ECL sensor for selective determination of citrate ions as a prostate cancer biomarker using polymer of intrinsic microporosity-1 nanoparticles/nitrogen-doped carbon quantum dots.

Urine citrate analysis is relevant in the screening and monitoring of patients with prostate cancer and calcium nephrolithiasis. A sensitive, fast, easy, and low-maintenance electrochemiluminescence (ECL) method with conductivity detection for the analysis of citrate in urine is developed and validated by employing polymer of intrinsic microporosity-1 nanoparticles/nitrogen-doped carbon quantum dots (nano-PIM-1/N-CQDs). Using optimum conditions, the sensor was applied in ECL experiments in the presence of different concentrations of citrate ions. The ECL signals were quenched gradually by the increasing citrate concentration. The linear range of the relationship between the logarithm of the citrate concentration and ΔECL (ECL of blank - ECL of sample) was obtained between 1.0 × 10-7 M and 5.0 × 10-4 M. The limit of detection (LOD) was calculated to be 2.2 × 10-8 M (S/N = 3). The sensor was successfully applied in real samples such as human serum and patient urine.

Graphene-family materials in electrochemical aptasensors.

The study of graphene-based carbon nanocomposites has remarkably increased in recent years. Functionalized graphene-based nanostructures, including graphene oxide and reduced graphene oxide, have great potential as new innovative electrode materials in the fabrication of novel electrochemical sensors. Electrochemical sensors based on aptamers attracted great attention because of their high sensitivity and selectivity, and simple instrumentation, as well as low production cost. Aptamers as a potent alternative to antibodies are functional nucleic acids with a high tendency to specific analytes. Electrochemical aptasensors show specific recognition ability for a wide range of analytes. Although aptamers are selected in vitro in contrast to antibodies, they are interesting due to advantages like high stability, easy chemical modifications, and the potential to be employed in nanostructured device fabrication or electrochemical sensing devices. Recently, new nanomaterials have shown a significant impact on the production of electrochemical sensors with high efficiency and performance. This review aims to give an outline of electrochemical aptasensors based on the graphene family materials and discuss the detection mechanism in this type of aptasensors. The present review summarizes some of the recent achievements in graphene-based aptasensors and includes their recent electroanalytical applications. Graphical Abstract Graphical Abstract.

Non-enzymatic electrochemical cholesterol sensor based on strong host-guest interactions with a polymer of intrinsic microporosity (PIM) with DFT study.

Advances in materials science have accelerated the development of diagnostic tools with the last decade witnessing the development of enzyme-free sensors, owing to the improved stability, low cost and simple fabrication of component materials. However, the specificity of non-enzymatic sensors for certain analytes still represents a challenging task, for example the determination of cholesterol level in blood is vital due to its medical relevance. In this work, a reagent displacement assay for cholesterol sensing in serum samples was developed. It is based on coating of a glassy carbon electrode with a polymer of intrinsic microporosity (PIM) that forms a host-guest complex with methylene blue (MB). In the presence of cholesterol, the MB electroactive probe was displaced due to the stronger association of cholesterol guest to the PIM host. The decrease in the oxidative current was proportional to the cholesterol concentration achieving a detection limit of approximately 0.1 nM. Moreover, to further assist the experimental studies, comprehensive theoretical calculations are also performed by using density functional theory (DFT) calculations.

Carbon-based quantum particles: an electroanalytical and biomedical perspective.

Carbon-based quantum particles, especially spherical carbon quantum dots (CQDs) and nanosheets like graphene quantum dots (GQDs), are an emerging class of quantum dots with unique properties owing to their quantum confinement effect. Many reviews appeared recently in the literature highlighting their optical properties, structures, and applications. These papers cover a broad spectrum of carbon-based nanoparticles, excluding a more detailed discussion about some important aspects related to the definition of carbon-based particles and the correlation of optical and electrochemical aspects in relation to sensing and biomedical applications. A large part of this review is devoted to these aspects. It aims, in particular, to act as a bridge between optical and electrochemical aspects of carbon-based quantum particles, both of which are associated with the electronic nature of carbon-based quantum particles. A special focus will be on their use in electroanalysis, notably their benefits in redox, and in electrochemical analysis with emphasis on their application as sensors. Electroanalysis is an easy and cost-effective means of providing qualitative and quantitative information of a specific analyte in solution in a time scale of some minutes. The integration of carbon-based quantum particles into these detection schemes as well as their incorporation into composite nanomaterials have largely improved detection limits with possibilities for their integration in aspects ranging from point-of-care devices to personalized medicine. This review will focus on some of these aspects while also covering the nanomedical aspects of carbon-based quantum particles, ultimately correlated for such developments.

