A Low Driving-Voltage Hybrid-Electrolyte Electrochromic Window with Only Ferreous Redox Couples

Even after decades of development, the widespread application of electrochromic windows (ECW) is still seriously restricted by their high price and inadequate performance associated with structural/fabrication complexity and electrochemical instability. Herein, a simple hybrid electrochromic system based on PFSA (perfluorosulfonic acid)-coated Prussian blue (PB, Fe4III [FeII(CN)6]3) film and Ferricyanide-Ferrocyanide ([Fe(CN)6]4-/[Fe(CN)6]3-)-containing hybrid electrolyte is reported. The PB film and the [Fe(CN)6]4-/[Fe(CN)6]3- couple show near redox potentials well inside the electrochemical window of water, resulting in a low driven voltage (0.4 V for coloring and -0.6 V for bleaching) and a relatively long lifespan (300 cycles with 76.9% transmittance contrast retained). The PFSA layer, as a cation-exchange structure, significantly improves the transmittance modulation amplitude (ΔT: 23.3% vs. 71.9% at a wavelength of 633 nm) and optical memory abilities (ΔT retention: 10.1% vs. 67.0% after 300 s open-circuit rest increases) of the device, by means of preventing the direct contact and charge transfer between the PB film and the [Fe(CN)6]4-/[Fe(CN)6]3- couple. This "hybrid electrolyte + electron barrier layer" design provides an effective way for the construction of simple structured electrochromic devices.

Chitosan enhanced the stability and antibiofilm activity of self-propelled Prussian blue micromotor

The emergence, spread and difficult removal of bacteria biofilm, represent an ever-increasing persistent infections and medical complications challenge worldwide. Herein, a self-propelled system Prussian blue micromotor (PB MMs) were constructed by gas-shearing technology for efficient degradation of biofilms by combining chemodynamic therapy (CDT) and photothermal therapy (PTT). With the interpenetrating network crosslinked by alginate, chitosan (CS) and metal ions as the substrate, PB was generated and embedded in the micromotor at the same time of crosslinking. The micromotors are more stable and could capture bacteria with the addition of CS. The micromotors show excellent performance, containing photothermal conversion, reactive oxygen species (ROS) generation and bubble produced by catalyzing Fenton reaction for motion, which served as therapeutic agent could chemically kill bacteria and physically destroy biofilm. This research work opens a new path of an innovative strategy to efficiently remove biofilm.

Meniscus-Guided Micro-Printing of Prussian Blue for Smart Electrochromic Display

Using energy-saving electrochromic (EC) displays in smart devices for augmented reality makes cost-effective, easily producible, and efficiently operable devices for specific applications possible. Prussian blue (PB) is a metal-organic coordinated compound with unique EC properties that limit EC display applications due to the difficulty in PB micro-patterning. This work presents a novel micro-printing strategy for PB patterns using localized crystallization of FeFe(CN)₆ on a substrate confined by the acidic-ferric-ferricyanide ink meniscus, followed by thermal reduction at 120 °C, thereby forming PB. Uniform PB patterns can be obtained by manipulating printing parameters, such as the concentration of FeCl₃ ·K₃ Fe(CN)₆ , printing speed, and pipette inner diameter. Using a 0.1 M KCl (pH 4) electrolyte, the printed PB pattern is consistently and reversibly converted to Prussian white (CV potential range: -0.2-0.5 V) with 200 CV cycles. The PB-based EC display with a navigation function integrated into a smart contact lens is able to display directions to a destination to a user by receiving GPS coordinates in real time. This facile method for forming PB micro-patterns could be used for advanced EC displays and various functional devices.

PEI-coated Prussian blue nanocubes as pH-Switchable nanozyme: Broad-pH-responsive immunoassay for illegal additive

