Improving the dispersity of detonation nanodiamond: differential scanning calorimetry as a new method of controlling the aggregation state of nanodiamond powders

Abstract

Detonation nanodiamond (ND) is a suitable source material to produce unique samples consisting of almost uniform diamond nanocrystals (d = 3-5 nm). Such samples exist in the form of long stable aqueous dispersions with narrow size distribution of diamond particles. The material is finding ever increasing application in biomedicine. The major problem in producing monodispersed diamond colloids lies in the necessity of deagglomeration of detonation soot and/or removing of clusters formed by already isolated core particles in dry powders. To do this one must have an effective method to monitor the aggregation state or dispersity of powders and gels prior to the preparation of aqueous dispersions. In the absence of dispersity control at various stages of preparation the reproducibility of properties of existing ND materials is poor. In this paper we introduce differential scanning calorimetry (DSC) as a new tool capable to distinguish the state of aggregation in dry and wetted ND materials and to follow changes in this state under different types of treatment. Samples with identical X-ray diffraction patterns (XRD) and high resolution transmission electron microscopy (HRTEM) images gave visibly different DSC traces. Strong correlation was found between dynamic light scattering (DLS) data for colloids and DSC parameters for gels and powders of the same material. Based on DSC data we improved dispersity of existing ND materials and isolated samples with the best possible DSC parameters. These were true monodispersed easily dispersible fractions of ND particles with diameters of ca. 3 nm.

The interaction of fluorescent nanodiamond probes with cellular media

“…Forming of aggregates or the formation of a protein layer on the diamond can increase the distance between the NV center and the target molecule. It has to be noted that our study is different from well-known aggregation in detonation nanodiamonds [15, 16]. These aggregate during synthesis without the presence of other molecules.…”

Nanodiamond–TiO2 composites for photocatalytic degradation of microcystin-LA in aqueous solutions under simulated solar light

“…Even so, it was possible to conclude that C-O (287.0 eV) 37, 38 is the main bond in the composite (as expected due to the known carbon sp 3 hybridization in diamonds), followed by C-C/C-H (285.0 eV) and C=O (288.9 eV), 37, 38 while other type of chemical bonds cannot be confirmed by this characterization technique. These results are in agreement with TPD analysis, 12 were phenol or ether (C-OH, C-O-C; 286.3 eV 36 ) and quinone (C=O) groups were detected, while carboxylic acids (-COOH), carboxylic anhydrides (-C(O)2O) and lactones (-COO) were not identified in the composite.Several authors39,40 have reported that detonated NDs when dispersed in liquid medium induce strong particle aggregation, attributing the phenomenon to the harsh conditions in the detonation chamber that leads to the creation of dandling bonds on the ND surface. The free electron surfaces can cooperate via intermolecular surface forces such as van der Waals and hydrogen bonding creating covalent bonds between the primary particles 39.…”

Communication: Three-dimensional model for phonon confinement in small particles: Quantitative bandshape analysis of size-dependent Raman spectra of nanodiamonds

“…24,25 In conclusion, we propose a physically consistent way of interpreting Raman spectra of nanoparticles. Since the 3D dispersion function takes into account the anisotropy of the phonon dispersion, the model built in this way has a straightforward physical meaning.…”