Search Results (16)

Electrochemical enzyme biosensors are extensively utilized in clinical analysis and environmental monitoring, yet achieving effective enzyme immobilization while maintaining high activity remains a challenge. In this work, we developed a flow-through enzyme biosensor system using a 3D-printed flow-through electrochemical cell fabricated from commercially available poly (lactic acid). After modification with thiacalixarene-functionalized oligo (lactic acids) (OLAs), the material enabled efficient immobilization of uricase on the inner surface of a replaceable reactor of the cell. Swelling and hydrolytic stability of OLAs in cone, partial cone, and 1,3-alternate conformations were studied, with 1,3-alernate conformation demonstrating superior stability and enzyme immobilization performance. The use of OLAs enhanced immobilization efficiency by over 30% and protected the reactor from swelling, hydrolytic degradation, and enzyme loss. The biosensor was validated for amperometric uric acid determination, with a screen-printed carbon electrode modified with carbon black and Prussian Blue. This modification reduced the cathodic potential for uric acid detection to –0.05 V. The biosensor exhibited a linear detection range of 10 nM to 30 μM with a detection limit of 7 nM, and it performed effectively in artificial urine and synthetic blood plasma. The novel cell design, featuring easy assembly and low-cost replaceable parts, makes this biosensor a promising candidate for routine clinical analysis and other practical applications. Full article

Microbial fuel cell (MFC) can degrade pesticide wastewater and recovery energy simultaneously, and the activated carbon (AC) air cathode has great prospects for practical application. However, insufficient active sites and the limitation of multi-step electron transfer for oxygen reduction reaction (ORR) requires that AC should be modified by highly efficient electrocatalysts. Herein, busing the confinement effect of carbon-encapsulated metal and hollow carbon, we designed a unique ORR catalyst of Fe-Fe₃O₄-NC through utilizing the 2D leaf-like nanoplates of Zn-ZIF-L to load Prussian blue (PB) particles. The volatilization of low-boiled Zn and the catalysis of iron compounds led to the formation of confined walls of hollow carbon shell and carbon-encapsulated Fe/Fe₃O₄ particles on N-doped carbon substrate. Multivalent iron, a large surface area (368.11 m²·g⁻¹), N doping, a heterojunction interface, and the confinement effect provided all the Fe-Fe₃O₄-NC-modified AC air cathodes with excellent ORR activity. The optimal samples of AC-Fe-Fe₃O₄-NC-3 achieved a peak power density of 1213.8 mW·m⁻², demonstrating a substantial 82.8% increase over that of the bare AC. Furthermore, its efficiency in glyphosate removal reached 80.1%, surpassing the 23.2% of the bare AC. This study offers new ideas in constructing composite confined structures and the as-designed Fe-Fe₃O₄-NC is a promising modification candidate for the commercial adoption of AC air cathodes. Full article

Prussian blue analogues (PBAs) have recently emerged as effective materials in different functional applications, ranging from energy storage to electrochemical water splitting, thence to more “traditional” heterogeneous catalysis. Their versatility is due to their open framework, compositional variety, and fast and efficient internal charge exchange, coupled with a self-healing ability that makes them unique. This review paper presents and discusses the findings of the last decade in the field of the catalytic and photocatalytic application of PBAs in water remediation (via the degradation of organic pollutants and heavy metal removal) and the catalytic oxidation of organics and production or organic intermediates for industrial synthesis. Analysis of the catalytic processes is approached from a critical perspective, highlighting both the achievements of the research community and the limits still affecting this field. Full article

Recycling and revalorization of waste are currently essential for sustainable growth. Mill scale, a waste product from steel production industries, which contains high levels of iron and minimal impurities, is proposed in this study as the source to synthesize magnetite nanoparticles (Fe₃O₄) for an enhancement of a lactate biosensor range. The synthesized Fe₃O₄ nanoparticles were coated with polydopamine (PDA) to prevent aggregation and degradation, creating a stable platform for immobilizing lactate oxidase enzyme (LOx) on their surfaces. The characterization of the Fe₃O₄@PDA material was carried out using transmission electron microscopy (TEM), dynamic light scattering (DLS), and measurement of the polydispersity index (PdI). The Fe₃O₄@PDA-LOx material was then deposited on a screen-printed carbon electrode modified with Prussian blue (SPCE-PB) for lactate detection. The biosensor exhibited a broad, dual linear concentration-response range, one from 0.1 to 4.62 mM with a limit of detection of 0.32 mM and sensitivity of 1.54 $\mathsf{\mu }\mathrm{A}{\mathrm{m}\mathrm{M}}^{-1}{\mathrm{c}\mathrm{m}}^{-2}$, and another one from 4.62 to 149.21 mM with a limit of detection of 6.31 mM and sensitivity of 0.08 $\mathsf{\mu }\mathrm{A}{\mathrm{m}\mathrm{M}}^{-1}{\mathrm{c}\mathrm{m}}^{-2}$. The dual-range concentration response of the biosensor makes it an ideal tool for lactate determination in various applications, including sports medicine, clinical diagnosis, and industrial bioprocessing. Full article