Nanozymes are commonly used in the construction of immunosensors, yet they are generally susceptible to pH condition, which greatly hindered their practical use. To break the limitation of pH conditions, polyethyleneimine-coated Prussian blue nanocubes (PBNCs@PEI) were synthesized as the pH-switchable nanozyme, which can show peroxidase-like and catalase-like activity in acidic and alkaline condition, respectively. Besides, the modification of PEI can largely improve the catalytic activity of PBNCs. Herein, the pH-switchable catalytic property of PBNCs@PEI was used to construct the dual-mode immunosensor for the detection of illegal additive, rosiglitazone. In acidic condition, PBNCs@PEI showed excellent peroxidase-like activity, which can trigger the colorimetric reaction of Au nanostars with TMB2+/CTAB. In alkaline condition, the catalase-like activity of PBNCs@PEI prevailed, thus the decomposition of H2O2 can generate O2 to initiate the aerobic oxidation of 4-chloro-1-naphthol (4-CN), which can decrease the fluorescence intensity of 4-CN. Based on the competitive immunoassay, both the localized surface plasmon resonance wavelength shift of Au nanostars and the fluorescence intensity change of 4-CN were quantitatively related with rosiglitazone concentration, thus shedding a new light on the construction of broad-pH-responsive immunosensor. Besides, a smart device was developed to transfer the chroma value of Au nanostars into the RSG concentration, making this sensor a promising method in on-site and point-of-care detection.

Paper-based colorimetric glucose sensor using Prussian blue nanoparticles as mimic peroxidase

A novel paper-based colorimetric glucose sensor was proposed employing Prussian blue nanoparticles (PB NPs) as mimic peroxidase. The sensor was manufactured by spraying solution containing PB NPs, glucose oxidase and chromogenic agents into a paper, then coating the filter layer and spreading layer on the top. The layer-by-layer structure enabled the sensor detect glucose in whole blood, as well as elimination of the coffee-ring effect which ensure the performance. As a powerful alternative to natural peroxidase, PB NPs showed the mimic enzymatic activity well preserved in dry environment. The manufacture process of the sensor is easy to be industrialized. Under optimal conditions, the sensor exhibited a linear range from 2.5 mM to 25 mM for glucose in blood with satisfactory reproducibility (the coefficient of variant <4%), great storage stability (1 month at 45 °C) and excellent linearity compared with those commercial kits (R > 0.99). Coupled with a handhold device, the PB NPs-based test strip realized the goal of personal operation, user-friendly control, automatic readouts, and data storage, and able to link the Cloud, showing unique potential in clinical application, especially in community-level medical scenarios.

Portable Prussian Blue-Based Sensor for Bacterial Detection in Urine

Bacterial infections can affect the skin, lungs, blood, and brain, and are among the leading causes of mortality globally. Early infection detection is critical in diagnosis and treatment but is a time- and work-consuming process taking several days, creating a hitherto unmet need to develop simple, rapid, and accurate methods for bacterial detection at the point of care. The most frequent type of bacterial infection is infection of the urinary tract. Here, we present a wireless-enabled, portable, potentiometric sensor for E. coli. E. coli was chosen as a model bacterium since it is the most common cause of urinary tract infections. The sensing principle is based on reduction of Prussian blue by the metabolic activity of the bacteria, detected by monitoring the potential of the sensor, transferring the sensor signal via Bluetooth, and recording the output on a laptop or a mobile phone. In sensing of bacteria in an artificial urine medium, E. coli was detected in ~4 h (237 ± 19 min; n = 4) and in less than 0.5 h (21 ± 7 min, n = 3) using initial E. coli concentrations of ~10³ and 10⁵ cells mL^-1, respectively, which is under or on the limit for classification of a urinary tract infection. Detection of E. coli was also demonstrated in authentic urine samples with bacteria concentration as low as 10⁴ cells mL^-1, with a similar response recorded between urine samples collected from different volunteers as well as from morning and afternoon urine samples.

Rapid Measurement of Lactate in the Exhaled Breath Condensate: Biosensor Optimization and In-Human Proof of Concept

Lactate concentration is of increasing interest as a diagnostic for sepsis, septic shock, and trauma. Compared with the traditional blood sample media, the exhaled breath condensate (EBC) has the advantages of non-invasiveness and higher user acceptance. An amperometric biosensor was developed and its application in EBC lactate detection was investigated in this paper. The sensor was modified with PEDOT:PSS-PB, and two different lactate oxidases (LODs). A rotating disk electrode and Koutecky-Levich analysis were applied for the kinetics analysis and gel optimization. The optimized gel formulation was then tested on disposable screen-printed sensors. The disposable sensors exhibited good performance and presented a high stability for both LOD modifications. Finally, human EBC analysis was conducted from a healthy subject at rest and after 30 min of intense aerobic cycling exercise. The sensor coulometric measurements showed good agreement with fluorometric and triple quadrupole liquid chromatography mass spectrometry reference methods. The EBC lactate concentration increased from 22.5 μM (at rest) to 28.0 μM (after 30 min of cycling) and dropped back to 5.3 μM after 60 min of rest.

