Recent Advances and Perspective on Design and Synthesis of Electrode Materials for Electrochemical Sensing of Heavy Metals

The increase in release of toxic heavy metals into natural water attracts much attention due to its devastating effect on ecology and human health.The design and implementation of green electrode materials is pivotal for improving the electrochemical performance of in situ heavy metal monitoring.

Synthesis and electrochemical properties of environmental free Lglutathione grafted graphene oxide/ZnO nanocomposite for highly selective piroxicam sensing

A simple and reliable strategy was proposed to engineer the glutathione grafted graphene oxide/ZnO nanocomposite(glutathione-GO/ZnO)as electrode material for the high-performance piroxicam sensor.The prepared glutathione-GO/ZnO nanocomposite was well characterized by X-ray diffraction(XRD),Fourier transform infrared spectrum(FTIR),X-ray photoelectron spectroscopy(XPS),field emission scanning electron microscopy(FE-SEM),cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS)and differential pulse voltammetry(DPV).The novel nanocomposite modified electrode showed the highest electrocatalytic activity towards piroxicam(oxidation potential is 0.52 V).Under controlled experimental parameters,the proposed sensor exhibited good linear responses to piroxicam concentrations ranging from 0.1 to 500 μM.The detection limit and sensitivity were calculated as 1.8 μM and 0.2 μA/μM·cm^(2),respectively.Moreover,it offered excellent selectivity,reproducibility,and long-term stability and can effectively ignore the interfering candidates commonly existing in the pharmaceutical tablets and human fluids even at a higher concentration.Finally,the reported sensor was successfully employed to the direct determination of piroxicam in practical samples.

Revisiting Some Recently Developed Conducting Polymer@Metal Oxide Nanostructures for Electrochemical Sensing of Vital Biomolecules:A Review

Polymers and metal oxides are well-known materials for various electrochemical sensing applications due to their distinctive properties.In the current decades,the use of composites and nanocomposites of polymer and/or metal oxide in the sensing domain has been drastically explored.This review conveys the pursuance of several conducting and non-conducting polymers such as polypyrrole,polyvinylpyrrolidone,polyaniline,polythiophene,polyacetylene and their derivatives with several metal oxides(such as TiO_(2),SiO_(2),CeO2,ZnO,CuO,MnO_(2),Fe_(3)O_(4))in the area of electrochemical sensing of some important biomolecules.Herein,various methods of synthesis of nanocomposites,different characterization techniques employed,electrode modification and fabrication methods adopted are cited with rich comparative discussion for sensing applications,specifically in the field of electrochemical and bio-sensing impact using various electrochemical methods are also reviewed.The review will provoke and support the modern researchers of the field to approach new avenues.

Molybdenum disulfide-graphene van der Waals heterostructures as stable and sensitive electrochemical sensing platforms

Atomic layers are sought after for molecular sensing due to their available high surface interaction area,and different types of monolayers are attempted for sensing in the recent past.However,their chemical stability towards these molecules is questioned in recent times and alternate methods need to be developed to circumvent such issues,while maintaining high sensitivity.Here,the van der Waals(vdWs)stacks of molybdenum disulfide(MoS_(2))and graphene are shown for their stable electrochemical sensing towards ascorbic acid(AA)and dopamine(DA)-two important biomolecules.AA is known to chemically react with MoS_(2) leading to unstable sensing platform,while here the graphene coverage is shown to protect the MoS_(2) even from low-energy plasma exposure while keeping the same high sensitivity.Upon proving the graphene-based protection of the sensor,such a sensing platform is shown for its applicability in DA sensing,where it is found to give a linear response in a wide range of concentrations(2.5 to 600μmol·L^(−1))and even selective sensing in the presence of AA.Such a stack is found to be not merely giving protection to the beneath MoS_(2) layer but also the inter-layer charge transfer due to work function differences being beneficial in bringing fast and high sensitivity to the next-generation sensors and point-of-care devices.

Advances on ultra-sensitive electrospun nanostructured electrochemical and colori metric sensors for diabetes mellitus detection

Recent developments in the biochemical and medicinal industries have been heavily focused on producing affordable glucose biosensors due to the condi nuous annual increase of diabetic patients worldwide.The devel-opment of a fast,accurate,and reliable glucose sensor will increase confidence in controlling di abetes mellitus and its assoclated health complications among the diabetic community.Electraspinning is a versatile method that can produce complex nanofbrous assemblies with attractiwe and functional characteristics from varlous polymers.Electrospun nanofibers demonstrated high efficiency in the immobilization of biological molecules,which can improve the sensing performance further.Integr ation of polymer electrospun nanofibers with metal nanoparticles,metal oxde or transition metal in producing nanobiocomposites is also a highly popul ar approach in the past few years.This report presents the current progress and research trends of the technique,focusing on varous ma-terials and fabrication strategies used to produce biosensing interfaces.This helps readers decide the suitable approach in designing highly sensitive,selective,fast,and inexpensive glucose sensors.