Nanoarchitecturing of Mo2C nanospheres on carbon cloth as an electrochemical sensing platform for determination of caffeic acid in tea samples.

In the present paper, carbon cloth (CC) as a flexible substrate was modified by molybdenum carbide nanospheres (Mo2C NSs @CC) by the drop-coating method to develop a sensitive electrochemical platform for detecting caffeic acid. The uniform Mo2C NSs were prepared via an easy route followed by pyrolyzing the precursor of the Mo-polydopamine (Mo-PDA) NSs. The Mo2C NSs were characterized and analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FE-SEM/EDS), Raman spectroscopy (RS), and electrochemical methods. CC not only gave a flexible feature to the sensor but also provided a larger surface area for Mo2C NSs. Meanwhile, the excellent conductivity and large electroactive specific surface area of Mo2C NSs exhibited excellent electrocatalytic performance for caffeic acid determination. The developed sensor showed high sensitivity and selectivity, good reproducibility, and long-term stability with a limit of detection (LOD) and a wide linear range of 0.001 µM (S/N = 3) and 0.01-50 µM, respectively. In addition, the Mo2C NSs @CC sensor showed a promising application prospect for the detection of caffeic acid in green and black tea samples, indicating its importance in food safety and the food industry.

Nanomaterial-based electrochemical sensors for detection of amino acids.

Amino acids are the building blocks of proteins and muscle tissue. They also play a significant role in physiological processes related to energy, recovery, mood, muscle and brain function, fat burning and stimulating growth hormone or insulin secretion. Accurate determination of amino acids in biological fluids is necessary because any changes in their normal ranges in the body warn diseases like kidney disease, liver disease, type 2 diabetes and cancer. To date, many methods such as liquid chromatography, fluorescence mass spectrometry, etc. have been used for the determination of amino acids. Compared with the above techniques, electrochemical systems using modified electrodes offer a rapid, accurate, cheap, real-time analytical path through simple operations with high selectivity and sensitivity. Nanomaterials have found many interests to create smart electrochemical sensors in different application fields e.g. biomedical, environmental, and food analysis because of their exceptional properties. This review summarizes recent advances in the development of nanomaterial-based electrochemical sensors in 2017-2022 for the detection of amino acids in various matrices such as serum, urine, blood and pharmaceuticals.

Achievements of Graphene and Its Derivatives Materials on Electrochemical Drug Assays and Drug-DNA Interactions.

Graphene, emerging as a true two-dimensional (2D) material, has attracted increasing attention due to its unique physical and electrochemical properties such as high surface area, excellent conductivity, high mechanical strength, and ease of functionalization and mass production. The entire scientific community recognizes the significance and potential impact of graphene. Electrochemical detection strategies have advantages such as being simple, fast, and low-cost. The use of graphene as an excellent interface for electrode modification provides a promising way to construct more sensitive and stable electrochemical (bio)sensors. The review presents sensors based on graphene and its derivatives for electrochemical drug assays from pharmaceutical dosage forms and biological samples. Future perspectives in this rapidly developing field are also discussed. In addition, the interaction of several important anticancer drug molecules with deoxyribonucleic acid (DNA) that was immobilized onto graphene-modified electrodes has been detailed in terms of dosage regulation and utility purposes.

Indirect Determination of Amikacin by Gold Nanoparticles as Redox Probe.

BACKGROUND: Amikacin is an aminoglycoside antibiotic used for many gram-negative bacterial infections like infections in the urinary tract, infections in brain, lungs and abdomen. Electrochemical determination of amikacin is a challenge in electroanalysis because it shows no voltammetric peak at the surface of bare electrodes. OBJECTIVE: In this approach, a very simple and easy method for indirect voltammetric determination of amikacin presented in real samples. Gold nanoparticles were electrodeposited at the surface of glassy carbon electrode in constant potential. METHODS: The effect of several parameters such as time and potential of deposition, pH and scan rates on signal were studied. The cathodic peak current of Au3+ decreased with increasing amikacin concentration. Quantitative analysis of amikacin was performed using differential pulse voltammetry by following cathodic peak current of gold ions. RESULTS: Two dynamic linear ranges of 1.0 × 10-8-1.0 × 10-7 M and 5.0 × 10-7-1.0 × 10-3 M were obtained and limit of detection was estimated 3.0× 10-9 M. CONCLUSION: The method was successfully determined amikacin in pharmaceutical preparation and human serum. The effect of several interference in determination of amikacin was also studied.

