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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]

A large volume of scientific literature has pointed toward the potentially important role of functional hybrid nanostructure materials (FHNMs) in the monitoring and analysis of volatile organic compounds (VOCs) with unprecedented sensitivity. In light of the potentially significant role of FHNMs, this review describes the working principles, performance, and advantages of using these materials in sensing applications. To this end, we discuss the recent progress in the use of FHMNs in the detection of VOCs. Finally, this review was extended to cover the current research activities of FHMNs along with their future opportunities/challenges in this emerging field. [ABSTRACT FROM AUTHOR]

As non-biological molecules, molecular imprinted polymers (MIPs) can be made as antibody mimics for the development of luminescence sensors for various targets. The combination of MIPs with nanomaterials is further recognized as a useful option to improve the sensitivity of luminescence sensors. In this work, the recent progresses made in the fabrication of fluorescence, phosphorescence, chemiluminescence, and electrochemiluminescence sensors based on such combination have been reviewed with emphasis on the detection of pesticides/herbicides. Accordingly, the materials that are most feasible for the detection of such targets are recommended based on the MIP technologies. [Display omitted] • MIP-materials have been evaluated for luminescent sensing of pesticides/herbicides. • Dopant and nanomaterials are used to impart luminescence properties in MIPs. • Performance of sensors is evaluated by LOD, detection time, and linear range. • The europium doped MIP was found most sensitive with 0.005 ng/L LOD. [ABSTRACT FROM AUTHOR]

[Display omitted] • HMIPs are an advanced option for solid phase extraction analysis in complex matrices. • Various preparation strategies of HMIPs are described for their environmental applications. • Prospects for a widespread use of HMIPs are discussed based on their merits and demerits. Molecular imprinting technology (MIT) offers a lock-and-key mechanism for template molecules using molecularly imprinted polymers (MIPs) with tailor-made binding sites. Recently, MIPs have been utilized in a wide range of applications in various fields due to their excellent recognition specificity and high sensitivity for template molecules. However, as the practical use of traditional MIPs has been limited by a number of flaws (e.g., poor site accessibility toward templates, slow mass transfer, and unsatisfactory resolution), hollow porous MIPs (HMIPs) have been proposed as an effective remedy. Herein, we reviewed the recent advances in HMIPs with respect to strategies for their fabrication and extraction application (e.g., solid phase extraction and dispersive solid phase extraction) towards sample preparation from complex environmental matrices for analytical applications. A performance analysis of diverse MIPs is presented in terms of LOD and adsorption capacity to support superiority of HMIPs in environmental analysis. The challenges and prospects of the HMIPs are also discussed for their viable applications in environmental analysis. [ABSTRACT FROM AUTHOR]

Arsenic, As(III) is one of the highly toxic metalloid ions present in the earth's crust. Its availability especially in groundwater, soil, and plant products can impose significant environmental and health risks. In order to examine aforementioned matrices for the presence of As(III), we have fabricated a sensitive electrochemical bionanoprobe using As(III) specific aptamer modified glutathione (GSH)-capped gold nanoparticles. The developed probe demonstrated remarkable sensing performance for a wide concentration range of As(III) (e.g., 0.1–1000 mg/L) with extremely high sensitivity of 0.0875 µA/(mg/L.mm2). Moreover, we have achieved an exceptionally low limit of detection (0.13 µg/L) for As(III) using the developed bionanoprobe. Furthermore, it displayed excellent performance in monitoring As(III) in groundwater, soil, and rice samples. [Display omitted] • GSH-AuNPs-based aptasensing probe is developed for arsenic. • Straightforward approach for the sensing of 0.1–1000 ppm of arsenic. • A sensitivity of 0.0875 µA/(ppm.mm²) has been achieved for arsenic. • The developed bionanoprobe exhibited an LOD of ∼0.13 ppb for arsenic. • Successfully used for arsenic sensing in groundwater, soil, and rice samples. [ABSTRACT FROM AUTHOR]

