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Antioxidants are key components in a multitude of food, plant, and pharmacological products. The quantitative, selective, and facile assessment of antioxidants has thus become crucial in evaluating the quality of such products and their health effects. In this respect, it is important to recognize the great potential of advanced materials, especially metal-organic frameworks (MOF) for the construction of highly efficient sensing platforms against antioxidants. In this article, the practical utility of MOFs is highlighted in the optical and electrochemical sensing of antioxidants in relation to their sensing mechanisms and performances (in terms LOD, sensing range, and detection time). The best MOF-based sensing platforms for antioxidants are after all recommended along with a discussion on the future of this technology. [Display omitted] • The sensing potentials of MOFs have been assessed against antioxidants. • MOF-based optical and electrochemical sensors are explored. • Basic QA parameters are examined to assess their sensing performances. • Mi-UiO-66 and Mi-UiO-67 are the best performers in terms of LOD. • Optical sensors are far more sensitive (e.g., 24 times) than electrochemical sensors. [ABSTRACT FROM AUTHOR]

Abstract In recent years, nanomaterials have become a rapidly developing material technology due to their numerous advantages (e.g., high surface area, tunable surface structures, and advanced optical/electrical/mechanical features) and tremendous potential in biomedical, environmental, and energy applications. Here, we offer a comprehensive review on the advances, challenges, and opportunities of nanomaterial-based sensing technology for narcotics. To this end, the synthesis and applicability of nanomaterials (e.g., carbon-based nanostructures, semiconductor nanoparticles, metal nanoparticles, and polymer nanostructures) for narcotics sensing are described in detail along with their diverse principles/mechanisms (e.g., electrochemical, colorimetric, fluorescent, surface plasmon resonance (SPR), and surface enhanced Raman spectroscopy (SERS)). Recent progress in the development of nanomaterials has been evaluated based on sensing performance (and operational conditions) including parameters related to efficiency, sensitivity, accuracy, precision, reusability, and economic viability. At last, this review offers prospects for the future research and development needed for nanomaterial-based sensing technology for the detection of narcotics. Graphical abstract Image 1 Highlights • In this review, the advances of nanomaterial-based sensing technology for narcotics are described. • To this end, their synthesis and applicability are dealt with their diverse principles/mechanisms. • Recent progress in this field is evaluated based on sensing performance and operational conditions. • The future research and development for narcotics sensing are proposed after all. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H 2 S) is and a colorless, corrosive, flammable, and toxic gas with a characteristic rotten egg smell. Although its detection can be conducted by conventional methods (like gas chromatography), highly effective and sensitive detection of H 2 S has been realized with the usage of various nanomaterials (e.g., carbon nanostructures, metal nanoparticles, metal oxide nanoparticles, and quantum dots). Metal-organic frameworks (MOFs), as employed for such applications either in their pristine or modified forms, have been recognized as the effective media for sensing of H 2 S due to synergistic effects in addition to their well-known merits (e.g., the large specific surface). This review has been organized to describe the potential applicability of MOF-based sensing against H 2 S through comparative evaluation of their capability against other materials or tools. We also discuss the present obstacles and outline the future scope of research on MOF-based sensing tools. [ABSTRACT FROM AUTHOR]

Ammonia (NH 3) is one of the most abundant inorganic pollutants present in air. Efficient and rapid detection of ammonia is important to maintain the quality of air in both indoor as well as outdoor environment. Among various sensing principles, resistive sensing is a very popular option for the accurate detection of ammonia levels. Further, out of all the materials for sensing applications, polyaniline (PANI) is reported as a highly recommendable option for the construction of such sensing system. Specifically, the utility of PANI modifed by a facile electrospinning method has been demonstrated in the fabrication of efficient sensing systems for gaseous ammonia. This review was organized to offer insight into the potential utility of electrospinning approaches in the construction of PANI-based chemoresistive sensors for gaseous ammonia. The reliability of diverse electrospun PANI-based sensing systems for ammonia was assessed based on a comprehensive evaluation of their performance with respect to key sensing parameters (e.g., sensitivity, selectivity, response time, and limit of detection). • The electrospinning can generate high quality polymers for versatile sensing applications. • PANI is one of the most suitable polymers for sensing gaseous ammonia. • Combination of electrospinning and PANI can fabricate high performance ammonia sensors. • PANI and its composite structures were developed through electrospinning for sensing NH 3. • The PANI/TiO 2 composite can show extremely low detectivity against NH 3 such as 50 ppt. [ABSTRACT FROM AUTHOR]

As one of the most explored carbon nanostructures, graphene has spurred research in building of diverse sensing platforms for various targets (including formaldehyde (FA)) due to the unique electrical/optical properties. Unlike most other nanomaterial-based sensors, graphene-based sensors show distinctive advantages to operate under ambient conditions. To review graphene sensors in detail, we divided them into three classes: those based on pristine, functionalized, or composite forms of graphene. The synergistic interactions of its nanostructured composites (with metals, metals oxides, semiconductor nanostructures, polymers, etc.) have helped them improve the sensing performance substantially. In this review article, we provide a detailed discussion of the development of graphene-based formaldehyde sensors. We evaluate the performance of the three different classes of graphene-based structures in terms of operational parameters, sensing range, detection limit, sensitivity, response time, and recovery time. We conclude this review with challenges and future directions for graphene-based formaldehyde sensors. Image 1 • The review evaluates graphene-based material for the sensing of gaseous FA. • Graphene-based materials are excellent in improving performances of FA sensors. • Graphene-based materials can efficiently operate under ambient conditions. • The basic QA parameters have been evaluated to compare the performances of different FA sensors. • Graphene-based materials are highly efficient platform to determine gaseous FA. [ABSTRACT FROM AUTHOR]

Abstract Nanomaterials have been the subject of intense and extensive research in developing various optical sensing tools due to their light dependent remarkable structural and functional attributes. In this review, we conducted a comprehensive and critical assessment of the optical sensing methods (e.g., colorimetry and fluorometry) using various types of nanomaterials (e.g., metal organic frameworks, metal nanoparticles, carbon nanomaterials, quantum dots, chiral molecules, and polymers). Special emphasis was placed on explaining key factors that govern their sensing capabilities, sensing mechanisms, and practical applications toward optical sensing of diverse metal species. Some recent case studies elaborating on the detection of toxic and heavy metal species are described in depth. The discussion is also extended to assess the reliability of nanomaterial-based optical sensing approaches with respect to their performance along with the major challenges and constraints in this research field. Highlights • The practicality of optical sensing toward metal ions is greatly recognized. • Factors governing the optical sensing are assessed against diverse optically active NMs. • The sensing mechanisms for optically active NMs are justifiably described. • Performance of each optical sensing platform is assessed for optimum detection of metals. [ABSTRACT FROM AUTHOR]

Schiff bases and their metal complexes have become well-known for catalytic (e.g., in various synthetic processes) and biological properties (e.g., antifungal, antibacterial, anti-malarial, and antiviral characteristics) since their discovery by Hugo Schiff in 1864. As synthetic compounds, they are employed as versatile tools in numerous applications such as fluorescent turn-on/turn-off sensors for the determination of diverse analytes (e.g., metallic components). As such, they can offer a way to identify toxic ions and/or to provide their speciation in environmental media. This review covers a broad range of Schiff bases that are used in sensing applications for metallic cations and anions in various kinds of environmental and biological media. [ABSTRACT FROM AUTHOR]