A novel engineered label-free Zn-based MOF/CMC/AuNPs electrochemical genosensor for highly sensitive determination of Haemophilus Influenzae in human plasma samples

Electrospun EU/HPMC nanofibers decorated by ZIF-8 nanoparticle as the advanced electrochemical biosensor modifier for sensitive and selective detection of c-MET cancer biomarker in human plasma sample

This research presents a selective and sensitive electrochemical biosensor for the detection of the mesenchymal-epithelial transition factor (c-MET). The biosensing is based on a modification of the SPCE (screen-printed carbon electrode) with the electrospun nanofiber containing eudragit (EU), hydroxypropyl methylcellulose (HPMC), and Zeolite imidazolate frameworks (ZIF-8) nanoparticles. EU/HPMC/ZIF-8 nanofibers have presented a high capability of electron transfer, and more active surface area than bare SPCE due to synergistic effects between EU, HPMC, and ZIF-8. On the other hand, EU/HPMC nanofibers provided high porosity, flexible structures, high specific surface area, and good mechanical strength. The presence of ZIF-8 nanoparticles improved the immobilization of anti-c-MET on the modified SPCE and also resulted in increasing the conductivity. By c-MET incubation on the modified SPCE, c-MET was connected to anti-c-MET, and consequently the electrochemical signal of [Fe(CN)6]3-/4- as the anion redox probe was reduced. In order to investigate the structural and morphological characteristics and elemental composition of electrospun nanofibers, various characterization methods including FE-SEM, XRD, FTIR, and EDS were used. Under optimum conditions with a working potential range -0.3-0.6 V (vs. Ag/AgCl), linear range (LR), correlation coefficient (R2), sensitivity, and limit of detection (LOD) were acquired at 100 fg/mL-100 ng/mL, 0.9985, 53.28 μA/cm2.dec, and 1.28 fg/mL, respectively. Moreover, the mentioned biosensor was investigated in a human plasma sample to determine c-MET and showed ideal results including reproducibility, stability, and good selectivity against other proteins.

Exploring the potential of SrTi0.7Fe0.3O3 perovskite/Chitosan nanosheets for the development of a label-free electrochemical sensing assay for determination of naproxen in human plasma samples

Naproxen is a nonsteroidal anti-inflammatory drug used to treat nonrheumatic inflammation, migraine, and gout. Therefore, the determination of naproxen in pharmaceutical and biological samples is of particular importance. In the present work, SrTi0.7Fe0.3O3 perovskite/Chitosan nanosheets were used to modify the surface of a glassy carbon electrode (GCE) for highly sensitive determination of naproxen. To ensure the successful synthesis of the perovskite nanosheets, morphological studies including scanning electron microscopy (SEM), Energy-dispersive X-ray (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) were carried out. The electrochemical investigations of naproxen on the modified surface of GCE were investigated and the limit of detection (LOD) and limit of quantification (LOQ) were acquired 0.50 and 1.67 μM, respectively. Additionally, the linear range (LR) of 1.99-130.84 μM was obtained for the oxidation of naproxen. The obtained results have been proved that the mentioned method is simple, sensitive, and specific with a short analysis time. The dominant analytical features of the designed sensor are possessing a low detection limit, excellent stability, repeatability, and high selectivity in the presence of naproxen. For investigation of the applicability of the designed assay in real sample analysis, human plasma samples have been examined and a recovery index was acquired 95%.

Research progress of metal-organic framework nanozymes in bacterial sensing, detection, and treatment

The high efficiency and specificity of enzymes make them play an important role in life activities, but the high cost, low stability and high sensitivity of natural enzymes severely restrict their application. In recent years, nanozymes have become convincing alternatives to natural enzymes, finding utility across diverse domains, including biosensing, antibacterial interventions, cancer treatment, and environmental preservation. Nanozymes are characterized by their remarkable attributes, encompassing high stability, cost-effectiveness and robust catalytic activity. Within the contemporary scientific landscape, metal-organic frameworks (MOFs) have garnered considerable attention, primarily due to their versatile applications, spanning catalysis. Notably, MOFs serve as scaffolds for the development of nanozymes, particularly in the context of bacterial detection and treatment. This paper presents a comprehensive review of recent literature pertaining to MOFs and their pivotal role in bacterial detection and treatment. We explored the limitations and prospects for the development of MOF-based nanozymes as a platform for bacterial detection and therapy, and anticipate their great potential and broader clinical applications in addressing medical challenges.

