ISSN 0012-5008, Doklady Chemistry, 2016, Vol. 467, Part 2, pp. 118–121. © Pleiades Publishing, Ltd., 2016. Original Russian Text © A.M. Demin, M.V. Ulitko, A.S. Minin, Yu.V. Kuznetsova, S.V. Rempel’, V.P. Krasnov, A.A. Rempel’, 2016, published in Doklady Akademii Nauk, 2016, Vol. 467, No. 5, pp. 543–546. 118 Quantum dots (QDs) based on Cd, Zn, and Ag sul- fides (or selenides) are often used in biology and med- icine for visualization of various types of tissues including tumor tissues and to study the cell structure and intracellular processes [1, 2]. The key advantages of such materials over organic luminescent dyes, which are traditionally used for this purpose, are sta- bility in biological objects and stability against pho- tobleaching [3]. By varying the nanoparticle size and chemical composition, it is possible to obtain lumines- cent materials with an emission band in any spectral region, in particular, in the near IR range (e.g., QDs based on Ag 2 S) [4]. Currently, considerable interest has been expressed in hybrid nanoparticles combining magnetic and luminescent properties [5, 6]. Owing to the presence of magnetic properties, these materials can be detected by MRI and can be magnetically con- trolled, while luminescent properties allow optical visualization. Therefore, preparation of hybrid nano- materials would help to implement new approaches in cell culture visualization to study the structures of cells. In this work, we used hybrid nanoparticles based on magnetic Fe 3 O 4 nanoparticles (MNPs) and CdS QDs (Fe 3 O 4 –MPS–CdS) obtained by immobilization of 3-mercaptopropylsilane- modified CdS QDs (CdS– MPS) on Fe 3 O 4 MNPs in an aqueous suspension. Our objective was to study the possibility of using these materials for cell visualization in experiments in vitro. RESULTS AND DISCUSSION The hybrid nanoparticles Fe 3 O 4 –MPS–CdS based on MNPs and QDs combining magnetic and lumines- cence properties, were synthesized using stable sus- pensions of MNPs and QDs prepared beforehand. The Fe 3 O 4 MNPs were obtained using N-(phospho- nomethyl)iminoacetic acid taken in equimolar amount with respect to Fe 3 O 4 , while the stable aque- ous suspension of CdS QDs was prepared using 3- mercaptopropyltrimethoxysilane (MPTMS) by anal- ogy with [7]. This reagent is bound to the CdS surface via the mercapto group, while its silanol group can form a Fe–O–Si covalent bond with the MNP surface [8]. Hybrid nanoparticles were obtained by adding a freshly prepared solution of CdS–MPS to an aqueous suspension of MNPs in a Fe 3 O 4 : CdS molar ratio of 5 : 1. The resulting Fe 3 O 4 –MPS–CdS was precipi- tated using a magnetic field, washed three times with CHEMISTRY The Design of Hybrid Materials Based on Magnetic Fe 3 O 4 Nanoparticles and Luminescent CdS Nanoparticles for Cell Visualization A. M. Demin a , M. V. Ulitko b, c , A. S. Minin d , Yu. V. Kuznetsova e , S. V. Rempel’ e, b , V. P. Krasnov a , and Corresponding Member of the RAS A. A. Rempel’ e Received October 28, 2015 Abstract—Hybrid nanoparticles based on Fe 3 O 4 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. DOI: 10.1134/S0012500816040042 a Postovsky Institute of Organic Synthesis, Ural Branch, Russian Academy of Sciences, ul. S. Kovalevskoi 22, Yekaterinburg, 620137 Russia b Ural Federal University named after the first President of Russia B. N. Yeltsin, ul. Mira 19, Yekaterinburg, 620049 Russia c Research Institute of Medical Cell Technologies, ul. Karla Marksa 22a, Yekaterinburg, 620049 Russia d Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, ul. S. Kovalevskoi 18, Yekaterinburg, 620990 Russia e Institute of Solid-State Chemistry, Ural Branch, Russian Academy of Sciences, ul. Pervomaiskaya 91, Yekaterinburg, 620990 Russia e-mail: demin@ios.uran.ru