Styrene Sulphonic Acid Doped Polyaniline Based Immunosensor for Highly Sensitive Impedimetric Sensing of Atrazine

Theoretical Study of Vinyl-Sulfonate Monomers and Their Effect as the Dopants of Polyaniline Dimers

Establishing the structure–property relationships of monomers and polymers via theoretical chemistry is vital for designing new polymer structures with a specific application. Developing bifunctional monomers with selective polymerizable sites is one of the strategies employed to obtain complex polymeric systems. In this work, a theoretical study on anilinium 2-acrylamide-2-methyl-1-propanesulfonate (ani-AMPS) and anilinium 4-styrenesulfonate (ani-SS) monomers and their respective doped polyaniline dimer (PAni-d AMPS or PAni-d SS) was performed. The study focused on understanding the susceptibility of the vinyl group to a radical attack and the conformation changes resulting from the coordinated covalent bond between sulfonate and aniliniun. Applying Density Functional Theory with the B3LYP functional and a basis set of 6 − 31 + G(d,p), the structures of the ani-AMPS, ani-SS, PAni-d AMPS, and PAni-d SS were optimized, and the different chemical descriptors were determined. The simulation showed that the reactivity of the vinyl group in the ani-AMPS is slightly higher. The sulfonate group undergoes a conformational change when bonding with PAni-d AMPS or PAni-d SS compared to its respective bifunctional monomer. Additionally, the electronegativity of PAni-d depends on the dopant’s structure. Thus, the bonded spacer between the vinyl and sulfonate groups (dopant) plays a notable role in the final characteristics of ani-AMPS, ani-SS, PAni-d AMPS, and PAni-d SS.

Xenobiotics-Division and Methods of Detection: A Review

Xenobiotics are compounds of synthetic origin, usually used for domestic, agricultural, and industrial purposes; in the environment, they are present in micropollutant concentrations and high concentrations (using ng/L to µg/L units). Xenobiotics can be categorized according to different criteria, including their nature, uses, physical state, and pathophysiological effects. Their impacts on humans and the environment are non-negligible. Prolonged exposure to even low concentrations may have toxic, mutagenic, or teratogenic effects. Wastewater treatment plants that are ineffective at minimizing the release of xenobiotic compounds are one of the main sources of xenobiotics in the environment (e.g., xenobiotic compounds reach the environment, affecting both humans and animals). In order to minimize the negative impacts, various laws and regulations have been adopted in the EU and across the globe, with an emphasis on xenobiotics removal from the environment, in a way that is economically, environmentally, and socially acceptable, and will not result in their accumulation, or creation of compounds that are more harmful. Detection methods allow detecting even small concentrations of xenobiotics in samples, but the problem is the diversity and mix of compounds present in the environment, in which it is not known what their effects are). In this review, the division of xenobiotics and their detection methods will be presented.

Insights and Perspectives Regarding Nanostructured Fluorescent Materials toward Tackling COVID-19 and Future Pandemics

The COVID-19 outbreak has exposed the world's preparation to fight against unknown/unexplored infectious and life-threatening pathogens. The unavailability of vaccines, slow or sometimes unreliable real-time virus/bacteria detection techniques, insufficient personal protective equipment (PPE), and a shortage of ventilators and many other transportation equipments have further raised serious concerns. Material research has been playing a pivotal role in developing antimicrobial agents for water treatment and photodynamic therapy, fast and ultrasensitive biosensors for virus/biomarkers detection, as well as for relevant biomedical and environmental applications. It has been noticed that these research efforts nowadays primarily focus on the nanomaterials-based platforms owing to their simplicity, reliability, and feasibility. In particular, nanostructured fluorescent materials have shown key potential due to their fascinating optical and unique properties at the nanoscale to combat against a COVID-19 kind of pandemic. Keeping these points in mind, this review attempts to give a perspective on the four key fluorescent materials of different families, including carbon dots, metal nanoclusters, aggregation-induced-emission luminogens, and MXenes, which possess great potential for the development of ultrasensitive biosensors and infective antimicrobial agents to fight against various infections/diseases. Particular emphasis has been given to the biomedical and environmental applications that are linked directly or indirectly to the efforts in combating COVID-19 pandemics. This review also aims to raise the awareness of researchers and scientists across the world to utilize such powerful materials in tackling similar pandemics in future.

Nanomaterial-based immunosensors for ultrasensitive detection of pesticides/herbicides: Current status and perspectives

The increasing level of pesticides and herbicides in food and water sources is a growing threat to human health and the environment. The development of portable, sensitive, specific, simple, and cost-effective sensors is hence in high demand to avoid exposure or consumption of these chemicals through efficient monitoring of their levels in food as well as water samples. The use of nanomaterials (NMs) for the construction of an immunosensing system was demonstrated to be an efficient and effective option to realize selective sensing against pesticides/herbicides. The potential of such applications has hence been demonstrated for a variety of NMs including graphene, carbon nanotubes (CNTs), metal nanoparticles, and nano-polymers either in pristine or composite forms based on diverse sensing principles (e.g., electrochemical, optical, and quartz crystal microbalance (QCM)). This article evaluates the development, applicability, and performances of NM-based immunosensors for the measurement of pesticides and herbicides in water, food, and soil samples. The performance of all the surveyed sensors has been evaluated on the basis of key parameters, e.g., detection limit (DL), sensing range, and response time.