Recent advances in electrochemical aptasensors and genosensors for the detection of pathogens

In recent years, pathogenic microorganisms have caused significant mortality rates and antibiotic resistance and triggered exorbitant healthcare costs. These pathogens often have high transmission rates within human populations. Rapid diagnosis is crucial in controlling and reducing the spread of pathogenic infections. The diagnostic methods currently used against individuals infected with these pathogens include relying on outward symptoms, immunological-based and, some biomolecular ones, which mainly have limitations such as diagnostic errors, time-consuming processes, and high-cost platforms. Electrochemical aptasensors and genosensors have emerged as promising diagnostic tools for rapid, accurate, and cost-effective pathogen detection. These bio-electrochemical platforms have been optimized for diagnostic purposes by incorporating advanced materials (mainly nanomaterials), biomolecular technologies, and innovative designs. This review classifies electrochemical aptasensors and genosensors developed between 2021 and 2023 based on their use of different nanomaterials, such as gold-based, carbon-based, and others that employed other innovative assemblies without the use of nanomaterials. Inspecting the diagnostic features of various sensing platforms against pathogenic analytes can identify research gaps and open new avenues for exploration.

Fiber Integrated Metal-Organic Frameworks as Functional Components in Smart Textiles

Owing to high modularity and synthetic tunability, metal-organic frameworks (MOFs) on textiles are poised to contribute to the development of state-of-the-art wearable systems with multifunctional performance. While these composite materials have demonstrated promising functions in sensing, filtration, detoxification, and biomedicine, their applicability in multifunctional systems is only beginning to materialize. This review highlights the multifunctionality and versatility of MOF-integrated textile systems. It summarizes the operational goals of MOF@textile composites, encompassing sensing, filtration, detoxification, drug delivery, UV protection, and photocatalysis. Building upon these recent advances, this review concludes with an outlook on emerging opportunities for the diverse applications of MOF@textile systems in the realm of smart wearables.

Label-free electrochemical immunosensor for detection of insulin-like growth factor-1 (IGF-1) using a specific monoclonal receptor on electrospun Zein-based nanofibers/rGO-modified electrode

A novel electrochemical immunosensor was developed for ultrasensitive determination of the hormone insulin-like growth factor 1 (IGF-1) based on immobilization of a specific monoclonal antibody on the electrospun nanofibers of Polyacrylonitrile (PAN)/Zein-reduced graphene oxide (rGO) nanoparticle. The nanofibers deposited on glassy carbon electrode (GCE) showed good electrochemical behaviors with synergistic effects between PAN, Zein, and rGO. PAN/Zein nanofibers were used due to flexibility, high porosity, good mechanical strength, high specific surface area, and flexible structures, while rGO nanoparticles were used to improve the detection sensitivity and anti-IGF-1 immobilizing. Different characterization techniques were applied consisting of FE-SEM, FT-IR, and EDS for the investigation of morphological features and nanofiber size. The redox reactions of [Fe(CN)6]4-/3- on the modified electrode surface were probed for studying the immobilization and determination processes, using differential pulse voltammetry (DPV) and cyclic voltammetry (CV). Under optimal conditions, LOD (limit of detection) and LOQ (limit of quantification) were obtained as 55.72 fg/mL and 185.73 fg/mL respectively, and sensitivity was acquired 136.29 μA/cm2.dec. Moreover, a wide linear range was obtained ranging from 1 pg/mL to 10 ng/mL for IGF-1. Furthermore, the proposed method was applied for the analysis of IGF-1 in several human plasma samples with acceptable results, and it also exhibited high selectivity, stability, and reproducibility.

Detection of receptor tyrosine kinase-orphan receptor-2 using an electrochemical immunosensor modified with electrospun nanofibers comprising polyvinylpyrrolidone, soy, and gold nanoparticles

An electrochemical immunosensing platform was developed for the detection of receptor tyrosine kinase-orphan receptor-2 (ROR2) at a glassy carbon electrode (GCE) modified with the electrospun nanofiber containing polyvinylpyrrolidone (PVP), soy, and Au nanoparticles (AuNPs). The PVP/soy/AuNP nanofiber exhibited good electrochemical behavior due to synergistic effects between PVP, soy, and AuNPs. The PVP/soy in the modified film provided good mechanical strength, high porosity, flexible structures, and high specific surface area. On the other hand, the presence of AuNPs effectively improved conductivity, as well as the immobilization of anti-ROR2 on the modified GCE, leading to enhanced sensitivity. Various characterization approaches such as FE-SEM, FTIR, and EDS were used for investigating the morphological and structural features, and the elemental composition. The designed immunosensor performance was investigated using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and differential pulse voltammetry (DPV). Under optimum conditions with a working potential range from -0.2 to 0.6 V (vs. SCE), sensitivity, linear range (LR), limit of detection (LOD), and correlation coefficient (R2) were acquired at 122.26 μA/cm2 dec, 0.01-1000 pg/mL, 3.39 fg/mL, and 0.9974, respectively. Furthermore, the determination of ROR2 in human plasma samples using the designed immunosensing platform was examined and exhibited satisfactory results including good selectivity against other proteins, reproducibility, and cyclic stability.