We studied the painted decorations found during recent restoration work in the Alexander Palace in Tsarskoye Selo. Optical/laser spectroscopic methods were applied to obtain a characterization of the materials, pigments, and binders in use and, possibly, their degradation. We analyzed samples of the original Art Nouveau style decoration that was detached in 2019 during conservation work at the State Office of Emperor Nicholas II. A combination of Raman microscopy, infrared spectroscopy, and elemental analysis (obtained from the optical emission following laser plasma formation) allowed us to obtain detailed information on the materials used. The precious pigments of the artist’s green-blue palette and the binder used (drying oil) were identified. A mixture of blue (Prussian blue and ultramarine blue), white (lead white and barium white), and yellow (chrome yellow and zinc yellow) pigments determined the different blue hues used. The use of bronze paint in the dark blue area, which was identified as a brass powder applied with a drying oil as a binder, was also demonstrated. Full article

We present some results, obtained using a multi-scale approach, based on the employment of different and complementary techniques, i.e., Optical Microscopy (OM), Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS), X-ray diffraction (XRD), Raman and µ-Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy equipped with Attenuated Total Reflectance (ATR) analyses, Inductively Coupled Plasma–Mass Spectrometry (ICP-MS), and Thermal Ionization Mass Spectrometry (TIMS), of an integrated activity focused on the characterization of micro-fragments of original and previously restored paintings of the pictorial cycle at the San Panfilo Church in Tornimparte, sampled from specific areas of interest. The study was aimed, on one hand, at the identification of the overlapping restoration materials used during previous conservation interventions (documented and not), and, on the other hand, at understanding the degradation phenomena (current or previous) of the painted surfaces and the architectural structures. The study of stratigraphy allowed us to evaluate the number of layers and the materials (pigments, minerals, and varnishes) present in each layer. As the main result, the identification of blue, black, yellow, and red pigments (both ancient and modern) was achieved. In the case of blue pigments, original (azurite and lazurite) and retouching (Prussian blue and phthalo blue) materials were recognized, together with alteration products (malachite and atacamite). Traces of yellow ochre were found in the yellow areas, and carbon black in the blue and brown areas. In the latter, hematite and red ochre pigments were also recognized. The obtained results are crucial to support the methodological choices during the restoration intervention of the site, and help to ensure the compatibility principles of the materials on which a correct conservative approach is based. Full article

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. Full article

Bismuth vanadate (BiVO₄, BV) is a widely explored photocatalyst for photo(electro)chemical applications, but its full photocatalytic potential is hindered by the fast recombination and low mobility of photogenerated charge carriers. Herein, we propose the photodeposition of different amounts of Prussian blue (PB) cocatalysts on the surface of monoclinic BV to obtain BV-PB composite photocatalysts with increased photoactivity. The as-prepared BV and BV-PB composites were characterized by an array of analytic techniques such scanning eletron microscopy (SEM), transmission eletron microscopy (TEM), X-day diffraction (XRD), and spectroscopic techniques including Fourier-transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS), electrochemical impedance spectroscopy (EIS), photoluminescence (PL), and Raman spectroscopy. The addition of PB not only increases the absorption of visible light, as indicated by DRS, but also improves the charge carriers’ transfer across the photocatalysts/solution interface and hence reduces electron-hole (e⁻-h⁺) recombination, as confirmed by EIS and PL measurements. Resultantly, the BV-PB composite photocatalysts with optimum PB loading exhibited enhanced Cr(VI) photoreduction efficiency as compared to pristine BV under visible light illumination from low-power blue light-emitting diodes (LEDs), thanks to the cocatalyst role of PB which mediates the transfer of photoexcited conduction band (CB) electrons from BV to Cr(VI) species in solution. Moreover, as compared to pristine BV and BV + H₂O₂, a drastic increase in the methylene blue (MB) photo-oxidation efficiency was observed for BV-PB in the presence of a minute quantity of H₂O₂ due to a synergic effect between the photocatalytic and Fenton-like processes. While pure BV photodegraded around 70% of MB dye within 120 min, the BV-PB/H₂O₂ and BV/H₂O₂ system could degrade almost 100% of the dye within 20 min (k_obs. = 0.375 min⁻¹) and 40 min (k_obs. = 0.055 min⁻¹), respectively. The practical approach employed in this work may pioneer new prospects for synthesizing new BV-based photocatalytic systems with low production costs and high photoredox efficiencies. Full article

