Prussian Blue Research Articles

Boosting Water Oxidation Activity via Carbon–Nitrogen Vacancies in NiFe Prussian Blue Analogue Electrocatalysts

The development of electrocatalysts for oxygen evolution reactions (OERs) is of great significance for hydrogen production. Defect engineering is an effective strategy to improve the OER performance of electrocatalyst by regulating the local electronic and atomic structures of electrocatalysts. Here, we successfully synthesized defective Prussian blue analogues (PBAs) with rich CN vacancies (D-NiFe PBA) as efficient OER electrocatalysts. The optimized D-NiFe PBA exhibited an overpotential of 280 mV at 10 mA cm−2 and a superior stability for over 100 h in KOH electrolytes. The formation of CN vacancies in the NiFe PBA could effectively inhibit the loss of Fe active sites, promote the reconstruction of the NiFe oxygen (hydroxide) active layer in the OER process, and further improve the electrocatalytic activity and stability of the VCN-NiFe PBA. This work presents a feasible approach for the wide application of vacancy defects in PBA electrocatalysts.

Catalytically synthesized Prussian Blue nanozymes as labels for electrochemical DNA/RNA sensors

We propose catalytically synthesized nanozymes based on Prussian Blue (PB) and azidomethyl-substituted poly (3,4-ethylenedioxythiophene) (azidomethyl-PEDOT) as novel electrocatalytic labels for DNA/RNA sensors. Catalytic approach allowed to synthesize highly redox and electrocatalytically active Prussian Blue nanoparticles functionalized with azide groups that enable ‘click’ conjugation with alkyne-modified oligonucleotides. Both competitive and sandwich-type schemes were realized. As the sensor response the direct (mediator-free) electrocatalytic current of H2O2 reduction can be measured, which is proportional to the concentration of the hybridized labeled sequences. The current of H2O2 electrocatalytic reduction is only 3–8 times increased in the presence of the freely diffusing mediator catechol, which indicates high efficiency of direct electrocatalysis with the elaborated labels. Electrocatalytic amplification of the signal allows robust detection of (63–70)-base target sequences with concentrations below 0.2 nM in blood serum within an hour. We believe, the use of advanced Prussian Blue based electrocatalytic labels sets new avenues for point-of-care DNA/RNA sensing.

Flexible, Bifunctional Sensing Platform Made with Biodegradable Mats for Detecting Glucose in Urine

We report on a flexible, bifunctional platform made with solution-blow spinning fiber mats of polylactic acid (PLA) and polyethylene glycol (PEG). The PLA/PEG mats were designated bifunctional because they were used as a substrate for screen-printed carbon electrodes (SPCEs) and as a matrix to attach glucose oxidase (GOx) covalently. By attaching GOx only on the fiber mats, and not on the SPCE, the detection of hydrogen peroxide generated from glucose oxidation by the enzyme was efficient, especially with Prussian blue (PB) nanoparticles electrodeposited on the SPCE surface. The bifunctional device detected hydrogen peroxide (H2O2) in synthetic and human urine at a low applied potential (0 V vs Ag/AgCl) in the range from 1.0 to 6.0 mM, with a detection limit of 0.197 mM, being also interference-free. The biosensor whose cost is <US$ 0.25 per unit (estimated from the price of the materials used) had performance comparable to the gold standard method while measuring glucose in human urine samples, in addition to exhibiting a rapid response and long lifetime. The design of the bifunctional device is generic and may be extended to other biosensors for on-site monitoring as well as for wearable devices and in monitoring the environment and water in varied resources.

