Biocompatible nanoparticles of KGd(H₂O)₂[Fe(CN)₆]·H₂O with extremely high T₁-weighted relaxivity owing to two water molecules directly bound to the Gd(III) center

Europium-151 and iron-57 nuclear resonant vibrational spectroscopy of naturally abundant KEu(III)Fe(II)(CN)6 and Eu(III)Fe(III)(CN)6 complexes

We have performed and analyzed the first combined 151Eu and 57Fe nuclear resonant vibrational spectroscopy (NRVS) for naturally abundant KEu(III)[Fe(II)(CN)6] and Eu(III)[Fe(III)(CN)6] complexes. Comparison of the observed 151Eu vs.57Fe NRVS spectroscopic features confirms that Eu(III) in both KEu(III)[Fe(II)(CN)6] and Eu(III)[Fe(III)(CN)6] occupies a position outside the [Fe(CN)6] core and coordinates to the N atoms of the CN- ions, whereas Fe(III) or Fe(II) occupies the site inside the [Fe(CN)6]4- core and coordinates to the C atoms of the CN- ions. In addition to the spectroscopic interest, the results from this study provide invaluable insights for the design and evaluation of the nanoparticles of such complexes as potential cellular contrast agents for their use in magnetic resonance imaging. The combined 151Eu and 57Fe NRVS measurements are also among the first few explorations of bi-isotopic NRVS experiments.

Diverse physical functionalities of rare-earth hexacyanidometallate frameworks and their molecular analogues

The combination of rare-earth metal complexes and hexacyanidometallates of transition metals is a fruitful pathway for achieving functional materials exhibiting a wide scope of mechanical, magnetic, optical, and electrochemical properties.

Tailored ultra-small Prussian blue-based nanoparticles for MRI imaging and combined photothermal/photoacoustic theranostics

Ultrasmall sub-10 nm nanoparticles of Prussian blue analogues incorporating GdIII ions at their periphery revealed longitudinal relaxivities above 40 mM-1 s-1 per GdIII regardless of the nature of the core and the polymer coating. Large T1-weighted contrast enhancements were achieved in addition to a highly efficient photothermal effect and in vivo photoacoustic imaging in tumors.

Prussian blue nanoparticles: Synthesis, surface modification, and application in cancer treatment

This review outlines recently developed Prussian blue nanoparticle (PB NPs)-based multimodal imaging-guided chemo-photothermal strategies for cancer diagnosis and treatment in order to provide insight into the future of the field. The primary limitation of existing therapeutics is the lack of selectivity in drug delivery: they target healthy and cancerous cells alike. In this paper, we provide a thorough review of diverse synthetic and surface engineering techniques for PB NP fabrication. We have elucidated the various targeting approaches employed to deliver the therapeutic and imaging ligands into the tumor area, and outlined methods for enhancement of the tumor ablative ability of the NPS, including several important combinatorial approaches. In addition, we have summarized different in vitro and in vivo effects of PB NP-based therapies used to overcome both systemic and tumor-associated local barriers. An important new approach - PB NP-based immune drug delivery, which is an exciting and promising strategy to overcome cancer resistance and tumor recurrence - has been discussed. Finally, we have discussed the current understanding of the toxicological effects of PB NPs and PB NP-based therapeutics. We conclude that PB NP-based multimodal imaging-guided chemo-photothermal therapy offers new treatment strategies to overcome current hurdles in cancer diagnosis and treatment.

