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Chemical warfare victims suffer from bronchiolitis and chronic pulmonary obstruction caused by sulfur mustard (SM) toxicity. Despite the mesenchymal stem cells capacity to alleviate inflammation, their low survival rate under oxidative stress severely limits their effectiveness. This study aimed to examine how natural (Crocin) and synthetic (Dexamethasone) antioxidants might affect MSC efficacy. MSCs were treated with the optimal doses of Crocin (Cr.), Dexamethasone (Dex.), and their combination. The A549 cells line was pretreated with the optimal dose of the CEES to mimic the lung disease. Then, the affected A549 cells were exposed to the preconditioned MSCs and conditioned media, and then their survival rates were estimated by MTTor2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Annexin-V PI apoptosis test was conducted for MSCs and A549 cells. Reactive Oxygen Species (ROS) assay and Enzyme-linked immunosorbent assay (ELISA) test demonstrated the percentage of production of ROS and the cytokines levels in A549/CEES, respectively. The results revealed significant increases in Cr. + Dex. treated MSCs (P

A facile and sensitive approach is introduced to precisely determine trace amounts of prostate specific antigen (PSA) by gold nanostructures deposited on fluorine-doped tin oxide (FTO) electrodes. The gold electrode fabrication is carried out by integration of two techniques of vacuum-deposition and electrochemical growth. The electrode was successfully used as a label-free immunosensor for PSA determination in human serum samples. The dependency of the biosensor performance on various fabrication parameters have been investigated and the optimized fabrication rout has been specified. This label-free immunosensor presents a noticeable performance with a large range of linearity from 0.05 to 30 ng/mL, a low detection limit of 5.7 pg/mL, and a long-term stability of 4 weeks. The obtained results for PSA determination in real samples show a good agreement with ELISA results with less than 10% deviation.

The increasing efforts devoted to fabricating electrochromic (EC) devices have motivated a lot of studies to develop new EC materials. Herein, we introduce two poly(phenothiazine)-type redox active polymer films as new EC materials. Poly(methylene blue) (PMB) and poly(thionine) (PTH) films were electrochemically deposited onto the transparent fluorine-doped tin oxide (FTO) electrode modified with multi-walled carbon nanotubes (MWCNTs), which are named as FTO/MWCNTs/PMB and FTO/MWCNTs/PTH, respectively. The as-prepared polymer films were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared (FT-IR), cyclic voltammetry (CV), and spectroelectrochemical techniques. Both polymer films exhibited EC behavior at approximately 600 nm. PMB and PTH films are blue and pale purple, respectively, in the oxidized state and change their color to colorless, if reduced at − 0.6 V. In particular, FTO/MWCNTs/PMB showed a satisfactory ΔT (24%) at 600 nm. The obtained results demonstrate that PMB and PTH, as derivatives of phenothiazine dyes, can be introduced as novel EC materials.

In the current research, a double Z-scheme photocatalyst C3N4-TE@TiO2/UiO-66 (CNTU) is fabricated via a two-steps facile solvothermal method from Z-scheme C3N4-TE@TiO2 (CNT). This double Z-scheme photocatalyst reveals greater performance for the removal of tetracycline (TC) than pristine C3N4-TE, TiO2, UiO-66 (U66), and their binary compounds. The optimized composite 35C3N4-TE@TiO2/35UiO-66 (35CNTU), exhibitions photocatalytic performance for antibiotic removal (TC) more than 5,4 and 2 times higher than that pure TiO2, UiO-66, and C3N4-TE, respectively. The physical and chemical features of synthesized samples were described via FTIR, XRD, SEM-EDX, TEM, BET, UV–Vis DRS, and PL. The key parameters on photocatalytic performances of 35CNTU such as pH, the amount of catalyst, and the primary concentration of TC were clarified. The advancement of the photocatalytic process for 35CNTU is due to the increase in the surface area and structure of double Z-scheme in this compound, which growths the active sites of the reaction as well as better separation of the photo-induced electron and hole pairs. Furthermore, 35CNTU can be recycled with superior stability for 5 cycles. The photocatalytic removal proficiency of TC over 35CNTU under visible light achieves 96% in 40 min. The findings of this study could inspire various novel plans for fabricating practical double Z-scheme photocatalyst for great performance and extensive useful applications.

