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Manganese ferrite (MnFe2O4) nanoparticle, a spinel ferrite nanomaterial, is one of the important magnetic metal oxide nanoparticles with distinctive physical and chemical properties. ...This nanoparticle can be easily synthesized through various methods with controllable size and desired morphology. MnFe2O4 is an efficient candidate for various applications like biomedical, analytical, and storage devices. In this review, several synthesis methods and physicochemical properties of MnFe2O4 nanoparticles are discussed. Then, a comprehensive overview of the latest and most promising researches on massive applications of MnFe2O4-based nanostructures, including hyperthermia cancer therapy, magnetic resonance imaging (MRI), energy conversion and storage devices like Lithium-ion batteries and supercapacitors, as well as catalytic activities, sensors, hydrogen production, heavy metal removal, and drug delivery are presented. Overall, herein, a deep understanding of the unlimited ability of MnFe2O4 nanoparticles in diverse applications is provided.
Carbon cloth and carbon paper have unique characteristics such as conductivity, mechanical strength, porosity, reduced dimensions, and adjustable size and shape. With these materials, different ...simple modification strategies can be employed, with emphasis on the direct growth of metal-based catalysts through single-step hydrothermal methods. Thus, owing to these interesting features, highly efficient, versatile, and disposable electrochemical (bio)sensors based on carbon cloth and carbon paper have been designed for biomolecules, biomarkers, and hazardous and chemical compounds detection in clinical, environmental and food samples, as well as in industrial products. Moreover, the advantage of facile integration in miniaturized and portable devices, envisages their successful application in point-of-care diagnostics and in-situ measurements. Therefore, this review highlights the main advances and the current research gaps concerning the design of these novel electroanalytical tools.
•CC and CP present high electrical conductivity, porosity, and adjustable size/shape.•Single-step hydrothermal methods are the most used for CC and CP modification.•CC and CP (bio)sensors successfully used in clinical, environmental and food analysis.•Excellent performance of CP and CC (bio)sensors reaching sub-micromolar levels of LOD.•Facile integration in miniaturized and portable devices for in-situ measurements.
This review summarizes the recent and updated development of the fluoroquinolone antibiotics electrochemical detection. This research topic has gained attention only in the last 10 years and ...coincides with the increasing awareness about the antimicrobial resistance. Provided classification is based on the detection mechanisms or the type of an applied electrified interface decoration (if any) and includes sensing at non-modified solid electrodes, electrodes decorated with nano-, bio-, carbon-based or polymeric materials and finally soft junctions in a form of the electrified liquid-liquid interfaces or polymeric membranes. The most promising sensing examples exhibiting superior electroanalytical performance are underlined. We finish this work by concluding remarks where we stress out the existing gap that should shape future development.
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•Most of the available works describe fluoroquinolone antibiotics (FAs) detection in real samples.•FAs electroanalysis emerged only recently. More than 75% of reports appeared in the last 10 years.•Detection of fluoroquinolone antibiotics can be performed at the bare and modified electrified interfaces.•The best, to date, electroanalytical parameters for FAs detection were obtained with electrodes decorated with MIP.
The opioid crisis has proliferated at an unprecedented rate worldwide, posing significant public health challenges. This review presents the current state of electrochemical methods to positively ...identify and quantify fentanyl, a potent and popular opioid, and its analogs in liquid and solid matrices. Specific emphasis is placed on point-of-use sensors, which are urgently needed to provide first responders with tools to identify unknown powders and treat victims of an opioid overdose. Electroanalytical techniques are uniquely poised to generate such sensors based on their portability, low cost, and ease of use. However, significant challenges remain, including enhancing sensor sensitivity for quantification of fentanyl at biologically relevant concentrations (<80 nM), and the extension of electrochemical methods to selectively identify common fentanyl analogs. Critically examining the strengths and weaknesses of electrochemical analysis for fentanyl detection and quantification is paramount for the continued development of deployable sensors to assist first responders in the control of this illicit family of substances.