Boron-doped diamond nanosheet volume-enriched screen-printed carbon electrodes: a platform for electroanalytical and impedimetric biosensor applications

This paper focuses on the development of a novel electrode based on boron-doped diamond nanosheet full-volume-enriched screen-printed carbon electrodes (BDDPE) for use as an impedimetric biosensor. Impedimetric biosensors offer high sensitivity and selectivity for virus detection, but their use as point-of-care devices is limited by the complexity of nanomaterials' architecture and the receptor immobilisation procedures. The study presents a two-step modification process involving the electroreduction of diazonium salt at the BDDPE and the immobilisation of antibodies using zero-length cross-linkers for a selective impedimetric biosensor of Haemophilus influenzae (Hi). The incorporation of diamond nanosheets into BDDPE leads to enhanced charge transfer and electrochemical behaviour, demonstrating greatly improved electrochemically active surface area compared with unmodified screen-printed electrodes (by 44% and 10% on average for [Ru(NH3)6]Cl2 and K3[Fe(CN)6], respectively). The presented sensing system shows high specificity towards protein D in Hi bacteria, as confirmed by negative controls against potential interference from other pathogens, with an estimated tolerance limit for interference under 12%. The Hi limit of detection by electrochemical impedance spectroscopy was 1 CFU/mL (measured at - 0.13 V vs BDDPE pseudo-reference), which was achieved in under 10 min, including 5 min sample incubation in the presence of the analyte.

Designing of a unique bioreceptor and fabrication of an efficient genosensing platform for neonatal sepsis detection

We report the results of studies related to the fabrication of a nanostructured graphene oxide (GO)-based electrochemical genosensor for neonatal sepsis detection. Initially, we selected the fimA gene of E. coli for nenonatal sepsis detection and further designed a 20-mer long amine-terminated oligonucleotide. This designed oligonucleotide will work as a bioreceptor for the detection of the virulent fimA gene. An electrochemical genosensor was further developed where GO was used as an immobilization matrix. For the formation of a thin film of GO on an indium tin oxide (ITO)-coated glass electrode, an optimized DC potential of 10 V for 90 s was applied via an electrophoretic deposition unit. Thereafter, the designed oligonucleotides were immobilized through EDC-NHS chemistry. The nanomaterial and fabricated electrodes were characterized via X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and cyclic voltammetry techniques. The fabricated genosensor (BSA/pDNA/GO/ITO) has the ability to detect the target fimA gene with a linear detection range of 10-12 M to 10-6 M, a lower detection limit of 10-12 M and a sensitivity of 114.7 μA M-1 cm-2. We also investigated the biosensing ability of the developed genosensor in an artificial serum sample and the obtained electrochemical results were within the acceptable percentage relative standard deviation (% RSD), indicating that the fabricated genosensor can be used for the detection of neonatal sepsis by using a serum sample.

A Time-Division Multiplexing Multi-Channel Micro-Electrochemical Workstation with Carbon-Based Material Electrodes for Online L-Trosine Detection

In the background of the rapid development of artificial intelligence, big data, IoT, 5G/6G, and other technologies, electrochemical sensors pose higher requirements for high-throughput detection. In this study, we developed a workstation with up to 10 channels, which supports both parallel signal stimulation and online electrochemical analysis functions. The platform was wired to a highly integrated Bluetooth chip used for wireless data transmission and can be visualized on a smartphone. We used this electrochemical test platform with carbon-graphene oxide/screen-printed carbon electrodes (CB-GO/SPCE) for the online analysis of L-tyrosine (Tyr), and the electrochemical performance and stability of the electrodes were examined by differential pulse voltammetry (DPV). The CB-GO-based screen-printed array electrodes with a multichannel electrochemical platform for Tyr detection showed a low detection limit (20 μM), good interference immunity, and 10-day stability in the range of 20-200 μM. This convenient electrochemical analytical device enables high-throughput detection and has good economic benefits that can contribute to the improvement of the accuracy of electrochemical analysis and the popularization of electrochemical detection methods in a wide range of fields.

Valorised polypropylene waste based reversible sensor for copper ion detection in blood and water

Heavy metals and plastic pollutants are the two most disastrous challenges to the environment requiring immediate actions. In this work, a techno-commercially feasible approach to address both challenges is presented, where a waste polypropylene (PP) based reversible sensor is produced to selectively detect copper ions (Cu2+) in blood and water from different sources. The waste PP-based sensor was fabricated in the form of an emulsion-templated porous scaffold decorated with benzothiazolinium spiropyran (BTS), which produced a reddish colour upon exposure to Cu2+. The presence of Cu2+ was checked by naked eye, UV-Vis spectroscopy, and DC (Direct Current) probe station by measuring the current where the sensor's performance remained unaffected while analysing blood, water from different sources, and acidic or basic environment. The sensor exhibited 1.3 ppm as the limit of detection value in agreement with the WHO recommendations. The reversible nature of the sensor was determined by cyclic exposure of the sensor towards visible light turning it from coloured to colourless within 5 min and regenerated the sensor for the subsequent analysis. The reversibility of the sensor through exchange between Cu2+- Cu+ was confirmed by XPS analysis. A resettable and multi-readout INHIBIT logic gate was proposed for the sensor using Cu2+ and visible light as the inputs and colour change, reflectance band and current as the output. The cost-effective sensor enabled rapid detection of the presence of Cu2+ in both water and complex biological samples such as blood. While the approach developed in this study provides a unique opportunity to address the environmental burden of plastic waste management, it also allows for the possible valorization of plastics for use in enormous value-added applications.