Oral formulation of Prussian blue with improved efficacy for prophylactic use against thallium

Objective The present study is aimed to enhance the efficacy of Insoluble Prussian blue (PB) in the stomach. PB formulation was developed comprising of PB in combination with pH modifying agents particularly magnesium hydroxide, calcium carbonate, sodium carbonate, and sodium bicarbonate. pH profile and the binding efficacy of the final formulation was evaluated in simulated gastric fluid (SGF). Methods The capsule formulation was optimized with desired in vitro characteristics. The final formulations (FF1–FF4) were evaluated for drug release, pH profile, and binding efficacy for thallium (Tl). The stability studies were performed in terms of drug assay, Fourier-transformed infrared (FTIR) spectroscopy and Thermo-gravimetric analysis (TGA). The in vivo study was performed in rats to determine the removal efficacy of optimized formulation (FF4) for Tl. Results The PB formulation consisting of optimized PB granules and pH modifying agents showed a significant increase in the binding efficacy for Tl in SGF at an equilibrium time of 24 h. The Maximum Binding Capacity (MBC) of FF1–FF4 was found to be higher than commercially available Radiogardase®-Cs capsules and PB granules alone in SGF. The blood Tl level in rats treated with FF4 showed three-fold decreases in the level of Tl in the blood (C max) and Area under Curve (AUC) as compared to the control. Conclusion The results revealed that the developed oral PB formulation has a significantly higher efficiency of binding Tl at the acidic pH of the stomach thereby reducing its absorption into the systemic circulation. Thus, the optimized formulation of PB with pH-modifying agents is a better drug for prophylactic use in thallium ingestion.

Facile Hydrothermal Synthesis of Prussian Blue Films Using Hydrobromic Acid and their Electrochromic Properties

Prussian Blue (PB) films were directly grown on FTO glass by a hydrothermal method only using potassium ferricyanide and hydrobromic acid as raw reagents. Hydrobromic acid plays the role of both providing acidic conditions and as a reducing agent which improves the atomic utilization of the raw materials. The as-prepared PB devices exhibited multicolor electrochromic properties: Blue, green and transparent states, reversibly. The maximum optical modulations of PB device could reach the range of 47.7%. The PB films also have a fast coloration/bleaching time of 1.9/1.3[Formula: see text]s, respectively. This study provided a novel method for preparing PB films by a facile hydrothermal method.

Efficient removal of Cs ion by electrochemical adsorption and desorption reaction using NiFe Prussian blue deposited carbon nanofiber electrode.

Prussian blue (PB) analog (NiFe, CoFe, FeFe, and commercial(cPB)) decorated carbon nanofiber (CNF) electrodes were synthesized by the drop casting method in this study to investigate the interaction between PB and CNF for the electrochemical adsorption (EA) and electrochemical desorption (ED) of Cs ion (Cs+). The adhesion of PB on the electrode and the EA and ED of Cs+ were substantially higher when the CNF electrode was used, compared with the fluorine-doped tin oxide supporting electrode. The use of CNF led to the smooth occurrence of EA and ED of Cs+, where the reported efficiency was: NiFe >FeFe >cPB. The EA and ED of Cs+ on NiFe decorated CNF (C-NiFe) were strongly affected by the loading amount of NiFe. Although the strongest EA capacity was identified when 1mg of NiFe was used, it decreased as the loading amount of NiFe increased. Thus, the EA of Cs+ occurs under the reduction of NiFe with some Fe(III) reduced to Fe(II) of NiFe, thus inducing more adsorption of Cs+. Overall, we confirmed that the C-NiFe electrode with appropriate thickness of NiFe layer is potentially an excellent adsorbent for Cs removal.

Designing Prussian blue coated iron electrode with exceptional cyclic and rate performance on potassium-ion storage

The larger size of K+ was a major hurdle that greatly restricted the rapid development of potassium-ion batteries (PIBs). Indiscriminate transplantation of lithium-ion storage materials in PIBs was sure to fail because of unexpected structural collapse caused by huge volume change and sluggish ionic kinetics in electrode. In this work, we designed an open-up core-shell structure, which contained inner iron core and outer Prussian blue (PB) shell. Electrons from external circuit preferred to get into conductive iron core and thereafter transmit to PB shell through large-angle scattering. Meanwhile, K+ ions from electrolyte could readily diffuse into PB lattice cavities and participate in redox reactions along with the scattered electrons. Thereupon, this core-shell structure could boost K-storage capability without sacrificing conductivity. It delivered a capacity of 402 mAh g−1 after 1000 cycles at 0.2 A g−1 and exhibited a capacity of 321 mAh g−1 at 5 A g−1.