An Overview on Electrochemical Sensors Based on Nanomaterials for the Determination of Drugs of Abuse.

Drug abuse is considered a serious source of economic and social problems. The identification of drugs of abuse is in demand in forensic and clinical toxicology. There are various methods for the determination of these materials, including chromatographic and mass spectrometric techniques. However, most of these techniques need high-cost equipment, they are time-consuming, and they suffer from complicated sample preparation protocols. In contrast, electrochemical methods are low cost, mobile, and they do not require complicated sample preparation protocols. The use of nanomaterials in electroanalysis has gained significant attention in order to improve selectivity, enhance sensitivity, and lower the limit of detections. Nanomaterials have significantly gained research-interest due to their low cost (due to low amounts of materials being used) and their uniquely size-dependent properties. The incorporation of nanomaterials into host matrices is important to prepare nanocomposite sensor films. Unique properties of nanomaterials and hybrid materials, such as mechanical strength, electrical conductivity, optical responsiveness, specific catalytic and magnetic properties, in addition to high surface area per mass ratio are attractive. Besides providing novel properties, nanomaterials allow low-cost electrode fabrication based on simple technologies. The combination of nanotechnology with modern electroanalytical techniques allows innovation in electrical sensing devices with features like increased mass transport, high sensor surface area, and controlled electrode surface micro-environment. The aim of this review is to give an outline of electroanalytical determination based on nanomaterials focusing on illicit drugs in matrices, such as urine, blood, or saliva. We summarize developments in field-based sensors for determining drugs of abuse.

Smartphone Overuse from Iranian University Students' Perspective: A Qualitative Study.

BACKGROUND: Smartphone usage has increasing during recent years. Since its excessive use can have negative consequences, it is important to know how users use it and become dependent on it. This study was aimed at exploring how university students use their phones, how they depend on them, and the possible consequences of overusing them. METHODS: This study was conducted using a qualitative design and with a thematic analysis method. Data were collected using 3 focus group discussions regarding experiences of using smartphones among 22 smartphone owners who reported smartphone overuse. They were chosen through snowball sampling at a University of Medical Sciences in Tehran (Iran). FINDINGS: Based on the analysis, the 3 categories of process usage (sub-categories: doing daily routines, information seeking, to take a picture or video, entertainment, academic work, making money, to escape real-life, and passing the time), social usage (sub-categories: relationship with family, relationship with friends, interact with the opposite gender, to be seen and heard, approval seeking, and free expression), and disadvantages (sub-categories: interference with other essential activities, decreased face-to-face communications, overdependence, automatic use, loss of sense of time, stress, fatigue, sleep disturbances, physical inactivity, eye problems, high bills, and distraction) were developed. CONCLUSION: In this research, participants mentioned various uses of their smartphones that enable them to meet their personal needs and, in spite of the negative consequences of its overuse, cause them to continue to use it. Some uses seem to be affected by environmental and cultural conditions.

The problematic use of mobile phone and mental health: A review study in Iran.

There is growing evidence that the problematic use of mobile phone is an evolving problem. Although some studies have noted a greater prevalence in the Middle East, intercultural differences have not been sufficiently studied to date. The present study, therefore, aims at reviewing Iranian published studies on the problematic use of mobile phone in Iran. This study was conducted as a review study. For this purpose, we searched all published studies in this field that were conducted in Iran and reviewed all of the articles by studying the prevalence of the problematic use of cell phone in Iran, the adopted measuring instruments, the employed terms, predictors of the problematic use of cell phone, and the consequences of the problematic use of cell phone. After applying the inclusion and exclusion criteria, 47 articles were selected for evaluation. Among the problematic consequences, sleep disturbance was the most studied factor. Additionally, gender, feeling of loneliness, attachment stiles and age were mostly referred to as predictors. In addition, the reported prevalence varied from 0.9% to 64.5%, depending on the studied population and the measuring instruments. The diversity of reported prevalence rate of problematic use of mobile phone in Iran can be related to the ambiguity of the concept of "problematic use" and the diversity of the employed measuring tools. Thus, care should be taken in generalizing and interpreting the results.

The comparison of histopathological characteristics of polyps in asthmatic and nonasthmatic patients.

