On the nature of fibres grown from nanodiamond colloids

Nitrogen Fixation and Biological Behavior of Nanodiamond Colloidal Solutions

“…[25] Thus, the compositions of 2-to 9-week old NDF (with C : N ratio from 25 to 11) are fit for a mixture of DND particles with such organisms, as argued above. This confirms our earlier conclusion that NDF are fungi occluding DND particles, in agreement with the refractive index of NDF (1.64-1.67) [13] being intermediate between those of DND (2.04) [13] and living cells (1.35-1.37), [26] and with TEM experiments where NDF were destroyed under the electron beam but left behind 'skeletons' of DND particles. [13] The latter result is remarkably similar to earlier observations [16] of fibers shrinking in volume under laser ablation to yield chains consisting of DND particles alone (and which probably led to subsequent misconception that these fibers were pure DND from the start).…”

“…1) NDF merely concentrates nitrogen impurities already present in DND (see above), without any overall accumulation of nitrogen. This can be rejected, as we found [13] that NDF can also grow in DW made with micro-powders ground from ordinary synthetic diamond prepared by high (static) pressure-high temperature treatment of C/Ni/Mn alloys (HPHT diamond), which does not contain nitrogen. 2) Trace amounts of ammonia and nitrogen-containing organic compounds, as well as proteins from airborne microorganisms, which are always present in the air (especially in inhabited buildings), can gradually build-up nutrient (including bioaccessible nitrogen) content in inorganic media to a level supporting the growth of bacteria, [28] which in turn can support fungi -notoriously capable to grow under oligotrophic conditions.…”

“…It must be emphasized that this effect is very specific to diamond nanoparticles (whether DND or HPHT): analogous experiments with nanoparticles of sulfur, boron and even graphite gave no fungal growth. [13] Generally, studies of biological effects of nanomaterials usually focus on their cytotoxicity, either as a health hazard or a possible application (e. g. silver nanoparticles inhibiting both bacteria and fungi [38] ). Biological studies of DND, while very extensive, [1][2][3][4] are mainly concerned with its biomedical applications (drug delivery, intracellar probes, etc.)…”

“…Recently we found [13] that the so-called 'nanodiamond fibres' (NDF, Figure 1) forming spontaneously on storage in highly diluted aqueous nanodiamond colloids ('diamond water', DW), [14] are in fact biological entities (probably fungi) containing ND particles inside them, [15][16][17] as was demonstrated (indirectly) by various physico-chemical properties and by cell membrane staining, although the organisms involved were not identified. Besides obvious implications that these results may have for biomedical safety of DND (see above), they pose an intriguing question: as these organisms were thriving in the absence of any apparent source of nutrients other than DND itself, where did they obtain bioaccessible nitrogen?…”

Novel synthesis and properties of hydrogen-free detonation nanodiamond

“…Another currently ongoing study in our laboratory concerns aqueous colloids of various types of ND (including HFND), both as an important stage in ND preparation [1,12,46] and because of their unique physical properties [30,47] and peculiar biological behavior [58].…”