Fluorescent nanodiamonds made from high-pressure high-temperature diamond are increasingly used in biological imaging and sensing applications. To date, only red and green fluorescent nanodiamonds are widely available, severely limiting nanodiamond-based multiplexed imaging. Here, we report on recent progress in the fabrication and characterization of fluorescent nanodiamonds with fluorescence colors from 450 nm to 900 nm. The fluorescence originates from a range of fluorescent color centers based on nitrogen, silicon, nickel and vacancy defects in the diamond lattice. The optical properties of these color centers in diamond nanoparticles are discussed in detail and the utility of nanodiamond-based multiplexed bioimaging demonstrated in experiments in-vitro.
In the article for the first time the properties of nanodiamond complexes with dexamethasone obtained by two different approaches - attachment of the drug to the surface of nanodiamond and to the nanodiamond, covered by silica layer – were compared. It was found that the synthesized nanocomposite ND@silica@Dex is able to retain a greater amount of drug and allows achieving prolonged release of dexamethasone. These properties of the complexes ND@silica@Dex provide prospects for their use as drug carries.
Optically active nanodiamond particles remain one of the most popular research topics due to the photoluminescent properties of crystallographic defects in the diamond lattice, referred to as color centers. A number of groups are currently undertaking efforts to commercialize this material. Recently, our group succeeded in large-scale production of fluorescent diamond particles containing nitrogen-vacancy (NV) color centers in hundred-gram per batch scales using irradiation with 2-3 MeV electrons. Production of ND-NV fractions with median sizes ranging between 10 nm and 100 nm was achieved. While 100 nm fluorescent nanodiamonds (FNDs) are ~10x brighter than a conventional dye (Atto 532), the brightness of FNDs drops with decreasing particle size. Because of this, significant efforts must be undertaken to elucidate the size/brightness compromise and identify relevant application niches for FND in bioimaging and biolabeling. In order for a new material to be considered for applications in the overcrowded optical reagent market, the reagent must be convenient to use by an end user from the biomedical community, be validated both in vitro and in vivo, and offer measurable and significant (rather than incremental) benefit to end users in specific applications. This paper reports on the characteristics of the ultrasmall (10-40nm) and larger fluorescent nanodiamonds as well as our efforts toward their adaptation for use in the biological science community.
The principle possibility of extraction of fluorescence of nanoparticles in the presence of background autofluorescence of a biological environment using neural network algorithms is demonstrated. It is shown that the methods used allow detection of carbon nanoparticles fluorescence against the background of the autofluorescence of egg white with a sufficiently low concentration detection threshold (not more than 2 μg/ml for carbon dots and 3 μg/ml for nanodiamonds). It was also shown that the use of the input data compression can further improve the accuracy of solving the inverse problem by 1.5 times.