INTRODUCTION: Considering the different clinical aspects of polyps in asthmatic and nonasthmatic patients, we aimed to explore their histopathological characteristics. MATERIAL AND METHODS: Twenty-five asthmatic patients and 25 nonasthmatic patients with polypoid chronic rhinosinusitis (29 male, 21 female; mean age 41.3 +/- 13.27; range 15-78 years) were enrolled in the study to be compared on the basis of histopathological characteristics. They were compared according to the following seven light microscopic findings: basement membrane thickness, goblet cell hyperplasia, subepithelial edema, submucous gland formation, eosinophilic infiltration, lymphocytic infiltration, and polymorphonuclear infiltration. RESULTS: Basement membrane thickening, goblet cell hyperplasia, and eosinophilic and lymphocytic infiltration were more prominent in the asthmatic compared with the nonasthmatic group (P < 0.05), whereas polymorphonuclear infiltration was more prominent in nonasthmatics (P < 0.05). No statistically significant differences were found between the two groups with regard to submucosal gland hyperplasia or subepithelial edema. CONCLUSION: Asthmatic patients present histopathological characteristics of a marked chronic inflammatory reaction, which might explain the negative effect on chronic rhinosinusitis outcome and the severity of the disease in this group.

Entrapment of uropathogenic E. coli cells into ultra-thin sol-gel matrices on gold thin films: A low cost alternative for impedimetric bacteria sensing.

Bacterial infections are causing worldwide morbidity and mortality. One way to limit infectious outbreaks and optimize clinical management of infections is through the development of fast and sensitive sensing of bacteria. Most sensing approaches are currently based on immunological detection principles. We report here on an impedimetric sensor to selectively and sensitive detect uropathogenic E. coli cells (E. coli UTI89) using artificial recognition sites. We show here the possibility to imprint the rod-shape structure of E. coli UTI 89 into ultra-thin inorganic silica coatings on gold electrodes in a reproducible manner. A linear range from to 1 × 100 -1 × 104 cfu mL-1 is obtained. With a detection limit for E. coli UTI89 below 1 cfu mL-1 from five blank signals (95% confidence level) and excellent selective binding capabilities, these bacterial cell imprinted electrodes brings us closer to a low cost specific bacterial recognition surfaces.

Electrochemical Methodologies for the Detection of Pathogens.

Bacterial infections remain one of the principal causes of morbidity and mortality worldwide. The number of deaths due to infections is declining every year by only 1% with a forecast of 13 million deaths in 2050. Among the 1400 recognized human pathogens, the majority of infectious diseases is caused by just a few, about 20 pathogens only. While the development of vaccinations and novel antibacterial drugs and treatments are at the forefront of research, and strongly financially supported by policy makers, another manner to limit and control infectious outbreaks is targeting the development and implementation of early warning systems, which indicate qualitatively and quantitatively the presence of a pathogen. As toxin contaminated food and drink are a potential threat to human health and consequently have a significant socioeconomic impact worldwide, the detection of pathogenic bacteria remains not only a big scientific challenge but also a practical problem of enormous significance. Numerous analytical methods, including conventional culturing and staining techniques as well as molecular methods based on polymerase chain reaction amplification and immunological assays, have emerged over the years and are used to identify and quantify pathogenic agents. While being highly sensitive in most cases, these approaches are highly time, labor, and cost consuming, requiring trained personnel to perform the frequently complex assays. A great challenge in this field is therefore to develop rapid, sensitive, specific, and if possible miniaturized devices to validate the presence of pathogens in cost and time efficient manners. Electrochemical sensors are well accepted powerful tools for the detection of disease-related biomarkers and environmental and organic hazards. They have also found widespread interest in the last years for the detection of waterborne and foodborne pathogens due to their label free character and high sensitivity. This Review is focused on the current electrochemical-based microorganism recognition approaches and putting them into context of other sensing devices for pathogens such as culturing the microorganism on agar plates and the polymer chain reaction (PCR) method, able to identify the DNA of the microorganism. Recent breakthroughs will be highlighted, including the utilization of microfluidic devices and immunomagnetic separation for multiple pathogen analysis in a single device. We will conclude with some perspectives and outlooks to better understand shortcomings. Indeed, there is currently no adequate solution that allows the selective and sensitive binding to a specific microorganism, that is fast in detection and screening, cheap to implement, and able to be conceptualized for a wide range of biologically relevant targets.

Palladium nanoparticles in electrochemical sensing of trace terazosin in human serum and pharmaceutical preparations.