CRISPR-Cas12a-Empowered Electrochemical Biosensor for Rapid and Ultrasensitive Detection of SARS-CoV-2 Delta Variant

Coronavirus disease 2019(COVID-19)is a highly contagious disease caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).The gold standard method for the diagnosis of SARS-CoV-2 depends on quantitative reverse transcription-polymerase chain reaction till now,which is time-consuming and requires expensive instrumentation,and the confirmation of variants relies on further sequencing techniques.Herein,we first proposed a robust technique-methodology of electrochemical CRISPR sensing with the advantages of rapid,highly sensitivity and specificity for the detection of SARS-CoV-2 variant.To enhance the sensing capability,gold electrodes are uniformly decorated with electro-deposited gold nanoparticles.Using DNA template identical to SARS-CoV-2 Delta spike gene sequence as model,our biosensor exhibits excellent analytical detection limit(50 fM)and high linearity(R2=0.987)over six orders of magnitude dynamic range from 100 fM to 10 nM without any nucleic-acid-amplification assays.The detection can be completed within 1 h with high stability and specificity which benefits from the CRISPR-Cas system.Furthermore,based on the wireless micro-electrochemical platform,the proposed biosensor reveals promising application ability in point-of-care testing.

Stretchable Electrochemical Sensors: From Electrode Fabrication to Cell Mechanotransduction Monitoring

Electrochemical sensing faces huge challenges in characterizing the transient release of biochemical molecules from deformed cells,due to the severely mechanical mismatch between rigid electrodes and soft cells.In recent years,the emergence of stretchable electrochemical sensors has made a breakthrough by complying with the deformation of living cells and simultaneous monitoring of mechanically evoked biochemical signals.This review first summarizes two fundamental strategies for the fabrication of stretchable electrodes from the points of structure and material.Next,recent progresses in construction of functionalized interface to improve the performance of stretchable electrochemical sensors are presented.Then,the application of stretchable electrochemical sensors in real-time monitoring of biomolecules released by mechanically sensitive cells is introduced.Finally,some perspectives and challenges of stretchable electrochemical sensors regarding cell detection are discussed.

Shining light on transition metal tungstate-based nanomaterials for electrochemical applications:Structures,progress,and perspectives

Transition metal tungstate-based nanomaterials have become one of the research hotspots in electrochemistry due to their abundant natural resources,low costs,and environmental friendliness.Extensive studies have demonstrated their significant potentials for electrochemical applications,such as supercapacitors,Li-ion batteries,Na-ion batteries,electrochemical sensing,and electrocatalysis.Considering the rapidly growing research enthusiasm for this topic over the last several years,herein,a critical review of recent progress on the application of transition metal tungstates and their composites for electrochemical applications is summarized.The relationships between synthetic methods,nano/micro structures and electrochemical properties are systematically discussed.Finally,their promising prospects for future development are also proposed.It is anticipated that this review will inspire ongoing interest in rational designing and fabricating novel transition metal tungstate-based nanomaterials for high-performance electrochemical devices.

Trends in Gunshot Residue Detection by Electrochemical Methods for Forensic Purpose

Gunshot Residue(GSR)has been a subject of interest for the forensic fraternity.Numerous analytical contributions towards the GSR analysis have been reported.Sensitivity,portability,cost-effectiveness,speed,etc.are such factors of electrochemical methods that have attracted the researchers across the globe to test the applicability of these as a potential analytical tool for forensic evaluation of GSR.With the development of scientific technology,efforts have been made towards the handheld device for the on-field analysis of GSR.Recently,chemometric treatment of data generated from the electrochemical analysis of GSR has offered more effective approach.It makes the analysis more conclusive and minimizes the chances of false-positive detection.It will be very fruitful to anticipate the analytical potential of electrochemical tools for GSR analysis.This article reviews the research progress towards the development of electrochemical sensor for GSR detection reported during 2013-2020 along with challenges and future perspectives.

Hydroxyl-and-carboxyl ligand concatenating multi-lanthanide substituted tellurotungstates and electrochemical detection of noradrenaline

Developing and exploring organic-inorganic hybrid multi-lanthanide(Ln)implanted heteropolyoxometalates(HPOMs)has bloomed into an emerging research fieId.In this article,two neoteric Dgluconic acids(H_(6)GA)concatenating multi-Ln^(Ⅲ) implanted heteropoly tungstates K_(14)H_(10)[Ln_(4)(H_(2)O)_(4)W_(6)(H_(2)-GA)_(4) O_(12)(B-α-TeW_(9)O_(33))_(4)]·60 H_(2)O(Ln=La^(3+)(1),Pr^(3+)(2))were obtained in acidic aqueous system.Attractively,in the polyanion structure of 1 and 2,six WⅥand four LnⅢcenters are connected by four flexible H_(2)GA^(4-) ligands via carboxyl and hydroxyl groups,resulting in the heterometallic[Ln_(4)(H_(2)O)_(4)W_(6)H_(2)GA)_(4)O_(12)]^(8+)cluster and then the heterometallic cluster is surrounded by four[B-α-TeW_(9)O_(33)]^(8-)segments.Electrochemical measurements for the 1@CFMCN/GCE sensor(CFMCN=carboxylfunctionalized multiwalled carbon nanotube;GCE=glass carbon electrode)demonstrate that 1@CFMCN/GCE shows benign recognition response to detecting noradrenaline(NDA).This research expands the structural diversity of Ln-implanted HPOMs and presents an electrochemical platform of recognizing NDA in the field of biosensors.