²⁰¹Tl⁺-labelled Prussian blue nanoparticles as contrast agents for SPECT scintigraphy

Nanosized Prussian blue and its analogs for bioimaging and cancer theranostics

Prussian blue (PB) nanoparticles (NPs) and Prussian blue analogs (PBAs) can form metal-organic frameworks through the programmable coordination of ferrous ions with cyanide. PB and PBAs represent a burgeoning class of hybrid functional nano-systems with a wide-ranging application spectrum encompassing biomedicine, cancer diagnosis, and therapy. A comprehensive overview of recent advancements is crucial for gaining insights for future research. In this context, we reviewed the synthesis techniques and surface modification strategies employed to tailor the dimensions, morphology, and attributes of PB NPs. Subsequently, we explored advanced biomedical utilities of PB NPs, encompassing photoacoustic imaging, magnetic resonance imaging, ultrasound (US) imaging, and multimodal imaging. In particular, the application of PB NPs-mediated photothermal therapy, photodynamic therapy, and chemodynamic therapy to cancer treatment was reviewed. Based on the literature, we envision an evolving trajectory wherein the future of Prussian blue-driven biological applications converge into an integrated theranostic platform, seamlessly amalgamating bioimaging and cancer therapy. STATEMENT OF SIGNIFICANCE: Prussian blue, an FDA-approved coordinative pigment with a centuries-long legacy, has paved the way for Prussian blue nanoparticles (PB NPs), renowned for their remarkable biocompatibility and biosafety. These PB NPs have found their niche in biomedicine, playing crucial roles in both diagnostics and therapeutic applications. The comprehensive review goes beyond PB NP-based cancer therapy. Alongside in-depth coverage of PB NP synthesis and surface modifications, the review delves into their cutting-edge applications in the realm of biomedical imaging, encompassing techniques such as photoacoustic imaging, magnetic resonance imaging, ultrasound imaging, and multimodal imaging.

Nitroprusside─Expanding the Potential Use of an Old Drug Using Nanoparticles

For more than 70 years, sodium nitroprusside (SNP) has been used to treat severe hypertension in hospital emergency settings. During this time, a few other clinical uses have also emerged such as in the treatment of acute heart failure as well as improving mitral incompetence and in the intra- and perioperative management during heart surgery. This drug functions by releasing nitric oxide (NO), which modulates several biological processes with many potential therapeutic applications. However, this small molecule has a short lifetime, and it has been administered through the use of NO donor molecules such as SNP. On the other hand, SNP also has some setbacks such as the release of cyanide ions, high water solubility, and very fast NO release kinetics. Currently, there are many drug delivery strategies that can be applied to overcome many of these limitations, providing novel opportunities for the use of old drugs, including SNP. This Perspective describes some nitroprusside properties and highlights new potential therapeutic uses arising from the use of drug delivery systems, mainly silica-based nanoparticles. There is a series of great opportunities to further explore SNP in many medical issues as reviewed, which deserves a closer look by the scientific community.

Post-synthetic modification of Prussian blue type nanoparticles: tailoring the chemical and physical properties

This review focuses on recent advances in the post-synthetic modification of nano-sized Prussian blue and its analogues and compares them with the current strategies used in metal–organic frameworks to give future outlooks in this field.

A rational study of the influence of Mn2+-insertion in Prussian blue nanoparticles on their photothermal properties

We investigated a series of Mn²⁺-Prussian blue (PB) nanoparticles Na_zMn_xFe_1-x[Fe(CN)₆]_1-y□y·nH₂O of similar size, surface state and cubic morphology with various amounts of Mn²⁺ synthesized through a one step self-assembly reaction. We demonstrated by a combined experimental-theoretical approach that during the synthesis, Mn²⁺ substituted Fe³⁺ up to a Mn/Na-Mn-Fe ratio of 32 at% in the PB structure, while for higher amounts, the Mn₂[Fe(CN)₆] analogue is obtained. For comparison, the post-synthetic insertion of Mn2+ in PB nanoparticles was also investigated and completed with Monte-Carlo simulations to probe the plausible adsorption sites. The photothermal conversion efficiency (η) of selected samples was determined and showed a clear dependence on the Mn²⁺amount with a maximum efficiency for a Mn/Na-Mn-Fe ratio of 10 at% associated with a dependence on the nanoparticle concentration. Evaluation of the in vitro photothermal properties of these nanoparticles performed on triple negative human breast adenocarcinoma (MDA-MB-231) cells by using continuous and pulsed laser irradiation confirm their excellent PTT efficiency permitting low dose use.

Fluorescent, Prussian Blue-Based Biocompatible Nanoparticle System for Multimodal Imaging Contrast

(1) Background. The main goal of this work was to develop a fluorescent dye-labelling technique for our previously described nanosized platform, citrate-coated Prussian blue (PB) nanoparticles (PBNPs). In addition, characteristics and stability of the PB nanoparticles labelled with fluorescent dyes were determined. (2) Methods. We adsorbed the fluorescent dyes Eosin Y and Rhodamine B and methylene blue (MB) to PB-nanoparticle systems. The physicochemical properties of these fluorescent dye-labeled PBNPs (iron(II);iron(III);octadecacyanide) were determined using atomic force microscopy, dynamic light scattering, zeta potential measurements, scanning- and transmission electron microscopy, X-ray diffraction, and Fourier-transformation infrared spectroscopy. A methylene-blue (MB) labelled, polyethylene-glycol stabilized PBNP platform was selected for further assessment of in vivo distribution and fluorescent imaging after intravenous administration in mice. (3) Results. The MB-labelled particles emitted a strong fluorescent signal at 662 nm. We found that the fluorescent light emission and steric stabilization made this PBNP-MB particle platform applicable for in vivo optical imaging. (4) Conclusion. We successfully produced a fluorescent and stable, Prussian blue-based nanosystem. The particles can be used as a platform for imaging contrast enhancement. In vivo stability and biodistribution studies revealed new aspects of the use of PBNPs.