In this approach, palladium nanoparticle film was simply fabricated on the surface of carbon paste electrode by electrochemical deposition method. The film was characterized using scanning electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry. The prepared electrode exhibited an excellent electrocatalytic activity toward detection of trace amounts of terazosin, which is an antihypertensive drug. Under the optimum experimental conditions, a linear range of 1.0×10-8-1.0×10-3molL-1 with a detection limit of 1.9×10-9molL-1 was obtained for determination of terazosin using differential pulse voltammetry as a sensitive method. The efficiency of palladium nanoparticle film on the surface of carbon paste electrode successfully proved for determination of terazosin in pharmaceutical sample and human serum sample with promising recovery results. The effect of some foreign species has been studied.

Adsorption of Amlodipine at the Surface of Tosyl─Carbon Nanoparticles for Electrochemical Sensing.

The adsorption processes of amlodipine onto hydrophilic carbon nanoparticles (Emperor 2000TM) are investigated. The significant increase in voltammetric responses for pre-adsorbed amlodipine compared with those for solution confirms high affinity of amlodipine to carbon nanoparticles (possibly due to π-π stacking interaction between aromatic rings of amlodipine and surface-sulfonated carbon nanoparticles). To obtain the optimum of adsorption conditions, the effects of pH, agitation rate, and adsorption time are investigated. Under differential pulse voltammetry conditions, the peak current for the oxidation of amlodipine shows two linear relationships with concentration in the range from 1000 µM to 10.0 µM and 10.0 µM to 10.0 nM. The limit of detection is estimated to be 1.0 nM. Determination of amlodipine in real samples such as human serum and commercial tablets is demonstrated.

A cryogenic rotation stage with a large clear aperture for the half-wave plates in the Spider instrument.

We describe the cryogenic half-wave plate rotation mechanisms built for and used in Spider, a polarization-sensitive balloon-borne telescope array that observed the cosmic microwave background at 95 GHz and 150 GHz during a stratospheric balloon flight from Antarctica in January 2015. The mechanisms operate at liquid helium temperature in flight. A three-point contact design keeps the mechanical bearings relatively small but allows for a large (305 mm) diameter clear aperture. A worm gear driven by a cryogenic stepper motor allows for precise positioning and prevents undesired rotation when the motors are depowered. A custom-built optical encoder system monitors the bearing angle to an absolute accuracy of ±0.1(∘). The system performed well in Spider during its successful 16 day flight.

Carbon nanoparticles with tosyl functional group for distinguishing voltammetric peaks of ascorbic acid and uric acid.

In this approach, electro-oxidation of a mixture of uric acid and ascorbic acid at the surface of tosyl surface carbon nanoparticles/glassy carbon electrode has been performed. The electro-oxidation of these compounds at bare electrode is sluggish and there is no suitable peak separation between them. However, using functionalized carbon nanoparticles, two well-defined anodic peaks with a considerable enhancement in the peak current and a remarkable peak potential separation near 452 mV is obtained. The porous interfacial layer of the carbon nanoparticles modified electrode with a high specific surface area increases the conductive area; molecules can penetrate through the conductive porous channels onto the electrode more easily so leading to higher sensitivity and selectivity. The dynamic linear ranges of 1.0 × 10(-5) to 3.0 × 10(-3)M and 1.0 × 10(-7) to 1.0 × 10(-4)M with detection limits 1.0 × 10(-5)M and 2.0 × 10(-8)M (for S/N=3) were obtained for ascorbic acid and uric acid, respectively. Analytical utility of the modified electrode has been examined successfully using human urine samples and vitamin C commercial tablets.

Interfacial electron-shuttling processes across KolliphorEL monolayer grafted electrodes.

Covalently grafted KolliphorEL (a poly(ethylene glycol)-based transporter molecule for hydrophobic water-insoluble drugs; MW, ca. 2486; diameter, ca. 3 nm) at the surface of a glassy-carbon electrode strongly affects the rate of electron transfer for aqueous redox systems such as Fe(CN)6(3-/4-). XPS data confirm monolayer grafting after electrochemical anodization in pure KolliphorEL. On the basis of voltammetry and impedance measurements, the charge transfer process for the Fe(CN)6(3-/4-) probe molecule is completely blocked after KolliphorEL grafting and in the absence of a "guest". However, in the presence of low concentrations of suitable ferrocene derivatives as guests, mediated electron transfer across the monolayer via a shuttle mechanism is observed. The resulting amplification of the ferrocene electroanalytical signal is investigated systematically and compared for five ferrocene derivatives. The low-concentration electron shuttle efficiency decreases in the following sequence: (dimethylaminomethyl)ferrocene > n-butyl ferrocene > ferrocene dimethanol > ferroceneacetonitrile > ferroceneacetic acid.