Application in Cancer Treatment

Nanodiamonds (NDs) are used more frequently as drug carriers through absorption or chemical modification. In this report, we describe the chemical binding of metal β-diketonato complexes onto the ND surface using an aminosilane linker. The metals used were iron(III) and copper(II), with β-diketones, acetylacetone, trifluoroacetylacetone, and the naturally occurring curcumin, which is known for its biological activity. Improved cytotoxicity was observed with metal complexes bound to the drug carrier compared to the free metal complexes as a result of increased stability when bound to a carrier. The curcumin-containing copper(II) conjugate demonstrated an IC₅₀ of 1.85 μM against the HeLa cell line and showed no toxicity in a larval zebrafish bioassay.