A review of rapid food safety testing: using lateral flow assay platform to detect foodborne pathogens

The detrimental impact of foodborne pathogens on human health makes food safety a major concern at all levels of production. Conventional methods to detect foodborne pathogens, such as live culture, high-performance liquid chromatography, and molecular techniques, are relatively tedious, time-consuming, laborious, and expensive, which hinders their use for on-site applications. Recurrent outbreaks of foodborne illness have heightened the demand for rapid and simple technologies for detection of foodborne pathogens. Recently, Lateral flow assays (LFA) have drawn attention because of their ability to detect pathogens rapidly, cheaply, and on-site. Here, we reviewed the latest developments in LFAs to detect various foodborne pathogens in food samples, giving special attention to how reporters and labels have improved LFA performance. We also discussed different approaches to improve LFA sensitivity and specificity. Most importantly, due to the lack of studies on LFAs for the detection of viral foodborne pathogens in food samples, we summarized our recent research on developing LFAs for the detection of viral foodborne pathogens. Finally, we highlighted the main challenges for further development of LFA platforms. In summary, with continuing improvements, LFAs may soon offer excellent performance at point-of-care that is competitive with laboratory techniques while retaining a rapid format.

Self-assembled monolayer-assisted label-free electrochemical genosensor for specific point-of-care determination of Haemophilus influenzae

For sensitive detection of the L-fuculokinase genome related to the Haemophilus influenzae (H. influenzae), this research work demonstrates the label-free electrochemical-based oligonucleotide genosensing assay relying on the performing hybridization process. To enhance the electrochemical responses, multiple electrochemical modifier-tagged agents were effectively utilized. For attaining this goal, NiCr-layered double hydroxide (NiCr LDH) has been synthesized and combined with biochar (BC) to create an efficient electrochemical signal amplifier that has been immobilized on the surface of the bare Au electrode. Low detection and quantification limits (LOD and LOQ) associated with the designed genosensing bio-platform to detect L-fuculokinase have been achieved to 6.14 fM and 11 fM, respectively. Moreover, the wide linear range of 0.1 to 1000 pM demonstrates the capability of the designed platform. Investigated were the 1-, 2-, and 3-base mismatched sequences, and the negative control samples clarified the high selectivity and better performance of the engineered assay. The values of 96.6-104% and 2.3-3.4% have been obtained for the recoveries and RSDs, respectively. Furthermore, the repeatability and reproducibility of the associated bio-assay have been studied. Consequently, the novel method is appropriate for rapidly and quantitatively detecting H. influenzae, and is considered a better candidate for advanced tests on biological samples such as urine samples.

An Ultrasensitive miRNA-Based Genosensor for Detection of MicroRNA 21 in Gastric Cancer Cells Based on Functional Signal Amplifier and Synthesized Perovskite-Graphene Oxide and AuNPs

In the present research work, the state-of-art label-free electrochemical genosensing platform was developed based on the hybridization process in the presence of [Fe(CN)₆]^3-/4- as an efficient redox probe for sensitive recognition of the miRNA-21 in human gastric cell lines samples. To attain this aim, perovskite nanosheets were initially synthesized. Afterward, the obtained compound was combined with the graphene oxide resulting in an effective electrochemical modifier, which was dropped on the surface of the Au electrode. Then, AuNPs (Gold Nano Particles) have been electrochemically-immobilized on perovskite-graphene oxide/Au-modified electrode surface through the chronoamperometry (CA) technique. Finally, a self-assembling monolayer reaction of ss-capture RNA ensued by the thiol group at the end of the probe with AuNPs on the modified electrode surface. miRNA-21 has been cast on the Au electrode surface to apply the hybridization process. To find out the effectiveness of the synthesized modifier agent, the electrochemical behavior of the modified electrode has been analyzed through DPV (differential pulse voltammetry) and CV (cyclic voltammetry) techniques. The prepared biomarker-detection bioassay offers high sensitivity and specificity, good performance, and appropriate precision and accuracy for the highly-sensitive determination of miRNA-21. Different characterization methods have been used, such as XRD, Raman, EDS, and FE-SEM, for morphological characterization and investigation of particle size. Based on optimal conditions, the limit of detection and quantification have been acquired at 2.94 fM and 8.75 fM, respectively. Furthermore, it was possible to achieve a wide linear range which is between 10^-14 and 10^-7 for miRNA-21. Moreover, the selectivity of the proposed biosensing assay was investigated through its potential in the detection of one, two, and three-base mismatched sequences. Moreover, it was possible to investigate the repeatability and reproducibility of the related bio-assay. To evaluate the hybridization process, it is important that the planned biomarker detection bio-assay could be directly re-used and re-generated.