Electrochemical sensors and biosensors based on the use of polyaniline and its nanocomposites: a review on recent advances

Polyaniline and its composites with nanoparticles have been widely used in electrochemical sensor and biosensors due to their attractive properties and the option of tuning them by proper choice of materials. The review (with 191 references) describes the progress made in the recent years in polyaniline-based biosensors and their applications in clinical sensing, food quality control, and environmental monitoring. A first section summarizes the features of using polyaniline in biosensing systems. A subsequent section covers sensors for clinical applications (with subsections on the detection of cancer cells and bacteria, and sensing of glucose, uric acid, and cholesterol). Further sections discuss sensors for use in the food industry (such as for sulfite, phenolic compounds, acrylamide), and in environmental monitoring (mainly pesticides and heavy metal ions). A concluding section summarizes the current state, highlights some of the challenges currently compromising performance in biosensors and nanobiosensors, and discusses potential future directions. Graphical abstract Schematic presentation of electrochemical sensor and biosensors applications based on polyaniline/nanoparticles in various fields of human life including medicine, food industry, and environmental monitoring. The simultaneous use of suitable properties polyaniline and nanoparticles can provide the fabrication of sensing systems with high sensitivity, short response time, high signal/noise ratio, low detection limit, and wide linear range by improving conductivity and the large surface area for biomolecules immobilization.

Design of a facile and label-free electrochemical aptasensor for detection of atrazine

A facile and label-free electrochemical aptasensor for detection of atrazine (ATZ) was designed based on nickel hexacyanoferrate nanoparticles (NiHCF NPs) and electrochemically reduced graphene oxide (ERGO). Because of ERGO perfect electrochemical conductivity and large surface area, it was first modified on glassy carbon electrode (GCE) surface by electrochemical reduction. NiHCF NPs were immobilized on ERGO/GCE as a signal probe with well-defined peaks and good stability. Subsequently, gold nanoparticles (Au NPs) were electrodeposited on NiHCF NPs/ERGO to anchored aptamer and increase the conductivity and stability of the electrode. When ATZ was added, ATZ-aptamer complexes generated with poor conductivity on the sensor surface increased the hindrance of electron transfer, leading to electrochemical signal decrease. The signal change was used to detect ATZ quantitatively. The designed aptasensor exhibited good analytical performance for determining ATZ. A linear curve was obtained in the range of 0.25-250 pM with a low detection limit of 0.1 pM, and it showed perfect selectivity for ATZ in the presence of diverse interferents. Meanwhile, the electrochemical aptasensor was employed to evaluate ATZ content in the samples.

Emerging Robust Heterostructure of MoS2-rGO for High-Performance Supercapacitors

The intermittent nature of renewable energy resources has led to a continuous mismatch between energy demand and supply. A possible solution to overcome this persistent problem is to design appropriate energy-storage materials. Supercapacitors based on different nanoelectrode materials have emerged as one of the promising storage devices. In this work, we investigate the supercapacitor properties of a molybdenum disulfide-reduced graphene oxide (rGO) heterostructure-based binder-free electrode, which delivered a high specific capacitance (387.6 F g^-1 at 1.2 A g^-1) and impressive cycling stability (virtually no loss up to 1000 cycles). In addition, the possible role of rGO in the composite toward synergistically enhanced supercapacitance has been highlighted. Moreover, an attempt has been made to correlate the electrochemical impedance spectroscopy studies with the voltammetric analyses. The performance exceeds that of the reported state-of-the-art structures.

A highly selective and sensitive chemosensor forl-tryptophan by employing a Schiff based Cu(ii) complex

Construction of a new Cu(ii) complex (1) based modified glassy carbon electrode (1-GCE) for highly selective and sensitive detection ofl-tryptophan (l-Trp).

Multifunctional porous NiCo2O4 nanorods: sensitive enzymeless glucose detection and supercapacitor properties with impedance spectroscopic investigations

Multifunctional NiCo₂O₄ nanorods fabricated by a simple two-step method exhibit excellent performance in glucose sensors as well as supercapacitors.

Microwave assisted fabrication of a nanostructured reduced graphene oxide (rGO)/Fe2O3 composite as a promising next generation energy storage material

A supercapacitor electrode material, rGO–Fe₂O₃ composite, prepared by a facile microwave assisted in situ technique, delivers a high specific capacitance of 577.5 F g⁻¹ at a current density of 2 A g⁻¹ with a long cycle life and high rate performance.

Non-enzymatic amperometric sensing of glucose by employing sucrose templated microspheres of copper oxide (CuO)

An enzymeless glucose sensor (MCSPE) based on copper oxide microspheres (CMS) prepared by hydrothermal reaction of copper nitrate and sucrose, can sense glucose in a wide linear detection range with good sensitivity and low detection limit.

Immunosensing of Atrazine with Antibody-Functionalized Cu-MOF Conducting Thin Films

This work reports the assembly of thin films of a silica (SiO2)-modified copper-metal organic framework, Cu3(BTC)2 [Cu3(BTC)2@SiO2, BTC = benzene-1,3,5-tricarboxylic acid] on a conducting substrate of NH2-BDC [NH2-BDC = 2-aminobenzene-1,4-dicarboxylic acid] doped polyaniline (PANI). Assembled Cu3(BTC)2@SiO2/BDC-PANI thin films displayed electrical conductivity in the range of 35 μA. These thin films were conjugated with antiatrazine antibodies to create a novel immunosensing platform. Various structural and spectral characteristics of the synthesized material and its bioconjugate were investigated. The developed immunosensor was used for the conductometric sensing of atrazine. The detection of atrazine was achieved with a high sensor sensitivity (limit of detection = 0.01 nM) and specificity in the presence of diverse pesticides (e.g., endosulfan, parathion, paraoxon, malathion, and monochrotophos).