Finely tuned Prussian blue-based nanoparticles and their application in disease treatment

The Prussian blue (PB) based nanostructure is a mixed-valence coordination network with excellent biosafety, remarkable photothermal effect and multiple enzyme-mimicking behaviours. Compared with other nanomaterials, PB-based nanoparticles (NPs) exhibit several unparalleled advantages in biomedical applications. This review begins with the chemical composition and physicochemical properties of PB-based NPs. The tuning strategies of PB-based NPs and their biomedical properties are systemically demonstrated. Afterwards, the biomedical applications of PB-based NPs are comprehensively recounted, mainly focusing on treatment of tumors, bacterial infection and inflammatory diseases. Finally, the challenges and future prospects of PB-based NPs and their application in disease treatment are discussed.

Fashioning Prussian Blue Nanoparticles by Adsorption of Luminophores: Synthesis, Properties, and in Vitro Imaging

We report the postsynthetic functionalization of Prussian blue (PB) nanoparticles by two different luminophores (2-aminoanthracene and rhodamine B). We show that the photoluminescence properties of the fluorophores are modified by a confinement effect upon adsorption and demonstrate that such multifunctional nanosized systems could be used for in vitro imaging.

Progress in Applications of Prussian Blue Nanoparticles in Biomedicine

Prussian blue nanoparticles (PBNPs) with favorable biocompatibility and unique properties have captured the attention of extensive biomedical researchers. A great progress is made in the application of PBNPs as therapy and diagnostics agents in biomedicine. This review begins with the recent synthetic strategies of PBNPs and the regulatory approaches for their size, shape, and uniformity. Then, according to the different properties of PBNPs, their application in biomedicine is summarized in detail. With modifiable features, PBNPs can be used as drug carriers to improve the therapeutic efficacy. Moreover, the exchangeable protons and adsorbability enable PBNPs to decontaminate the radioactive ions from the body. For biomedical imaging, photoacoustic and magnetic resonance imaging based on PBNPs are summarized, as well as the strategies to improve the diagnostic effectiveness. The applications related to the photothermal effects and nanoenzyme activities of PBNPs are described. The challenges and critical factors for the clinical translation of PBNPs as multifunctional theranostic agents are also discussed. Finally, the future prospects for the application of PBNPs are considered. The aim of this review is to provide a better understanding and key consideration for rational design of this increasingly important new paradigm of PBNPs as theranostics.

Multimodal Prussian blue analogs as contrast agents for X-ray computed tomography

Prussian blue analogs (PBAs) are versatile materials with a wide range of applications. Due to their tunability, intrinsic biocompatibility, as well as low toxicity, these nanoscale coordination polymers have been successfully studied as multimodal contrast agents for multiple imaging techniques. Herein, we report the expanded biomedical application of PBAs to X-ray computed tomography (CT). In our systematic study of the series A{MnII[FeIII(CN)6]} (A = K+, Rb+, Cs+), we showed that derivatives incorporating Rb+ and Cs+ ions in the tetrahedral sites of the parent face-centered cubic cyano-bridged networks exhibited substantially increased X-ray attenuation coefficients, thus yielding significant contrast compared to the clinically approved X-ray contrast agent iohexol at the same concentrations. Additionally, our μ-CT studies revealed that these PBAs could be useful as dual-energy CT contrast agents for different biological specimens by using the lower varying scanning X-ray tube voltages. Finally, in vitro studies using U87-Luc cells treated with PBAs, including cellular CT imaging and bioluminescence cell viability assays, revealed that PBAs were taken up by the glioblastoma cells, with moderate biocompatibility at concentrations below the mM range.

Multifunctional manganese-doped Prussian blue nanoparticles for two-photon photothermal therapy and magnetic resonance imaging

Here we demonstrate for the first time that Mn²⁺-doped Prussian blue nanoparticles of c.a. 70 nm act as effective agents for photothermal therapy under two-photon excitation with an almost total eradication of malignant cells (97 and 98%) at a concentration of 100 μg mL^-1 24 h after NIR excitation. This effect combined with interesting longitudinal NMR relaxivity values offer new perspectives for effective imaging and cancer treatment.

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.

Facile synthesis of magnetic core-shell nanocomposites for MRI and CT bimodal imaging

With the development of nanotechnology, nanocomposites have been used as bimodal contrast agents for magnetic resonance (MR) and computed tomography (CT) imaging. We have developed a facile method for the synthesis of iron oxide@bismuth sulfide magnetic core-shell nanocomposites. These bifunctional nanocomposites can be made water-soluble via PEG coating and present strong MRI/CT contrast enhancement. Evaluation of cytotoxicity by MTT assay shows that the nanocomposites have low cytotoxicity. The results illustrate that the nanocomposites have great potential as bimodal imaging agents for MR/CT.

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.

Synthesis of heterodimer radionuclide nanoparticles for magnetic resonance and single-photon emission computed tomography dual-modality imaging

We report a facile synthesis of bifunctional Fe3O4-Ag(125)I heterodimers for use as dual-modality imaging agents in magnetic resonance (MR) and single-photon emission computed tomography (SPECT). We introduced (125)I, which is a clinically used radioisotope, as a SPECT reporter, into Fe3O4-Ag heterodimer nanoparticles to provide a new type of bifunctional contrast agent for MRI and SPECT imaging.

Assorted morphosynthesis: access to multi-faceted nano-architectures from a super-responsive dual π-functional amphiphilic construct

An electronically segmented amphiphile was created by conjugating two π-functional units (HQ/NDI) for the first time.