Advances in layered double hydroxide based labels for signal amplification in ultrasensitive electrochemical and optical affinity biosensors of glucose

Since the development of enzyme electrodes, the research area of glucose biosensing has seen outstanding progress and improvement. Numerous sensing platforms have been developed based on different immobilization techniques and improved electron transfer between the enzyme and electrode. Interestingly, these platforms have consistently used innovative nanostructures and nanocomposites. In recent years, layered double hydroxides (LDHs) have become key tools in the field of analytical chemistry owing to their outstanding features and benefits, such as facile synthesis, cost-effectiveness, substantial surface area, excellent catalytic performance, and biocompatibility. LDHs are often synthesized as nanomaterial composites or manufactured with specific three-dimensional structures. The purpose of this review is to illustrate the biosensing prospects of LDH-based glucose sensors and the need for improvement. First, various clinical and conventional approaches for glucose determination are discussed. The definitions, types, and various synthetic methodologies of LDHs are then explained. Subsequently, we discuss the various research studies regarding LDH-based electrochemical and optical assays, focusing on modified systems, improved electron transfers pathways (through developments in surface science), and different sensing designs based on nanomaterials. Finally, a summary of the current limitations and future challenges in glucose analysis is described, which may facilitate further development and applications.

State-of-the-art progress of metal-organic framework-based electrochemical and optical sensing platforms for determination of bisphenol A as an endocrine disruptor

Considering the low concentration levels of bisphenol compounds present in environmental, food, and biological samples, and the difficulty in analyzing the matrices, the main challenge is with the cleanup and extraction process, as well as developing highly sensitive determination methods. Recent advances in the field of metal-organic frameworks (MOFs) due to their large surface area, low weight, and other extraordinary physical, chemical, and mechanical features have made these porous materials a crucial agent in developing biosensing assays. This review focuses on MOFs across their definition, structural features, various types, synthetic routes, and their significant utilization in sensing assays for bisphenol A (BPA) determination. Additionally, recent improvements in characteristics and physio-chemical features of MOFs and their functional applications in developing electrochemical and optical sensing assays via different recognition elements for detecting BPA are comprehensively discussed. Finally, the existing boundaries of the current advances including future challenges concerning successful construction of sensing approaches by employing functionalized MOFs are addressed.

Dual-reverse-signal ratiometric fluorescence method for malachite green detection based on multi-mechanism synergistic effect

The proposition of ratiometric detection mode has demonstrated great superiority in improving analysis accuracy by forming self-calibration. Herein, the novel dual-reverse-signal ratiometric fluorescence detection for malachite green (MG) was first achieved based on synergistic effect of fluorescence resonance energy transfer (FRET) and inner filter effect (IFE). The ratiometric fluorescence probe (B-RCDs) was self-assembled via electrostatic attraction between blue-emission carbon dots (BCDs) and red-emission carbon dots (RCDs), followed with FRET effect from BCDs to RCDs and exhibited dual-emission at 450 nm and 627 nm. In the presence of MG, the IFE effect between MG and RCDs quenched the fluorescence at 627 nm and restored the fluorescence at 450 nm, sending out two reverse signals along with an obvious color change from pink to purple (302 nm UV lamp). This ratiometric method not only simplified the preparation process, but also improved the detection sensitivity, showing a low limit of detection (LOD) of 41.8 nM, which exhibited superiority than that of single-signal RCDs (157.3 nM). This method held a rapid response of 10 min and represented satisfactory recoveries (99.14%-109.08%) in real water samples, revealing it was a promising candidate in the fast, sensitive and practical detection of MG. Moreover, the design of synergistic effect supplied a new perspective for the development of ratiometric sensing in the future.

Recent trends in layered double hydroxides based electrochemical and optical (bio)sensors for screening of emerging pharmaceutical compounds

The rapid expansion of the human population has given rise to new environmental and biomedical concerns, contributing to different advancements in the pharmaceutical industry. In the field of analytical chemistry over the last few years, layered double hydroxides (LDHs) have drawn significant attention, owing to their extraordinary properties. Furthermore, the novel advancement of LDH-based optical and electrochemical platforms to detect different pharmaceutical materials has acquired substantial attention because of their outstanding specificity, actual-time controlling, and user-friendliness. This review aims to recapitulate advanced LDHs-based optical and electrochemical sensors and biosensors to identify and measure important pharmaceutical compounds, such as anti-depressant, anti-inflammatory, anti-viral, anti-bacterial, anti-cancer, and anti-fungal drugs. Additionally, fundamental parameters, namely interactions between sensor and analyte, design rationale, classification, selectivity, and specificity are considered. Finally, the development of high-efficiency techniques for optical and electrochemical sensors and biosensors is featured to deliver scientists and readers a complete toolbox to identify a broad scope of pharmaceutical substances. Our goals are: (i) to elucidate the characteristics and capabilities of available LDHs for the identification of pharmaceutical compounds; and (ii) to deliver instances of the feasible opportunities that the existing devices have for the developed sensing of pharmaceuticals regarding the protection of ecosystems and human health at the global level.

