A nanohybrid of Prussian blue supported by boracic acid-modified g-C3N4 for Raman recognition of cell surface sialic acid and photothermal/photodynamic therapy

Theranostic nanoplatforms with accurate diagnosis and effective therapy show a bright prospect for tumor treatments. Herein, a novel boracic acid-modified graphite carbon nitride and Prussian blue nanohybrid (PB@B-g-C₃N₄) was developed, which provides sialic acid-targeted Raman recognition and synergistic photothermal/photodynamic therapy in the near-infrared region. Owing to the specific interaction between boracic acid and sialic acid and Raman response at 2157 cm^-1 of PB, the nanohybrids exhibit high specificity and Raman sensitivity for detection of the overexpressed sialic acid on tumor cells. Moreover, the photothermal conversion efficiency of PB@B-g-C₃N₄ is as high as 47.0% with 808 nm laser irradiation due to the enhanced absorbance of PB@B-g-C₃N₄. PB@B-g-C₃N₄ also possesses excellent photodynamic activity, which is attributed to the energy transfer of PB (type I) and electron transfer between PB and B-g-C₃N₄ (type II). This nanotheranostic agent for Raman recognition of cancer markers and synergistic photothermal/photodynamic therapy holds great potential for the development of efficient theranostic nanoplatforms.

Synthesis of NiSe2 /Fe3 O4 Nanotubes with Heteroepitaxy Configuration as a High-Efficient Oxygen Evolution Electrocatalyst

The rational design of high-efficient non-noble metal electrocatalysts for oxygen evolution reactions (OER) is of significance in electrochemical energy conversion. However, such low-cost but highly active electrocatalysts remain poorly developed because of the daunting synthetic challenge. Here, the synthesis of NiSe₂ /Fe₃ O₄ nanotubes via a facile self-templating strategy, which manifests unique tetragonal morphology, asymmetric hollow interior, and unusual but adaptable heteroepitaxy structure, is reported. Benefiting from sufficient active sites and their improved activity around the heterointerface, accompanied by the good conductivity, the NiSe₂ /Fe₃ O₄ nanotubes exhibit as a superior OER electrocatalyst, which affords the current density of 10 mA cm^-2 at a very small overpotential of 199 mV, high attainable current density beyond 200 mA cm^-2 , and mass activity of 984.5 A g^-1 , as well as excellent stability for 100 h in the alkaline media. This work provides a unique synthetic pathway to fabricate superior OER electrocatalysts by optimizing their composition and architecture.

Prussian Blue Nanozyme Promotes the Survival Rate of Skin Flaps by Maintaining a Normal Microenvironment

Ischemia-reperfusion (I/R) injury leads to a low success rate of skin flap transplantation in reconstruction surgery, thus requiring development of new treatments. Necroptosis and apoptosis pathways, along with overexpression of reactive oxygen species and pro-inflammatory factors in skin flap transplantation, are deemed as potential therapeutic targets. This study provides a paradigm for nanozyme-mediated microenvironment maintenance to improve the survival rate of the transplanted skin flap. Prussian blue nanozyme (PBzyme) with multiple intrinsic biological activities was constructed and selected for this proof-of-concept study. The prepared PBzyme shows anti-inflammatory, antiapoptotic, antinecroptotic, and antioxidant activities in both in vitro and in vivo models of I/R injured skin flaps. The multiple inhibitory effects of PBzyme maintained a normal microenvironment and thus significantly promoted the survival rate of the I/R injured skin flap (from 37.21 ± 8.205% to 79.61 ± 7.5%). Of note, PBzyme regulated the expression of the characteristic signal molecules of necroptosis, including Rip 1, Rip 3, and pMLKL, indicating that PBzyme may be a therapeutic agent for necroptosis-related diseases. This study shows great prospects for clinical application of PBzyme in the treatment of skin flaps via local administration.