Investigation of H2O2 Electrochemical Behavior on Ferricyanide-Confined Electrode Based on Ionic Liquid-Functionalized Silica-Mesostructured Cellular Foam

In this work, ionic liquid (IL) of 1-propyl-3-methyl imidazolium chloride-functionalized silica-mesostructured cellular foam (MCF) was prepared. The obtained MCF-IL was used to construct the Fe(CN)₆^3--confined electrode (MCF-IL-Fe(CN)₆^3-/PVA) and H₂O₂ electrochemical behavior on the electrode was investigated. It was found that H₂O₂ was oxidized on the freshly prepared electrode while catalytically electro-reduced on the acid pretreated one. Cyclic voltametric results revealed that the real catalyst for catalytic reduction of H₂O₂ was Prussian blue (PB) rather than Fe(CN)₆^3-. The electrocatalytic ability of the acid-pretreated MCF-IL-Fe(CN)₆^3-/PVA electrode offered a wide linear range for H₂O₂ detection. The present study on H₂O₂ electrochemical behavior on an MCF-IL-Fe(CN)₆^3-/PVA electrode might provide useful information for further developing integrated Fe(CN)₆^3--mediated biosensors as H₂O₂ is extensively involved in the classic reaction containing oxidase enzymes.

Comparison of Physical/Chemical Properties of Prussian Blue Thin Films Prepared by Different Pulse and DC Electrodeposition Methods

Prussian Blue (PB) thin films were prepared by DC chronoamperometry (CHA), symmetric pulse, and non-symmetric pulse electrodeposition techniques. The formation of PB was confirmed by infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX) and UV-Vis transmission measurements. X-ray diffraction (XRD) shows the stabilization of the insoluble form of PB. From scanning electron microscopy (SEM) studies, an increase in porosity is obtained for the shorter pulse widths, which tends to improve the total charge exchange and electrochemical stability of the films. While the film prepared by CHA suffered a degradation of 82% after 260 cycles, the degradation reduced to 24% and 34% for the samples prepared by the symmetric and non-symmetric pulse methods, respectively. Additionally, in the non-symmetric pulse film, the improvement in the charge exchange reached ~522% after 260 cycles. According to this study, the deposition time distribution affects the physical/chemical properties of PB films. These results then render pulse electrodeposition methods especially suitable to produce high-quality thin films for electrochemical devices, based on PB.

Size-Controllable Prussian Blue Nanoparticles Using Pluronic Series for Improved Antioxidant Activity and Anti-Inflammatory Efficacy

Prussian blue (PB) is a metal cluster nanoparticle (NP) of cyanide-bridged iron(II)-iron(III) and exhibits a characteristic blue color. Its peroxidase-, catalase-, and superoxide-dismutase-like activities effectively remove excess reactive oxygen species that induce inflammation and tumorigenesis. However, the dispersion of PB NPs is not sufficiently stable for their application in the biomedical field. In this study, we developed Pluronic-stabilized Prussian blue nanoparticles (PB/Plu NPs) using a series of Pluronic triblock copolymers as a template material for PB NPs. Considering the hydrophilic-lipophilic balance (HLB) values of the Pluronic series, including F68, F127, L35, P123, and L81, the diameters of the PB/Plu NPs decreased from 294 to 112 nm with decreasing HLB values. The smallest PB NP stabilized with Pluronic P123 (PB/PP123 NP) showed the strongest antioxidant and anti-inflammatory activities and wound-healing efficacy because of its large surface area. These results indicated that the spatial distribution of PB NPs in the micelles of Pluronic greatly improved the stability and reactive oxygen species scavenging activity of these NPs. Therefore, PB/Plu NPs using U.S.-FDA-approved Pluronic polymers show potential as biocompatible materials for various biomedical applications, including the treatment of inflammatory diseases in the clinic.

WITHDRAWN: Prussian blue nanozymes coated with pluronic attenuate inflammatory osteoarthritis by blocking c-Jun N-terminal kinase phosphorylation

This article has been withdrawn: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). This article has been withdrawn at the request of the editor and publisher. The publisher regrets that an error occurred which led to the premature publication of this paper. This error bears no reflection on the article or its authors. The publisher apologizes to the authors and the readers for this unfortunate error.

