In this work, the fluorescence quenching of two types of bioactive molecules – of the protein lysozyme and of the drug doxorubicin – by carboxylated detonation nanodiamonds in the result of their interaction has been studied. It was demonstrated that nanodiamonds effectively quench the fluorescence of lysozyme and doxorubicin but by different mechanisms. It was found that the fluorescence quenching of lysozyme by nanodiamonds is caused only by a static type of quenching while the fluorescence quenching of doxorubicin by nanodiamonds is caused by both static and dynamic types of quenching. We propose a hypothesis that the surface groups of nanodiamonds are the quenchers of the fluorescence and the variety of surface groups with which a fluorescent molecule interacts determines the fluorescence quenching mechanism. The accounting of our results will provide the insight in the nanodiamonds’ visualization as well as the possible way to track the loading and subsequent unloading of drugs from the nanodiamonds’ surface.
In the present work an influence of interactions between detonation nanodiamonds and biomacromolecules (DNA and lysozyme) on fluorescent properties of nanodiamonds was studied. Formation mechanisms of complexes of nanodiamonds with DNA and lysozyme molecules were investigated. It was found that fluorescent intensity of detonation nanodiamonds changes in different ways for nanoparticles with different surface composition. It was established that fluorescent intensity of nanodiamonds increases in case of the interaction with a sufficient number of biomacromolecules.
This work presents the results of study of the influence of BDND on hydrogen bonds of protonic solvents. In addition, the comparative analysis of the interactions of BDND and DND-COOH with solvents molecules was carried out. The analysis of temperature dependences of the quantitative characteristics of the stretching bands of OH groups of the solvents and the suspensions of NDs has shown that the BDND and DND differently weaken the hydrogen bonds in water and in water-ethanol solution with 70 vol. % ethanol content. In water-ethanol solution with 20 vol. % of ethanol the both NDs practically does not change the network of hydrogen bonds.
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.