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•Electrochemical sensors are ideal for on-site determination of fentanyl and its analogs based on low-cost and portability.•Increased sensitivity is essential for detecting biologically relevant concentrations of fentanyl (10s of nM).•Fentanyl oxidation produces electroactive products which may be used to gain selectivity against common interferants.
Rational design and construction of electrochemical sensing platforms with high sensitivity and selectivity is one of the challenges in practical application. Although single-atom catalysts (SACs) ...have attracted extensive attention, atomically dispersed metal catalysts (ADCs) with multi-atom sites can further compensate for the deficiencies of SACs, which have gradually been a research hotspot in recent years. Herein, atomically dispersed Ru3 site catalyst (Ru3/NC) is employed to catalyze small biomolecule oxidation, which exhibits much superior electrocatalytic ability of uric acid (UA) to Ru single-atom catalyst (Ru1/NC). What's more, theoretical calculations reveal that the enhanced performance is mainly derived from the dominant electronic structure of ADCs with multi-atom sites compared to SACs, leading to the more favorable adsorption of hydroxy anion groups, which can serve as one part of the active moiety and “promoter” to achieve the fast oxidation of small biomolecules. Our findings provide a new paradigm for designing promising catalysts to realize highly sensitive and selective small biomolecule detection and explore the catalytic mechanisms of small biomolecules at the atomic scale.
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Herein, we developed a unique screen-printed carbon electrode (SPCE) with three-dimensional melamine-doped graphene oxide/MXene composite aerogel (3D MGMA) modification, which is used for the ...simultaneous and sensitive detection of three metal ions (Zn2+, Cd2+, and Pb2+) in the environment. A self-assembly method was used to fabricate 3D MXene aerogels based on MXene, graphene oxide (GO), and melamine. Notably, the network-like 3D structure combining 2D MXene and rGO sheets can provide a high ratio of surface area and enriched functional clusters, which are beneficial for improving the electrical conductivity and promoting the uptake of heavy metal ions. In the linear range of 3–900 μg L-1, the constructed innovative sensing platform can sensitively detect Zn2+, Cd2+, and Pb2+ simultaneously, with detection limits of 0.48 μg L-1,0.45 μg L-1 and 0.29 μg L-1 respectively. This work reflects precision and reliability in the detection of three water samples (tap water, Minzhu lake and Yangtze River) and four cereal samples (sorghum, rice, wheat and corn), proposing a novel strategy for monitoring heavy metal ions in the natural environment.
Schematic diagram of 3D MGMA/SPCE for Zn2+, Cd2+, and Pb2+ detection in environmental samples. Display omitted
•Three-dimensional porous graphene oxide/MXene composite aerogel was firstly applied to simultaneous electrochemical determination of Zn2+, Cd2+, and Pb2+.•Portable functionalized screen-printed electrode exhibits low detection limits and broad linear range.•The recovery outcomes in challenging real samples are satisfactory.•3D MGMA/SPCE provides 3.5 times larger electroactive surface area than bare SPCE.
•MOF composites has strong electrocatalytical activity.•MOF-modified carbon based electrodes can be applied for biomolecules sensing such as glucose and secondary metabolites.•MOF-modified carbon ...based electrodes are being developed for heavy metal quantification in aqueous media.
Metal-organic frameworks are novel materials with specific pore-size that presents unlimited applications in material sciences. The presence of metallic ions in the MOF structure offers a redox active material with electrocatalytical properties towards diverse biomolecules, organic compounds and heavy metals. This property can be combined with nanomaterials for create cheap carbon based electrodes with enhanced electroanalytical features (like selectivity, good low detection limits and high stability on alkali or acid media). In this review, we have collected recent information about MOF applications in carbon electrodes and fundamental aspects on the electroactive MOFs design, fabrication of MOF-modified carbon based electrodes, characterization of electrodes and examples of direct sensing with MOF-modified electrodes.
