Controllable synthesis of rare earth (Gd3+,Tm3+) doped Prussian blue for multimode imaging guided synergistic treatment.

Gd3+ and Tm3+ doped Prussian blue (Gd/Tm-PB) with high uniformity and dispersibility was synthesized by a facile solvothermal method. The conditions for the synthesis of Gd/Tm-PB were explored. Through the regulation of the ratio of Gd3+/Tm3+, the Gd/Tm-PB particles with the optimal size (about 150-200 nm) and the best fluorescence and photothermal effect were obtained. On the basis of the optimal Gd/Tm-PB, further coated by polydopamine (PDA) functionalized metal-organic frameworks (MOFs), a multifunctional platform Gd/Tm-PB@ZIF-8/PDA for cancer diagnosis and treatment was established. Doxorubicin (DOX) was selected as a drug model and the drug loading of Gd/Tm-PB@ZIF-8/PDA was found to be 81 mg g-1. Cytotoxicity analysis indicated that Gd/Tm-PB@ZIF-8/PDA was highly biocompatible. The DOX release at different pH values and GSH concentrations revealed an excellent pH/GSH-triggered drug release. Through the combination of the near infrared photothermal performance of Gd/Tm-PB, chemo-photothermal therapy can be achieved to further improve the anti-cancer efficiency. In addition, the Gd/Tm-PB@ZIF-8/PDA nanoparticles can be tracked by fluorescence imaging (FOI) and magnetic resonance imaging (MRI). Cell FOI and in vivo MRI experiments showed the potential application of Gd/Tm-PB@ZIF-8/PDA in dual mode imaging guided therapy. In vivo antitumor experiments demonstrated the higher anticancer efficacy of Gd/Tm-PB@ZIF-8/PDA with a combined effect of chemo-photothermal therapy. This work provides a new strategy for nano-drug carriers in the direction of integrated diagnosis and treatment.

An optical sensing platform based on hexacyanoferrate intercalated layered double hydroxide nanozyme for determination of chromium in water.

In this work, hexacyanoferrate intercalated Ni/Al LDH (Ni/Al-Fe(CN)6 LDH) nanozyme was synthesized by one-pot co-precipitation method and used for determination of chromium in water samples by employing its peroxidase mimicking activity. The synthesized nanozyme can effectively catalyze the oxidation of fluorometric peroxidase substrate terephthalic acid by H2O2 to produce a highly fluorescent product. It was found that Cr(VI) promotes the peroxidase-like activity of Ni/Al-Fe(CN)6 LDH and this effect was intensified by increasing the Cr(VI) concentration. Several variables affecting the fluorescence intensity including the concentration of nanoparticles and reagents as well as reaction time were investigated and optimized. Under the optimal conditions, good linearity was observed in the range of 0.067-10 µM Cr(VI), and limit of detection and quantification were found to be 0.039 and 0.131 µM, respectively. Furthermore, the developed method showed good applicability for the determination of total Cr based on the oxidation of Cr (III) to Cr (VI). The applicability of the proposed method was demonstrated by analyzing various environmental water samples. The presented nanozyme displayed superior benefits in terms of reusability, repeatability, cost and environment-friendly features. The present work aims to expand LDHs based enzyme mimics to optical sensor fields.

A facile biosensor for Aß40O based on fluorescence quenching of prussian blue nanoparticles.

Amyloid ß peptide oligomeFrs (AßOs) have been proved to be crucial biomarkers of Alzheimer's disease (AD). To explore an applicable method for the determination of AßOs is significant for the early AD diagnosis. Prussian blue nanoparticles (PBNPs), as one excellent nanomaterials, have the advantages of good stability, favorable biocompatibility, low cost, easy preparation and controllable shape. PBNPs was found to be of the fluorescence quenching ability to fluorophores, and the adsorption of DNA onto PBNPs surface occurred via the binding of phosphate skeleton in DNA to Fe2+/Fe3+ in PBNPs. On basis of this, carboxyl fluorescein (FAM) modified Aß40O-targeting aptamer (FAM-AptAß) was adsorbed onto PBNPs. And FAM-AptAß@PBNPs-based fluorescent aptasensor for the determination of Aß40O was developed. Upon incubating FAM-AptAß@PBNPs with Aß40O, the fluorescence intensity of the FAM-AptAß@PBNPs obviously increased comparing to the initial fluorescence intensity of the FAM-AptAß@PBNPs. The changes in the fluorescence intensity of the FAM-AptAß@PBNPs were linear with the Aß40O concentrations ranging from 1.00 nM to 100 nM. Moreover, AD patients and healthy persons can be distinguished using this method to determine Aß40O concentrations in human cerebrospinal fluid samples from AD patients and healthy persons. It demonstrates that this PBNPs-based aptasensor is not only simple and cost-effective, but also sensitive, selective and more applicable. This fluorescent sensing strategy is promising for the development of aptasensor in clinical fields.

