Monodisperse superparamagnetic Fe3O4 nanoparticles coated with oleic acid were prepared by thermal decomposition of Fe(III) glucuronate. The shape, size, and particle size distribution were controlled by varying the reaction parameters, such as the reaction temperature, concentration of the stabilizer, and type of high-boiling-point solvents. Magnetite particles were characterized by transmission electron microscopy (TEM), as well as electron diffraction (SAED), X-ray diffraction (XRD), dynamic light scattering (DLS), and magnetometer measurements. The particle coating was analyzed by atomic absorption spectroscopy (AAS) and attenuated total reflection (ATR) Fourier transform infrared spectroscopy (FTIR) spectroscopy. To make the Fe3O4 nanoparticles dispersible in water, the particle surface was modified with α-carboxyl-ω-bis(ethane-2,1-diyl)phosphonic acid-terminated poly(3-O-methacryloyl-α-D-glucopyranose) (PMG-P). For future practical biomedical applications, nontoxicity plays a key role, and the PMG-P&Fe3O4 nanoparticles were tested on rat mesenchymal stem cells to determine the particle toxicity and their ability to label the cells. MR relaxometry confirmed that the PMG-P&Fe3O4 nanoparticles had high relaxivity but rather low cellular uptake. Nevertheless, the labeled cells still provided visible contrast enhancement in the magnetic resonance image. In addition, the cell viability was not compromised by the nanoparticles. Therefore, the PMG-P&Fe3O4 nanoparticles have the potential to be used in biomedical applications, especially as contrast agents for magnetic resonance imaging.

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Biocompatible monodisperse PEG-modified magnetic Fe3O4&SiO2 core–shell nanoparticles with controlled size provided sufficient contrast for magnetic resonance imaging (MRI).

Development of therapeutic systems to treat glioblastoma, the most common and aggressive brain tumor, belongs to priority tasks in cancer research. We have synthesized colloidally stable magnetic nanoparticles (Dh=336 nm) coated with doxorubicin (Dox) conjugated copolymers of N,N‐dimethylacrylamide and either N‐acryloylglycine methyl ester or N‐acryloylmethyl 6‐aminohexanoate. The terminal carboxyl groups of the copolymers were reacted with alendronate by carbodiimide formation. Methyl ester groups were then transferred to hydrazides for binding Dox by a hydrolytically labile hydrazone bond. The polymers were subsequently bound on the magnetic nanoparticles through bisphosphonate terminal groups. Finally, the anticancer effect of the Dox‐conjugated particles was investigated using the U‐87 glioblastoma cell line in terms of particle internalization and cell viability, which decreased to almost zero at a concentration of 100 μg of particles per ml. These results confirmed that poly(N,N‐dimethylacrylamide)‐coated magnetic nanoparticles can serve as a solid support for Dox delivery to glioblastoma cells.

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The influence of magnetite nanoparticles coated with poly(acrylic acid) (Fe 3 O 4 @PAA NPs) on the organization of block copolymer thin films via a self-assembly process was investigated. Polystyrene-b-poly(4-vinylpyridine) films were obtained by the dipcoating method and thoroughly examined by X-ray reflectivity, transmission electron microscopy, atomic force microscopy, and grazing incidence small-angle scattering. Magnetic properties of the films were probed via superconducting quantum interference device (SQUID) magnetometry. It was demonstrated that due to the hydrogen bonding between P4VP and PAA, the Fe 3 O 4 @PAA NPs segregate selectively inside P4VP domains, enhancing the microphase separation process. This in turn, together with employing carefully optimized dip-coating parameters, results in the formation of hybrid thin films with highly ordered nanostructures. The addition of Fe 3 O 4 @PAA nanoparticles does not change the average interdomain spacing in the film lateral nanostructure. Moreover, it was shown that the nanoparticles can easily be removed to obtain well-ordered nanoporous templates.

Photodynamic therapy (PDT) has garnered immense attention as a minimally invasive clinical treatment modality for malignant cancers. However, its low penetration depth and photodamage of living tissues by UV and visible light, which activate a photosensitizer, limit the application of PDT. In this study, monodisperse NaYF4:Yb3+/Er3+ nanospheres 20 nm in diameter, that serve as near‐infrared (NIR)‐to‐visible light converters and activators of a photosensitizer, were synthesized by high‐temperature co‐precipitation of lanthanide chlorides in a high‐boiling organic solvent (octadec‐1‐ene). The nanoparticles were coated with a thin shell (≈3 nm) of homogenous silica via the hydrolysis and condensation of tetramethyl orthosilicate. The NaYF4:Yb3+/Er3+@SiO2 particles were further functionalized by methacrylate‐terminated groups via 3‐(trimethoxysilyl)propyl methacrylate. To introduce a large number of reactive amino groups on the particle surface, methacrylate‐terminated NaYF4:Yb3+/Er3+@SiO2 nanospheres were modified with a branched polyethyleneimine (PEI) via Michael addition. Aluminum carboxyphthalocyanine (Al Pc‐COOH) was then conjugated to NaYF4:Yb3+/Er3+@SiO2‐PEI nanospheres via carbodiimide chemistry. The resulting NaYF4:Yb3+/Er3+@SiO2‐PEI‐Pc particles were finally modified with succinimidyl ester of poly(ethylene glycol) (PEG) in order to alleviate their future uptake by the reticuloendothelial system. Upon 980 nm irradiation, the intensive red emission of NaYF4:Yb3+/Er3+@SiO2‐PEI‐Pc‐PEG nanoparticles completely vanished, indicating efficient energy transfer from the nanoparticles to Al Pc‐COOH, which generates singlet oxygen (1O2). Last but not least, NaYF4:Yb3+/Er3+@SiO2‐PEI‐Pc‐PEG nanospheres were intratumorally administered into mammary carcinoma MDA‐MB‐231 growing subcutaneously in athymic nude mice. Extensive necrosis developed at the tumor site of all mice 24–48 h after irradiation by laser at 980 nm wavelength. The results demonstrate that the NaYF4:Yb3+/Er3+@SiO2‐PEI‐Pc‐PEG nanospheres have great potential as a novel NIR‐triggered PDT nanoplatform for deep‐tissue cancer therapy.