Tunable Hollow Bimetallic MnFe Prussian Blue Analogue as the Targeted pH-Responsive Delivery System for Anticancer Drugs

S-Doped Hollow Multi-Metallic Prussian Blue Analogue (PBA) Nanoplatform for Enhanced Anticancer for Cervical Cancer

Purpose

Developing novel multimodal nanomaterials-based anticancer agents to meet complex clinical demands is an urgent challenge. This study presents a novel uniform hollow S-doped NiCuFe Prussian blue analogue (NiCuFe-S) with satisfactory size and properties as anticancer agents for efficient cervical cancer therapy using a simple and environmentally friendly procedure.

Methods

The formation mechanism and the reason for enhanced performance of NiCuFe-S were characterized and discussed by diverse spectroscopic and microscopic methods. Moreover, to demonstrate the anti-cancer ability of NiCuFe-S, in vitro and in vivo experiments were carried out.

Results

Compared to the non-doped NiCuFe, the NiCuFe-S exhibited significantly enhanced photothermal and catalytic activity attributed to the electronic bandgap-narrowing effect and the increased electron circuit paths resulting from S doping. The hollow structure of NiCuFe-S facilitated the loading of small-molecule drugs, such as doxorubicin (DOX), transforming it into a multimodal nanoplatform for cervical cancer treatment. In vitro and in vivo experiments proved the potential of the NiCuFe-S nanotheranostic agent for chemodynamic therapy (CDT), photothermal therapy (PTT), and chemotherapy for cervical cancer.

Conclusion

This research not only overcomes inherent limitations but also significantly broadens the applications of Prussian blue analogues in biomedicine.

From lab to field: Prussian blue frameworks as sustainable cathode materials

Prussian blue and Prussian blue analogues have attracted increasing attention as versatile framework materials with a wide range of applications in catalysis, energy conversion and storage, and biomedical and environmental fields. In terms of energy storage and conversion, Prussian blue-based materials have emerged as suitable candidates of growing interest for the fabrication of batteries and supercapacitors. Their outstanding electrochemical features such as fast charge-discharge rates, high capacity and prolonged cycling life make them favorable for energy storage application. Furthermore, Prussian blue and its analogues as rechargeable battery anodes can advance significantly by the precise control of their structure, morphology, and composition at the nanoscale. Their tunable structural and electronic properties enable the detection of many types of analytes with high sensitivity and specificity, and thus, they are ideal materials for the development of sensors for environmental detection, disease trend monitoring, and industrial safety. Additionally, Prussian blue-based catalysts display excellent photocatalytic performance for the degradation of pollutants and generation of hydrogen. Specifically, their excellent light capturing and charge separation capabilities make them stand out in photocatalytic processes, providing a sustainable option for environmental remediation and renewable energy production. Besides, Prussian blue coatings have been studied particularly for corrosion protection, forming stable and protective layers on metal surfaces, which extend the lifespan of infrastructural materials in harsh environments. Prussian blue and its analogues are highly valuable materials in healthcare fields such as imaging, drug delivery and theranostics because they are biocompatible and their further functionalization is possible. Overall, this review demonstrates that Prussian blue and related framework materials are versatile and capable of addressing many technical challenges in various fields ranging from power generation to healthcare and environmental management.

A Prussian blue analog as a decorporation agent for the simultaneous removal of cesium and reactive oxygen species

Radioactive cesium (Cs) is a significant concern due to its role as a major byproduct of nuclear fission and its potential for radioactive contamination. Internal contamination with radioactive Cs is characterized by immoderate production of reactive oxygen species (ROS), resulting in severe radiation damage. Therefore, the development of therapeutic strategies should focus on enhancing the excretion of radioactive Cs and reducing radiation-induced oxidative damage. However, current therapeutic drugs like Prussian blue (PB) have limited efficacy in addressing these issues. In this study, we present Cu3[Fe(CN)6]2 (CuFe) nanoparticles, a Prussian blue analog (PBA), which can not only efficiently sequester Cs but also exhibit resistance against radiation damage. The results of the adsorption studies demonstrate that CuFe outperforms PB in terms of adsorption performance. Further mechanistic investigations indicate that the increased adsorption capacity of CuFe may be attributed to the presence of additional defects resulting from the [Fe(CN)6] missing linkers. Moreover, CuFe mimics the functions of catalase (CAT) and superoxide dismutase (SOD) by effectively eliminating O2˙- and H2O2 while scavenging ˙OH, thereby mitigating ROS induced by radiative Cs. Importantly, in vivo study confirms the efficient Cs decorporation capability of CuFe. The fecal cumulative excretion rate of CuFe reaches 69.5%, which is 1.45 times higher than that of PB (48.8%). These findings demonstrate that CuFe exhibits excellent Cs removal performance and ROS scavenging ability, making it an attractive candidate for the treatment of Cs contamination.