Reforming Magnet Waste to Prussian Blue for Sustainable Sodium-Ion Batteries

Increasing generation of permanent magnet waste has resulted in an urgent need to preserve finite resources. Reforming these wastes as feedstock to produce renewables is an ideal strategy for addressing waste and energy challenges. Herein, our work reports a smart and sustainable strategy to convert iron in magnet wastes into Prussian blue analogues that can serve as cathode materials for sodium-ion batteries. Moreover, a method to control feed rates is proposed to generate high-quality materials with fewer [Fe(CN)₆] vacancies at a feed rate of 3 mL min^-1. The recycled Na_1.46Fe[Fe(CN)₆]_0.85·□_0.15 shows low vacancies and excellent cycling stability over 300 cycles (89% capacity retention at 50 mA g^-1). In operando, evidence indicates that high-quality Prussian blue allows fast sodium-ion mobility and a high degree of reversibility over the course of cycling, although with a three-phase-transition mechanism. This study opens up a future direction for magnet waste created with the expectation of being environmentally reused.

Application of Prussian Blue in Electrochemical and Optical Sensing of Free Chlorine

In this paper, an electrochemical free chlorine (FCL) sensor was formed by modifying a fluorine-doped tin oxide-coated glass slide (glass|FTO) with a layer of Prussian blue (glass|FTO|PB). The glass|FTO|PB sensor exhibited a wide linear detection range from 1.7 to 99.2 μmol L^-1 of FCL with a sensitivity of ~0.8 µA cm^-2 μmol^-1 L and showed high selectivity for FCL. However, ClO3-, ClO4- and NO3- ions have induced only a negligible amperometric response that is highly beneficial for a real-life sample analysis as these ions are commonly found in chlorine-treated water. Moreover, in this work, optical absorption measurement-based investigations of partially reduced PB were carried out as a means to characterize PB catalytic activity towards FCL and to investigate the possibility of applying PB for the optical detection of FCL.

New carbon black-based conductive filaments for the additive manufacture of improved electrochemical sensors by fused deposition modeling

The development of a homemade carbon black composite filament with polylactic acid (CB-PLA) is reported. Optimized filaments containing 28.5% wt. of carbon black were obtained and employed in the 3D printing of improved electrochemical sensors by fused deposition modeling (FDM) technique. The fabricated filaments were used to construct a simple electrochemical system, which was explored for detecting catechol and hydroquinone in water samples and detecting hydrogen peroxide in milk. The determination of catechol and hydroquinone was successfully performed by differential pulse voltammetry, presenting LOD values of 0.02 and 0.22 µmol L-1, respectively, and recovery values ranging from 91.1 to 112% in tap water. Furthermore, the modification of CB-PLA electrodes with Prussian blue allowed the non-enzymatic amperometric detection of hydrogen peroxide at 0.0 V (vs. carbon black reference electrode) in milk samples, with a linear range between 5.0 and 350.0 mol L-1 and low limit of detection (1.03 µmol L-1). Thus, CB-PLA can be successfully applied as additively manufactured electrochemical sensors, and the easy filament manufacturing process allows for its exploration in a diversity of applications.

Prussian Blue Nanozyme Normalizes Microenvironment to Delay Osteoporosis

Osteoporosis (OP) is the most common orthopedic disease in the elderly and the main cause of age-related mortality and disability. However, no satisfactory intervention is currently available in clinical practice. Thus, an effective therapy to prevent or delay the development of OP should be devised. Osteoclastogenesis overactivation and excessive bone resorption are the main characteristics of OP. Accordingly, a paradigm for nanozyme-mediated normalization of the disease microenvironment to regulate osteoclast differentiation and delay OP is proposed. Hollow Prussian blue nanozymes (HPBZs) are prepared via template-free hydrothermal synthesis and selected as representative nanozymes. The intrinsic osteoclast activity-remodeling bioactivities of the HPBZs are explored in vitro and in vivo, focusing on their impact on osteogenesis and specific molecular mechanisms using an OP murine model. The HPBZs significantly normalize the OP microenvironment, thereby inhibiting osteoclast formation and osteoclast resorption, possibly owing to the suppression of intracellular reactive oxygen species generation, the mitogen-activated protein kinase, and nuclear factor κB signaling pathways. Consistently, in an ovariectomy-induced OP murine model, HPBZ treatment significantly attenuates osteoporotic bone loss in vivo. The findings confirm the HPBZ-mediated normalization of the disease microenvironment for the treatment of OP and suggest its application to other inflammation-related diseases.