Recent Advances in Early Diagnosis of Viruses Associated with Gastroenteritis by Biosensors

Gastroenteritis, as one of the main worldwide health challenges, especially in children, leads to 3-6 million deaths annually and causes nearly 20% of the total deaths of children aged ˂5 years, of which ~1.5 million gastroenteritis deaths occur in developing nations. Viruses are the main causative agent (~70%) of gastroenteritis episodes and their specific and early diagnosis via laboratory assays is very helpful for having successful antiviral therapy and reduction in infection burden. Regarding this importance, the present literature is the first review of updated improvements in the employing of different types of biosensors such as electrochemical, optical, and piezoelectric for sensitive, simple, cheap, rapid, and specific diagnosis of human gastroenteritis viruses. The Introduction section is a general discussion about the importance of viral gastroenteritis, types of viruses that cause gastroenteritis, and reasons for the combination of conventional diagnostic tests with biosensors for fast detection of viruses associated with gastroenteritis. Following the current laboratory detection tests for human gastroenteritis viruses and their limitations (with subsections: Electron Microscope (EM), Cell Culture, Immunoassay, and Molecular Techniques), structural features and significant aspects of various biosensing methods are discussed in the Biosensor section. In the next sections, basic information on viruses causing gastroenteritis and recent developments for fabrication and testing of different biosensors for each virus detection are covered, and the prospect of future developments in designing different biosensing platforms for gastroenteritis virus detection is discussed in the Conclusion and Future Directions section as well.

Nanomaterials and metal-organic frameworks for biosensing applications of mutations of the emerging viruses

The world today lives in a state of terrible fear due to the mutation of the emerging COVID-19. With the continuation of this pandemic, there is an urgent need for fast, accurate testing devices to detect the emerging SARS-CoV-2 pandemic in terms of biosensors and point-of-care testing. Besides, the urgent development in personal defense tools, anti-viral surfaces and wearables, and smartphones open the door for simplifying the self-diagnosis process everywhere. This review introduces a quick COVID-19 overview: definition, transmission, pathophysiology, the identification and diagnosis, mutation and transformation, and the global situation. It also focuses on an overview of the rapidly advanced technologies based on nanomaterials and MOFs for biosensing, diagnosing, and viral control of the SARS-CoV-2 pandemic. Finally, highlight the latest technologies, applications, existing achievements, and preventive diagnostic strategies to control this epidemic and combat the emerging coronavirus. This humble effort aims to provide a helpful survey that can be used to develop a creative solution and to lay down the future vision of diagnosis against COVID-19.

Surfactant stabilized gold nanomaterials for environmental sensing applications - A review

Surfactant stabilized Gold (Au) nanomaterials (NMs) have been documented extensively in recent years for numerous sensing applications in the academic literature. Despite the crucial role these surfactants play in the sensing applications, the comprehensive reviews that highlights the fundamentals associated with these assemblies and impact of these surfactants on the properties and sensing mechanisms are still quite scare. This review is an attempt in organizing the vast literature associated with this domain by providing critical insights into the fundamentals, preparation methodologies and sensing mechanisms of these surfactant stabilized Au NMs. For the simplification, the surfactants are divided into the typical and advanced surfactants and the Au NMs are classified into Au nanoparticles (NPs) and Au nanoclusters (NCs) depending upon the complexity in structure and size of the NMs respectively. The preparative methodologies are also elaborated for enhancing the understanding of the readers regarding such assemblies. The case studies regarding surfactant stabilized Au NMs were further divided into colorimetric sensors, surface plasmonic resonance (SPR) based sensors, luminescence-based sensors, and electrochemical/electrical sensors depending upon the property utilized by the sensor for the sensing of an analyte. Future perspectives are also discussed in detail for the researchers looking for further progress in that particular research domain.

Paper-based microfluidic colorimetric sensor on a 3D printed support for quantitative detection of nitrite in aquatic environments

