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Gadolinium-based contrast agents (GdCAs) have been the most frequently used T1-weighted magnetic resonance imaging (MRI) contrast agents for decades. However, they have serious disadvantages such as low longitudinal relaxivity value (r1) and high dose associated-nephrotoxicity that restrict their wide applications. These emphasize the need for an ideal stable and biocompatible T1-weighted CA with high contrast enhancement performance. Here, we propose a wet-chemical synthesis technique to form a nanocomposite consisting of ultrasmall iron oxide nanoparticles (US-IO) and Gd2O3 hybrid nanoparticles stabilized with dextran (FG-HNPs) for T1-weighted MR imaging. Relaxometry study showed that FG-HNPs have a high r1 value (42.28 mM−1S−1) and low relaxivity ratio (r2/r1: 1.416) at 3.0T. In vivo MRI contrast enhancement factor (ΔSNR) for FG-HNPs (257.025 ± 17.4%) was found to be 1.99-fold higher than US-IO (129.102 ± 15%) and 3.35-fold higher than Dotarem (76.71 ± 14.2%) as routinely used T1-weighted CA. The cytotoxicity assay and histological examination confirmed the biocompatibility of FG-HNPs. The biodistribution study, transmission electron microscopy (TEM) and Prussian blue (PB) staining of tumor tissue proved the effective tumor localization of FG-HNPs. Therefore, FG-HNPs can be suggested as a promising CA for T1-weighted MRI of tumors by virtue of their remarkable relaxivities and high biocompatibility. [ABSTRACT FROM AUTHOR]

Photothermal therapy (PTT) is a nanotechnology-assisted cancer hyperthermia approach in which the interaction between laser light and plasmonic nanoparticles (NPs) generates localized heating. The exploitation of plasmonic NPs in association with active targeting moieties causes the preferential accumulation of NPs inside cancer cells, thereby providing targeted PTT. Herein, we evaluate the effect of folic acid (FA) as an active targeting agent in enhancing the photothermal efficiency of multifunctional Iron (III) Oxide (Fe2O3)@Au core- shell NPs. Fe2O3@Au NPs were synthesized, modified with FA and then characterized. Human nasopharyngeal (KB) cancer cells were treated with different concentrations of Fe2O3@Au, with and without FA modification and the temperature rise profiles of the cells were measured upon administration of the near-infrared (NIR) laser (808 nm, 6 W/cm2, 10 min). The recorded temperature profiles of the cells were used for thermal dose calculation. Finally, the level of induced apoptosis was determined by flow cytometry using an annexin V-fluorescein isothiocyanate/propidium iodide apoptosis detection kit. The characterization data showed that the Fe2O3@Au NPs are spherical, with a hydrodynamic size of 33 nm. The data corroborated the successful conjugation of the NPs with FA. The thermometry results indicated the superior temperature elevation rate of the cells in the presence of the NPs upon NIR irradiation. Meanwhile, the higher heating rate and the higher thermal dose were obtained for the cells exposed to FA-targeted Fe2O3@Au rather than the non-targeted nanocomplex. Flow cytometry studies revealed that FA-targeted Fe2O3@Au induced higher level of apoptosis than non-targeted Fe2O3@Au NPs. In conclusion, our findings suggest that the synthesized FA-targeted Fe2O3@Au NP has high potentials to be considered as an efficient thermosensitizer in the process of targeted cancer hyperthermia. [ABSTRACT FROM AUTHOR]

This study reports the synthesis and characterization of poly(ethylene glycol) coated gold@iron oxide core-shell nanoparticles conjugated with folic acid (FA-PEG-Au@IONP). Also, targeted therapeutic properties of such a nanocomplex were studied on human nasopharyngeal carcinoma cell line KB and human breast adenocarcinoma cell line MCF-7 in vitro. The synthesized nanocomplex was characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), UV-Vis spectroscopy, vibrating sample magnetometry (VSM), and Fourier transform infrared (FTIR) spectroscopy. The photothermal effects of nanocomplex on both KB and MCF-7 cell lines were studied. Cell death and apoptosis were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry using an annexin V-fluorescein isothiocyanate/propidiumiodide apoptosis detection kit. It was found that nanocomplex is spherical in shape and its size is approximately 60 nm. UV-vis spectrum showed that nanocomplex has appropriate absorption near infrared region. FTIR spectra obtained from nanocomplex before and after conjugation with FA confirmed the formation of folate conjugated nanocomplex. Significant cell lethality was observed for KB (∼62%) and MCF-7 (∼33%) cells following photothermal therapy. Also, it was found that majority of the cell deaths were related to apoptosis process. It can be concluded that, the synthesized nanocomplex is an effective and promising multifunctional nanoplatform for targeted photothermal therapy of cancer. [ABSTRACT FROM AUTHOR]