Efficient removal of Cs(I) from water using a novel Prussian blue and graphene oxide modified PVDF membrane: Preparation, characterization, and mechanism

The Prussian blue (PB) blending membranes are promising candidates for the removal of trace radionuclide Cs⁺. Constructing a membrane with high flux and selectivity are challenging in its practical application. Here, a novel polyvinylidene fluoride (PVDF)-PB-graphene oxide (GO) modified membrane was fabricated via phase inversion for trace radionuclide cesium (¹³⁷Cs) removal from water. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to analyze chemical composition and morphology of the membrane, and the properties in terms of water flux and Cs⁺ removal were studied under different PB dosage, pH and co-existing ions conditions. It was observed that the addition of GO improved the dispersion of PB, and the PVDF-PB-GO membrane presented the highest Cs⁺ removal efficiency (99.6 %) and water flux (1638.2 LMH/bar) at pH = 7 with 0.1 wt% GO and 5 wt% PB. In addition, Langmuir and pseudo-second-order kinetics models fitted well for Cs⁺ adsorption by the PVDF-PB-GO membrane, illustrating that the Cs⁺ was removed via chemical adsorption dominated by Fe(CN)₆^4- defect sites of PB and the oxygen groups of GO. Furthermore, the membrane showed a significant selectivity and reusability towards trace radioactive cesium, even in the presence of excess co-existing ions and in real water, which strongly verified that the modified membrane had application potential.

Electrochemical determination of acetamiprid using PEDOT sensing coating functionalized with carbon quantum dots and Prussian blue nanoparticles

A dual-mode electrochemical biosensor for acetamiprid detection was proposed for the first time based on carbon quantum dots/Prussian blue (CQDs/PB)-functionalized poly(3,4-ethylenedioxythiphene) (PEDOT) nanocomposite. The nanocomposite with spherical stacking nanostructure showed high surface area, excellent catalytic ability, and cycling stability. The biosensor can be effortlessly constructed after the immobilization of acetamiprid aptamer. The concentration of acetamiprid can be determined by differential pulse voltammetry (DPV) based on its signal change deduced from the pristine PB. With the capture of acetamiprid, the response current (I-T) signal generated by hydrogen peroxide catalysis from the biosensor can also been used to establish the method for monitoring acetamiprid. The dual-mode biosensor showed a wide linear range from 10^-12 g mL^-1 to 10^-6 g mL^-1, low detection limits of 6.84 × 10^-13 g mL^-1 and 4.99 × 10^-13 g mL^-1, and ultrafast detection time of 25 s and 5 s through DPV and I-T mode, respectively. The biosensor possessed excellent selectivity and stability. More importantly, the biosensor was successfully applied to detect acetamiprid residues in vegetables, proving a promising approach for routine detection of pesticide in real samples. The biosensor based on PEDOT/CQDs/PB for acetamiprid can be effortlessly constructed through both the increase of differential pulse voltammetry (DPV) signal change deduced by the pristine PB and the decrease of the response current (I-T) signal of the reduction of hydrogen peroxide catalyzed by PEDOT/CQDs/PB.

Incorporating Near-Pseudocapacitance Insertion Ni/Co-Based Hexacyanoferrate and Low-Cost Metallic Zn for Aqueous K-Ion Batteries

The limited availability of cathode materials with high specific capacity and significant cycling stability for aqueous K-ion batteries (AKIBs) hinder their further development owing to the large radius of K⁺ (1.38 Å). Prussian blue and its analogs with a three-dimensional frame structure possessing special energy storage mechanism are promising candidates as cathode materials for AKIBs. In this study, K_0.2 Ni_0.68 Co_0.77 Fe(CN)₆  ⋅ 1.8H₂ O (KNCHCF) was prepared as a cathode material for AKIBs. Both the electrochemical activity of Co ions and the near-pseudocapacitance intercalation of KNCHCF enhance K⁺ storage. Therefore, KNCHCF exhibits a superior capacity maintenance rate of 86 % after 1000 cycles at a high current density of 3.0 A g^-1 . The storage mechanism of K⁺ in AKIBs was revealed through ex situ X-ray diffraction, ex situ Fourier transform infrared spectroscopy, and ex situ X-ray photoelectron spectroscopy measurements. Moreover, the assembled K-Zn hybrid battery showed good cycling stability with 93.1 % capacity maintenance at 0.1 A g^-1 after 50 cycles and a high energy density of 96.81 W h kg^-1 . Hence, KNCHCF may be a potential material for the development of AKIBs.

