Anti-interference Property Research Articles

Four-in-one multifunctional self-driven photoelectrocatalytic system for water purification: Organics degradation, U(VI) reduction, electricity generation and disinfection against bacteria

This study addresses the energy-intensive nature of conventional wastewater treatment processes and proposes a solution through the development of a green, low-energy, and multifunctional wastewater treatment technology. The research focuses on a multifunctional self-driven photoelectrocatalytic (PEC) system, exploring its four-in-one applications in eliminating organic pollutants, reducing U(VI), generating electrical energy, and disinfecting pathogenic microorganisms. A TiO2-decorated carbon felt (CF@TiO2) cathode is synthesized to enhance interfacial charge transfer, with TiO2 coating improving surface binding sites (edge TiO and adsorbed -OH) for UO22+ adsorption and reduction. The self-driven PEC system, illuminated solely with simulated sunlight, exhibits remarkable efficiency in removing nearly 100 % of uranium within 0.5 h and simultaneously degrading 99.9 % of sulfamethoxazole (SMX) within 1.5 h, all while generating a maximum power output density (Pmax) of approximately 1065 μW·cm−2. The system demonstrates significant anti-interference properties across a wide pH range and coexisting ions. Moreover, 49.4 % of the fixed uranium on the cathode is reduced into U(IV) species, limiting its migration. The self-driven PEC system also excels in detoxifying various toxic organic compounds, including tetracycline, chlortetracycline, and oxytetracycline, and exhibits exceptional sterilization ability by disinfecting nearly 100 % of Escherichia coli within 0.5 h. This work presents an energy-saving, sustainable, and easily recyclable wastewater purification system with four-in-one capabilities, relying solely on sunlight for operation.

Event-triggered adaptive control for quadrotor unmanned aerial vehicle with prescribed performance

This paper proposes an event-triggered adaptive control algorithm with prescribed performance for quadrotor unmanned aerial vehicles (UAVs). The dynamic uncertainty and unknown external interference of the system are compensated by the property of approximation in a radial basis function (RBF) neural network. Based on this, introduce a performance constraint function to ensure that the trajectory tracking error of quadrotor UAV converges to a preset area, thereby guaranteeing transient and steady-state performance. In addition, design an event-triggered adaptive controller with the combination of the event-triggered mechanism, reducing the controller’s update frequency. Simulation results demonstrate that this algorithm exhibits strong anti-interference properties and effectively resolves the flight control problem of quadrotor UAV.

Mechanism for the synergistic removal of Sb(Ⅲ) and Sb(V) from printing and dyeing wastewater by polyferric sulfate

Herein, the synergistic removal of Sb(Ⅲ) and Sb(Ⅴ) from wastewater by polymeric ferric sulfate (PFS) and the oxidation process were investigated. The results showed that PFS exhibited superior performance on Sb(Ⅲ) removal in terms of coagulant dosage, applied pH, and anti-interference properties than Sb(V) removal. For the Sb liquid in pure water matrix (Sb=1000 μg/L), when the dose was 60 mg/L and the final pH was 5.0, the independent removal of Sb(Ⅲ) and Sb(V) was 95% and 90%, respectively. Meanwhile, Sb(Ⅲ) removal in the PFS coagulation system remained stable within a wider pH range (pH=3–9). Sb(Ⅲ) could be preferentially removed in the solution column and had an inhibitory effect on the adsorption of Sb(V). Sb(Ⅲ) was also partially oxidized to Sb (V) during the coagulation process, which was influenced by the coagulant dosage and the solution pH. The results of the actual printing and dyeing wastewater (PDW) treatment indicated that the pre-reduction of Sb(V) to Sb(Ⅲ) could significantly increase the total Sb removal from 72.0% to 97.5%. The characterization results, such as Zeta potential and x-ray photoelectron spectroscopy (XPS), indicated that the Sb(Ⅲ) removal by PFS was achieved mainly through chemical adsorption. While the Sb(V) removal was realized by both chemical adsorption and electrostatic adsorption, the electrostatic adsorption contributed more than the chemical adsorption. This study provides a new idea for understanding the synergistic removal of Sb(Ⅲ) and Sb(V) using PFS in PDW advanced treatment.

