The use of detonation nanodiamond (DND) slurries in biomedical applications requires the understanding of interactions at the particle/solvent interphase. In this article, interactions of nanodiamond particles with molecules of protic solvents (water and water−ethanol mixture) were studied by the methods of laser Raman and fluorescence spectroscopy. It was found that nanodiamonds modified by carboxyl groups significantly decrease the average hydrogen bonds energy in protic solvents. In turn, the strength of hydrogen bonds at the DND/solvent interphase influences the fluorescent properties of nanodiamonds: the weaker the effect of the hydrogen bonds, the stronger is the fluorescence of DNDs in suspensions.

Local targeted “inside-out” hyperthermia of tumors via nanoparticles is able to sensitize tumor cells to chemotherapy, radiation therapy, gene therapy, immunotherapy, or other effects, significantly reducing the duration and intensity of treatment. In this article, new nanomaterials are proposed to be used as anticancer agents: boron-doped nanodiamonds with sizes of about 10 nm synthesized for the first time by the high-temperature high-pressure (HTHP) method. The heating ability of boron-doped nanodiamonds was investigated under different heating conditions in different environments: water, chicken egg white, and MCF-7 breast cancer cells. It was discovered that, with the same conversion of the absorbed energy into heat, the ability to heat the environment when excited at a wavelength of 808 nm of boron-doped nanodiamonds is much higher than that of detonation nanodiamonds. It was established that boron-doped nanodiamonds are extremely promising for carrying out hyperthermia and thermoablation of tumors.

In this work, the effective heating of surrounding water by heavily-boron-doped nanodiamonds (NDs) under laser irradiation of visible wavelength was found. Using Raman scattering spectroscopy of aqueous suspensions of boron-doped NDs, it was found that this abnormally high heating results in the weakening of hydrogen bonds much more so (2-5 times stronger) than for undoped NDs. The property of boron-doped NDs to heat a solvent under the influence of laser radiation (1-5 W cm −2 ) opens broad prospects for their use to create nanoagents for medical oncology and local hyperthermia.

The interactions of one of the most famous enzymes, lysozyme, with carboxylated nanodiamonds in water were studied. It was found that stable complexes are formed as a result of lysozyme adsorption on the surface of nanodiamonds. Based on the obtained adsorption isotherms and change in the fluorescence of nanodiamonds during the adsorption of lysozyme on them, it is concluded that lysozyme is adsorbed on carboxylated nanodiamonds in two layers. Numerical estimates and IR absorption spectroscopy data showed that the lysozyme has different adsorption orientations in the first and second layers, with preferential side-on and end-on orientations, correspondingly. Moreover, in the first layer, lysozyme undergoes significant conformational changes. The enzymatic activity of adsorbed lysozyme in both layers is discussed.

Nanoparticles’ environment, in particular pH, can strongly affect their photoluminescence (PL). This can be especially true for the surface PL of nanodiamonds (NDs) known to be dependent on the composition of surface groups. In this paper, the effect of environmental pH in the range from 2 to 12.5 on the surface photoluminescence of oxidized NDs of various syntheses and surface treatments was investigated. For the first time, the varying changes of the NDs’ PL with the pH were shown, having, however, an essential common feature: they were observed in the same pH regions from 2 to 5 and from 9 to 12.5, while in the pH region from 5 to 9, the PL intensity of all samples was almost constant. Obtained dependences of NDs’ ζ-potentials on pH and quantum mechanical modeling showed that all changes of NDs’ PL are due to the (de)­protonation of surface groups: carboxyl at pH from 2 to 5 and hydroxyl on sp2-hybridized carbon at pH from 9 to 12.5. The varying response of NDs’ PL to such deprotonation shows the possibility of tuning the surface photoluminescence of NDs for use in industry and biomedicine beyond what is possible by only controlling the nanodiamonds’ surface groups.