Preparation of a pH-responsive controlled-release electrochemical immunosensor based on polydopamine encapsulation for ultrasensitive detection of alpha-fetoprotein

To accomplish ultra-sensitive detection of alpha-fetoprotein(AFP), a novel electrochemical immunosensor using polydopamine-coated Fe₃O₄ nanoparticles (PDA@Fe₃O₄ NPs) as a smart label and polyaniline (PANI) and Au NPs as substrate materials has been created. The sensor has the following advantages over typical immunoassay technology: (1) The pH reaction causes PDA@Fe₃O₄ NPs to release Prussian blue (PB) prosoma while also destroying the secondary antibody label and immunological platform and lowering electrode impedance; (2) PB has a highly efficient catalytic effect on H₂O₂, allowing for the obvious amplification of electrical impulses; (3) PANI was electrodeposited on the electrode surface to avoid PB loss and signal leakage, which effectively absorbed and fixed PB while considerably increasing electron transmission efficiency. The sensor's detection limit was 0.254 pg·mL^-1 (S/N = 3), with a detection range of 1 pg·mL^-1 to 100 ng·mL^-1. The sensor has a high level of selectivity, repeatability, and stability, and it is predicted to be utilized to detect AFP in real-world samples.

Blood-brain barrier Permeable nanoparticles for Alzheimer's disease treatment by selective mitophagy of microglia

Current treatments for Alzheimer's disease (AD) that focus on inhibition of Aβ aggregation failed to show effectiveness in people who already had Alzheimer's symptoms. Strategies that synergistically exert neuroprotection and alleviation of oxidative stress could be a promising approach to correct the pathological brain microenvironment. Based on the key roles of microglia in modulation of AD microenvironment, we describe here the development of Prussian blue/polyamidoamine (PAMAM) dendrimer/Angiopep-2 (PPA) nanoparticles that can regulate the mitophagy of microglia as a potential AD treatment. PPA nanoparticles exhibit superior blood-brain barrier (BBB) permeability and exert synergistic effects of ROS scavenging and restoration of mitochondrial function of microglia. PPA nanoparticles effectively reduce neurotoxic Aβ aggregate and rescue the cognitive functions in APP/PS1 model mice. Together, our data suggest that these multifunctional dendrimer nanoparticles exhibit efficient neuroprotection and microglia modulation and can be exploited as a promising approach for the treatment of AD.

An Endogenous H2S-Activated Nanoplatform for Triple Synergistic Therapy of Colorectal Cancer

Overproduced hydrogen sulfide (H₂S) is a highly potential target for precise colorectal cancer (CRC) therapy; herein, a novel 5-Fu/Cur-P@HMPB nanomedicine is developed by coencapsulation of the natural anticancer drug curcumin (Cur) and the clinical chemotherapeutic drug 5-fluorouracil (5-Fu) into hollow mesoporous Prussian blue (HMPB). HMPB with low Fenton-catalytic activity can react with endogenous H₂S and convert into high Fenton-catalytic Prussian white (PW), which can generate in situ a high level of ^•OH to activate chemodynamic therapy (CDT) and meanwhile trigger autophagy. Importantly, the autophagy can be amplified by Cur to induce autophagic cell death; moreover, Cur also acted as a specific chemosensitizer of the chemotherapy drug 5-Fu, achieving a good synergistic antitumor effect. Such a triple synergistic therapy based on a novel nanomedicine has been verified both in vitro and in vivo to have high efficacy in CRC treatment, showing promising potential in translational medicine.