Electrochemical Transparency of Graphene

In the present study, we used the electrochemical transparency of graphene to show that the direct intercalation of alkali-metal cations is not a prerequisite for the redox reaction of Prussian blue (PB). PB thin films passivated with monolayer graphene still underwent electrochemical redox reactions in the presence of alkali-metal ions (K⁺ or Na⁺) despite the inability of the cations to penetrate the graphene and be incorporated into the PB. Graphene passivation not only preserved the electrochemical activity of the PB but also substantially enhanced the stability of the PB. As a proof of concept, we showed that a transparent graphene electrode covering PB can be used as an excellent hydrogen peroxide transducer, thereby demonstrating the possibility of realizing an electrochemical sensor capable of long-term measurements.

Intrinsic Multienzyme-like Activities of the Nanoparticles of Mn and Fe Cyano-Bridged Assemblies

This study investigates the intrinsic multienzyme-like properties of the non-stabilized nanocrystalline nanoparticles of manganese-doped Prussian blue (Mn-PB) nanozymes and Prussian blue (PB) nanozymes in chemical and electrocatalytic transformations of reactive oxygen species. The effect of manganese doping on the structural, biomimetic, and electrocatalytic properties of cyano-bridged assemblies is also discussed.

Interfacial Mn Vacancy for Li-Rich Mn-Based Oxide Cathodes

Apart from the O releasing at a low rate, large polarization at a high rate is also a big challenge for Li-rich Mn-based oxide (LMO). Prussian blue (PB) with a specific redox potential is regarded as a suitable coating layer to overcome these drawbacks, while its stability is easily destroyed by the intrinsic Jahn-Teller effect after a long run. Herein, Mn vacancy (M_V) is introduced into the PB coating layer to enhance its stability. Consequently, such an electrode (M_V-PB@LMO) presents a prolonged lifespan compared to the electrode with a PB coating layer only. Furthermore, it is found that the electrode with Mn vacancy in LMO (M_V@LMO) shows superior reversibility, which displays a boosted activity of LMO. This research exhibits the advanced merits of Mn vacancy for LMO, and further work may pay more attention to strengthening of the stability of M_V@LMO.

Dual stabilization in potassium Prussian blue and cathode/electrolyte interface enables advanced potassium-ion full-cells

Potassium Prussian Blue (KPB) have been investigated as promising cathode materials for potassium-ion batteries. However, numerous structure defects and side reactions at electrode/electrolyte interface will deteriorate the electrochemical properties. Herein, dual stabilization strategy of structure of KPB particles and cathode/electrolyte interface is reported to enhance the capacity and electrochemical stability. The structure of KPB is stabilized through inhibiting nucleation and growth by addition of ethylenediaminetetraacetic acid dipotassium salt during co-precipitation, which can enlarge the particle size. Meanwhile, stabilizing the cathode/electrolyte interface via changing potassium hexafluorophosphate to potassium bis (fluorosulfonyl) imide (KFSI) electrolyte can further reduce side reactions to boost the coulombic efficiency of KPB cathode. Benefiting from dual engineering in structure of KPB and cathode/electrolyte interface, the half-cell in KFSI electrolyte possesses two discharge potential plateaus at 3.4 and 4.0 V with reversible capacity of 92.7 mAh g^-1 at 0.03 A g^-1. To demonstrate its practical use, KPB//graphite full-cell device is successfully constructed, exhibiting the capacity up to 102.4 mAh g^-1 at 0.1 A g^-1, high-rate (40.4 mAh g^-1 at 1.5 A g^-1) and superior cyclic stability (88% capacity retention from cycle 25 to 400 at 1 A g^-1). This work provides a synergetic engineering strategy to realize the powerful application of high-performance potassium-ion full-cell devices in energy storage.