• Urea, which is synthesized during the metabolism of N -containing compounds in mammals. • Increasing urea levels in milk samples are suspected to reflect pathological problems. • We developed direct and mediator-free urea sensors based on screen-printed electrodes (SPEs). • To this end, graphene nanoplatelets/graphitized nanodiamonds (GNPlts/GNDs) was synthesized. • The developed platform was a highly reliable and sensitive tool for the detection of urea. Urea is well-known to offer tremendous scope for sensing/diagnosing such as adulteration in dairy products or diseases in human body. This study was organized to describe and validate a new mediator-free, unsophisticated, and direct current voltage (IV)-based sensor for facile detection of urea using nanocomposites made of urease-immobilized graphene nanoplatelets and graphitized nanodiamonds. This nanocomposite displayed sensitive and direct signal in the form of current at 0 V without the need of any complex chemical reaction. This platform was highly sensitive (limit of detection of 5 μg/mL) far superior to the comparable systems introduced recently. The incorporation of graphitized nanodiamonds within the graphene nanoplatelets layers helped improve the sensitivity by a factor of three (up to 806.3 µA (mg mL−1)−1 cm−2) with 20 s response time. As such, the use of this nanocomposite was helpful in improving sensing performances with enhanced enzyme loading capacity. [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]

Cancer is the second most common cause of death in the world. The principal limitations thus far encountered in the clinical practice of probing cancer are diverse and include low sensitivity, time consumption, bulkiness, and cost. In this respect, nanomaterial (NM)‐based sensing techniques are recognized as a superior alternative to efficiently resolve such limitations. A better understanding of NM‐based sensing platforms is thus important so that these novel avenues can easily be explored for clinical applications. These platforms have the merits of high sensitivity, high specificity, rapid response, and easy‐to‐read signals. This review offers a comprehensive survey of NM‐based advanced cancer‐sensing techniques and will help the scientific community establish optimum sensing strategies based on an accurate assessment of the interactions between cancer biomarkers and NM‐based platforms. [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]

Herein, a sensitive, selective, and facile sensing approach was developed by tailoring gold nanoparticles (AuNPs) to detect phenolic compounds in water and food/plant products across a range of concentrations. Sensing probes selective toward four different concentration ranges of phenolic compounds were constructed by varying the capping amounts (µg/mL) of tyrosinase (Ty) on the AuNP surface such as 5, 10, 50, and 100 µg/mL. Accordingly, an ultralow limit of detection (LOD) for phenolic compounds was achieved at 0.01 ppb (along with the upper bound detection of 50,000 ppm) via spectroscopic methodology. Interestingly, the absorbance of the developed sensing probe increased in the presence of phenolic compounds due to separation of Cu (present in Ty) from the proximity of AuNPs. A novel sensing mechanism has been proposed in light of interaction between enzyme substrate and copper of Ty with gold nanoparticles. Moreover, the applicability of the developed sensing probe is successfully validated using the tea leaves samples. • Ty-AuNPs probes were developed for ultrasensitive sensing of phenolic compounds. • The spectroscopic and color-based sensing was performed. • The sensor works well for 0.01 ppb- 50,000 ppm of phenolic compounds. • The lowest LOD value of 0.01 ppb was achieved by Ty-AuNPs (5). • A novel Cu-based sensing mechanism has been proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co and Mo Engineered MOF is prepared for specific and sensitive sensing of As. • Co/Mo MOF is utilized for paper-based and spectroscopic sensing. • The sensor works well for 0.05 ppb to 1000 ppm of As(V). • LOD values of 0.02 and 0.04 ppb for As (V) was achieved by spectroscopic and paper-based sensors, respectively. • The Mo-As interactions is responsible for detection of As(V) ions. As one of the most toxic contaminants, arsenic (As) is well-known for diverse types of adversary effects on the life of living beings. Unfortunately, as the conventional methods of its detection generally suffer from several demerits (e.g., long duration, high cost, and complexity), the engineering of advanced materials could be a solution for the development of next generation sensors. In an effort to validate such proposition, we developed a molybdenum based metal–organic framework (Mo-MOF) by modifying a common form of [(Mo 2 O 6)(4,4′–bpy)] n) as a new sensing platform for As. We have successfully developed and characterized a mixed metal (Co/Mo) MOF for the specific, sensitive, and expeditious detection of As(V) metal ions. The color changing capacity (from purple to blue) of Co/Mo-MOF is found to maintain a good linear relationship with changes in the concentration of As(V) from 0.05 ppb to 1000 ppm. This Mo-based MOF sensor, when bound with spectroscoptic and paper-based methods, offered exceptionally low limits of detection (LOD) for As(V) ions such as 0.02 and 0.04 ppb, respectively. [ABSTRACT FROM AUTHOR]