Current Innovations of Metal Hexacyanoferrates-Based Nanocomposites toward Electrochemical Sensing: Materials Selection and Synthesis Methods.

Mixed valence transition metal hexacyanoferrates (MeHCF)-Prussian blue and its analogs receive enormous research interest in the electrochemical sensing field. In recent years, conducting materials such as conducting polymer, carbon nanomaterial, and noble metals have been used to form nanocomposites with MeHCF. The scope of this review offers the reasons behind the preparation of various MeHCF based nanocomposite toward electrochemical detection. We primarily focus on the current progress of the development of MEHCF-based nanocomposites. The synthesis methods for these nanocomposites are also reviewed and discussed.

A sensitive and selective electrochemical sensor based on N, P-Doped molybdenum Carbide@Carbon/Prussian blue/graphite felt composite electrode for the detection of dopamine.

In this paper, a composite electrode of N,P-doped Mo2C@C/Prussian blue (PB)/graphite felt (N,P-Mo2C@C/PB/GF) was prepared by a simple method and used for sensitive and effective detection of dopamine (DA). N,P-doped Mo2C nanospheres were prepared by using phosphomolybdic acid (PMo12) as an initiator to promote the polymerization of polypyrrole. Such nanospheres were used to accelerate the deposition process of PB from K3[Fe(CN)6] and FeCl3 in solution. The N,P-Mo2C@C/PB nanohybrid was then anchored to GF in order to obtain the electrochemical sensor. Two linear ranges were extrapolated for dopamine detection: from 0.18 to 30 µmol L-1 with a sensitivity of 0.268 µA µmol-1, and from 30 to 280 µmol L-1 with a sensitivity of 0.045 µA µmol-1. The device showed a detection limit as low as 0.011 µmol L-1, an excellent selectivity to DA over common interfering analytes, and a favorable long-time stability. Finally, the sensor was used for quantitative analysis of DA in the 10-fold dilution of human serum (10%) and exhibited a satisfactory recovery.

An in situ microenvironmental nano-regulator to inhibit the proliferation and metastasis of 4T1 tumor.

Tumor microenvironment, such as hypoxia and presence of immune cells, plays a critical role in cancer initiation, growth as well as progression, and seriously affects antitumor effect. Accordingly, we constructed a kind of multifunctional nanoparticles (NPs) with macrophage transformation and oxygen (O2) generation characteristics, to regulate the tumor microenvironment. Methods: In this study, we synthesized mesoporous Prussian blue (MPB) NPs with low molecular weight hyaluronic acid (LMWHA) surface modification (LMWHA-MPB), and discovered that LMWHA-MPB could be used as an in situ macrophages converter and O2 generator. Results:In vitro results showed after uptake by M2 macrophages, LMWHA-MPB displayed the potential in remodeling tumor-associated macrophages (TAMs) phenotype (pro-tumor M2→anti-tumor M1), and anti-metastatic effect on 4T1 cells. Furthermore, in vivo visualized near-infrared (NIR) imaging data proved IR783 labeled LMWHA-MPB NPs could selectively accumulate in tumor sites. Then plenty of O2 generated to alleviate tumor hypoxia via catalytic decomposition of endogenous hydrogen peroxide (H2O2). Based on these outstanding characteristics, LMWHA-MPB NPs were adopted as multifunctional nanocarriers to load sonosensitizer hematoporphyrin monomethyl ether (HMME) for O2 self-provided sonodynamic therapy (SDT). In vivo anti-tumor results showed LMWHA-MPB/HMME could effectively inhibit the proliferation and metastasis of 4T1 tumors by improving tumor microenvironment. Conclusion: The multifunctional NPs can be used as in situ microenvironmental nano-regulators to inhibit the proliferation and metastasis of 4T1 tumor.

Facile synthesis of copper ferrocyanide-embedded magnetic hydrogel beads for the enhanced removal of cesium from water.

