A Simple and Soft Chemical Deaggregation Method Producing Single-Digit Detonation Nanodiamonds

Detonation nanodiamonds (DNDs) are a class of very small and spherical diamond nanocrystals. Used in polymer reinforcement materials, as drug delivery systems or as fluorescent biomarkers, only the final deaggregation step down to the single-digit nanometer size unfolds their full potential. All existing deaggregation methods rely on mechanical forces, such as high-power sonication or beads milling. We report a purely chemical deaggregation method by combining oxidation in air followed by a boiling acid treatment. Our DNDs are surface functionalized with carboxyl groups, the final boiling acid treatment removes primary metal contaminants and the nanoparticles remain dispersed over a wide pH range. Experiments can be easily carried out in a standard chemistry laboratory. This is a key step for many DND-based applications, ranging from material science to biological or medical applications and opens a way for inexpensive mass production on industrial scale.