Antithrombotic Therapy by Regulating the ROS-Mediated Thrombosis Microenvironment and Specific Nonpharmaceutical Thrombolysis Using Prussian Blue Nanodroplets

In thrombotic diseases, the effects of reactive oxygen species (ROS)-mediated oxidative stress as a "perpetrator" in thrombosis must be resolved. Accordingly, an insufficient understanding of thrombus therapy prompted the authors to pursue a more comprehensive and efficient antithrombotic treatment strategy. A Prussian blue (PB)-based nanodroplet system (PB-PFP@PC) is designed using PB and perfluorinated pentane (PFP) in the core, and a targeting peptide (CREKA, Cys-Arg-Glu-Lys-Ala) is attached to poly(lactic-coglycolic acid) (PLGA) as the delivery carrier shell. Upon near-infrared (NIR) laser irradiation, PB and PFP jointly achieve an unprecedented dual strategy for drug-free thrombolysis: photothermal therapy (PTT) combined with optical droplet vaporization (ODV). PB, a nanoenzyme, also regulates the vascular microenvironment via its antioxidant activity to continuously scavenge abnormally elevated ROS and correspondingly reduce inflammatory factors in the thrombus site. This study provides a demonstration of not only the potential of ODV in thrombus therapy but also the mechanism underlying PTT thrombolysis due to thermal ablation-induced fibrin network structural damage. Moreover, PB catalyzes ROS to generate oxygen (O₂ ), which combines with the ODV effect, enhancing the ultrasound signal. Thus, regulation of the thrombosis microenvironment combined with specific nonpharmaceutical thrombolysis by PB nanodroplets provides a more comprehensive and efficient antithrombotic therapeutic strategy.

Interstitial Water Improves Structural Stability of Iron Hexacyanoferrate for High-Performance Sodium-Ion Batteries

Prussian blue analogues (PBAs) are considered one of the promising cathodes for sodium-ion batteries because of their low cost and tunable structure. As an intrinsic characteristic, the influence of structured water in PBAs on the electrochemical properties is still controversial. Herein, low-vacancy iron hexacyanoferrate with different interstitial water contents is synthesized through the citric acid-assisted single iron source method. Ex situ Fourier transform infrared and X-ray diffraction characterization reveals that the interstitial water can stably exist in the Prussian blue framework during repeated cycling. The long-standing interstitial water can reduce the volume change during the Na⁺ insertion/extraction process, resulting in improved cycling stability. Thanks to the low Fe(CN)₆^4- vacancies and pillar role of interstitial water in the crystal framework, the HW-PB exhibits a high reversible capacity of 117 mAh g^-1 and excellent long cycle performance with a capacity retention of 91% after 1380 cycles. This work broadens the understanding of the relationship between the interstitial water in PBAs and Na-storage performances, providing guidance for the precise synthesis of high-quality PBAs.

Photothermal therapy with regulated Nrf2/NF-κB signaling pathway for treating bacteria-induced periodontitis

Periodontitis is an inflammatory disease initiated by bacterial infection, developed by excessive immune response, and aggravated by high level of reactive oxygen species (ROS). Hence, herein, a versatile metal-organic framework (MOF)-based nanoplatform is prepared using mesoporous Prussian blue (MPB) nanoparticles to load BA, denoted as MPB-BA. The established MPB-BA nanoplatform serves as a shelter and reservoir for vulnerable immunomodulatory drug BA, which possesses antioxidant, anti-inflammatory and anti-bacterial effects. Thus, MPB-BA can exert its antioxidant, anti-inflammatory functions through scavenging intracellular ROS to switch macrophages from M1 to M2 phenotype so as to relieve inflammation. The underlying molecular mechanism lies in the upregulation of phosphorylated nuclear factor erythroid 2-related factor 2 (Nrf2) to scavenge ROS and subsequently inhibit the nuclear factor kappa-B (NF-κB) signal pathway. Moreover, MPB-BA also exhibited efficient photothermal antibacterial activity against periodontal pathogens under near-infrared (NIR) light irradiation. In vivo RNA sequencing results revealed the high involvement of both antioxidant and anti-inflammatory pathways after MPB-BA application. Meanwhile, micro-CT and immunohistochemical staining of p-Nrf2 and p-P65 further confirmed the superior therapeutic effects of MPB-BA than minocycline hydrochloride. This work may provide an insight into the treatment of periodontitis by regulating Nrf2/NF-κB signaling pathway through photothermal bioplatform-assisted immunotherapy.

