Bisphenol A (BPA), one of the most important endocrine disrupting chemicals, is a threat to human and wildlife health. Electrochemical enzyme biosensor has been regarded as ideal alternative ...analytical technique for ultrasensitive and rapid detection of BPA, while the unstable and easily deactivated nature of enzyme limits its development. In order to improve the stability of enzyme, tyrosinase was chosen as a model enzyme, and tyrosinase nanocapsules (nTyr) were prepared by encapsulating a single tyrosinase molecule into a thin network polymer shell through in-situ polymerization method in aqueous solution. The characterization of particle size distribution, TEM and FTIR indicated the successful formation of single tyrosinase molecule nanocapsule. And the porous network polymer shell of nTyr ensured the maintenance of tyrosinase activity and fast substrate transportation. The obtained nTyr was used to construct an electrochemical biosensor for BPA detection, exhibiting a low detection limit of 12 nmol L-1 and a wide linear range from 5 × 10-8 to 2 × 10-6 mol L-1. Compared with native tyrosinase, the nTyr based biosensor displayed dramatically enhanced stability including thermal stability, organic solvent tolerance and acid/base tolerance. The excellent performance of nTyr based biosensor was not only attributed to the protection of biocompatible rigid polymer shells, but also the multipoint covalent attachments between tyrosinase cores and polymer shells. The robust biosensor was further used for rapid detection of BPA leached from plastic products with satisfactory results. The nTyr based nano-biosensor provides a prospective solution to resolve the stability problem of enzyme biosensors in different application scenarios.
•Robust single molecule enzyme nanocapsules of Tyrosinase (nTyr) were firstly synthesized.•Polymer shell effectively stabilized the interior tyrosinase core while enabling rapid substrate transportation.•A new class of highly stable nTyr based biosensors was constructed for detecting BPA in different application scenarios.•The nTyr based biosensor displayed significantly enhanced stability in extreme operational conditions.•The nTyr based biosensor provides a prospective solution to resolve the stability problem of enzyme biosensors.
MXene has emerged as an amazing family of two dimensional (2D) layered materials and drawn great attention from researchers of diverse scientific fields. MXenes are the recent advancements of ...materials chemistry which include early transition metal carbides, nitrides and carbonitrides produced by exfoliation of selective MAX phases. MAX phase corresponds to the general formula Mn+1AXn (n = 1, 2, 3) where M represents early d-block transition metals, A stands for main group sp elements (specifically groups 13 and 14) and X is either C or N atoms. MXenes have left a prodigious impact on scientific communities with new technological advancements for a plethora of potential applications in the field of catalysis, clean energy, electronics, fuel cells, supercapacitors etc. With high metallic conductivity, hydrophilicity, low diffusion barrier, high ion transport properties, biocompatibility, large surface area and ease of functionalization, the MXenes act as fascinating interface for designing next generation detection systems exploiting their utilization in analytical chemistry. Recent progress in the field of MXenes emphasizing their significant role in analytical sensing has been well discussed in this review. Future perspectives with a motivated research in the field of MXenes based sensors have been focused at the end. The underlying goal of this review is to acquaint the readers with the sensing applications of MXenes and to document the latest advancements made in this area till date.
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•MXenes: early transition metal carbides, nitrides and carbonitrides with unique layered morphology.•Emerging new generation platform for sensing and biosensing.•MXene based detection devices other than titanium (Ti) are very rare.•Exploitation of new MXene materials in sensing technology is highly anticipated.
•An SPE cleanup method of PCNs and dl-PCBs in complex samples was developed.•MgO microspheres and basic alumina were used as SPE adsorbents.•The method showed excellent efficiency to remove various ...interferences.•The ASE/SPE/GC–MS/MS method was used to analyze PCNs and dl-PCBs in samples.•The analytical method was simple, rapid, and environmentally friendly.
A solid-phase extraction (SPE) cleanup method was developed to purify the sample extracts for the analysis of polychlorinated naphthalenes (PCNs) and dioxin-like polychlorinated biphenyls (dl-PCBs). Monodisperse magnesium oxide (MgO) microspheres and basic alumina were used as SPE adsorbents. Important parameters of the SPE procedure were optimized, including the amount of basic alumina and the type and volume of the washing and elution solvents. The optimized SPE cleanup method exhibited excellent purification performance for the removal of organochlorinated compounds, lipid compounds, sulfur, and pigments. Additionally, it was found that the retention activities of congeners differed with the number and position of the chlorine substituents in PCNs. In this study, an analytical method based on a combination of accelerated solvent extraction (ASE) coupled with SPE cleanup and gas chromatography-triple quadrupole mass spectrometry (GC–MS/MS) is proposed for the analysis of PCNs and dl-PCBs in complex samples (sediment, pine needle, and scallop samples). The analytical method demonstrates good linearity, acceptable recovery (63–148%) and precision (relative standard deviations less than 26%). The limits of detection (LODs) of PCN and dl-PCB congeners were in the range of 0.6–19.1pgg−1 and 0.4–8.6pgg−1, respectively. The PCNs and dl-PCBs levels in these samples ranged from 0.16 to 3.07ngg−1 dry weight (dw) and from undetectable to 0.07ngg−1 dw, respectively.
