Olga Shenderova

Core-shell designs of photoluminescent nanodiamonds with porous silica coatings for bioimaging and drug delivery I: fabrication

A multifunctional core-shell nanocomposite platform consisting of a photoluminescent nanodiamond (ND) core with uniform porous silica coatings is presented. This design intended for drug delivery applications allows simultaneous stable fluorescent imaging with high loading capacity of bioactive molecules. Despite irregularly shaped starting cores, well-dispersed and uniformly shaped nanocomposite particles can be produced. Moreover, after optimization of the silica source-to-diamond ratio, the thickness of the porous layer can be tuned by adjusting the ethanol amount, allowing rational nanoparticle size control. The ND key property, photoluminescence, is not quenched regardless of coating with thick silica layers. The high loading capacity for incorporation of active agents, provided by the introduced porous layer, is demonstrated by adsorption of a hydrophobic model drug to the composite particles. The loading degree, as compared to a pure ND, increased by two orders of magnitude from 1 wt% for the ND to >100 wt% for the composite particles. Combining these two material classes, which both have well-documented excellent performance especially in biomedical applications, for the NDs with emphasis, but not exclusively, on imaging and mesoporous silica (MSN) on drug delivery, the advantages of both are shown here to be synergistically integrated into one multifunctional nanocomposite platform.

Detonation Nanodiamond Particles Processing, Modification and Bioapplications

This chapter will detail the requirements of modern detonation nanodiamonds (DNDs) intended for biomedical applications, beginning with DND material preparations and followed by bio-related applications developed at International Technology Center. DNDs are one of the most commercially promising nanodiamonds with a primary particle size of 4–5 nm, produced by detonation of carbon-containing explosives. The structural diversity of DNDs will be described, which depend upon synthesis conditions, postsynthesis processes, and modifications. Bioapplications reviewed include ballistic delivery of bio-functionalized DND into cells, photoluminescent biolabeling, biotarget capturing and collection by electrophoretic manipulation of DNDs, and health care applications. DNDs are advantageous when compared with the other types of nanoparticles due to DND large scale synthesis, small primary particle size, facile surface functionalization, stable photoluminescence as well as biocompatibility. Currently, biotechnology applications have shown that NDs can be used for bioanalytical purposes such as protein purification or fluorescent biolabeling, while research is in the developing stages for DNDs applied as diagnostic probes, delivery vehicles, enterosorbents and advanced medical device applications.

Optical imaging of fluorescent carbon biomarkers using artificial neural networks

Abstract. 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.

Producing Photoluminescent Species from Sp2 Carbons

The treatment of sp2 carbon materials, including micrographite, nanographite, HOPG, onion-like-carbon, and single-walled carbon nanotubes, in a 3:1 sulfuric to nitric acid mixture produced photoluminescent reaction solutions. These colloidal, aqueous solutions appeared photoluminescently stable under a UV lamp and ranged in color from red to blue. The photoluminescent wavelength shifted to shorter wavelength with increasing reaction time or increasing reaction temperature. Raman spectroscopy showed evidence of defect structures in graphitic residue, and transmission electron microscopy showed unusual structures present in the supernatant including graphitic balls.

Influence of hydrogen bonds on the colloidal and fluorescent properties of detonation nanodiamonds in water, methanol and ethanol

ABSTRACT This paper presents the results of research of influence of hydrogen bonds with different strength on fluorescence and colloidal properties of detonation nanodiamonds with surface carboxylic groups in the solvents. It is established that the colloidal properties of detonation nanodiamonds are almost independent on hydrogen bonds strength in water, methanol and ethanol. The fluorescent properties of detonation nanodiamonds are dependent on the type of solvent: the more intensive fluorescent properties correspond to weaker hydrogen bonds in solvents.

Interactions of nanodiamonds and surfactants in aqueous suspensions

One of the features for nanodiamonds (NDs) is their complex chemically active surface, due to which NDs can be widely used in biomedicine as drugs carriers, adsorbents, or as the basis for various bioconjugates [1, 2]. Alternatively, the chemical activity of the surface groups leads to the formation of ND’s aggregates [3]. To improve the NDs’ dispersibility, surfactants are often added in suspensions [4]. However, physical picture of the interactions between these nanoparticles and molecules of surfactants is not fully understood. It is known that in suspensions, surfactants [5], as well as NDs [3, 6, 7], substantially change the structure of solvent and, primarily, the strength of hydrogen bonds. The authors [6, 7] showed that in aqueous suspensions the detonation nanodiamonds (DNDs) weaken the hydrogen bonds in bulk water and such changes depend on the type of ND’s surface groups. In this study, we investigated the interactions of hydrophilic (DND–COOH) and hydrophobic (DND–H) surface groups of DNDs with the surfactant sodium octanoate in water using dynamic light scattering and Raman spectroscopy techniques.