A Redox-Probe-Free Immunosensor Based on Electrocatalytic Prussian Blue Nanostructured Film One-Step-Prepared for Zika Virus Diagnosis

The Zika virus (ZIKV) is a great concern for global health due to its high transmission, including disseminating through blood, saliva, urine, semen and vertical transmission. In some cases, ZIKV has been associated with microcephaly, neurological disorders, and Guillain−Barré syndrome. There is no vaccine, and controlling the disease is a challenge, especially with the co-circulation of the Dengue virus, which causes a severe cross-reaction due to the similarity between the two arboviruses. Considering that electrochemical immunosensors are well-established, sensitive, and practical tools for diagnosis, in this study we developed a sensor platform with intrinsic redox activity that facilitates measurement readouts. Prussian blue (PB) has a great ability to form electrocatalytic surfaces, dispensing redox probe solutions in voltammetric measurements. Herein, PB was incorporated into a chitosan−carbon nanotube hybrid, forming a nanocomposite that was drop-casted on a screen-printed electrode (SPE). The immunosensor detected the envelope protein of ZIKV in a linear range of 0.25 to 1.75 µg/mL (n = 8, p < 0.01), with a 0.20 µg/mL limit of detection. The developed immunosensor represents a new method for electrochemical measurements without additional redox probe solutions, and it is feasible for application in point-of-care diagnosis.

Reactive oxygen species scavenging nanofibers with chitosan-stabilized Prussian blue nanoparticles for enhanced wound healing efficacy

Chronic inflammatory wounds pose therapeutic challenges in the biomedical field. Polymeric nanofibrous matrices provide extracellular-matrix-like structures to facilitate wound healing; however, wound infection and the subsequent accumulation of reactive oxygen species (ROS) delay healing. Therefore, we herein developed electrospun nanofibers (NFs), composed of chitosan-stabilized Prussian blue (PBChi) nanoparticles (NPs) and poly(vinyl alcohol) (PVA), with ROS scavenging activity to impart antioxidant and wound healing properties. The PBChi NPs were prepared using chitosan with different molecular weights, and their weight ratio with respect to PVA was optimized to yield PBChi-NP-coated PVA NFs with well-defined NF structures. In situ and in vitro antioxidant activity assays showed that the PBChi/PVA NFs could effectively remove ROS. Particularly, PBChi/PVA NFs with a lower chitosan molecular weight exhibited greater antioxidant activity. The hydroxyl radical scavenging activity of PBChi10k/PVA NFs was 60.4 %, approximately two-fold higher than that of PBChi100k/PVA NFs. Further, at the concentration of 10 μg/mL, they could significantly lower the in vitro ROS level by up to 50.7 %. The NFs caused no significant reduction in cell viability, owing to the excellent biocompatibility of PVA with PBChi NPs. Treatment using PBChi/PVA NFs led to faster cell proliferation in in vitro scratch wounds, reducing their size from 202 to 162 μm. The PBChi/PVA NFs possess notable antioxidant and cell proliferation properties as ROS-scavenging wound dressings.

Biodegradable Hollow-Structured Nanozymes Modulate Phenotypic Polarization of Macrophages and Relieve Hypoxia for Treatment of Osteoarthritis

Nanozymes are widely applied for treating various major diseases, including neurological diseases and tumors. However, the biodegradability of nanozymes remains a great challenge, which hinders their further clinical translation. Based on the microenvironment of osteoarthritis (OA), a representative pH-responsive biodegradable hollow-structured manganese Prussian blue nanozyme (HMPBzyme) is designed and applied for treatment of OA. HMPBzyme with good pH-responsive biodegradability, biocompatibility, and multi-enzyme activities is constructed by bovine serum albumin bubbles as a template-mediated biomineralization strategy. HMPBzyme suppresses hypoxia-inducible factor-1α (HIF-1α) expression and decreases reactive oxygen species (ROS) level in the in vitro experiment. Furthermore, HMPBzyme markedly suppresses the expression of ROS and alleviates the degeneration of cartilage in OA rat models. The results indicate that the biodegradable HMPBzyme inhibits oxidative damage and relieves hypoxia synergistically to suppress inflammation and promote the anabolism of cartilage extracellular matrix by protecting mitochondrial function and down-regulating the expression of HIF-1α, which modulates the phenotypic conversion of macrophages from pro-inflammatory M1 subtype to anti-inflammatory M2 subtype for OA treatment. This research lays a solid foundation for the design, construction, and biomedical application of biodegradable nanozymes and promotes the application of nanozymes in biomedicine.

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.