A sandwich-type electrochemical immunoassay was introduced for the determination of the prostate-specific antigen (PSA) biomarker. A direct and simple galvanic replacement reaction was performed between the Ag framework and metallic salts of tetrachloroauric(iii) acid trihydrate and chloroplatinic acid to produce a trimetallic composite of AgAuPt. The trimetallic composite of AgAuPt was applied to the preparation of the capture layer of the immunoassay for stabilizing the primary Ab at the surface of the prepared composite. The immunoassay detection layer was also prepared using a labeled antibody containing a bimetallic composite of AgPt as a label. The various procedures in the immunoassay fabrication were monitored step by step using cyclic voltammetry and electrochemical impedance spectroscopy. Also, the electrochemical determination of PSA was performed using differential pulse voltammetry in the presence of the ferrocene redox probe and H2O2. Furthermore, the effective parameters in the fabrication of the immunoassay included the drop volume of the AgAuPt trimetallic composite and the incubation time for the immobilization of biomolecules (i.e., Ab1, BSA, PSA, and labeled Ab2), and the concentration of H2O2 were optimized during the determination of PSA. Then, the determination of PSA was performed under optimized conditions. It could be seen that there was a linear relation between the PSA concentration and DPV responses in the concentration range of 50 pg mL-1 to 500 ng mL-1 and the limit of detection (LOD) for the proposed immunoassay was calculated as 17.0 pg mL-1. In the following investigation, the cross-reactivity of the proposed immunoassay was studied in the presence of BSA, CEA, IgG, and human hepatitis surface antigen, in which the results showed a negligible change in the performance of the immunoassay.

Background: Scientific journals will gain real credit when they meet publication ethics standards. This study seeks to evaluate the current status of medical journals’ adherence to some ethical standards. Methods: The 412 scientific journals approved by the Ministry of Health and Medical Education were included in this study. The process of downloading articles and data extraction for seven general and specific indicators related to publication ethics was conducted by trained researchers. Different methods were implemented by the team of colleagues to prevent possible errors in data extraction. After data integration, data analysis was performed using SPSS version 23. Results: Overall, 408 journals and 3948 articles met the inclusion criteria. The distribution of journals according to the highest journal index was 5.4%, 13.7%, 8.3%, 8.1% and 64.5% for ISI, ESCI, PubMed, Scopus and Other indexes, respectively. In 27.7% of the articles, the review process took over 6 months. According to the results, 6.6% and 31.7% of the articles belonged to the journals’ editors and owner universities, respectively. Journal self-citation was seen in 19.2% of articles and in fewer than half of the articles (45.5%), the status of conflict of interest was declared. In 36.9% of the articles, the code of ethics or university ethics committee approval, and in 36.5% of clinical trial articles, the clinical trial registration code was reported. Conclusion: Modifying processes or introducing new rules for indicators of publication ethics by trustee organizations can improve the current status. These seven indicators can also be used to rank journals.