A simple one-step approach for fabricating copper ferrocyanide-embedded magnetic hydrogel beads (CuFC-MHBs) was designed, and the beads were applied to the effective removal of cesium (Cs) and then magnetically separated from water. The polyvinyl alcohol (PVA)-coated CuFC (PVA-CuFC) was first synthesized using PVA as a stabilizer and subsequently embedded in magnetic hydrogel beads made of a cross-linked network between the PVA and magnetic iron oxide nanoparticles that was prepared through the simple dropwise addition of a mixed solution of PVA-CuFC, PVA and iron salt into an ammonium hydroxide solution. The synthesis and chemical immobilization of the PVA-CuFC in the magnetic beads were simple, facile and achieved in one pot, and the process is scalable and convenient for the large-scale treatment of Cs-contaminated water. The resulting CuFC-MHBs showed effective Cs removal performance with a high Kd value of 66,780 mL/g and excellent structural stability without the release of CuFC for at least 1 month and could be effectively separated from water by an external magnet. Moreover, the CuFC-MHBs selectively adsorbed Cs with high Kd values in the presence of various competing ions, such as in simulated groundwater (24,500 mL/g) and seawater (8290 mL/g), and maintained their Cs absorption ability in a wide pH range from 3 to 11. The convenient fabrication method and effective removal of Cs from various aqueous media demonstrated that the CuFC-MHBs have great potential for practical application in the decontamination of Cs-contaminated water sources caused by nuclear accidents and radioactive liquid waste in various nuclear industry fields.

Progress in Applications of Prussian Blue Nanoparticles in Biomedicine.

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

Paper-based synthesis of Prussian Blue Nanoparticles for the development of whole blood glucose electrochemical biosensor.

Nowadays, environmentally friendly synthesis pathways for preserving the environment and minimizing waste are strongly required. Herein, we propose filter paper as a convenient scaffold for chemical reactions. To demonstrate this novel approach, Prussian Blue Nanoparticles (PBNPs) were synthesized on filter paper by utilizing few µL of its precursors without external inputs, i.e. pH, voltage, reducing agents, and without producing waste as well. The functional paper, named "Paper Blue", is successfully applied in the sensing field, exploiting the reduction of hydrogen peroxide at low applied potential. The eco-designed "Paper Blue" was combined with wax- and screen-printing to manufacture a reagentless electrochemical point-of-care device for diabetes self-monitoring, by using glucose oxidase as the biological recognition element. Blood glucose was linearly detected for a wide concentration range up to 25 mM (450 mg/dL), demonstrating its suitability for management of diabetes and glucose-related diseases. The Paper Blue-based biosensor demonstrated a correlation coefficient of 0.987 with commercial glucose strips (Bayer Contour XT). The achieved results demonstrated the effectiveness of this approach, which is also extendible to other (bio)systems to be applied in catalysis, remediation, and diagnostics.

Graphene oxide directed in-situ synthesis of Prussian blue for non-enzymatic sensing of hydrogen peroxide released from macrophages.

A novel electrochemical non-enzymatic hydrogen peroxide (H2O2) sensor has been developed based on Prussian blue (PB) and electrochemically reduced graphene oxide (ERGO). The GO was covalently modified on glassy carbon electrode (GCE), and utilized as a directing platform for in-situ synthesis of electroactive PB. Then the GO was electrochemically treated to reduction form to improve the effective surface area and electroactivity of the sensing interface. The fabrication process was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). The results showed that the rich oxygen containing groups play a crucial role for the successful synthesis of PB, and the obtained PB layer on the covalently immobilized GO has good stability. Electrochemical sensing assay showed that the modified electrode had tremendous electrocatalytic property for the reduction of H2O2. The steady-state current response increased linearly with H2O2 concentrations from 5µM to 1mM with a fast response time (less than 3s). The detection limit was estimated to be 0.8µM. When the sensor was applied for determination of H2O2 released from living cells of macrophages, satisfactory results were achieved.

Facile Synthesis of Prussian Blue Derivate-Modified Mesoporous Material via Photoinitiated Thiol-Ene Click Reaction for Cesium Adsorption.

A novel strategy to synthesize a functional mesoporous material for efficient removal of cesium is reported. Specifically, Prussian blue derivate-modified SBA-15 (SBA-15@FC) was prepared by photoinitiated thiol-ene reaction between thiol-modified SBA-15 and pentacyano(4-vinyl pyridine)ferrate complex. The effects of weight percentage of the Prussian blue derivate, pH, adsorbent dose, co-existing ions, and initial concentration were evaluated on the adsorption of cesium ions. The adsorption kinetically follows a pseudo-second-order model and reaches equilibrium within 2 h with a high adsorption capacity of about 13.90 mg Cs g(-1) , which indicates that SBA-15@FC is a promising adsorbent to effectively remove cesium from aqueous solutions.