Multiwalled carbon nanotubes decorated with molybdenum sulphide (MoS2@MWCNTs) for highly selective electrochemical picric acid (PA) determination

Nitrophenols are industrially versatile yet environmentally detrimental compounds. Herein, we have synthesised molybdenum sulphide based dichalcogenide supported multiwalled carbon nanotubes i.e. MoS2@MWCNTs electrocatalyst by simple wet chemical method for PA determination. The successful decoration of MoS2 over MWCNTs were confirmed by various characterizations techniques including scanning electron microscopy (SEM) shows MoS2 layers grown on MWCNTs and having average size is –80 nm. Energy dispersive X-ray analysis (EDAX) reveals elements are homogenously distributed in nanocomposite. High resolution-transmission electron microscopy (HR-TEM) shows increase in average diameter after decoration of MoS2 over MWCNTs from 30 nm to 70 nm. The Fourier transform infrared (FT-IR) analysis suggests the presence of Mo-S stretching frequency at 605 cm−1 in addition to hydroxyl, carbonyl, C–C, C–O stretching frequencies are also observed. In Raman spectrum from apart D and G bands, the characteristic intense bands E2g1 and A1g of MoS2 were pointed towards presence of molybdenum and sulphur. The X-ray diffraction (XRD) confirms synthesised electrocatalyst is in hexagonal crystal structure with P63/mmc space group. The X-ray photoelectron spectroscopy (XPS) reveals that for Mo 3d is found to be two characteristics peaks at 231.2 eV and 233.2 eV corresponds to Mo4+ 3d3/2 and 3d5/2 respectively. The peak at 229 eV corresponds to S 2s. Whereas, the signal appears at 162.7 eV, 165 eV, 169 eV and 170 eV shows sulphur is in 2S3/2 and 2S5/2 states. Electrochemical performance was examined by cyclic voltammetry (CV) tests. The Electrocatalyst is highly selective, having appreciable anti-interference property, lower limit of detection (LoD), i.e., 0.5 μM with wide linear range. The low Rct and high k⁰ pointed that MoS2@MWCNTs performed better towards electrochemical detection of PA.

EY@UiO-67-CDC-(CH3)2 as an ultra-sensitive ratiometric fluorescence sensor for visible and selective detecting of nitrite

Nitrite is widely used in production and daily life, and detecting this substance has always been crucial for human health or environment monitoring. Here, a dual-emitting dye@MOF composite, EY@UiO-67-CDC-(CH3)2, has been constructed and demonstrated that this material could detect nitrite ions with highly selective and anti-interference properties. By incorporating an organic anionic dye (Eosin Y) within a cationized EY@UiO-67-CDC-(CH3)2 framework through the post-synthetic method, the composite presents an effective combination due to electrostatic attraction. It features a dual emission effect, which belongs to the blue emission of MOF at 428 nm and yellow emission of EY at 559 nm, respectively. After adding NO2−, the fluorescence emission peaks of EY and MOF showed opposite changes due to the inner filter effect of NO2− and MOF, as well as effective excitation of the dye's fluorescence and slight dye leakage. Therefore, Idye/IMOF is used as the detection signal value instead of absolute fluorescence intensity, effectively reducing the detection limit to 0.224 μM and improving its detection accuracy. In addition, during the detection process, the fluorescence sensor showed noticeable color changes, so a smartphone-based analytical device without additional instruments was developed for the quantitative, visual analysis of nitrite by identifying the RGB values of the fluorescence sample solution, with a detection limit of 6.74 μM. The application of the sensor visualizes nitrite detection and reduces the cost of detection, providing a feasible method for on-site detection of nitrite in water samples.

A o-phenanthroline-based metal-organic framework for fluorescence sensing toward CrVI and antibiotics in aqueous phase

Herein, a novel o-phenanthroline-based ligand involving two naphthalenecarboxylate groups was first synthesized, and successfully employed to fabricate a fluorescent metal–organic framework 1 under solvothermal conditions. According to the single-crystal X-ray analysis of compound 1, the Cd(II) ions connected by organic ligands form a 2D layer structure with a unique metallacycle building unit, and adjacent 2D layers are further stacked into a 3D porous framework via numerous supramolecular interactions. Powder X-ray diffraction revealed that 1 exhibits exceptional stability in both water and common organic solvents. The fluorescence sensing experiments conducted with compound 1 toward anions and antibiotics, demonstrated its selective detection capabilities for CrVI anions (CrO42−/Cr2O72−) and nitrofuran antibiotics in aqueous solutions. Additionally, fluorescent 1 serves as an effective fluorescent probe for sensing nitro-aromatic compounds in dimethyl sulfoxide. Its robust anti-interference properties, recyclability, and resistance to water make compound 1 a promising candidate for pollutant detection in wastewater.