Nowadays, widespread researches have been focused on the development of effective photocatalysts to remove pollutants of the aquatic system. In accordance with the universal studies, two new sets of UiO-66@ metal oxide (including ZnO and TiO2)/graphene oxide heterojunctions were synthesized for photodegradation of aromatic (tetracycline) and nonaromatic (malathion) pollutants which are challenging cases in the environment. The dosage of the photocatalyst, pH of the solution, the type of metal oxide, and the presence of various scavengers are assayed parameters in this work. In the optimum condition, maximum photodegradation efficiency is achieved in 90 min for tetracycline (81%) and malathion (100%) by the UiO-66@ZnO/graphene oxide. The superior separation of charge carriers by Z-scheme mechanism, excellent electron mobility on layers of graphene oxide and high surface area are factors that enhanced the efficiency. Furthermore, in comparison with pure UiO-66, the band gaps belong to heterojunctions revealed a red shift in the absorption edge, which can be responsible for more expand adsorption of the solar spectrum. Total organic carbon analysis verified the decontamination of these pollutants in the solution. The produced main intermediates during the photocatalytic process were identified and the possible degradation pathway proposed. In general, the superior photocatalytic activity suggests that these designed photocatalysts can be a promising choice for having a clean future.

Nowadays, environmental pollution is one of the major worldwide problems. There are various types of pollutants (i.e., organic, inorganic, and biological materials), which can contaminant water resources, land, and air. Therefore, there is a high demand to develop and design new devices for the detection and determination of various contaminants in the environment. In this regard, the chemical and biological sensors are interesting tools for environmental applications. Recently, different types of chemical and biological sensors, such as electrochemical, fluorescence, and mass-based (bio)sensors, have been developed through the studies of researchers in the many fields of science by chemists, chemical engineers, physicists, etc. Among the developed sensors and biosensors, the electrochemical ones have many advantages, including low cost, easy to fabrication and use, ability to miniaturization, and application in the point-of-demand. Furthermore, the electrochemical biosensors have been classified as the electrochemical immunosensors, aptasensors, and genosensors, which have high selectivity and sensitivity toward the proposed targets, with an emphasis on opportunities for further improvement in contaminants diagnostics and monitoring. Considering these conditions, the main approach of this review is on the electrochemical immunosensors, aptasensors, and genosensors, which have been applied in the determination of various contaminants, including organophosphorus, toxic hydrocarbons and organic compounds, heavy metals, and toxic anions and cations. The figures of merits of some important studies and related data such as LOD, LDR, and electrochemical methods, which have been used to determination of contaminants as well as the (bio)sensor design, are presented in the tables to further comparison and information.

A sensitive biosensor for the detection of miR-141 has been constructed. The DNA-biosensor is prepared by first immobilizing the thiolated methylene blue-labeled hairpin capture probe (MB-HCP) on two-layer nanocomposite film graphene oxide-chitosan@ polyvinylpyrrolidone-gold nanourchin modified glassy carbon electrode. We used the hematoxylin as an electrochemical auxiliary indicator in the second stage to recognize DNA hybridization via the square wave voltammetry (SWV) responses that record the accumulated hematoxylin on electrode surfaces. The morphology and chemical composition of nanocomposite was characterized using TEM, FE-SEM, and FT-IR techniques. The preparation stages of the DNA-biosensor were screened by electrochemical impedance spectroscopy and cyclic voltammetry. The proposed DNA-biosensor can distinguish miR-141 from a non-complementary and mismatch sequence. A detection limit of 0.94 fM and a linear range of 2.0 -5.0 × 10

According to World Health Organization reports, large numbers of people around the globe have been infected or died for Covid-19 due to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Researchers are still trying to find a rapid and accurate diagnostic method for revealing infected people by low viral load with the overriding goal of effective diagnostic management. Monitoring the body metabolic changes is known as an effective and inexpensive approach for the evaluation of the infected people. Here, an optical sniffer is introduced to detect exhaled breath metabolites of patients with Covid-19 (60 samples), healthy humans (55 samples), and cured people (15 samples), providing a unique color pattern for differentiation between the studied samples. The sniffer device is installed on a thin face mask, and directly exposed to the exhaled breath stream. The interactions occurring between the volatile compounds and sensing components such as porphyrazines, modified organic dyes, porphyrins, inorganic complexes, and gold nanoparticles allowing for the change of the color, thus being tracked as the sensor responses. The assay accuracy for the differentiation between patient, healthy and cured samples is calculated to be in the range of 80%-84%. The changes in the color of the sensor have a linear correlation with the disease severity and viral load evaluated by rRT-PCR method. Interestingly, comorbidities such as kidney, lung, and diabetes diseases as well as being a smoker may be diagnosed by the proposed method. As a powerful detection device, the breath sniffer can replace the conventional rapid test kits for medical applications.