Cesium ion adsorption and desorption on electrospun mesoporous silica nanofibers immobilized with Prussian blue

To fabricate an efficient Cs ion adsorbent and prevent unexpected loss of Prussian blue (PB) colloidal particles during use, PB was immobilized on the surface of electrospun mesoporous silica nanofibers (MSFs) via a newly developed method of double exposure to Fe (III) ions. To introduce PB on MSFs, the MSFs were functionalized with ethylenediamine moiety to bind to Fe (III) ions, which would firmly anchor PB. MSFs were pretreated with Fe (III) ions and exposed to K₄ [Fe(II) (CN)₆] to form PB. We found that this process did not provide a sufficient PB amount on the MSFs. To increase the PB amount, after initial PB formation, the MSFs were treated with Fe (III) ions again so that the unreacted K₄ [Fe(II) (CN)₆] remaining on the MSFs could become PB. An investigation of the adsorption isotherms and kinetics of the nanofibrous adsorbent indicated that monolayer chemisorption had occurred. The maximum Cs ion adsorption capacity using the method of double exposure to Fe (III) ions was determined to be 14.66 mg/g, which was higher by a factor of 2.24 than the case that was not prepared by this method. Cs ions were selectively adsorbed over other cations and could be removed in both acidic and basic conditions, presumably because of the robust MSFs.

Glucose sensing on screen-printed electrochemical electrodes based on porous graphene aerogel @prussian blue

As one of the three major chronic diseases, diabetes often causes many complications, which can affect various parts of the body and even threaten the life of the patients. At present, the situation of diabetes in the world is quite serious. Accurate detection of blood glucose is very important for the diagnosis, treatment and medication of diabetes as well as the self-management of diabetic patients. In this paper, an electrochemical glucose biosensor was developed based on screen-printed electrode (SPE) modified with composite material of graphene aerogel (GA) and Prussian blue (PB) (denoted as GA@PB), which was fabricated via chemical reduction using L-ascorbic acid as a reducing agent through a freeze-drying process. Glucose was specifically captured by glucose oxidase (GOx) which were immobilized into the GA@PB by chitosan. The structure and performance of the sensor were characterized by scanning electron microscopy (SEM), Raman spectroscopy measurements, Fourier transform infrared spectrometer (FTIR), cyclic voltammetry (CV) and amperometric detection. The sensor exhibited a linear range of 0.5-6.0 mmol·L^-1 with limit of detection (LOD) of 0.15 mmol·L^-1, indicating that the combination of graphene aerogel and Prussian blue possess well conductivity and catalytic performance.

Three-Dimensional Ti3C2Tx MXene-Prussian Blue Hybrid Microsupercapacitors by Water Lift-Off Lithography

The construction of electrochemical energy-storage devices by scalable thin-film microfabrication methods with high energy and power density is urgently needed for many emerging applications. Herein, we demonstrate an in-plane hybrid microsupercapacitor with a high areal energy density by employing a battery-type CuFe-Prussian blue analogue (CuFe-PBA) as the positive electrode and pseudocapacitive titanium carbide MXene (Ti₃C₂T_x) as the negative electrode. A three-dimensional lignin-derived laser-induced graphene electrode was prepared as the substrate by laser exposure combined with an environmentally friendly water lift-off lithography. The designed hybrid device achieved enhanced electrochemical performance thanks to the ideal match of the two types of high-rate performance materials in proton-based electrolytes and the numerous electrochemically active sites. In particular, the device delivers a high areal capacitance of 198 mF cm^-2, a wide potential window (1.6 V), an ultrahigh rate performance (75.8 mF cm^-2 retained even at a practical/high current density of 100 mA cm^-2), and a competitive energy density of 70.5 and 27.6 μWh cm^-2 at the power densities 0.74 and 52 mW cm^-2, respectively. These results show that the Ti₃C₂T_x/CuFe-PBA hybrid microsupercapacitors are promising energy storage devices in miniaturized portable and wireless applications.