Chemically bonded Mn0.5Cd0.5S/BiOBr S-scheme photocatalyst with rich oxygen vacancies for improved photocatalytic decontamination performance

Devising exceptional S-scheme heterojunction photocatalysts utilized in annihilating pharmaceuticals and chromium contamination is significant for addressing the problem of global water pollution. In this work, a chemically bonded Mn0.5Cd0.5S/BiOBr S-scheme heterostructure with oxygen vacancies is ingeniously developed through a facile in-situ solvothermal synthesis. The designed Mn0.5Cd0.5S/BiOBr heterojunction exhibits eminently reinforced photo-activity for destruction of tetracycline hydrochloride and Cr(VI) as compared with its individual components. This substantial photo-redox performance amelioration is benefitted from the creation of an intense internal electric field (IEF) via supplying powerful driving force and migration highway by interfacial chemical bond to foster the S-scheme electron/hole disintegration. More intriguingly, the IEF at the hetero-interface drives the fast consumption of the photo-induced holes in Mn0.5Cd0.5S by the photoelectrons from BiOBr, profoundly boosting the enrichment of active photo-carriers and sparing the photo-corrosion of Mn0.5Cd0.5S. Furthermore, Mn0.5Cd0.5S/BiOBr with exceptional anti-interference property can work efficiently in real water matrices. Multiple uses of the recycled Mn0·5Cd0·5S/BiOBr evidence its prominent robustness and stability. This achievement indicates the vast potential of chemically bonded S-scheme photosystems with structural defects in the design of photo-responsive materials for effective wastewater treatment.

Electropolymerization of poly(phenol red) on laser-induced graphene electrode enhanced adsorption of zinc for electrochemical detection

We present a highly sensitive and selective electrode of laser-induced graphene modified with poly(phenol red) (P(PhR)@LIG) for measuring zinc nutrition in rice grains using square wave anodic stripping voltammetry (SWASV). The physicochemical properties of P(PhR)@LIG were investigated with scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), Fourier infrared spectroscopy (FT-IR) and Raman spectroscopy. The modified electrode demonstrated an amplified anodic stripping response of Zn2+ due to the electropolymerization of P(PhR), which enhanced analyte adsorption during the accumulation step of SWASV. Under optimized parameters, the developed sensor provided a linear range from 30 to 3000 μg L−1 with a detection limit of 14.5 μg L−1. The proposed electrode demonstrated good reproducibility and good anti-interference properties. The sensor detected zinc nutrition in rice grain samples with good accuracy and the results were consistent with the standard ICP-OES method.

The application of optical fiber in network communication

In recent years, optical fiber communication has gained widespread use in daily life due to its robust communication and transmission capabilities, strong confidentiality, anti-interference properties, and the availability of convenient and accessible materials. This technology has made remarkable strides in network communication and integrated device design, among other areas. This article will commence by discussing the fundamental structure of optical fibers and illustrating the propagation of optical signals within them. It will then analyze the benefits, such as higher transmission rates, wider frequency bands, and the low loss characteristics of optical fibers. Subsequently, the article will enumerate two of the most commonly utilized Optical Fiber Communication (OFC) technologies: Wavelength Division Multiplexing (WDM) technology and optical amplifier technology. It will summarize their principles and strengths. Finally, the article will showcase the practical applications of optical fiber communication, particularly focusing on its role in 5G mobile communication, military operations, and radio and television communication.