Prussian blue nanoparticles as isotope-labeled and fluorescent contrast material

The study presents the synthesis and development of a Prussian Blue based biocompatible and chemically stable T1 magnetic resonance imaging (MRI) contrast agent with near infrared (NIR) optical contrast for preclinical application. The physical properties of the Prussian blue nanoparticles (PBNPs) (iron (II); iron (III); octadecacyanide) were characterized with dynamic light scattering (DLS), zeta potential measurement, atomic force microscopy (AFM), and transmission electron microscopy (TEM). In vitro contrast enhancement properties of PBNPs were determined by MRI. In vivo T1-weighted contrast of the prepared PBNPs was investigated by MRI and optical imaging modality after intravenous administration to mice. PBNP-s doped with 201Tl isotope have also been synthetised and biodistribution in mice was determined by using SPECT and MRI. Activity concentrations (MBq/cm3) were calculated from the SPECT scans for each dedicated volume of interest (VOI) of liver, kidneys, salivary glands, heart, lungs, and brain. Isotope-labeled citrate-coated PBNP accumulation peaked at 2 hours after injection in the kidneys and the liver followed by a gradual decrease in activity in later time points. We synthesized, characterized, and radiolabeled a Prussian blue-based nanoparticle platform for contrast material applications. In vivo radiochemical stability and biodistribution open up the way for further diagnostic applications. The presence and detectability of PBNPs during initial biodistribution in the cardiovascular system indicates vascular contrast material applications, too.

Iron-Cobalt-Cerium Multimetallic Oxides Derived from Prussian Blue Precursors: Enhanced Oxygen Evolution Electrocatalysis.

Exploring non-precious metal-based electrocatalysts is still challenging in 21st century. In this work, a series of hexagonal bipyramidal Ce-based PBA materials as precursors with different Fe/Co metal ratios, namely as CeFex Co1-x -PBA, are successfully constructed via co-precipitation method and converted into corresponding metal oxides (denoted as Fex Co1-x CeOy ) via thermal treatment. Then, they as electrocatalysts realize highly efficient oxygen evolution reaction (OER). Especially, as-synthesized Fe0.7 Co0.3 CeOy electrocatalyst shows very low overpotentials of 320 mV at the current density of 10 mA cm-2 and the Tafel slop of 98.4 mV dec-1 in 1 M KOH with remarkable durability for 24 h, which was due to the synergistic effect of multi-metal FeCoCe centers. Furthermore, a two-electrode cell of Fe0.7 Co0.3 CeOy /NF||Pt/C/NF realizes outstanding overall water splitting with a voltage of only 1.71 V at 10 mA cm-2 and remarkable long-term durability, that is even superior to benchmark IrO2 /NF||Pt/C/NF counterpart.

Selective SERS identification and quantification of glucose enantiomers on homochiral MOFs based enzyme-free nanoreactors

Enantiomeric identification plays a critical role in diverse fields ranging from pharmaceutics, biologics, and stereoselective synthesis to daily life. In this study, an enantioselective surface-enhanced Raman scattering (SERS) substrate was developed by integrating homochiral MIL-101(Fe) with oxidase (GOx)-mimicking Au nanoparticles (Au/Chiral-MIL-101(Fe)) for identification and quantification of chiral molecules. Using L/d-glucose (Glu) as the model enantiomers, the homochiral environment of Au/Chiral-MIL-101(Fe) exhibited selective recognition abilities for Glu enantiomers. The captured Glu was further oxidized to hydrogen peroxide (H2O2) by GOx-like activity of Au nanoparticles. The generated H2O2 molecules reduced Fe(III) nodes in MIL-101(Fe) to Fe(II) for the growth of Prussian blue (PB) on site. Benefitting from the pre-concentrated feature and confinement effect of the porous metal–organic frameworks (MOFs) structure, the Au/Chiral-MIL-101(Fe) hybrid based nanoreactors exhibited high catalytic performance for H2O2 generation and further PB growth, resulting in an excellent sensitivity for Glu quantification. The enantioselective discrimination between l-Glu and d-Glu was directly determined from the intensity of PB signals at 2150 cm−1. Using this sensing strategy, Glu enantiomers could be quantified with a limit of detection (LOD) of 0.09 µM for l-Glu and 0.08 μM for d-Glu. Owing to its enzyme-free nature and universal characteristic for the discrimination of other monosaccharide enantiomers, this design provides an attractive substrate for sensing chiral molecules by Raman technology.