The present study demonstrates the use of highly stable single-molecule enzyme nanocapsules (SMENs) instead of traditional native enzyme as biorecognition element in enzyme-based biosensors. The main ...purpose of this study is to resolve the major obstacle and challenge in the biosensor field, i.e., the poor stability of enzyme-based biosensors, including thermal stability, organic solvent tolerance, long-term operational stability, etc. Highly active and robust SMENs of glucose oxidase (GOx, as a model enzyme) were synthesized (nGOx) using an in situ polymerization strategy in an aqueous environment. The particle-size distribution, transmission electron microscopic (TEM) images, and UV–vis spectral characterization revealed the formation of a thin polymer layer around each enzyme molecule. The polymer shell effectively stabilized the GOx enzyme core while enabling rapid substrate transportation, resulting in a new class of biocatalytic nanocapsules. Multiple covalent attachments between a thin polymer layer and an enzyme molecule strengthened the encapsulated GOx molecule. Encapsulation created a favorable microenvironment to avoid any structural dissociation at high temperature and helped to retain essential water during the organic solvent operation. The present work reports a study implementing nGOx SMENs as highly stable nano(bio)sensors for point-of-care diagnostic applications. Prepared nGOx SMENs manifested significantly improved thermal stability (even at 65 °C) and organic solvent tolerance without any compromise in biocatalytic activity. For example, the native GOx-based biosensor lost its catalytic activity for glucose after 4 h of incubation at high temperature (65 °C), while the nGOx/N-CNTs-Chi/GCE nano(bio)sensor maintained ∼56% of its original catalytic activity for glucose oxidation. The proposed SMENs-based nano(bio)sensors with robust stability in variable working environment could promote the development and applications of biosensors in point-of care diagnostics, biomedical detection, wearable devices, implantable equipment, and biofuel cells.
Textile and their composite-based functional sensors are extensively acknowledged and preferred detection platforms in recent times. Developing suitable methodologies for fabricating textile sensors ...can be achieved either by integration of conductive fibers and yarns into textiles using technologies such as weaving, knitting and embroidery; or by functionalization of textile materials with conductive nanomaterials/inks using printing or coating methods. Textile materials are gaining enormous attention for fabricating soft lab-on-fabric devices due to their unique features such as high flexibility, wear and wash resistance, mechanical strength and promising sensing performances. Owing to these collective properties, textile-based electrochemical transducers are now showcasing rapid and accurate electrical measurements towards real time point-of-care diagnostics and environmental monitoring applications. The present review provides a brief overview of key progress made in the field of developing textile materials and their composites-based electrochemical sensors and biosensors in recent years where electrode configurations are specifically based on either natural or synthetic fabrics. Different ways to fabricate and functionalize textiles for their application in electrochemical analysis are briefly discussed. The review ends with a conclusive note focusing on the current challenges in the fabrication of textile-based stable electrochemical sensors and biosensors.
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•Textile materials as electrochemical sensors and biosensors.•Fabrication of conductive textile sensors by different methods.•Electro-analysis of relevant analytes based on textile sensors for real time applications.•Utilization of textile materials in organic electrochemical transistors.
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► A nano graphene-multiwalled carbon nanotubes (nGN-MWCNTs) composite film based sensor was fabricated. ► Sensor showed excellent electrocatalytic activity to the oxidation of ...anti-arrhythmic agent quinidine. ► A sensitive, rapid and simple electroanalytical method was developed for quinidine. ► The sensor was successfully applied for detection of quinidine in tablet dosage form using a solubilized system.
An ultrasensitive electrochemical sensor based on the electrocatalytic properties of nano graphene (nGN) and multiwalled carbon nanotubes (MWCNTs) for the detection of quinidine (QD) in solubilized systems has been developed. This nano graphene-multiwalled carbon nanotube (nGN-MWCNT) composite film modified sensor shows the higher stability and stronger catalytic activity towards oxidation of quinidine and the over-potential decreased significantly compared with the bare glassy carbon electrode (GCE). The electrochemical characterization of the sensor was done by scanning electron microscopy (SEM) and cyclic voltammetry (CV) with working electrode surface area 0.56cm2 and diffusion coefficient 2.15×10−3cm2s−1. Under the optimized conditions, the oxidation peak current of QD is found to be proportional to its concentration in the range of 60ng–50μg with a detection limit of 0.186ng. The sensor was successfully employed for the detection of quinidine in bulk drugs and in its commercial pharmaceutical formulation.
With the emerging interest in layered transition metal dichalcogenides (TMDs), MoS2 has occupied a unique place in recent times as graphene (GR) analog. Development of novel state of the art ...electrochemical approaches at MoS2 modified working surfaces is an upcoming field and holds great promise for design and development of next generation sensing devices. Large available surface area, high biocompatibility and structural versatility of 2D/3D MoS2 nanostructures have produced numerous hybrid sensors and biosensors which have demonstrated their prominent role in biological, environmental, pharmaceutical, chemical, industrial and food analysis. A comprehensive and critical detail of recent advancements of MoS2 based sensors for real time applications have been presented in the present review. Overall conclusion related to sensing performances of MoS2 nanostructures and future needs to further exploit the unusual properties of mono and few layer of other TMDs for developing advance recognition systems have been concluded at the end.