A colorimetric sensor array designed on a paper substrate with a microfluidic structure has been developed. This array is capable of detecting COVID-19 disease by tracking metabolites of urine samples. In order to determine minor metabolic changes, various colorimetric receptors consisting of gold and silver nanoparticles, metalloporphyrins, metal ion complexes, and pH-sensitive indicators are used in the array structure. By injecting a small volume of the urine sample, the color pattern of the sensor changes after 7 min, which can be observed visually. The color changes of the receptors (recorded by a scanner) are subsequently calculated by image analysis software and displayed as a color difference map. This study has been performed on 130 volunteers, including 60 patients infected by COVID-19, 55 healthy controls, and 15 cured individuals. The resulting array provides a fingerprint response for each category due to the differences in the metabolic profile of the urine sample. The principal component analysis-discriminant analysis confirms that the assay sensitivity to the correctly detected patient, healthy, and cured participants is equal to 73.3%, 74.5%, and 66.6%, respectively. Apart from COVID-19, other diseases such as chronic kidney disease, liver disorder, and diabetes may be detectable by the proposed sensor. However, this performance of the sensor must be tested in the studies with a larger sample size. These results show the possible feasibility of the sensor as a suitable alternative to costly and time-consuming standard methods for rapid detection and control of viral and bacterial infectious diseases and metabolic disorders.

In this study, the dual signal-labeled hairpin-structured DNA (dhDNA)-based probes have been developed to construct a novel nano-biosensor. This one hairpin-structured probe consists of a thiolated methylene blue-labeled hairpin capture probe (MB-HCP) as an inner reference probe and a ferrocene-modified anti-miRNA-21 DNA probe (Fc-AP-21). This novel integrated structure of MB-HCP and Fc-AP-21 was designed on one sensing interface for sensitive and simultaneous detection of the miRNA-141 and miRNA-21 in one single assay. The proposed strategy has a good ability to reduce the interference of environmental factors and it was designed to control the initial responses of Fc-AP to MB-HCP ((I

In the present work, a novel electrochemical sensor modified glassy carbon electrode with ion-imprinted polymers (IIP-GCE) was applied for uranyl ions (UO

The aim of this work is to fabricate a sensitive and novel enzymeless electrochemical sensor for the simultaneous determination of parathion and paraoxon using the Nd-UiO-66@MWCNT nanocomposite. For this purpose, Neodymium (Nd) was introduced into a Universitetet i Oslo (UiO-66) structure to construct Nd-UiO-66 and then, adding multi-walled carbon nanotubes to the Nd-UiO-66 to increase the electrocatalytic activity and surface area of the obtained composite. The Nd-UiO-66@MWCNT has numerous advantages like excellent conductivity, tunable texture, and large surface area and can be used as a distinctive structure for the construction of modified glassy carbon electrode (GCE) to enhance the charge-transfer and the efficiency of electrochemical sensors. This modified electrode showed sensitive and selective determination of paraoxon and parathion over the linear ranges of 0.7-100 and 1-120 nM, with detection limits of 0.04 and 0.07 nM, respectively. The proposed Nd-UiO-66@MWCNT/GCE sensor in this study can be applied in environmental and toxicological laboratories and field tests to detect parathion and paraoxon levels.