A hydrogel electrolyte based on hydroxypropyl methylcellulose modified polyacrylamine for efficient electrochromic energy storage devices

The electrolyte play a crucial role for the efficient operation of electrochemical devices. In this work, we developed a new hydrogel electrolyte based on hydroxypropyl methylcellulose modified polyacrylamine framework for electrochromic energy storage devices. By using the present electrolyte, the sandwich electrochemical devices based on complementary electrodes of prussian blue (PB) and tungsten trioxide (WO3) thin films exhibited reversible electrochromic switch between colorless and dark blue, with large optical contrast over 80 %, short response time below 2 s, high coloration efficiency over 168 cm2/C, and good cycle stability. Moreover, the devices showed good energy storage ability with an area capacitance of 6.32 mAh/m2 at a current density of 0.02 mA/cm2. The dual functional electrochemical devices showed potential application in energy saving smart windows.

Zero-Valence Selenium-Enriched Prussian Blue Nanozymes Reconstruct Intestinal Barrier against Inflammatory Bowel Disease via Inhibiting Ferroptosis and T Cells Differentiation.

The structural disruption of mechanical barrier and dysfunction of immune barrier in intestinal, are important factors, that aggravate inflammatory bowel disease (IBD). To tackle this challenge, a multifunctional nanozyme capable of scavenging reactive oxygen species (ROS) and inhibiting ferroptosis or T cells differentiation for IBD therapy is here reported. In this work, zero-valence selenium-enriched Prussian blue nanozymes (Se-HMPB nanozymes) are prepared via the hard template method. PB nanozymes with multi-enzyme activities can effectively scavenge various ROS in inflammatory tissues. Meanwhile, the presence of selenium element endows the glutathione peroxidase activity of Se-HMPB nanozymes, which can inhibit ferroptosis and reverse the lipid peroxidation of intestinal epithelial cells to protect the intestinal mechanical barrier in ulcerative colitis (UC) model. In addition, selenium supplementation can realize efficient inhibition on the differentiation of T cells in Crohn's disease (CD) model, regulating the intestinal immune barrier. Thus, the Se-HMPB nanozymes reconstructed intestinal barrier via inhibiting ferroptosis and T cells differentiation in UC and CD models, depicting great potential to alleviate IBD.

In situ synthesized nanozyme for photoacoustic-imaging-guided photothermal therapy and tumor hypoxia relief

Nanozymes have attracted extensive research interest due to their ideal enzymatic catalytic performance; however, uncontrollable activities and nonspecific accumulation limit their further clinical application. To overcome these obstacles, we proposed in situ synthesized nanozyme, and realized the concept through anintelligent nanosystem (ISSzyme) based on Prussian blue (PB) precursor. PB nanozyme was synthesized at the tumor sites through the interaction of ISSzyme with glutathione, which was demonstrated by comparing with conventional PB nanozyme. ISSzyme is capable of tumor-specific photoacoustic imaging (PAI) and photothermal therapy (PTT), reducing the false-positive signals of PAI and the treatment side effects of PTT. ISSzyme has catalase-like activities, resulting in tumor hypoxia relief and metastasis inhibition. More importantly, the in situ synthesized PB nanozyme has the favorable property of minimal liver accumulation. Considering the above advantages, ISSzyme is expected to shed light on the design of the next-generation artificial enzymes, with many new biomedical applications.