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•MoS2 is an extraordinary transition metal dichalcogenide (TMDs) material with unique electronic features.•Exfoliated layered MoS2 hold great promise for design and development of next generation sensing devices.•Recent advancements made in the field of electrochemical sensing and biosensing at MoS2 based interfaces have been provided.•Possibilities of TMDs based electrodes other than MoS2 for electrochemical sensing applications have also been discussed.
A novel GR based zinc oxide nanorods nanocomposite modified glassy carbon electrode (GR/ZnORs/GCE) sensor has been developed for electroquantification of tizanidine in micellar medium.
•Graphene ...based zinc oxide nanorods nanocomposite sensor has been fabricated.•High electrocatalytic performance towards reduction of tizanidine.•A successful method for electroquantification of tizanidine has been developed at GR/ZnORs/GCE sensor in surfactant medium of CTAB.
A new graphene/zinc oxide nanorods modified glassy carbon electrode (GR/ZnORs/GCE) based electrochemical sensor has been developed for the sensitive determination tizanidine (TZ) in solubilized system. The fabricated sensor was characterized by various electrochemical methods. Different kinetic parameters affecting the monitored electrocatalytic response were investigated and optimized for tizanidine determination at fabricated GR/ZnORs/GCE sensor and successfully compared with the results obtained at GR/SiO2/GCE, GR/GCE and at bare GCE. Under optimized conditions the square wave current is linear over the concentration range 0.80ngmL−1 to 10.0μgmL−1 with detection limit and quantification limit of 0.10ngmL−1 and 3.45ngmL−1 respectively. The applicability of proposed method is further extended to in vitro determination of the drug in pharmaceutical formulation with an acceptable recovery from 97.89% to 101.09%.
Hydrogels are hydrophilic polymeric networks prepared by physical or chemical cross-linking of gelator molecules under optimum conditions. Being sensitive to external stimuli, hydrogels are ...integrated into signal transduction systems for generating possible responses upon interaction with target analytes to study various physiochemical/biochemical molecular recognition processes. In recent times, polymer based hydrogel materials have emerged as unique electrode modifying materials providing highly permeable matrix for easy diffusion of analytes and rapid electron transport. Polymeric architectures of hydrogels can accommodate different nanomaterials within its matrix through suitable interactions to form hydrogel nanocomposites. Further, high biocompatibility of hydrogels facilitates facile encapsulation and cross-linking of bioreceptors (eg. nucleic acid, protein) into polymer matrix and helps to retain their bioactivity during practical applications. Polymer hydrogel materials enable easy prototyping of electrodes using novel printing technologies for designing next generation advanced, flexible and portable bioelectronics with excellent sensing performances. The present article focuses on the implication of polymer hydrogels as high performance electrode materials. Taking relevant examples, nanomaterials incorporated polymer hydrogel based chemical sensors and bioreceptors embedded biosensors have been discussed for electrochemical detection of different analytes. Preparation of hydrogel modified electrodes and state-of-the-art sensing mechanisms have been briefly emphasized. Concluding remarks and future prospects regarding fabrication of hydrogel based smart electronics have been provided at the end.
•Polymer based hydrogels as electrode interfaces in electrochemical sensing strategies.•Facile encapsulation and cross-linking of biorecepters due to high biocompatibility of hydrogels.•Hydrogel nano(bio)composite sensors for analyte detection through electrochemical transduction mechanisms.•Future prospects regarding fabrication of hydrogel based smart electronics have been provided.
Graphdiyne (GDY), a new two-dimensional all-carbon allotrope composed of benzene rings and alkyne unites, was successfully synthesized via a crossing-coupling reaction with much intriguing properties ...especially highly π-conjugated structure, attractive electronic and chemical properties, good biocompatibility and dispersion in aqueous solution. The as-prepared graphdiyne was explored for the first time as an extremely attractive matrix for tyrosinase (a model enzyme) immobilization to construct a mediator-free GDY-based biosensor for rapid detection of bisphenol A (BPA). The response of GDY-based tyrosinase biosensor is linear over the range of 1.0 × 10−7 to 3.5 × 10−6 mol L−1 with a high sensitivity of 2990.8 mA cm−2 M−1 and a low detection limit of 24 nmol L−1. The proposed GDY-based tyrosinase biosensor exhibited better analytical performances for BPA detection than CNTs and graphene based biosensors. The excellent performance of the biosensor should partially be ascribed to the strong π-π interactions between graphdiyne and BPA, which could enrich available BPA concentration on the electrode to react with tyrosinase. The robust GDY-based tyrosinase biosensor was used for BPA detection in drinking bottles and tap water with satisfactory results. As a new 2D all-carbon nanomaterial, graphdiyne is proved to be a powerful electrochemical enzyme biosensor platform for biomolecules (as recognition elements) immobilization and biosensor fabrication, and provides great application prospect for biomedical detection and environmental analyses.
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