Error analysis and modeling of the racetrack magnetohydrodynamic linear motion sensor

Micro-vibration measurement methods for spacecraft structures mainly include the use of an accelerometer, laser, and magnetohydrodynamic (MHD) measurement methods. The micro-vibration measurement sensor developed based on the MHD measurement method has no mechanical wear between internal components, a fast high-frequency vibration response, and strong anti-interference properties. To reduce the measurement error of the racetrack MHD linear motion sensor developed in the laboratory, this paper investigated the sensor error, analysed the error source, combined the BP neural network optimized by particle swarm optimization (PSO) with variational mode decomposition (VMD), used the VMD-PSO-BP neural network to establish the error compensation model of the racetrack MHD linear motion sensor, and combined the PSO-BP neural network with wavelet threshold de-noising (WTD). The WTD-PSO-BP and RBF neural networks were used to develop the error compensation model of the racetrack MHD linear motion sensor. Comparing the three models, the experimental results show that the VMD-PSO-BP model has the best compensation effect. The mean absolute error of the output signal of the racetrack MHD linear motion sensor compensated by the VMD-PSO-BP neural network model was 1–2 times lower than that before compensation, the signal-to-noise ratio was 10 times higher on average, and the correlation coefficient was more than 0.95.

Metal-organic-framework-confined quantum dots enhance photocurrent signals: A molecularly imprinted photoelectrochemical cathodic sensor for rapid and sensitive tetracycline detection

BackgroundTetracycline (TC), a cost-effective broad-spectrum antibacterial drug, has been excessively utilized in the livestock and poultry industry, leading to a serious overabundance of TC in livestock wastewater. However, conventional analytical methods such as liquid chromatography and gas chromatography face challenges in achieving sensitive detection of trace amounts of TC in complex substrates. Therefore, it is imperative to develop a highly sensitive and anti-interference analytical method for the detection of tetracycline in livestock wastewater. ResultsA porphyrin-based MOF (PCN-224)-confined carbon dots (CDs) material (CDs@PCN-224) was synthesized by a “bottle-around-ship” strategy. The reduced carrier migration distance is conducive to the separation of electron-hole pairs and enhanced the photocurrent signal due to the tight coupling of CDs and PCN-224. Further, molecularly imprinted polymer (MIP) was synthesized by rapid in-situ UV-polymerization and employed as a recognition element. The specific recognition of the target by imprinted cavities blocks electron transfer, resulting in a “turn off” response signal, thus realizing the selective detection of TC. Under optimal conditions, the constructed MIP-PEC cathodic sensor detected 1.00 × 10−12 M to 1.00 × 10−7 M of TC sensitively, with a limit of detection of 3.72 × 10−13 M. In addition, the proposed MIP-PEC sensor demonstrated good TC detection performance in actual livestock wastewater. SignificanceThe strategy based on MOF pore-confined quantum dots can effectively enhance the photocurrent response of the photosensitive substrate. Simultaneously, the MIP constructed by in-situ rapid UV-polymerization showed excellent anti-interference and reusable properties. This work provides a promising MIP-PEC cathodic sensing method for the rapid and sensitive detection of antibiotics in complex-matrix environmental samples.

Rational design and synthesis of triazene-amonafide derivatives as novel potential antitumor agents causing oxidative damage towards DNA through intercalation mode

In this work, we rationally designed and synthesized two novel triazene-amonafide derivatives 2-(2-(diisopropylamino)ethyl)-5-(3,3-dimethyltriaz-1-en-1-yl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (D-11) and 5-(3,3-diethyltriaz-1-en-1-yl)-2-(2-(diisopropylamino)ethyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (D-12) as potential antitumor agents. The DNA damage induced by the intercalation mode of D-11 (D-12) towards DNA was electrochemically detected through the construction of efficient biosensors. The consecutive processes of reversible redox of naphthylimide ring and irreversible oxidation of triazene moiety were elucidated on the surface of glassy carbon electrode (GCE) by CV, SWV, and DPV methods. Electrochemical biosensors were obtained through the immobilization of ctDNA, G-quadruplexes, poly(dG), and poly(dA), respectively, on the clean surface of GCE. After the incubation of biosensors with D-11 or D-12, the peaks of dGuo and dAdo decreased prominently, and the peak of 8-oxoGua appeared at +0.50 V, suggesting that the interaction between D-11 (D-12) and DNA could result in the oxidative damage of guanine. Unexpected, the as-prepared DNA biosensor possessed satisfactory anti-interference property and good practicability in real samples. UV–vis and fluorescence spectra, and gel electrophoresis assays were employed to further confirm the intercalation mode of D-11 (D-12) towards DNA base pairs. Moreover, D-11 was proved to exhibit stronger anti-proliferation activity than mitionafide and amonafide against both A549 and HeLa cell lines.