Hierarchically superstructured prussian blue analogues: spontaneous assembly synthesis and applications as pseudocapacitive materials.

Hierarchically superstructured Prussian blue analogues (hexacyanoferrate, M=Ni(II) , Co(II) and Cu(II) ) are synthesized through a spontaneous assembly technique. In sharp contrast to macroporous-only Prussian blue analogues, the hierarchically superstructured porous Prussian blue materials are demonstrated to possess a high capacitance, which is similar to those of the conventional hybrid graphene/MnO2 nanostructured textiles. Because sodium or potassium ions are involved in energy storage processes, more environmentally neutral electrolytes can be utilized, making the superstructured porous Prussian blue analogues a great contender for applications as high-performance pseudocapacitors.

Evaluation of silica/ferrocyanide composite as a dual-function material for simultaneous removal of ¹³7Cs⁺ and 99TcO4⁻ from aqueous solutions.

A novel mesoporous silica-coated ferrocyanide (MSCFC) composite was successfully synthesized and evaluated as a dual-function material for simultaneous removal of (137)Cs(+) cations and (99)TcO4(-) anions from aqueous solutions. Sorption behavior of both radionuclides on MSCFC under different experimental conditions has been studied using a batch technique. Results revealed that about 100% of (137)Cs(+) and 97% of (99)TcO4(-) were removed by MSCFC in the pH ranges of 2.2-12.4 and 4.1-9.5, respectively. Sorption kinetic data were analyzed by pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models, while Langmuir and Freundlich models were applied for the sorption isotherms. The maximum sorption capacity of MSCFC for radiocesium was determined and compared with other reported sorbents. Applicability of the coated ferrocyanide for simultaneous removal of (137)Cs(+) and (99)TcO4(-) from low-level liquid radioactive waste (LLLW) was also tested, and the data revealed that 99.91% and 98.34% were removed from (137)Cs(+) and (99)TcO4(-), respectively. It is concluded that MSCFC exhibits excellent efficiency for simultaneous removal of the mixed radionuclides with different charge from LLLW.

Gallium analogue of soluble Prussian blue KGa[Fe(CN)6]·nH2O: synthesis, characterization, and potential biomedical applications.

The gallium analogue of the soluble Prussian blue with the formula KGa[Fe(CN)6]·nH2O is synthesized and structurally characterized. A simple aqueous synthetic procedure for preparing nanoparticles of this novel coordination polymer is reported. The stability, in vitro ion exchange with ferrous ions, cytotoxicity, and cellular uptake of such nanoparticles coated with poly(vinylpyrrolidone) are investigated for potential applications of delivering Ga(3+) ions into cells or removing iron from cells.

Visible spectrophotometric method for amiodarone.

Amiodarone is an antiarrhythmic agent used for various types of tachyarrhythmia, both ventricular and supraventricular (atrial) arrhythmia. A spectrophotometric method for the assay of amiodarone was established. Based on the reduction of potassium ferricyanide in hydrochloric acid medium to potassium ferrocyanide forming a blue colored complex ferric ferrocyanide with Fe (III) ions. The compound was most stable in a mixture of ethylic alcohol and water (2:1, v/v) and it had an absorption maximum at 725 nm. The data were according to the Lambert-Beer Law in the concentration range of 0.5-5.0 microg/sample: correlation and coefficient R = 0.99977, R2 = 0.999541, slope of the line 0.12775, intercept 0.042077. The detection limit (DL) was 0.1032 microg/sample and the quantification limit (QL) 0.344 microg/ sample.

Interface synthesis, assembly and characterization of close-packed monolayer of prussian blue/polypyrrole nanocomposites.

The self-assembly of nanomaterials into ordered two- or three-dimensional structures has been extensively explored over the past years due to the great application potential. This paper reports a simple one-step methodology for the synthesis and assembly of Prussian blue/polypyrrole (PBPPy) nanocomposites into close-packed monolayer at a toluene-water interface where the formation of PBPPy and evaporation of organic phase happen simultaneously. The formed films could be easily transferred onto the glass carbon surface by layer-by-layer technique. The obtained PBPPy nanocomposites and their assembled film were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, UV-vis spectroscopy and cyclic voltammetry. The PBPPy nanocomposite film on the electrode surface exhibits excellent electron transfer and high electrocatalysis toward the reduction of H2O2. Herein, PPy component in PBPPy nanocomposites plays a great role in this great electrochemical performance. On the one hand, the presence of PPy is helpful of the formation of close-packed monolayer of PBPPy nanocomposites, and the adhesion of the ordered monolayer or multilayer onto the electrode surface due to the molecular interaction of PPy or the surface group of electrode. On the other hand, the conductive PPy facilitates the electron transfer between PB and PB or PB and electrode. The suggested method can be extended to a wide range of nanomaterials assembly and devise development.