Laser-induced graphene (LIG) electrodes have become popular for electrochemical sensor fabrication due to their simplicity for batch production without the use of reagents. The high surface area and ...favorable electrocatalytic properties also enable the design of small electrochemical devices while retaining the desired electrochemical performance. In this work, we systematically investigated the effect of LIG working electrode size, from 0.8 mm to 4.0 mm diameter, on their electrochemical properties, since it has been widely assumed that the electrochemistry of LIG electrodes is independent of size above the microelectrode size regime. The background and faradaic current from cyclic voltammetry (CV) of an outer-sphere redox probe Ru(NH3)63+ showed that smaller LIG electrodes had a higher electrode roughness factor and electroactive surface ratio than those of the larger electrodes. Moreover, CV of the surface-sensitive redox probes Fe(CN)63– and dopamine revealed that smaller electrodes exhibited better electrocatalytic properties, with enhanced electron transfer kinetics. Scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy showed that the physical and chemical surface structure were different at the electrode center versus the edges, so the electrochemical properties of the smaller electrodes were improved by having rougher surface, more density of the graphitic edge planes, and more oxide-containing groups. The difference could be explained by the different photothermal reaction time from the laser scribing process that causes different stable carbon morphology to form on the polymer surface. Our results give a new insight on relationships between surface structure and electrochemistry of LIG electrodes and are useful for designing miniaturized electrochemical devices.
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This study describes the development of a new electrochemical paper-based analytical device (ePAD) on alumina sandpaper substrate through a pencil-drawing process for square wave voltammetry ...measurements of midazolam maleate used as a “date rape drug” in beverages. The proposed ePAD was assembled on a reusable 3D printed holder to delimit its geometric area and ensure better robustness. The ePAD was characterized by scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy and Raman spectroscopy. The direct drawing of ePADs on sandpaper platforms through a graphite pencil has offered suitable repeatability (RSD = 1.0%) and reproducibility (RSD = 4.0%) using Fe(CN)64– as redox probe. The proposed ePAD provided linear behaviour in the midazolam maleate concentration range between 2.5 and 150 mg L−1 and a limit of detection of 2.0 mg L−1. The feasibility of the ePAD for forensic application was successfully demonstrated through the detection of midazolam in different beverages (water, beer, liquor, and vodka). The intended application revealed low interference of other compounds present in beverages. Based on the achieved results, the proposed ePAD has offered great accuracy with no statistical difference at 95% confidence level from the data recorded by high performance liquid chromatography. The operational simplicity and the robustness ensured by the assembling on a reusable 3D printed holder make the ePAD drawn on sandpaper platform a powerful and promising analytical tool for the analysis of “date rape drugs” opening new possibilities for on-site forensic investigations.
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•Sandpaper substrate was explored to fabricate electrochemical devices through pencil drawing protocol.•ePADs were assembled on a reusable 3D-printed holder and covered with PDMS to define the geometric area.•The forensic feasibility was demonstrated through the detection of date rape drug.•The achieved results revealed good agreement with the data recorded using HPLC.•The proposed assembled device offered operational simplicity and an environmentally friendly strategy.
The review provides a concise summary of recent works carried in the area of electro-chemical driven sensor systems which particularly utilize MXenes or its derivatives as hybrids or composites to ...serve as a suitable direct or indirect transducer platform
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MXenes have emerged as versatile 2D materials that are already gaining paramount attention in the areas of energy, catalyst, electromagnetic shielding, and sensors. The unique surface chemistry, graphene-like morphology, high hydrophilicity, metal-like conductivity with redox capability identifies MXenes, as an ideal material for surface-related applications. This short review summarizes the most recent reports that discuss the potential application of MXenes and their hybrids as a transducer material for advanced sensors. Based on the nature of transducing signals, the discussion is categorized into three sections, which include electrochemical (bio) sensors, gas sensors, and finally, electro-chemiluminescence & fluorescent sensors. The review provides a concise summary of all the analytical merits obtained subsequent to the use of MXenes, followed by endeavors that have been made to accentuate the future perspective of MXenes in sensor devices.
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