Multifunctional In-MOF and Its S-Scheme Heterojunction toward Pollutant Decontamination via Fluorescence Detection, Physical Adsorption, and Photocatalytic REDOX.

A novel doubly interpenetrated indium-organic framework of 1 has been assembled by In3+ ions and highly conjugated biquinoline carboxylate-based bitopic connectors (H2L). The isolated 1 exhibits an anionic framework possessing channel-type apertures repleted with exposed quinoline N atoms and carboxyl O atoms. Owing to the unique architecture, 1 displays a durable photoluminescence effect and fluorescence quenching sensing toward CrO42-, Cr2O72-, and Cu2+ ions with reliable selectivity and anti-interference properties, fairly high detection sensitivity, and rather low detection limits. Ligand-to-ligand charge transition (LLCT) was identified as the essential cause of luminescence by modeling the ground state and excited states of 1 using DFT and TD-DFT. In addition, the negatively charged framework has the ability to rapidly capture single cationic MB, BR14, or BY24 and their mixture, including the talent to trap MB from the (MB + MO) system with high selectivity. Moreover, intrinsic light absorption capacity and band structure feature endow 1 with effective photocatalytic decomposition ability toward reactive dyes RR2 and RB13 under ultraviolet light. Notably, after further polishing the band structure state of 1 by constructing the S-scheme heterojunction of In2S3/1, highly efficient photocatalytic detoxification of Cr(VI) and degradation of reactive dyes have been fully achieved under visible light. This finding may open a new avenue for designing novel multifunctional MOF-based platforms to address some intractable environmental issues, i.e., detection of heavy metal ions, physical capture of pony-sized dyes, and photochemical decontamination of ultrastubborn reactive dyes and highly toxic Cr(VI) ions from water.

Rapid determination of 87 prohibited ingredients in cosmetics by ultra performance liquid chromatography-tandem mass spectrometry

The methods of detecting numerous prohibited components are not included in the Technical Specifications for Cosmetic Safety (2015 Edition). Recently, owing to its high speed, sensitivity, and anti-interference properties, ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) became the preferred method of detecting banned substances in cosmetics. In this study, a UPLC-MS/MS method was developed for use in determining 87 prohibited ingredients in cosmetics, including 33 sex hormones, 20 anti-infective drugs, 15 antihistamines, 7 coumarins, 4 sedative-hypnotic drugs, 4 antipyretic and analgesic drugs, 2 allergenic fragrances, and 2 drugs with vasoconstriction effects. The main factors affecting the response, recovery, and sensitivity of the method, such as the type of extraction solvent, extraction time, ratio of the mobile phases, and MS conditions, were optimized during sample pretreatment and instrumental analysis. Accordingly, approximately 0.2 g of the toner or cream sample was dispersed in 2 mL acetonitrile in a 10 mL colorimetric tube. After diluting to 10 mL with 50% acetonitrile aqueous solution, the sample was ultrasonically extracted for 20 min and centrifuged, and the mixture was then filtered through a 0.22 μm membrane. Approximately 0.2 g of the oil sample was dispersed in 2 mL n-hexane in a 15 mL polypropylene centrifuge tube and extracted twice with 3 mL 70% acetonitrile aqueous solution. The extracts were transferred into a 10 mL colorimetric tube and diluted to 10 mL with 50% acetonitrile aqueous solution, and the mixture was then filtered through a 0.22 μm membrane. The samples were separated using a CORTECS C18 column (150 mm×2.1 mm, 2.7 μm), employing a gradient elution program with acetonitrile and 0.1% formic acid aqueous solution as the mobile phases. The flow rate, column temperature, and injection volume were respectively set at 0.3 mL/min, 40 ℃, and 2 μL. The 87 compounds were monitored in multiple reaction monitoring (MRM) mode with electrospray ionization (ESI) under positive and negative conditions. Matrix-matched external standard calibration was used for quantification, and the analysis was completed within 33 min. The prohibited compounds exhibited good linear relationships, with r values of >0.99, and the limits of detection (LODs) and quantification (LOQs) for the 87 compounds were 0.07-0.38 and 0.21-1.15 μg/g, respectively. Three types of cosmetic matrices were selected to verify the recovery and precision of the method at LOQ, 2 LOQ, and 10 LOQ levels. The average recoveries of the 87 prohibited compounds were in the range of 81.7%-115.4%, and the relative standard deviations (RSDs, n=6) were 0.4%-9.9%. The reliability of the developed method was demonstrated by applying it to 349 commercial cosmetics obtained from the market, and 8 positive samples were identified. The positive components included trimethoprim, terbinafine, naphazoline, 7-methoxycoumarin, and 7-methylcoumarin. The established method displays the advantages of simple operation and rapidness and a high sensitivity and good recovery. And, this method provides technical support for rapid risk screening and the revision of national standards for cosmetics.