Progress in the preparation of Prussian blue-based nanomaterials for biomedical applications

Prussian blue (PB) is composed of the coordination network of Fe²⁺-CN-Fe³⁺ mixed valence state as a classic metal complex, which includes a C atom and Fe²⁺ (low spin), N atom and Fe³⁺ (high spin). PB and its analogues (PBA) have excellent biosafety, good magnetic properties, outstanding photothermal properties and the ability to mimic enzymatic behaviors due to their stable structure, tunable size, controllable morphology, abundant modification methods and excellent physicochemical properties. They have received increasing research interest and have shown promising applications in the biomedical field. Here, progress in the preparation of PB-based nanomaterials for biomedical applications is summarized and discussed. The preparation strategies, traditional synthesis and emerging preparation methods of PB are summarized systematically in this review. The design and preparation of PBA, PB(PBA)-based hollow structures and PB(PBA)-based composites are also included. While introducing the preparation status, some PB-based nanomaterials that have performed well in specific biomedical fields are emphasized. More importantly, the key factors and future development of PB for the clinical translation as multifunctional nanomaterials are also discussed. This review provides a reference for the design and biomedical application of PB-based nanomaterials.

Novel targeted pH-responsive drug delivery systems based on PEGMA-modified bimetallic Prussian blue analogs for breast cancer chemotherapy

The development of novel nanoparticle-based drug delivery systems (nano-DDSs) with high loading capacity, low toxicity, precise targeting, and excellent biocompatibility remains urgent and important for the treatment of breast cancer (BC). Herein, novel BC-targeted nano-DDSs based on bimetallic Prussian blue analogs (PBA-DDSs) for intracellular doxorubicin (DOX) delivery and pH-responsive release were developed. Two kinds of bimetallic PBA, namely CuFe (copper-iron) PBA and CoFe (cobalt-iron) PBA, were synthesized by a coprecipitation method, followed by modification with polyethyleneglycol methacrylate (PEGMA) via surface-initiated atom transfer radical polymerization and immobilization with the AS1411 aptamer to obtain two kinds of novel BC-targeted nano-DDS. CuFePBA@PEGMA@AS1411 and CoFePBA@PEGMA@AS1411 showed high drug loading efficiency of 80% and 84%, respectively, for DOX, while 56.0% and 75.9% DOX release could be achieved under acidic pH conditions. In vitro cell viability and in vivo experiments proved the good biocompatibility of both PBA-DDSs. Cellular uptake and in vivo distribution suggested that both PBA-DDSs had efficient nucleolin-targeting capability, indicating the targeted delivery of DOX in tumor tissues. In vivo evaluation of anti-BC efficacy further confirmed that the obtained PBA-DDSs exhibited excellent therapeutic efficacy with limited side-effects. Therefore, the proposed novel PBA-DDSs can be used as secure and effective drug nano-DDSs for BC chemotherapy.

Formation mechanisms of hollow manganese hexacyanoferrate particles and construction of a multiple-shell structure

Formation mechanisms of hollow manganese hexacyanoferrate (Mn-HCF) particles have been investigated. Mn-HCF particles, which were precipitated by mixing an aqueous solution of K3[Fe(CN)6] with MnCl2 in the presence of sodium citrate, could be converted into a hollow structure just by washing with distilled water. The powder X-ray diffractometry suggested that the as-prepared particle has a core/shell morphology with different crystal structures: cubic-core and monoclinic-shell. The time evolutions of the particle size and shell thickness indicated that the core was rapidly (but not instantaneously) formed at the initial stage of the precipitation process, followed by a slower shell growth. In addition, the solubility of the cubic core was estimated to be about 2.5 times higher than that of the monoclinic shell, resulting in the preferential dissolution of the interior of the particle by the washing process. The formation procedure has been used to construct multiple-shell hollow Mn-HCF particles containing up to quadruple separated nesting shells by associating an additional growth technique.

Outstanding Drug-Loading/Release Capacity of Hollow Fe-Metal-Organic Framework-Based Microcapsules: A Potential Multifunctional Drug-Delivery Platform

Owing to their characteristic structures, metal-organic frameworks (MOFs) are considered as the leading candidate for drug-delivery materials. However, controlling the synthesis of MOFs with uniform morphology and high drug-loading/release efficiencies is still challenging, which greatly limits their applications and promotion. Herein, a multifunctional MOF-based drug-delivery system (DDS) with a controlled pore size of 100-200 nm for both therapeutic and bioimaging purposes was successfully synthesized in one step. Fe-MOF-based microcapsules were synthesized through a competitive coordination method, which was profited from the intrinsic coordination characteristics of the Fe element and the host-guest supramolecular interactions between Fe³⁺ and polyoxometalates anions. This as-synthesized macroporous DDS could greatly increase the drug-loading/release rate (77%; 83%) and serve as a magnetic resonance (MR) contrast agent. Because an Fe-containing macroporous DDS presents ultrahigh drug loading/release, the obtained 5-FU/Fe-MOF-based microcapsules displayed good biocompatibility, extremely powerful inhibition of tumor growth, and satisfactory MR imaging capability. Given all these advantages, this study integrates high therapeutic effect and diagnostic capability via a simple and effective morphology-controlling strategy, aiming at further facilitating the applications of MOFs in multifunctional drug delivery.

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.