In this study, we report the synthesis of gold-coated iron oxide nanoparticles capped with polyvinylpyrrolidone (Fe@Au NPs). The as-synthesized nanoparticles (NPs) exhibited good stability in aqueous media and excellent features as contrast agents (CA) for both magnetic resonance imaging (MRI) and X-ray computed tomography (CT). Additionally, due to the presence of the local surface plasmon resonances of gold, the NPs showed exploitable “light-to-heat” conversion ability in the near-infrared (NIR) region, a key attribute for effective photothermal therapies (PTT). In vitro experiments revealed biocompatibility as well as excellent efficiency in killing glioblastoma cells via PTT. The in vivo nontoxicity of the NPs was demonstrated using zebrafish embryos as an intermediate step between cells and rodent models. To warrant that an effective therapeutic dose was achieved inside the tumor, both intratumoral and intravenous routes were screened in rodent models by MRI and CT. The pharmacokinetics and biodistribution confirmed the multimodal imaging CA capabilities of the Fe@AuNPs and revealed constraints of the intravenous route for tumor targeting, dictating intratumoral administration for therapeutic applications. Finally, Fe@Au NPs were successfully used for an in vivo proof of concept of imaging-guided focused PTT against glioblastoma multiforme in a mouse model.

The flexibility of polymer backbones constitutes one key aspect in their molecular recognition properties. This investigation characterizes the structure of the gas-phase complexes formed by the cyclic and linear polyethers with the heavier alkali metal cations. In particular, the cyclic 15-crown-5 ether (15c5), (OCH₂CH₂)₅, and the polyethylene glycol linear chains PEG4 and PEG9, H(OCH₂CH₂)_n=4,9OH, are considered. Infrared multiple photon dissociation spectroscopy is applied to probe the polymer vibrational modes within the spectral range 800–1500 cm⁻¹, in combination with Density Functional Theory calculations. The experimental spectra of the 15c5-M⁺ (M = K, Rb, Cs) complexes correlate with distorted asymmetric backbone structures in which the cation lies above the ether ring, and four oxygens are oriented toward the cation. In contrast, the PEG4-K⁺ complex features an inclusion-like fivefold coordination structure in which the cation and four oxygens are quasi-coplanar and one terminal oxygen lies out of plane. For the PEG9-K⁺ complex, the ether chain builds stable cages involving a coordination of eight oxygens with the cation, sustained by hydrogen bonds between the terminal hydroxyl groups.