Facile synthesis of sulphur-doped carbon dots (S-CDs) using a hydrothermal method for the selective sensing of Cr6+ and Fe3+ ions: application to environmental water sample analysis.

In this work, we used a one-step hydrothermal method to synthesize blue-emission sulfur-doped carbon dots (S-CDs) using jaggery as a carbon precursor. The synthesized carbon quantum dots showed low toxicity, good water solubility, anti-interference properties, and stable fluorescence. When excited at 310 nm, the S-CDs produced bright emission with a quantum yield of 7.15% at 397 nm. The S-CDs exhibited selective and sensitive quenching responses with limits of detection (LODs) of 4.25 μg mL-1 and 3.15 μg mL-1 for variable concentrations of Cr6+ and Fe3+, respectively, accompanied by a consistent linear relationship between fluorescence intensity and these concentrations. Fluorescence lifetime measurements were used to investigate the fluorescence quenching mechanism, which supports the static type of quenching. Outstanding benefits of the developed S-CD based fluorescence probe include its low cost, excellent sensitivity and selectivity, and ease of use for the detection of Cr6+ and Fe3+ ions. The developed carbon dot based fluorescent probe was successfully used to detect Cr6+ and Fe3+ ions in real water samples with an excellent recovery ratio.

Iron-based metal-organic framework/graphene oxide composite electrodes for efficient flow-injection amperometric detection of dexamethasone.

A highly stable flow-injection amperometric sensor for dexamethasone (DEX) was developed using a pencil graphite electrode (PGE) modified with Fe-based metal organic frameworks, MIL-100(Fe) and graphene oxide composite materials (MIL-100(Fe)/GO). Scanning electron microscopy and energy-dispersive X-ray spectroscopy, transmission electron microscopy, powder X-ray diffraction, and Fourier-transform infrared spectroscopy were used to characterize the MIL-100(Fe) composites. The MIL-100(Fe)/GO-modified PGE (denoted MIL-100(Fe)/GO/PGE) was further electrochemically characterized using cyclic voltammetry. As an electrode material, MIL-100(Fe) is a sensing element that undergoes oxidation from Fe(ii)-MOF to Fe(iii)-MOF, and GO possesses high conductivity and a large surface area, which exhibits high absorbability. In the presence of DEX, Fe(iii) is reduced, which accelerates electron transfer at the electrode interface. Therefore, DEX can be quantitatively detected by analyzing the anodic current of MIL-100(Fe). When coupled with amperometric flow injection analysis, excellent performance can be obtained even when a low detection potential is applied (+0.10 V vs. Ag/AgCl). The concentration was linear in the range 0.10-5.0 μM and 0.010-5.0 mM with LOD of 0.030 μM based on 3(sd/slope). The modified electrode also exhibited a remarkably stable response under optimized conditions, and up to 55 injections can be used per electrode. The sensor exhibits high repeatability, reproducibility, and anti-interference properties when used for DEX detection. The effective determination of dexamethasone in real pharmaceutical and cosmetic samples demonstrated the feasibility of the electrochemical sensor, and the results were in good agreement with those obtained from the HPLC-DAD analysis. Acceptable percentage recoveries from the spiked pharmaceutical and cosmetic samples were obtained, ranging from 93-111% for this new method compared with 84-107% for the HPLC-DAD standard method.

Ultrasensitive detection of dopamine using Au microelectrodes integrated with mesoporous silica thin films.