To ensure safe drinking water, it is necessary to have a simple method by which the probable pollutants are detected at the point of distribution. Nitrite contamination in water near agricultural locations could be an environmental concern due to its deleterious effects on the human population. The development of a frugal paper-based microfluidic sensor could be desirable to achieve the societal objective of providing safe drinking water. This work describes the development of a facile and cost-effective microfluidic paper-based sensor for quantitative estimation of nitrite in aquatic environments. A simple punching machine was used for fabrication and rapid prototyping of paper-based sensors without the need of any specialized equipment or patterning techniques. A reusable 3D printed platform served as the support for simultaneous testing of multiple samples. The nitrite estimation was carried out with smartphone-assisted digital image acquisition and colorimetric analysis. Under optimized experimental conditions, the variation in average grayscale intensity with concentration of nitrite was linear in the range from 0.1 to 10 ppm. The limits of detection and quantitation were 0.12 ppm and 0.35 ppm respectively. The reproducibility, expressed as relative standard deviation was 1.31%. The selectivity of nitrite detection method was determined by performing interference studies with commonly existing co-ions in water, such as bicarbonates, chloride and sulphate. The paper-based sensor was successfully applied for estimation of nitrite in actual water samples and showed high recoveries in the range of 83.5-109%. The results were in good agreement with those obtained using spectrophotometry. The developed paper-based sensor method, by virtue of its simplicity, ease of fabrication and use, could be readily extended for detection of multiple analytes in resource-limited settings.

Recent advances in the highly sensitive determination of zearalenone residues in water and environmental resources with electrochemical biosensors

Zearalenone (ZEN), a significant class of mycotoxin which is considered as a xenoestrogen, permits, similar to natural estrogens, it's binding to the receptors of estrogen resulting in various reproductive diseases especially, hormonal misbalance. ZEN has toxic effects on human and animal health as a result of its teratogenicity, carcinogenicity, mutagenicity, nephrotoxicity, genotoxicity, and immunotoxicity. To ensure water and environmental resources safety, precise, rapid, sensitive, and reliable analytical and conventional methods can be progressed for the determination of toxins such as ZEN. Different selective nanomaterial-based compounds are used in conjunction with different analytical detection approaches to achieve this goal. The current review demonstrates the state-of-the-art advances of nanomaterial-based electrochemical sensing assays including various sensing, apta-sensing and, immunosensing studies to the highly sensitive determination of various ZEN families. At first, a concise study of the occurrence, structure, toxicity, legislations, and distribution of ZEN in monitoring has been performed. Then, different conventional and clinical techniques and procedures to sensitive and selective sensing techniques have been reviewed and the efficient comparison of them has been thoroughly discussed. This study has also summarized the salient features and the requirements for applying various sensing and biosensing platforms and diverse immobilization techniques in ZEN detection. Finally, we have defined the performance of several electrochemical sensors applying diverse recognition elements couples with nanomaterials fabricated using various recognition elements coupled with nanomaterials (metal NPs, metal oxide nanoparticles (NPs), graphene, and CNT) the issues limiting development, and the forthcoming tasks in successful construction with the applied nanomaterials.

State of the art: Lateral flow assays toward the point-of-care foodborne pathogenic bacteria detection in food samples

Diverse chemicals and some physical phenomena recently introduced in nanotechnology have enabled scientists to develop useful devices in the field of food sciences. Concerning such developments, detecting foodborne pathogenic bacteria is now an important issue. These kinds of bacteria species have demonstrated severe health effects after consuming foods and high mortality related to acute cases. The most leading path of intoxication and infection has been through food matrices. Hence, quick recognition of foodborne bacteria agents at low concentrations has been required in current diagnostics. Lateral flow assays (LFAs) are one of the urgent and prevalently applied quick recognition methods that have been settled for recognizing diverse types of analytes. Thus, the present review has stressed on latest developments in LFAs-based platforms to detect various foodborne pathogenic bacteria such as Salmonella, Listeria, Escherichia coli, Brucella, Shigella, Staphylococcus aureus, Clostridium botulinum, and Vibrio cholera. Proper prominence has been given on exactly how the labels, detection elements, or procedures have affected recent developments in the evaluation of diverse bacteria using LFAs. Additionally, the modifications in assays specificity and sensitivity consistent with applied food processing techniques have been discussed. Finally, a conclusion has been drawn for highlighting the main challenges confronted through this method and offered a view and insight of thoughts for its further development in the future.

A PCR-free genosensing platform for detection of Shigella dysenteriae in human plasma samples by porous and honeycomb-like biochar decorated with ultrathin flower-like MoS2 nanosheets incorporated with Au nanoparticles

Shigella dysenteriae, a gram-negative bacterium, which results in the most infectious of bacterial shigellosis and dysenteries. In this study, an innovative gene detection platform based on label-free DNA sequences was developed to detect Shigella dysenteriae in human plasma samples. The porous and honeycomb-like structure of biochar (BC) was first synthesized through a pyrolysis process. Then, the produced biochar was effectively decorated with flower-like MoS₂ nanosheets (MoS₂/BC). The resulting nanocomposite was incorporated with Au nanoparticles (AuNPs) by applying chronoamperometry technique, and then the subsequent product including MoS₂ nanosheets, biochar and AuNPs were immobilized on the Au electrode surface and used for modifier agent in electrochemical bio-assays. Structural and morphological study of the synthesized compounds were investigated using various characterization methods such as FE-SEM, TEM, EDS, FTIR, and XRD. Various electrochemical techniques including cyclic voltammetry (CV) and Differential pulse anodic stripping voltammetry (DPASV) have been used to investigate the applicability of the fabricated genosensing bio-assay. Under optimal conditions, LOD and LOQ were calculated 9.14 fM and 0.018 pM respectively. In addition, a linear range from 0.01 to 100 pM was obtained for single stranded-target DNA (ss-tDNA), with R² of 0.9992. The recoveries ranged from 98.0 to 101.3%. The fabricated bio-detection assay demonstrated high selectivity for 1, 2, and 3 base mismatch sequences. In addition, a negative control of the gene detection platform which was performed to study selectivity was provided by ss-tDNA from Haemophilusinfluenzae, and Salmonella typhimurium. Moreover, it is important to mention that the organized bioassay is simply reusable and reproducible with the RSD% (relative standard deviation) ˂ 5 to next detection assays.