As the main component of radioactive wastewater, the cesium ion has seriously endangered the environment and human health. Prussian blue nanoparticles (PB NPs) are used as adsorbents for the purification of cesium-containing wastewater because of their ability to selectively adsorb cesium ions. In this work, novel magnetic Prussian blue nanospheres (MPBNs) were developed from polylactic acid nanospheres as a carrier, loaded with Fe₃O₄ nanoparticles (Fe₃O₄ NPs) inside and PB NPs outside for the removal of cesium ions with the help of magnetic separation. Meanwhile, the effects on the adsorption efficiency of MPBNs, such as pH, time, temperature and initial concentration of cesium ion solution, were studied. The adsorption isotherms, kinetic models and adsorption thermodynamics were investigated to research the absorption mechanism. The results showed that MPBNs were spherical with a rough surface, and their particle size, iron content and saturation magnetization were 268.2 ± 1.4 nm, 40.01% and 41.71 emu/g, which can be recovered by magnetic separation. At 293 K, MPBNs could reduce the cesium ion solution from 40 mg/L to 4.8 mg/L, and its cesium ion removal rate and adsorption capacity were 82.46% and 16.49 mg/g, respectively. The optimum pH of MPBNs for cesium ion adsorption was 5~9, the adsorption equilibrium time was 60 min, and the maximum adsorption capacity was 17.03 mg/g. In addition, MPBNs were separated rapidly by an external magnetic field, and the adsorption process was an endothermic reaction. The adsorption isotherm and kinetics of MPBNs were in accordance with the Freundlich model and quasi-second-order fitting model, respectively, and the adsorption process of MPBNs was controlled by the diffusion step in particles. Notably, these MPBNs could be effectively separated from water by a magnetic field, facilitating engineering applications in cesium-containing wastewater. Full article

With the rapid development of electric power, lithium materials, as a rare metal material, will be used up in 50 years. Sodium, in the same main group as lithium in the periodic table, is abundant in earth’s surface. However, in the study of sodium-ion batteries, there are still problems with their low-temperature performance. Its influencing factors mainly include three parts: cathode material, anode material, and electrolyte. In the cathode, there are Prussian blue and Prussian blue analogues, layered oxides, and polyanionic-type cathodes in four parts, as this paper discusses. However, in the anode, there is hard carbon, amorphous selenium, metal selenides, and the NaTi₂(PO₄)₃ anode. Then, we divide the electrolyte into four parts: organic electrolytes; ionic liquid electrolytes; aqueous electrolytes; and solid-state electrolytes. Here, we aim to find electrode materials with a high specific capacity of charge and discharge at lower temperatures. Meanwhile, high-electrical-potential cathode materials and low-potential anode materials are also found. Furthermore, their stability in air and performance degradation in full cells and half-cells are analyzed. As for the electrolyte, despite the aspects mentioned above, its electrical conductivity in low temperatures is also reported. Full article

In recent years, the elimination of heavy metals from wastewater has become an important topic due to rapid industrialization, and it is of considerable interest to develop renewable and degradable materials for this purpose. In this work, a novel Prussian blue/polyaniline@cotton fibers (PB/PANI@CFs) composite was fabricated by a two-step process. Phytic acid doped PANI as a binding coating greatly promoted both the growth of PB and the adsorption of Cu²⁺. The deposition ratio of PB was as high as 24.68%. Scanning electron microscopy (SEM) displayed that PB nanoparticles were grown more uniformly in the composite and formed a perfect nanocube structure compared with PB@CFs. The successful deposition of both PB and PANI on CFs was demonstrated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FITR), and X-ray photoelectron spectroscopy (XPS). The effect of adsorption time, adsorbent dose, initial pH value, and initial copper sulphate concentration on the adsorption of PB/PANI@CFs composite for Cu²⁺ was studied by static adsorption and was compared with those of PANI@CFs and PB@CFs. The results showed that the maximum removal efficiency of Cu²⁺ by PB/PANI@CFs can reach 93.4% within 5 h, and the maximum adsorption capacity of Cu²⁺ can reach 31.93 mg·g⁻¹. The adsorption of Cu²⁺ on PB/PANI@CFs followed the pseudo-second order kinetic model and conformed to the Freundlich adsorption isothermal model. The PB-functionalized CFs provided new insights into the design of efficient and low-cost absorbents for heavy metal remediation. The proposed process solves two problems simultaneously, i.e., the utilization of environmentally friendly and biodegradable biomass resources and the adsorption of heavy metal ions, and is a good approach to achieve high-quality and sustainable development. Full article