A biodegradable "Nano-donut" for magnetic resonance imaging and enhanced chemo/photothermal/chemodynamic therapy through responsive catalysis in tumor microenvironment

Prussian blue (PB) is a safe photothermal agent for tumor therapy, yet poor photothermal effect and single therapeutic function severely restrict its further clinical applications. Herein, a biodegradable "Nano-donut" (CMPB-MoS₂-PEG) is fabricated for magnetic resonance (MR) imaging and enhanced photothermal therapy (PTT)/ chemodynamic therapy (CDT)/chemotherapy through responsive catalysis in tumor microenvironment (TME). The "Nano-donut" is organically composed of Cu/Mn ions doped-PB and MoS₂. The porous donut structure of CMPB-MoS₂-PEG endows them as a carrier for delivery of doxorubicin hydrochloride (DOX) to tumor site. The framework of Nano-donut specifically decomposes in TME due to the reaction between Fe²⁺/Fe³⁺ and H₂O₂. The multivalent elements (Cu/Fe/Mn ions) decrease the bandgap and then enhance CDT by synergistically catalyzing H₂O₂ into toxic ·OH. Meanwhile, the Mn⁴⁺ also reacts with H₂O₂ to generate O₂, improving the hypoxia of TME and enhancing the chemotherapy effect of released DOX. The MoS₂ mingles in the PB, which significantly enhances photothermal conversion efficiency (η) effect of PB from 16.02% to 38.0%. In addition, Fe³⁺ as T2-weighted MR imaging agent can achieve MR imaging-guided therapy. The data clearly shows Nano-donut/DOX nanocomposites (NCs) have a remarkable inhibition for cancer cells and excellent biological safety in tumor treatment.

The Effect of an External Magnetic Field on the Electrocatalytic Activity of Heat-Treated Cyanometallate Complexes towards the Oxygen Reduction Reaction in an Alkaline Medium

This work focuses on the development of an electrocatalytic material by annealing a composite of a transition metal coordination material, iron hexacyanoferrate (Prussian blue) immobilized on carboxylic-acid-functionalized reduced graphene oxide. Pyrolysis at 500 °C under a nitrogen atmosphere formed nanoporous core–shell structures with efficient activity, which mostly included iron carbide species capable of participating in the oxygen reduction reaction in alkaline media. The physicochemical properties of the iron-based catalyst were elucidated using transmission electron microscopy, X-ray diffraction, Mössbauer spectroscopy, and various electrochemical techniques, such as cyclic voltammetry and rotating ring–disk electrode (RRDE) voltammetry. To improve the electroreduction of oxygen over the studied catalytic material, an external magnetic field was utilized, which positively shifted the potential by ca. 20 mV. The formation of undesirable intermediate peroxide species was decreased compared with the ORR measurements without an external magnetic field.

Wide-Spectrum Modulated Electrochromic Smart Windows Based on MnO2/PB Films

Inorganic materials have been extensively studied for visible electrochromism in the past few decades. However, the single inorganic electrochromic (EC) material commonly exhibits a single color change, leading to a narrow spectrum of modulation, which offsets or limits the maximally energy-saving ability. Here, we present a wide-spectrum modulated EC device designed by combining the complementary EC nanocomposite of manganese dioxide (MnO₂) and Prussian blue (PB) for enhanced energy savings. Porous MnO₂ nanostructures serve as host frameworks for the templated growth of PB, resulting in MnO₂/PB nanocomposites. The complementary optical modulation ranges of MnO₂ and PB enable a widen-spectrum modulation across the solar region with the development of the MnO₂/PB nanocomposite. The colored MnO₂/PB device exhibited an optical modulation of 32.1% in the wide solar spectrum range of 320-1100 nm and blocked 72.0% of the solar irradiance. Furthermore, fast switching responses (2.7 s for coloration and 2.1 s for bleaching) and a high coloration efficiency (83.1 cm²·C^-1) of the MnO₂/PB EC device are also achieved. The high EC performance of the MnO₂/PB nanocomposite device provides a new strategy for the design of high-performance energy-saving EC smart windows.