Nickel–zinc ferrite (Ni0.5Zn0.5Fe2O4) nanosorbent was prepared and used for the efficient simultaneous preconcentration of arsenite and arsenate ions from aqueous solutions. The prepared nanoparticles were characterized by XRD measurements which indicated that the Ni0.5Zn0.5Fe2O4 nanoparticles were synthesized well. The SEM results showed an average diameter of 27 nm for the nanoparticles. The adsorption capacity was found to be 35.8 and 62.5 mg g−1 for As(III) and As(V), respectively. The adsorbed ions were then quantitatively eluted using 2 mL of 2 M NaOH solution as an elution solvent and determined spectrophotometrically. The maximum preconcentration factor for both the investigated ions was found to be 100. As(III) and As(V) species were determined in the mixture based on the difference in their adsorption behavior at different pHs. For an initial sample volume of 200.0 mL, the calibration graph was linear in the range 0.3–50.0 ng mL−1 of As(III) and 0.2–75.0 ng mL−1 of As(V) concentration. The method resulted in a successful determination of As(III) and As(V) in water samples.

In the present work, a novel platform has been designed to fabricate an electrochemical sensor composed of chitosan nanofibers modified with sodium dodecyl sulfate, a negatively charged surfactant, and hemoglobin protein for direct and sensitive determination of hydrogen peroxide. Chitosan nanofibers were synthesized through the electrospinning process and characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The synthesized nanofibers provided a large surface for the adsorption of hemoglobin. Immobilization of hemoglobin on the fibers was investigated by cyclic voltammetry, and the modification steps were followed by electrochemical impedance spectroscopy. Under the optimal conditions, the fabricated biosensor was employed for electrocatalytic determination of hydrogen peroxide by differential pulse voltammetric and amperometric methods in the linear range 3.0–2940.0 µM (detection limit = 0.16 µM) and 1.0–201.0 µM (detection limit = 0.05 µM), respectively. The applicability of the constructed biosensor was also evaluated by hydrogen peroxide determination in real samples, and satisfactory recoveries were obtained which confirmed that the proposed method provides a simple and sensitive method for the hydrogen peroxide monitoring.

In a wide range of events, people may be acutely exposured to chemical substances. Particular hospital preparedness plans and vital resources are essential for appropriate health-care measures. The present study aimed to conduct a systematic review to summarize and evaluate the existing evidence on hospital preparedness plans or protocols against chemical incidents and threats. In this aim, through May 15, 2018, 5 electronic databases were searched in MEDLINE (PubMed, Scopus, Web of Science, Cochrane Library, and Google Scholar) for the following key words: hospital preparedness, plan, protocol, chemical incident, and chemical threat. The final review included 11 peer-reviewed papers that met inclusion criteria. The systematic review was performed using the Preferred Reporting Items for the Systematic reviews and Meta-Analysis protocol (PRISMA) (www.prisma-statement.org). Finally, of 16,540 selected papers, 11 papers were included in the final analysis. The thematic analyses revealed 11 major categories of chemical incidents and threats planning, such as planning requirements, planning prerequisites, preparation team member (multidisciplinary team), decontamination, personal protective equipment, education and training, job descriptions and roles, communication, database, staff /volunteer organization, as well as planning barriers and challenges for chemical incidents. Most countries have launched hospital preparedness planning against chemical incidents and threat activities, but the preparedness of hospitals is often less than desirable. Many items, such as databases, hospital preparation team members, communications, etc., are still challenging.

The present study reports the wireless technique that generates asymmetric reactivity on the surface of the conducting substrate without any direct electrical connection in the electrolyte solution by inducing external power. In recent years, bipolar electrochemical systems have received special attention that they are used for new kinds of electrochemical applications ranging from electrodeposition to electroanalytical chemistry. Bipolar electrochemistry is a unique technique because of the lack of direct electrical connection to the bipolar electrode. In this perspective article, we first illustrate the concept and history of the bipolar electrochemistry as well as their application based on the open and closed bipolar configuration in different fields.