Electroless-deposition of AuPd alloy on Prussian blue derived Hematite/AuPd catalyst: Synergistic effect and potent reusable catalyst for treating environment pollutants

Electroless-deposition of bi-metallic AuPd alloy nanoparticles (5–10 nm) on Prussian blue (PB) cubes with uniform composition and size are prepared using a galvanic displacement reaction. In this study, such galvanic displacement reaction routes deed the different redox potentials of three elements (Fe, Au, and Pd) to buoy up their deposition between each other. In comparison with the previous study for the PB/Au system, verdicts in this study enlighten the significant features, possessions, and etiquettes required to form exothermic bi-metallic AuPd alloy nanoparticles onto the PB surface. The Hematite/AuPd catalyst is derived by annealing PB/AuCN–PdCN in the presence of air. During heat treatment, AuPd alloy nanoparticles anchored over the PB surface were become embedded into the Hematite crystallites and led to a core–shell structure. Such core–shell; AuPd-Hematite particles in association with “AuPd composition dependent synergism” reflects an efficient catalytic activity toward the reduction of the hazardous organic pollutant; p-nitrophenol.

CuCo Nanocube/N-Doped Carbon Nanotube Composites for Microwave Absorption

Metal–organic frameworks (MOFs) have come into the limelight in the field of microwave absorption since they can be developed into porous carbon-based MOF derivatives with a variety of features, such as controlled defects, tunable structures, and variable compositions. In this paper, Cu3[Co(CN)6]2 Prussian blue analogue (CuCo-PBA) precursors with a regular cubic morphology were synthesized by a simple co-precipitation method and converted into CuCo nanocube/N-doped carbon nanotube (CuCo/NCNT) derivatives by annealing them in argon. It was found that when the annealing temperature was 850 °C, the minimum reflection loss (RLmin) of CuCo/NCNT could reach −54.13 dB with an effective absorption bandwidth of 4.01 GHz. The excellent microwave absorption properties were attributed to the mutual synergy of conduction loss, interfacial polarization, magnetic resonance loss, and eddy current loss. Therefore, this work provides an effective preparation method for the design of lightweight carbon-based microwave-absorbing materials with heterogeneous interfaces using Prussian blue.

Lithiation-induced conductivity modulation in Prussian blue interlayer for stable Li/garnet solid-state batteries

The garnet-based solid-state batteries have the potential advantages of high energy density and safety. However, the poor solid–solid contact and Li dendrite growth at the anode interface lead to uneven Li deposition or short circuit, which hinders their practical application. Here, we propose a Prussian blue (PB) interlayer to improve the interface contact and charge transfer between Li anode and garnet electrolyte by lithiation-induced conductivity modulation. This mixed-conducting interlayer with unique 3D open framework enables a well welded interface with enhanced lithiophilicity and uniform Li diffusion. The Li/garnet interface resistance is significantly reduced. This lithiated PB interlayer is highly durable with invariable thickness during cycling, leading to a highly stable cycling of Li plating/stripping and corresponding LiFePO4 full cells without dendrite growth. The dual modulation of ion and electron transports in an integrated structure without phase segregation through thermal or electrochemical lithiation provides a solution to the challenge of solid–solid interfaces and the development of practical solid-state batteries.

Dose-response dependencies of Turnbull blue, modified Fricke, VIPET, and Presage® gel dosimeters in high-dose-rate radiation fields

Dose-response dependencies of the radiochromic Turnbull blue (TB), modified Fricke gel (FXO), polymer gel VIPET, and solid-state Presage® dosimeters were investigated, in high-dose-rate radiation fields, using spectrophotometry. A sealed radionuclide source (60Co) with a dose rate up to 9 Gy s−1 was used for irradiation. Standard liquid Fricke solution was used as a reference dosimeter. It was found that the properties of different types of gel dosimeters are affected by the dose rate. The results were compared with the predictions derived from the physical-chemical irradiation response principles. Considerable dose-rate dependencies were observed for all investigated 3D dosimeters. Dose responses of TB, VIPET, and FXO were decreased by 30–40% while the Presage® response were decreased by approximately 20% for dose rates from 7.2 × 10−3 to 9.01 Gy s−1. Presented results could have practical impact on some clinical applications, and therefore proper corrections might be needed.