Bimetallic Fe/Mn MOFs/MβCD/AuNPs stabilized on MWCNTs for developing a label-free DNA-based genosensing bio-assay applied in the determination of Salmonella typhimurium in milk samples

Monitoring of pathogenic bacteria plays a vital role in precluding foodborne disease outbreaks. In this research work, a genosensor based on innovative label-free DNA was developed for the detection of Salmonella. typhimurium (S. typhimurium) in the milk samples. To realize this objective, bimetallic Fe/Mn MOF is synthesized and mixed with methyl-β-cyclodextrin (MβCD) and AuNPs which are then stabilized on multi-walled carbon nanotubes (MWCNTs), and the obtained nanocomposite is immobilized on the Au electrode surface. Different characterization methods such as FE-SEM, TEM, EDS, FTIR, and XRD were used for investigating the particle size and morphological features. Electrochemical and impedimetric techniques were used for exploring the applicability of the fabricated genosensor. Under optimal circumstances, LOD and LOQ have acquired at 0.07 pM and 0.21 pM. Moreover, an extensive linear range of 1 pM-1 μM was resulted for ss-tDNA (single-stranded target DNA), R² obtained 0.9991. The recoveries were obtained 95.6-104%. Great selectivity against one, two, and three-base mismatched sequences was also shown for fabricated biosensing assay. Furthermore, negative genosensing assay control for investigating selectivity was provided by the ss-tDNAs of Haemophilusinfluenzae and Shigella dysenteriae bacteria. Well-fabricated genosensing bio-assay represents better performance, great specificity, high sensitivity, increased active sites, and finally results in an increase in the electron transfer rate. It is to be noted that the organized genosensing bio-assay is capable of being re-used and re-generated in a straightforward manner to estimate the hybridization process.

Nanoscale Metal-Organic Frameworks: Recent developments in synthesis, modifications and bioimaging applications

Porous Metal-Organic Frameworks (MOFs) have emerged as eye-catching materials in recent years. They are widely used in numerous fields of chemistry thanks to their desirable properties. MOFs have a key role in the development of bioimaging platforms that are hopefully expected to effectually pave the way for accurate and selective detection and diagnosis of abnormalities. Recently, many types of MOFs have been employed for detection of RNA, DNA, enzyme activity and small-biomolecules, as well as for magnetic resonance imaging (MRI) and computed tomography (CT), which are valuable methods for clinical analysis. The optimal performance of the MOF in the bio-imaging field depends on the core structure, synthesis method and modifications processes. In this review, we have attempted to present crucial parameters for designing and achieving an efficient MOF as bioimaging platforms, and provide a roadmap for researchers in this field. Moreover, the influence of modifications/fractionalizations on MOFs performance has been thoroughly discussed and challenging problems have been extensively addressed. Consideration is mainly focused on the principal concepts and applications that have been achieved to modify and synthesize advanced MOFs for future applications.

Emerging electrochemical sensing and biosensing approaches for detection of Fumonisins in food samples

Fumonisins (FBs) can be found extensively in feedstuffs, foodstuffs, and crops. The consumption of the fumonisin-contaminated corn can result in esophageal cancer. In addition, the secondary metabolites of fungi termed mycotoxins may have some adverse effects on animals and humans such as estrogenicity, immunotoxicity, teratogenicity, mutagenicity, and carcinogenicity. Hence, developing sensitivity techniques for mycotoxins determination is of great importance. This paper reports the latest developments of nanomaterial-based electrochemical biosensing, apta-sensing, sensing, and immunosensing analyses to detect fumonisins. A concise study of the occurrence, legislations, toxicity, and distribution of FBs in levels monitoring was done. The techniques, different detection matrices, and approaches to highly selective and sensitive sensing methods were reviewed. The review also summarizes the salient features and the necessity of biosensing assessments in FBs detection, and diverse immobilization techniques. Furthermore, this review defined the performance of various electrochemical sensors using different detection elements couples with nanomaterials fabricated applying different detection elements coupled with nanomaterials (metal oxide nanoparticles (NPs), metal NPs, CNT, and graphene), the factors limiting progress, and the upcoming tasks in successful aptasensor fabrication with the functionalized nanomaterials.