A new dual-modality immunosensor based on molecularly imprinted polymer (MIP) and a nanostructured biosensing layer has fabricated for the simultaneous detection of two important markers including prostate-specific antigen (PSA) and myoglobin (Myo) in human serum and urine samples. In the first step, 3,3′-dithiodipropionic acid di(N-hydroxysuccinimide ester) (DSP) was self-assembled on a gold screen printed electrode (SPE). Then, the target proteins were attached covalently to the DSP-SPE. The imprinted cocktail polymer ((MIP(PSA, Myo)-SPE)) was synthesized at the SPE surface using acrylamide as monomer, N,N′-methylenebisacrylamide as a crosslinker, and PSA and Myo as the templates, respectively. The MIP-SPE was specific for the impedimetric sensing of PSA and Myo. After that, a nanocomposite (NCP) was synthesized based on the decorated magnetite nanoparticles with multi-walled carbon nanotube, graphene oxide and specific antibody for PSA (Ab). Then, NCP incubated with (MIP(PSA, Myo)-SPE. The modified electrodes and synthesized nanoparticles were characterized using electrochemical impedance spectroscopy, dynamic light scattering, surface plasmon resonance and scanning electron microscopy. The limits of detections were found to be 5.4 pg mL−1 and 0.83 ng mL−1 with the linear dynamic ranges of 0.01–100 and 1–20000 ng mL−1 for PSA and Myo, respectively. The ability of proposed biosensor to detect PSA and Myo simultaneously with high sensitivity and specificity offers a powerful opportunity for the new generation of biosensors. This dual-analyte specific receptors-based device is highly desired for the integration with lab-on-chip kits to measure a wide panel of biomarkers present at ultralow levels during early stages of diseases progress.

The fabrication of flexible, freestanding, lightweight, renewable, low cost and also the high performance of novel supercapacitors is pivotal in electronic fields. In this work, two series of ternary bio-nanocomposite flexible aerogels based on bacterial cellulose (BC) as a template and containing silver nanoparticles (AgNPs) and polyaniline (PANI) as conductive agents facilely fabricate using an in situ method, in which Ag and PANI embedded within BC matrix as sequences. Morphology of ternary aerogels reveals the core-shell and branch-grape microstructures for BC/Ag/PANI and BC/PANI/Ag samples, respectively. BET analysis exhibits that specific surface area of BC/Ag/PANI (145 m2 g−1) is higher than BC/PANI/Ag (130 m2 g−1) aerogel. Electrical conductivity measurements indicated that BC/Ag/PANI (1.25 S cm−1) possesses higher electrical conductivity than BC/PANI/Ag (0.00693 S cm−1) aerogels. The coexistence of PANI and Ag within BC texture, significantly altered the interfacial polarization and relaxation spectra of ternary system. A specific capacitance 357 F g−1 at 0.5 A g−1 associated with 83% cyclic stability over 2000 cycles is observed for BC/Ag/PANI, while BC/PANI/Ag showed specific capacitance of 232 F g−1 at 0.5 A g−1 as well as 74% capacitance retention. Furthermore, in symmetrical supercapacitor setup for BC/Ag/PANI, a high energy density of 34 Wh kg−1 at a power density of 459 Wh kg−1 is obtained. These findings indicated that BC/Ag/PANI aerogel as a flexible and lightweight electrode could be highly used in the field of electrical energy storage.