Wearable healthcare smart electrochemical biosensors based on co-assembled prussian blue-graphene film for glucose sensing

Wearable film-based smart biosensors have been developed for real-time biomolecules detection. Particularly, interfacial co-assembly of reduced graphene oxide-prussian blue (PB-RGO) film through electrostatic interaction has been systematically studied by controllable pH values, achieving optimal PB-RGO nanofilms at oil/water (O/W) phase interface driven by minimization of interfacial free energy for wearable biosensors. As a result, as-prepared wearable biosensors of PB-RGO film could be easily woven into fabrics, exhibiting excellent glucose sensing performance in amperometric detection with a sensitivity of 27.78 µA mM^-1 cm^-2 and a detection limit of 7.94 μM, as well as impressive mechanical robustness of continuously undergoing thousands of bending or twist. Moreover, integrated wearable smartsensing system could realize remotely real-time detection of biomarkers in actual samples of beverages or human sweat via cellphones. Prospectively, interfacial co-assembly engineering driven by pH-induced electrostatic interaction would provide a simple and efficient approach for acquiring functional graphene composites films, and further fabricate wearable smartsensing devices in health monitoring fields.

Layered Double Hydroxide-Assisted Fabrication of Prussian Blue Membranes for Precise Molecular Sieving

Prussian Blue (PB), which was first discovered as robust blue-colored pigment in the year 1706, has shown promising prospects in disease treatment, energy conversion, water splitting, and sensing. Relying on the uniform 3.2 Å-sized pore channels as well as high stability in aqueous environments, in this study, we pioneered in situ preparation of polycrystalline PB membranes to justify their dye rejection and metal ion discrimination ability in aqueous environments. Among various factors, the introduction of calcined NiFe layered double hydroxide buffer layers on porous α-Al₂ O₃ substrates was found to play a paramount role in the formation of continuous polycrystalline PB membranes, thereby leading to excellent dye rejection efficiency (>99.0 %). Moreover, prepared PB membranes enabled discriminating different monovalent metal ions (e.g., Li⁺ , Na⁺ , and K⁺ ) depending on their discrepancy in Stokes diameters, showing great promise for lithium extraction from smaller-sized metal ions.

Old Materials for New Functions: Recent Progress on Metal Cyanide Based Porous Materials

Cyanide is the simplest ligand with strong basicity to construct open frameworks including some of the oldest compounds reported in the history of coordination chemistry. Cyanide can form numerous cyanometallates with different transition metal ions showing diverse geometries. Rational design of robust extended networks is enabled by the strong bonding nature and high directionality of cyanide ligand. By virtue of a combination of cyanometallates and/or organic linkers, multifunctional framework materials can be targeted and readily synthesized for various applications, ranging from molecular adsorptions/separations to energy conversion and storage, and spin-crossover materials. External guest- and stimuli-responsive behaviors in cyanide-based materials are also highlighted for the development of the next-generation smart materials. In this review, an overview of the recent progress of cyanide-based multifunctional materials is presented to demonstrate the great potential of cyanide ligands in the development of modern coordination chemistry and material science.