Reversible synthesis of sub-10†nm spherical and icosahedral gold nanoparticles from a covalent Au(CN)2(-) precursor and recycling of cyanide to form ferric ferrocyanide for cell staining.

A solution approach based on Au(CN)(2)(-) chemistry is reported for the formation of nanoparticles. The covalent character of the Au(CN)(2)(-) precursor was exploited in the formation of sub-10 nm nanospheres (≈2.4 nm) and highly monodisperse icosahedral Au nanoparticles (≈8 nm) at room temperature in a one-pot aqueous synthesis. The respective spherical and icosahedral Au morphologies can be controlled by either the absence or presence of the polymer polyvinylpyrrolidone (PVP). Using Au(CN)(2)(-) as a metal ion source, our findings suggest that the addition of citrate ions is necessary to enhance the particle formation rate as well as to generate a more homogeneous colloidal dispersion. Because of the presence of oxygen and the operation of a CN(-) etching process associated with Au(CN)(2)(-) complex formation, an interesting reversible formation-dissolution process was observed, which allowed us to repeatedly prepare spherical and icosahedral Au nanoparticles. Time-dependent TEM images and UV/Vis spectra were carefully acquired to study the reversibility of this formation-dissolution process. In view of the accompanying generation of toxic cyanide anions, we have developed a protocol to recycle cyanide in the presence of citrate ions through ferric ferrocyanide formation. After completion of particle formation, the residual solutions containing citrate ions and cyanide ions were processed to stain iron oxide nanoparticles endocytosized in cells. Additionally, the as-prepared 8 nm Au icosahedra could be isolated and grown to larger 57 nm-sized icosahedra using the seed-mediated growth approach.

An electrocatalytic transducer for L-cysteine detection based on cobalt hexacyanoferrate nanoparticles with a core-shell structure.

The electrocatalytic oxidation of L-cysteine (CySH) was studied on cobalt hexacyanoferrate nanoparticles with a core-shell structure (iron(III) oxide core-cobalt hexacyanoferrate shell) using cyclic voltammetry and chronoamperometry. Voltammetric studies represented two quasi-reversible redox transitions for the nanoparticles in phosphate buffer solution (pH 7.4). In the presence of CySH, the anodic peak current of the Fe(II)/Fe(III) transition was increased, followed by a decrease in the corresponding cathodic peak current, whereas the peak currents related to the Co(II)/Co(III) transition almost remained unchanged. The results indicated that the nanoparticles oxidized CySH via a surface mediation electrocatalytic mechanism. The catalytic rate constant, the electron transfer coefficient, and the diffusion coefficient involved in the electrooxidation process of CySH are reported here. Ultrasensitive and time-saving determination procedures were developed for the analysis of the CySH, and the corresponding analytical parameters are reported. According to the proposed methods, CySH was determined with detection limits of 40 and 20 nm in batch and flow systems, respectively. The proposed amperometric method was also applied to the analysis of CySH in human urine and serum blood samples.

Tunable synthesis of Prussian Blue in exponentially growing polyelectrolyte multilayer films.

Polyelectrolyte multilayer (PEM) films have become very popular for surface functionalization and the design of functional architectures such as hollow polyelectrolyte capsules. It is known that properties such as permeability to small ionic solutes are strongly dependent on the buildup regime of the PEM films. This permeability can be modified by tuning the ionization degree of the polycations or polyanions, provided the film is made from weak polyelectrolytes. In most previous investigations, this was achieved by playing on the solution pH either during the film buildup or by a postbuildup pH modification. Herein we investigate the functionalization of poly(allylamine hydrochloride)/poly(glutamic acid) (PAH/PGA) multilayers by ferrocyanide and Prussian Blue (PB). We demonstrate that dynamic exchange processes between the film and polyelectrolyte solutions containing one of the component polyelectrolyte allow one to modify its Donnan potential and, as a consequence, the amount of ferrocyanide anions able to be retained in the PAH/PGA film. This ability of the film to be a tunable reservoir of ferrocyanide anions is then used to produce a composite film containing PB particles obtained by a single precipitation reaction with a solution containing Fe(3+) cations in contact with the film. The presence of PB in the PEM films then provides magnetic as well as electrochemical properties to the whole architecture.