A sensitive prostate-specific antigen (PSA) detection method using a visual-readout closed bipolar electrode (BPE) system has been introduced by integration of hydrogen evolution reaction (HER) in cathodic pole and electrochemiluminescence (ECL) of luminol loaded within the MIL-53(Fe)-NH2 (L@MIL-53(Fe)-NH2) in the anodic pole. The cathode of the BPE was electrochemically synthesized by 3D porous copper foam, followed by decorating with nitrogen-doped graphene nanosheet and ruthenium nanoparticles. As an alternative, we employed carboxylate-modified magnetic nanoparticles (MNPs) for immobilization of the primary antibody (Ab1) and utilized the L@MIL-53(Fe)-NH2 conjugated to secondary antibody (Ab2) as a signaling probe and coreaction accelerator. After sandwiching the target PSA between Ab1 and Ab2, the MNP/Ab1-PSA-Ab2/L@MIL-53(Fe) were introduced to a gold anodic BPE. Finally, the resulting ECL of luminol and H2O2 at the anodic poles was monitored using a photomultiplier tube (PMT) or digital camera. The PMT and visual (camera)-based detections showed linear responses from 1 pg mL-1 to 300 ng mL-1 (limit of detection 0.2 pg mL-1) and 5 pg mL-1 to 200 ng mL-1 (limit of detection 0.1 pg mL-1), respectively. This strategy provides an effective method for high-performance bioanalysis and opens a new door toward the development of the highly sensitive and user-friendly device.

A highly sensitive nonenzymatic electrochemical sensor is designed for stripping voltammetric determination of paraoxon ethyl (PE) as a model for nitroaromatic organophosphates (OPs). Graphene-based NiFe bimetallic phosphosulfide nanocomposite is used for the first time as a novel electrocatalytic modifier for enhancing the electrochemical signal of PE. As a consequence of the efficient π-π stacking interactions between the aromatic structure of OPs and graphene and also due to the strong electrocatalytic properties of the bimetallic phosphosulfide, PE can strongly bind to the surface of modified glassy carbon electrodes and provide a dramatically enhanced voltammetric signal in a nonenzymatic determination method. Maximum square wave voltammetric (SWV) signals were obtained when the adsorption step was completed via 5-min convection at 1000 rpm in an analyte solution with the adjusted pH of 6. The SWV signal of PE was highly linear over the range of 12.3–10,000 nmol L−1 and with the detection limit of 3.7 nmol L−1 (S/N = 3). The developed sensor shows good reproducibility (RSD = 5.2%, N = 10). The study offers a promising application for bimetallic phosphosulfide compounds for developing fast, simple, and highly sensitive nonenzymatic determination protocol for nitroaromatic OPs.

BSA templated Au-Cu bimetallic nanoclusters (Au-Cu@BSA) were synthesized. The characteristics of the prepared bimetallic nanoclusters were demonstrated by UV–Vis absorption, fluorescence spectrometry and transmission electron microscopy. The Au-Cu@BSA was mixed by graphene nanoribbons (GNRs) and Au-Cu@BSA-GNRs was applied as a modifier of glassy carbon electrode (GCE). Also, the properties of the prepared sensors were investigated by cyclic voltammetry, square wave anodic stripping voltammetry and electrochemical impedance spectroscopy. Au-Cu@BSA-GNRs/GCE was employed for the low cost, high efficiency, rapid, selective and sensitive determination of bisphenol A (BPA) as an effective sensing layer of the electrochemical sensor. Upon the optimization of chemical and instrumental parameters, including pH, deposition potential and time, the oxidation peak current was linearly dependent on the concentration of BPA. The dynamic ranges of BPA were linear between 0.01 to 2.0 and 2.0 to 70 μmol L−1, with a limit of detection 0.004 μmol L−1. The Au-Cu@BSA-GNRs/GCE has high selectivity, stability, repeatability, and reproducibility. These results suggest that the constructed sensor has an excellent capacity as an alternative to routine analysis methods for the determination of BPA. The constructed electrode was used for electrochemical determination of BPA in tap water, bottled water, baby bottle and food storage container by the standard addition method. The obtained results indicate the ability of the proposed method to detect BPA in different real sample matrices.