Phytic Acid Doped Polypyrrole as a Mediating Layer Promoting Growth of Prussian Blue on Cotton Fibers for Solar-Driven Interfacial Water Evaporation

Phytic acid doped polypyrrole (PPy) as a mediating layer was in-situ coated on cotton fibers (CFs) to promote the growth of Prussian blue (PB) and construct the PB/PPy@CFs composite. The results showed that the proper amounts of PA doped PPy in-situ generated significantly promoted the growth of PB on CFs, the PB deposition ratio increased from 12.29% (PB@CFs) to 32.4% (PB/PPy@CFs), and the growth of PB on PPy@CFs could be completed in 4 h. Scanning electron microscopy (SEM) showed that the PB particles with perfect nano cubic structure were formed in the composite. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) showed that both PB and PPy were successfully deposited on CFs. The PB/PPy@CFs composite had excellent light absorption, hydrophilicity, wettability, and photothermal property, and the surface could be heated up to 81.5 °C under one sun illumination. The PB/PPy@CFs composite as a photothermal conversion material was used for solar-driven interfacial water evaporation, the water evaporation rate was 1.36 kg·m-2·h-1 at the optical concentration of 1 kW·m2, and the corresponding photothermal conversion efficiency increased from 81.69% (PB@CFs) to 90.96% (PB/PPy@CFs).

Construction multifunctional nanozyme for synergistic catalytic therapy and phototherapy based on controllable performance

Advances in nanozyme involve an efficient catalytic process, which has demonstrated great potential in tumor therapy. The key to improving catalytic therapy is to solve the limitation of the tumor microenvironment on Fenton reaction. In this work, Prussian blue nanoparticles doped with different rare earth ions (Yb³⁺, Gd³⁺, Tm³⁺) were screened to perform synergistic of photothermalandcatalytictumortherapy. The optimized catalytic performance can be further enhanced through photothermal effect to maximize the Fenton reaction to solve the limitation of the tumor microenvironment. Yb-PB, with the optimal photothermal and catalytic performance, was screened out. In order to avoid the scavenging effect of glutathione (GSH) on ·OH in tumor cells and the reaction with a bit H₂O₂ in normal cells, GSH targeted polydopamine (PDA) was wrapped on the surface of Yb-PB to obtain Yb-PB@PDA. It was found that enough hydroxyl radicals (·OH) can be generated even if at high GSH concentration and the NIR irradiation can help produce more ·OH. Cell fluorescence imaging (FOI) and in vivo magnetic resonance imaging (MRI) experiments showed the potential application in FOI/MRI dual-mode imaging guided therapy. In vivo anti-tumor experiments showed that Yb-PB@PDA has a satisfactory anti-cancer effect through the combined effect of catalytic/photothermal therapy. Thus, a multifunctional nanozyme for tumor therapy is constructed.

Triggering Drug Release and Thermal-Disrupting Interface Induced Mitigation of Composite Photothermal Hydrogel Treating Infectious Wounds

Introduction: With the development of photothermal technology, the appearance of composite photothermal hydrogels has increased the selectivity of treating infectious skin defects. However, how to design composite photothermal hydrogel with better antibacterial performance, reduce the resistance rate of bacteria, and the damage rate of normal tissue still needs further study. Methods: The Prussian blue and tannic acid were loaded on polyacrylamide hydrogels. Characterization of DLS, Zeta potential, UV absorption spectrum, hydrogel swelling rate, scanning electronic microscopic, drug release profile, photothermal properties, in vitro cytocompatibility, and antibacterial properties. Experiments were measured by skin defect repair, antibacterial detection, and histological staining experiments. Results: The polyacrylamide hydrogel with photothermal effect and controllable release of tannic acid was successfully prepared. The hydrogel has strong light transmittance and adhesion, and the swelling rate can reach 600%, which improves the self-cleaning ability. SEM results showed the porous structure of hydrogels, promoting cell growth. Through photothermal switches, the composite hydrogel represented adjustable and controllable drug release ability. Combined with the synergistic antibacterial effect of tannic acid, this further enhanced the antibacterial ability and reduced the probability of antibiotic resistance. The in vitro and in vivo experiments showed the hydrogel had good biocompatibility and excellent antibacterial properties, which could promote the repair of infectious skin defects in SD rats. Conclusion: We fabricated a hydrogel with a triggering drug release rate, alleviating heat damage, transparent morphology, mechanical stability, strong adhesion, good biocompatibility, and synergistic antibacterial ability, which presents new treatment options for infectious skin defect repair.

