Disaggregation, stabilization, and innovative functionalization/surface engineering of detonation nanodiamonds via ultrasonication-promoted ceric ammonium nitrate treatment

We present a novel method for aqueous effective disaggregation, dispersion, and stabilization of detonation nanodiamonds (NDs) that also allows easy further second-step nanodiamond (ND) functionalization/surface engineering through lanthanide-based coordination chemistry. This method includes ultrasonic irradiation of NDs in the presence of a strong mono-electronic ceric ammonium nitrate (CAN, [Ce(IV)(NH₄)₂(NO₃)₆]) oxidant. The resulting CAN-treated NDs are positively charged with lanthanide [CeL_n]^3/4+ complexes/cations, enabling an anti-aggregation effect together with the ability to be further surface-modified through [CeL_n]^3/4+ ligand exchange (lanthanide coordinative chemistry). Therefore, this method produces ~10 nm-sized CAN-modified nanoparticles (NDs-CAN NPs) that are highly positively charged (ξ potential maximal value: +45.7 mV & average zeta potential: +34.6 mV). The obtained ND surface modification by [CeL_n]^3/4+ complexes/cations enabled an organic-type coordination attachment of various different organic molecules. This innovative way of dealing with the well-known ND aggregation phenomenon enables a novel way for the development of a wide range of biomedical, imaging, and diagnostic-related ND-based applications.