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Small glucose-modified liposomes (GMLs) were loaded with magnetic Fe3O4 nanoparticles (MNPs) and fluorescein using a standard thin layer preparation procedure and a varying lipid/MNPs ratio. The liposomes were characterized with TEM and DLS measurements, and MNPs encapsulation rate was determined using ICP-OES. Prepared liposomes were stored at 5 °C for 30 days and subsequently exposed to an external magnetic field (20 mT) with varying exposure times (2‒20 min), at room temperature. The release of fluorescein from GMLs induced by the magnetic field exposures was quantified, showing a high release rate (25‒85%) depending on the concentration of MNPs in GMLs. EPR measurements were conducted during the liposomes storage period in order to provide semi-quantitative information of possible MNPs oxidation from Fe3O4 to Fe2O3 inside the liposomes, impacting MNPs magnetic properties. In contrast to the MNPs water dispersion, no significant change in the EPR signal of MNPs encapsulated inside GMLs was detected over the course of 30 days. The data presented in this study indicate that GMLs loaded with MNPs maintain a high stability for prolonged periods of time and that this delivery system may be used for magnetically assisted controlled drug release. [ABSTRACT FROM AUTHOR]

Different phosphates and phosphonates have shown excellent coating ability toward magnetic nanoparticles, improving their stability and biocompatibility which enables their biomedical application. The magnetic hyperthermia efficiency of phosphates (IDP and IHP) and phosphonates (MDP and HEDP) coated Fe3O4 magnetic nanoparticles (MNPs) were evaluated in an alternating magnetic field. For a deeper understanding of hyperthermia, the behavior of investigated MNPs in the non-alternating magnetic field was monitored by measuring the transparency of the sample. To investigate their theranostic potential coated Fe3O4-MNPs were radiolabeled with radionuclide 177Lu. Phosphate coated MNPs were radiolabeled in high radiolabeling yield (> 99%) while phosphonate coated MNPs reached maximum radiolabeling yield of 78%. Regardless lower radiolabeling yield both radiolabeled phosphonate MNPs may be further purified reaching radiochemical purity of more than 95%. In vitro stabile radiolabeled nanoparticles in saline and HSA were obtained. The high heating ability of phosphates and phosphonates coated MNPs as sine qua non for efficient in vivo hyperthermia treatment and satisfactory radiolabeling yield justifies their further research in order to develop new theranostic agents. [ABSTRACT FROM AUTHOR]

[Display omitted] • Proline, tryptophan, and poly- l -lysine functionalized MNPs were synthesized and characterized. • Dispersions of PLL-MNPs have demonstrated heating ability under applied magnetic fields. • Functionalized MNPs were radiolabeled with theranostic radionuclides 131I and 177Lu. • The highest radiochemical purity, in vitro and in vivo stability were obtained for 177Lu–PLL-MNPs. • 177Lu–PLL-MNPs heated at 80 °C exhibits promising potential as a theranostic nanoagent. Surface modification of magnetic nanoparticles with poly- l -lysine, proline, and tryptophan was used to design potential theranostic agents for the application in cancer diagnosis and radionuclide-hyperthermia therapy. Characterization of bare and functionalized magnetic nanoparticles was performed in detail. The transparency of the examined magnetic nanoparticles was measured in the non-alternating magnetic field for a complete and better understanding of hyperthermia. For the first time amino acid-functionalized magnetic nanoparticles were labeled with theranostic radionuclides 131I and 177Lu. The specific absorption rate (SAR) procured for poly- l -lysine functionalized magnetic nanoparticles (SAR values of 99.7 W/g at H 0 = 15.9 kA/m and resonant frequency of 252 kHz) demonstrated their possible application in magnetic hyperthermia. Poly- l -lysine functionalized magnetic nanoparticles labeled with 177Lu showed the highest radiochemical purity (>99.00 %) and in vitro stability in saline and serum (>98.00 % up to 96 h). The in vivo analysis performed after their intravenous administration in healthy Wistar rats presented good in vivo stability for several days. Encouraging results as well as magnetic and radiochemical properties of 177Lu–PLL-MNPs (80 °C) justify their further testing toward the potential use as theranostic agents for diagnostic and combined radionuclide-hyperthermia therapeutic applications. [ABSTRACT FROM AUTHOR]

Novel theranostic nanoplatform is expected to integrate imaging for guiding and monitoring of the tumor therapy with great therapeutic efficacy and fewer side effects. Here we describe the preparation of a multifunctional 99mTc–bisphosphonate–coated magnetic nanoparticles (MNPs) based on Fe 3 O 4 and coated with two hydrophilic bisphosphonate ligands, i. e., methylene diphosphonate (MDP) and 1–hydroxyethane-1,1- diphosphonate (HEDP). The presence of the bisphosphonates on the MNPs surface, enabled their biocompatibility, colloidal stability and successful binding of the radionuclide. The morphology, size, structure, surface charge and magnetic properties of obtained bisphosphonate–coated Fe 3 O 4 MNPs were characterized by transmission electron microscopy, X–ray powder diffraction, dynamic light scattering, laser Doppler electrophoresis, Fourier transform infrared spectroscopy and vibrating sample magnetometer. The specific power absorption values for Fe 3 O 4 –MDP and Fe 3 O 4 –HEDP were 113 W/g and 141 W/g, respectively, indicated their heating ability under applied magnetic field. Coated MNPs were radiolabeled with 99mTc using stannous chloride as the reducing agent in a reproducible high yield (95% for Fe 3 O 4 –MDP and 97% for Fe 3 O 4 –HEDP MNPs) and were remained stable in saline and human serum for 24 h. Ex vivo biodistribution studies presented significant liver and spleen uptake in healthy Wistar rats after intravenous administration at all examined time points due to the colloidal nature of both 99mTc–MNPs. Results of scintigraphy studies are in accordance with ex vivo biodistribution studies, demonstrating high in vivo stability of radiolabeled MNPs and therefore results of both methods were proved as accurate information on the biodistribution profile of investigated MNPs. Overall, in vitro and in vivo stability as well as heating ability, indicate that biocompatible radiolabeled bisphosphonate magnetic nanoparticles exhibit promising potential as a theranostic nanoagent. Unlabelled Image • Water dispersible bisphosphonate–coated Fe 3 O 4 NPs were obtained and examined. • Dispersions of bisphosphonate-coated MNPs were demonstrated heating ability under applied magnetic field. • Bisphosphonate-coated MNPs were radiolabeled with 99mTc in reproducible high yield. • Biodistribution and imaging studies displayed high in vivo stability of 99mTc–MNPs. • 99mTc-bisphosphonate-coated MNPs exhibit promising potential as a theranostic nanoagent. [ABSTRACT FROM AUTHOR]