Synthesis and Applications of Prussian Blue and Its Analogues as Electrochemical Sensors

Prussian blue (PB) and its analogue (PBA) are a kind of representative cyanide-based coordination polymer. They have received enormous research interest and have shown promising applications in the electrochemical sensing field due to their excellent electrochemical activity and unique structural characteristics including open framework structure, high specific surface area, and adjustable metal active sites. In this review, we summarize the latest research progress of PB/PBA as an electrochemical sensor in detail from three aspects: fabrication strategy, synthesis method and electrochemical sensor application. For the fabrication strategy, we discussed different fabrication methods containing the combination of PBA and carbon materials, metal nanoparticles, polymers, etc., respectively, as well as their corresponding sensing mechanism for improving performance. We also presented the synthesis methods of PB/PBA materials in detail, such as: coprecipitation, hydrothermal and electrodeposition. In addition, the effects of different methods on the morphology, particle size and productivity of PB/PBA materials are also concluded. For the application of electrochemical sensors, the latest progress of such materials as electrochemical sensors for glucose, H2O2, toxic compounds, and biomolecules have been summarized. Finally, we conclude remaining challenges of PB/PBA-based materials as electrochemical sensors, and provide personal perspectives for future research in this field.

Prussian blue modified CeO2 as a heterogeneous photo-Fenton-like catalyst for degradation of norfloxacin in water

The heterogeneous photo-Fenton-like process is emerging as a promising treatment of antibiotics-containing wastewater. The preparation of new efficient and stable catalysts is one of the research fields. A composite catalyst, prussian blue (PB) modified CeO₂ was prepared, characterized, and applied for photo-Fenton oxidation of norfloxacin (NOR) in this study. It was found that chemical doping of PB leaded to more oxygen vacancies and increased the surface area of CeO₂ obviously. PB/CeO₂ with more Ce³⁺ facilitated electron transfer between Fe³⁺/Fe²⁺ with Ce³⁺/Ce⁴⁺. PB could also improve the separation rate of photoexcited electron-hole pairs in CeO₂ nanostructures. When the doping ratio of PB and CeO₂ was 10%, PB/CeO₂ show the highest catalytic degradation ability and 88.93% of NOR could be degraded within 30 min. PB/CeO₂ composite showed well reactivity at the wide pH value range of 3-8. The reusable experiments and low iron dissolution with less than 1 mg/L indicated that PB/CeO₂ could be employed as an efficient heterogeneous photo-Fenton-like catalyst in organic contaminants degradation.

Polyvinylpyrrolidone-Bridged Prussian Blue/rGO Composite as a High-Performance Cathode for K-Ion Batteries

Prussian blue (PB) is a very promising cathode for K-ion batteries but its low electronic conductivity and deficiencies in the framework aggravate electrochemical performances. Compositing with conductive reduced graphene oxide (rGO) is an effective solution to address this problem. Nevertheless, little attention was paid to the loss of oxygen-containing functional groups on the rGO substrate during the compositing process, which weakens the interaction between PB and rGO and leads to poor electrochemical performance of PB/rGO. Herein, this interaction effect associated with surface functional groups is first openly debated. Two commonly used carbon substrates, graphene oxide (GO) and rGO, are investigated. A more stable interaction between PB and GO contributes to a higher capacity retention (91.8%) than that of PB/rGO (69.7%) after 300 cycles at a current density of 5 C. Meanwhile, polyvinylpyrrolidone (PVP) is employed to repair the weak interaction between PB and rGO substrates. PB is anchored to the rGO surface through the stable covalent linking of amide groups in PVP. A superior rate capability of 72 mA h g^-1 at 10 C and an improved capacity retention of 96.5% over 800 cycles at 5 C are obtained by as-prepared PB/PVP-rGO. This study provides a deeper understanding of fabricating PB/carbon composites with a robust connection.