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A review of recent advances in the development of luminescent inorganic nanoparticles doped with rare earth ions, which can be used for biomedical applications, is presented. Luminescent nanomaterials doped with rare earth ions are characterized by physicochemical properties such as long luminescence time, large Stokes and/or anti-Stokes shifts, narrow luminescence bands, high photostability, and low toxicity. These materials can be considered to be a new generation of biosensors along with conventional molecular probes such as organic dyes, quantum dots, and lanthanide labels based on organic chelates.

The possibility of using the transverse relaxation time T2 of protons in aqueous media for quantitative measurement of the capture of magnetic nanoparticles by cells has been studied and demonstrated. The measurement of T2 was performed on a portable original NMR relaxometer with a measuring cell for a standard well of a biological plate. The novelty of the approach is that quantitative measurements of the capture kinetics were carried out using measurements of the proton relaxation time of the nutrient medium, which is determined by the remaining number of magnetic particles (not captured by the cells) in the medium. To study the kinetics of capture, two types of magnetic nanoparticles were synthesized: magnetite particles Fe3O4 and composite particles Fe@C with an iron-carbon shell structure. The surface of the particles was functionalized with amine-and carboxyl groups. The capture of aminated particles of Fe@C cells is established by microscopy and NMR-relaxometry by measuring the time T2. It is shown that the proposed method makes it possible to register very small concentrations of trapped magnetic nanoparticles equal to tens of pg/cell.

For the culture of normal and transformed fibroblasts, the differential effect of two nanoclusters (Мо72Fe30, Мо132) has been shown. The Мо72Fe30 nanocluster is nontoxic to normal fibroblasts, while the Мо132 cluster shows toxicity to normal and transformed fibroblasts. An analysis of the ultrastructure of the cells under the influence of the nanoclusters has demonstrated the specificity of the changes. The dermal fibroblasts are more resistant to the action of Мо72Fe30; the Мо132 cluster causes extensive disorders in the membrane organelles both in normal and transformed fibroblasts. The results confirm the possibility of applying the Мо72Fe30 nanocluster in biomedicine and the use of the Мо132 nanocluster in oncology.

Hybrid nanoparticles based on Fe3O4 and CdS combining magnetic and luminescence properties were synthesized. The possibility of visualization of various cells by 3-mercaptopropylsilane-modified CdS nanoparticles and hybrid nanoparticles based on them using a confocal microscope was demonstrated. The synthesized materials did not show a clear-cut cytotoxicity.