This study aims to use a paper-based sensor array for point-of-care detection of COVID-19 diseases. Various chemical compounds such as nanoparticles, organic dyes and metal ion complexes were employed as sensing elements in the array fabrication, capturing the metabolites of human serum samples. The viral infection caused the type and concentration of serum compositions to change, resulting in different color responses for the infected and control samples. For this purpose, 118 serum samples of COVID-19 patients and non-COVID controls both men and women with the age range of 14-88 years were collected. The serum samples were initially subjected to the sensor, followed by monitoring the variation in the color of sensing elements for 5 min using a scanner. By taking into consideration the statistical information, this method was capable of discriminating COVID-19 patients and control samples with 83.0% accuracy. The variation of age did not influence the colorimetric patterns. The desirable correlation was observed between the sensor responses and viral load values calculated by the PCR test, proposing a rapid and facile way to estimate the disease severity. Compared to other rapid detection methods, the developed assay is cost-effective and user-friendly, allowing for screening COVID-19 diseases reliably.

The fast detection of trace amounts of hazardous contaminations can prevent serious damage to the environment. Paper-based sensors offer a new perspective on the world of analytical methods, overcoming previous limitations by fabricating a simple device with valuable benefits such as flexibility, biocompatibility, disposability, biodegradability, easy operation, large surface-to-volume ratio, and cost-effectiveness. Depending on the performance type, the device can be used to analyze the analyte in the liquid or vapor phase. For liquid samples, various structures (including a dipstick, as well as microfluidic and lateral flow) have been constructed. Paper-based 3D sensors are prepared by gluing and folding different layers of a piece of paper, being more user-friendly, due to the combination of several preparation methods, the integration of different sensor elements, and the connection between two methods of detection in a small set. Paper sensors can be used in chromatographic, electrochemical, and colorimetric processes, depending on the type of transducer. Additionally, in recent years, the applicability of these sensors has been investigated in various applications, such as food and water quality, environmental monitoring, disease diagnosis, and medical sciences. Here, we review the development (from 2010 to 2021) of paper methods in the field of the detection and determination of toxic substances.

The monitoring of profile concentrations of chemical markers in saliva samples can be used to diagnose COVID-19 patients, and differentiate them from healthy individuals. Here, this purpose is achieved by designing a paper-based colorimetric sensor with an origami structure, containing general receptors such as pH-sensitive organic dyes, Lewis donors or acceptors, functionalized nanoparticles, and ion metal complexes. The color changes taking place in the receptors in the presence of chemical markers are visually observed and recorded with a digital instrument. Different types and amounts of the chemical markers provide the sensor with a unique response for patients (60 samples) or healthy (55 samples) individuals. These two categories can be discriminated with 84.3% accuracy. This study evidences that the saliva composition of cured and healthy participants is different from each other with accuracy of 85.7%. Moreover, viral load values obtained from the rRT-PCR method can be estimated by the designed sensor. Besides COVID-19, it may possible to simultaneously identify smokers and people with kidney disease and diabetes using the specified electronic tongue. Due to its high efficiency, the prepared paper device can be employed as a rapid detection kit to detect COVID-19.

Developing new ultrasensitive assays for the detection of the presence, and determination of the serotype of the most poisonous material known i.e. botulinum neurotoxin (BoNT) is vital to human health and the wellbeing of the surrounding environment. Here, an electrochemical sandwich immunoassay with high sensitivity is adopted to achieve simultaneous determination of BoNT serotypes A and E based on polystyrene@polydopamine/Cd

Magnetic nanoparticles (MNPs) have garnered increasing attention for use in the improvement and production of magnetic biosensing, magnetic isolation and purification, drug delivery, quantitative investigation, and magnetic imaging for numerous usages. The latest improvements in the exploitation of nanomagnetic particles for amending various levels of analytical procedures are reviewed. According to the results obtained in the field of analytical chemistry research, the exploitation of magnetic fields affords useful and beneficial techniques for manipulating and examining particles at the molecular level. Among these different applications of magnetic nanomaterials in analytical chemistry, this chapter considers the usages of MNPs in colorimetric sensors. Colorimetric techniques have acquired noteworthy consideration due to such benefits as selectivity; easy preparation; and fast, sensitive, and cost-effective recognition; and it does not require advanced and sophisticated devices.