Engineered contrast agents in a single structure for T1-T2 dual magnetic resonance imaging

The development of contrast agents (CAs) for Magnetic Resonance Imaging (MRI) with T1-T2 dual-mode relaxivity requires the accurate assembly of T1 and T2 magnetic centers in a single structure. In this context, we have synthesized a novel hybrid material by monitoring the formation of Prussian Blue analogue Gd(H2O)4[Fe(CN)6] nanoparticles with tailored shape (from nanocrosses to nanorods) and size, and further protection with a thin and homogeneous silica coating through hydrolysis and polymerization of silicate at neutral pH. The resulting Gd(H2O)4[Fe(CN)6]@SiO2 magnetic nanoparticles are very stable in biological fluids. Interestingly, this combination of Gd and Fe magnetic centers closely packed in the crystalline network promotes a magnetic synergistic effect, which results in significant improvement of longitudinal relaxivity with regards to soluble Gd3+ chelates, whilst keeping the high transversal relaxivity inherent to the iron component. As a consequence, this material shows excellent activity as MRI CA, improving positive and negative contrasts in T1- and T2-weighted MR images, both in in vitro (e.g., phantom) and in vivo (e.g., Sprague-Dawley rats) models. In addition, this hybrid shows a high biosafety profile and has strong ability to incorporate organic molecules on the surface with variable functionality, displaying great potential for further clinical application.

KCa(H2 O)2 [FeIII (CN)6 ]⋅H2 O Nanoparticles as an Antimicrobial Agent against Staphylococcus aureus

Biocompatible nanoparticles based on a calcium analogue of Prussian blue were designed and synthesized to take advantage of their ability to penetrate the cell membrane in Staphylococcus aureus and to undergo selective ion exchange with intracellular iron to disrupt iron metabolism in such pathogenic bacteria for antibacterial applications. KCa(H₂ O)₂ [Fe^III (CN)₆ ]⋅H₂ O nanoparticles penetrate the bacterial cell membrane and sequester intracellular iron by ion exchange to form insoluble Prussian blue, thus inhibiting bacterial growth.

201Tl-labeled Prussian blue and Au@Prussian blue nanoprobes for SPEC-CT imaging: influence of the size, shape and coating on the biodistribution

²⁰¹Tl-labeled Prussian blue and core@shell Au@Prussian blue nanoparticles coated with the phospholipidic bilayer and dextran were investigated in vivo as nanoprobes by usingSPECT-CT scintigraphy.

Prussian blue type nanoparticles for biomedical applications

Prussian blue type nanoparticles are exciting nano-objects that combine the advantages of molecule-based materials and nanochemistry. Here we provide a short overview focalizing on the recent advances of these nano-objects designed for biomedical applications and give an outlook on the future research orientations in this domain.

Incorporation of gallium-68 into the crystal structure of Prussian blue to form K(68)GaxFe1-x[Fe(CN)6] nanoparticles: toward a novel bimodal PET/MRI imaging agent

Similarity between the Ga(+) ion and the Fe(3+) ion allows for partial replacement of Fe(3+) ions with Ga(3+) ions in the Fe(iii) crystallographic positions in Prussian blue (PB) to form various solid solutions KGaxFe1-x[Fe(CN)6] (0 < x < 1). Such solid solutions possess very high thermodynamic stability as expected from the parent PB structure. Consequently, a simple one-step (68)Ga-labeling method was developed for preparing a single-phase nanoparticulate bimodal PET/MRI imaging agent based on the PB structural platform. Unlike the typical (68)Ga-labelling reaction based on metal complexation, this novel chelator-free (68)Ga-labeling reaction was shown to be kinetically fast under the acidic conditions. The Ga(3+) ion does not hydrolyze, and affords the (68)Ga-labelled PB nanoparticles, which are easy to purify and have extremely high stability against radionuclidic leaching in aqueous solution.

Investigation of cyano-bridged coordination nanoparticles Gd(3+)/[Fe(CN)6](3-)/D-mannitol as T1-weighted MRI contrast agents

Cyano-bridged Gd(3+)/[Fe(CN)6](3-) coordination polymer nanoparticles of 3-4 nm stabilized with D-mannitol presenting a high r1 relaxivity value of 11.4 mM(-1) s(-1) were investigated in vivo as contrast agents (CA) for Magnetic Resonance Imaging (MRI). They allow an increase of the MR image contrast and can act as an efficient intravascular T1 CA with a relatively long blood-circulation lifetime (60 min) without specific toxicity.