Prussian Blue analogues (PBAs) are a promising class of electrode active materials for batteries. Among them, copper nitroprusside, Cu[Fe(CN)₅NO], has recently been investigated for its peculiar redox system, which also involves the nitrosyl ligand as a non-innocent ligand, in addition to the electroactivity of the metal sites, Cu and Fe. This paper studies the dynamics of the electrode, employing surface sensitive X-ray Photoelectron spectroscopy (XPS) and bulk sensitive X-ray absorption spectroscopy (XAS) techniques. XPS provided chemical information on the layers formed on electrode surfaces following the self-discharge process of the cathode material in the presence of the electrolyte. These layers consist mainly of electrolyte degradation products, such as LiF, Li_xPO_yFz and Li_xPF_y. Moreover, as evidenced by XAS and XPS, reduction at both metal sites takes place in the bulk and in the surface of the material, clearly evidencing that a self-discharge process is occurring. We observed faster processes and higher amounts of reduced species and decomposition products in the case of samples with a higher amount of coordination water. Full article

A composite sensor consisting of two separate inorganic layers of Prussian blue (PB) and a composite of cerium oxide nanoparticles (CeNPs) and graphene oxide (GO), is tested with •OH radicals. The signals from the interaction between the composite layers and •OH radicals are characterized using cyclic voltammetry (CV). The degradation of PB in the presence of H₂O₂ and •OH radicals is observed and its impact on the sensor efficiency is investigated. The results show that the composite sensor differentiates between the solutions with and without •OH radicals by the increase of electrochemical redox current in the presence of •OH radicals. The redox response shows a linear relation with the concentration of •OH radicals where the limit of detection, LOD, is found at 60 µM (100 µM without the PB layer). When additional composite layers are applied on the composite sensor to prevent the degradation of PB layer, the PB layer is still observed to be degraded. Furthermore, the sensor conductivity is found to decrease with the additional layers of composite. Although the CeNP/GO/PB composite sensor demonstrates high sensitivity with •OH radicals at low concentrations, it can only be used once due to the degradation of PB. Full article

Prussian blue and its analogues (PBA) based nanomaterials have been widely applied to removing pollutants in the recent years. However, easy aggregation and poor recycling largely limit their practical applications. In this work, spiderweb-like Fe-Co Prussian blue analogue/polyacrylonitrile (FCPBA/PAN) nanofibers were prepared by electrospinning and applied to degrading bisphenol-A (BPA) by activating peroxymonosulfate (PMS). Detailed characterization demonstrated that a high loading of FCPBA (86% of FCPBA in FCPBA/PAN) was successfully fixed on the PAN nanofibers. 67% of BPA was removed within 240 min when 500 mg·L⁻¹ PMS and 233 mg·L⁻¹ FCPBA/PAN were introduced in 20 mg·L⁻¹ BPA solution at initial pH of 2.8. Electron paramagnetic resonance (EPR) and radical inhibition experiments were performed to identify the possible degradation mechanism. For comparison, a low loading of FCPBA nanofibers (0.6FCPBA/PAN nanofibers, 43% of FCPBA in FCPBA/PAN) were also prepared and tested the catalytic performance. The results showed that the activity of FCPBA/PAN was much higher than 0.6FCPBA/PAN. Furthermore, a FCPBA/PAN packed column was made as a reactor to demonstrate the reusability and stability of FCPBA/PAN nanofibers, which also exhibited the bright future for the industrial application. This work makes it possible to fabricate efficient PBA nanocatalysts with excellent recyclability and promotes the application of PBA in industrial areas. Full article

Nanomedicine is an emerging field with great potential in disease theranostics. We generated sterically stabilized superparamagnetic iron oxide nanoparticles (s-SPIONs) with average core diameters of 10 and 25 nm and determined the in vivo biodistribution and clearance profiles. Healthy nude mice underwent an intraperitoneal injection of these s-SPIONs at a dose of 90 mg Fe/kg body weight. Tissue iron biodistribution was monitored by atomic absorption spectroscopy and Prussian blue staining. Histopathological examination was performed to assess tissue toxicity. The 10 nm s-SPIONs resulted in higher tissue-iron levels, whereas the 25 nm s-SPIONs peaked earlier and cleared faster. Increased iron levels were detected in all organs and body fluids tested except for the brain, with notable increases in the liver, spleen, and the omentum. The tissue-iron returned to control or near control levels within 7 days post-injection, except in the omentum, which had the largest and most variable accumulation of s-SPIONs. No obvious tissue changes were noted although an influx of macrophages was observed in several tissues suggesting their involvement in s-SPION sequestration and clearance. These results demonstrate that the s-SPIONs do not degrade or aggregate in vivo and intraperitoneal administration is well tolerated, with a broad and transient biodistribution. In an ovarian tumor model, s-SPIONs were shown to accumulate in the tumors, highlighting their potential use as a chemotherapy delivery agent. Full article