Investigations of Nanoparticle Suspensions of Prussian Blue and Its Copper Analogue: Amine Functionalization and Electrochemical Studies

Prussian blue (PB) and its analogues are promising materials for electrochemical energy storage, yet their use in flow-type devices is limited by their lack of redox responsiveness as colloidal suspensions. We have investigated the redox chemistry amine functionalization of PB along with its Cu analogue (CuPBA). No redox response of colloidal PB was observed and suspensions of CuPBA formed films on electrode surfaces with and without applied potentials; the films were redox-active but the material that remained suspended in solution did not participate in redox chemistry. Propylamine (pa), ethylenediamine (en), or tetramethylethylenediamine (TMEDA) were added in an attempt to maintain well dispersed suspensions through nanoparticle surface functionalization. Propylamine modifications resulted in a loss of the CuPBA network and subsequent precipitation of insoluble materials. Coordination of ethylenediamine prompted the formation of Cu and Fe monomers ([Cu(en)2]m+/[Fe(CN)6]n-]) that remained soluble in aqueous electrolytes. In the absence of supporting electrolytes, these monomers formed a one-dimensional (1D) polymeric structure (Cu2Fe-1D). TMEDA modification preserved the CuPBA extended structure with only modest precipitate formation over 30 min. The redox responsiveness of these suspensions depended on conditions; in 1 M KCl, no redox chemistry was observed for the CuPBA. In pH 4 potassium hydrogen phthalate buffer, a signal was observed that was attributed to the Fe centers of CuPBA. Under these conditions, the material precipitated in ∼15 min and the signal was lost. Although the Fe centers in these networks are redox-active, additional work is needed to realize longer-term redox activity and stability. Ligand modifications can alter the properties of these networks but within a given ligand class, e.g., amines, the effects can vary greatly from the deconstruction of the framework to preventing film formation.

Ratiometric Detection of Ochratoxin A Using a Regenerable COF-Au-MB-Apt Signal Probe on a Thermal-Regulated Sensor Module.

Ochratoxin A (OTA) frequently contaminates grains and consequently threatens human health. Herein, we develop a regenerable signal probe and apply it to a Au-based screen-printed electrode module (SPE) for OTA determination. The signal probe, containing a structural covalent organic framework, gold nanoparticles (AuNPs), indicative methylene blue (MB), and a highly selective aptamer, is synthesized with hydrothermal and self-assembly methods. The SPE is permanently functionalized with Prussian blue (PB), AuNPs, and semicomplementary ssDNA. The signal probe, absorbed onto this SPE via hybridization, is competitively expelled by OTA, providing a ratiometric readout of ΔIMB/IPB. Probe regeneration, to erase expired COF-Au-MB-Apt after each analysis, is established with the synergy of OTA-conducted Apt-ssDNA dissociation and on-chip thermal regulation. This advantage powerfully guarantees reduplicative analyses by avoiding irreversible Apt-OTA combination and accumulation on the sensing interface. Regenerations are performed in repetitive cycles (N = 7) with 98.5% reproduction efficiency, and IMB and IPB fluctuations are calculated as 1.45 and 1.12%. This method shows log-linear OTA response in a wide range from 0.2 pg/mL to 0.6 μg/mL, and the limit of detection is 0.12 pg/mL. During natural OTA determinations, recommended readouts match well with HPLC with less than 4.82% relative error.

Surface area independent response of closed bipolar electrodes

Here, we demonstrated the application of a closed bipolar electrode to measure the change in open circuit potential (OCP) of Prussian blue/white as a function of [Cl−] concentration independently of electrode surface area. In this bipolar scheme, a potentiostat holds a constant voltage across two separate cells linked by a shared electrode that is sensitive to [Cl−] on one end and electrodeposited by Prussian Blue on the other. As [Cl−] is added to the sample compartment, the ion associates with Ag+ to produce Ag/AgCl, altering the junction potential. This change is balanced electrochemically by a shift in the ratio of Prussian blue/ Prussian white. A second potentiostat is used to monitor these changes over the Prussian blue electrode, yielding a for the quantification of chloride. We measured a range of 1.0 mM – 55 mM [Cl−] over various electrode surface areas, demonstrating that the signal response is independent of electrode area. Additionally, the system had the capability to translate signal across a single bipolar electrode while using differently sized electrodes in each compartment, a property that could be beneficial for microarrays or signal amplification.