An electrochemical method was developed for ultrasensitive and selective detection of dopamine in human serum using mesoporous silica thin film modified gold microelectrodes. Vertically aligned mesoporous silica thin films were deposited onto Au microelectrodes by electrochemically assisted self-assembly (EASA). The mesochannels have uniform pore sizes of 2.1 nm in diameter and a negatively charged wall surface. Cyclic voltammetry reveals effective charge permselectivity through the negatively charged mesoporous channels. By using differential pulse voltammetry, the mesoporous silica thin film modified Au microelectrode can be employed for the ultrasensitive detection of dopamine with a detection limit as low as 0.084 μM. In addition, thanks to the electrostatic and steric effects of the silica mesochannels, excellent anti-interference and anti-fouling properties of the electrochemical sensors are demonstrated.

ZIF-12 @ polypyrrole nanowires for selective detection of cadmium ions in water samples

Cadmium ion detection is an important area of research since it is associated with numerous diseases in humans and the environment. In this study, selective Cd2+ ion detection using polypyrrole and ZIF-12 was investigated using the square wave voltammetry technique. A convenient chemical method is used to polymerize the pyrrole to form a composite, which provides a better electroactive surface area of 24.5 x 10-3 m2 for the ZIF-12@Ppy composite modified GCE. The –NH2 functional group in polypyrrole makes good adsorptive property for Cd2+ ion capture with a detection range of 10 µM to 5 mM, the regression equation of y = 0.0102 x + 43.289, and low detection limit of approximately 50 nM as a result of enhanced electrocatalytic activity. The good anti-interference properties, repeatability, and stability of the prepared composite successfully demonstrated for the detection of Cd2+ ions in real samples from various water sources. Overall, these studies provide good insights into the development of an effective device for the detection of Cd2+ ions using polypyrrole and ZIF-12 platform.

A recyclable Eu3+-functionalized dual-emissive metal-organic framework for portable, rapid detection and efficient removal of malachite green.

A europium-functionalized, dual-emissive, metal-organic framework-based fluorescence sensor (EuUCNDA) was constructed via post-synthetic modification of an UiO-66-type precursor through coordination interactions. EuUCNDA exhibited extremely high selectivity and sensitivity for malachite green (MG) with a low detection limit of 13.01 nM, a wide linear concentration range (0.05-50 μM), excellent anti-interference properties, a rapid response (<1 min), and the possibility of recycling. The good sensing performance of EuUCNDA enables the practical detection of MG in fish pond water and grass carp with good recoveries. Moreover, EuUCNDA can be reused for sensing MG and over 90% of fluorescence intensity can be restored after 7 cycles. Furthermore, EuUCNDA-embedded paper-based sensors combined with smartphone imaging afford portable and visual monitoring of MG in real samples. Notably, besides good sensing performance, EuUCNDA could efficiently remove MG from water. Hence, this work provides a recyclable and sensitive fluorescence sensor for portable, visual, rapid detection and efficient removal of MG.

Simple and direct electrochemical detection of rosmarinic acid in food samples based on nanochannel modified carbon electrode.

The detection of rosmarinic acid (Ros A) in food samples holds major significance. Simple and convenient electrochemical detection of Ros A with high performance remains a challenge. In this work, a nanochannel array-modified carbon electrode was constructed using a simple and convenient approach to achieve highly sensitive electrochemical detection of Ros A in food samples. Through simple electrochemical pre-activation of a glassy carbon electrode (GCE), oxygen-containing functional groups were introduced on the electrode surface (p-GCE). Vertically-ordered mesoporous silica film (VMSF) was stably grown on p-GCE through electrochemical-assisted self-assembly (EASA) without the introduction of another adhesive layer (VMSF/p-GCE). Transmission electron microscopy (TEM) characterization demonstrated the highly ordered structure of VMSF with a nanochannel diameter around 2.7 nm. Both p-GCE and the nanochannels significantly enhanced the electrochemical signals of Ros A on the electrode, exhibiting dual signal amplification. VMSF/p-GCE demonstrated sensitive detection of Ros A with a linear range of 500 nM to 1 μM and 1 μM to 35 μM. The detection limit (DL) was 26 nM. Combining the good anti-fouling and anti-interference properties of the nanochannels, VMSF/p-GCE can achieve direct electrochemical detection of Ros A in food samples. The sensor can be easily regenerated for repeated use. The simple fabrication, high detection sensitivity and selectivity of the sensor make it a new strategy for rapid preparation of high-performance electrochemical sensors.