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Monitoring of food-based products is mandatory in recent days as a result of increasing health-related issues and to produce ready-to-eat foods. Generally, in the food industry, the antioxidant property of phenolic compounds is utilized to improvize human health. Gallic acid (GA) is a widely known and abundant phenolic acid found used in numerous foods because of its huge health benefits. So far, many methods have been developed for the detection of GA using diverse nanocomposites. Likewise in the view of providing a simple and inexpensive material, we propose a zeolitic imidazolate framework (ZIF-8) functionalized with guar gum (GG) towards GA sensing. Here, the composite is prepared in a very easy and time-efficient manner using biocompatible GG. The physiochemical properties confirm the material formation due to the electrostatic interaction between the zinc ion of ZIF-8 and GG’s hydroxyl or carboxyl groups. Morphological studies confirm the nanostructured rhombic dodecahedral ZIF-8 particles embellished on the surface of GG’s microlayers. Further, electrochemical studies reveal the composite excellent behaviuor towards the GA sensing with a wide linear range of 200 nM–2.5 mM and a detection limit (LOD) of 60 nM. In addition to this, the composite offers significant selectivity, and good stability of up to 84% for 100 cycles along with acceptable repeatability and reproducibility. Finally, the investigation of the practical utility of unspiked wine, grape juice and tea samples also profound the composite’s exceptional sensing with remarkable recovery. Considering all these results, the proposed ZIF-8@GG composite can be fit for the fabrication of sensor devices towards food product testing in industries.

Bovine serum albumin (BSA) emerged as a potential bioprotein in the sensing field. Understanding the interactions of BSA with the analyte biomolecule has not been much reported. Herein, we report the functionally modified BSA (f-BSA) and its consecutive adsorption onto DNA for the ultrasensitive protein sensing. The DNA-modified f-BSA (DNA@f-BSA) composite was further characterized by using scanning electron microscopy, X-ray diffraction and Fourier transform-infrared spectroscopy. Obtained results demonstrated excellent composite formulation due to electrostatic interaction/binding intercalation and provided promising scaffold for protein biosensor. The as-prepared DNA modified f-BSA (DNA@f-BSA) based biocomposite can be used as a selective probe for the detection of BSA by recording square wave voltammetry signals. The sensitivity of the hybrid biosensor significantly improved the BSA detection over a wide concentration range from 1 × 10−20 g ml−1 to 1 × 10−4 g ml−1 with a detection limit of 2.18 × 10−21 g ml−1. Thus, the results have revealed the promising biosensor interactions which pave the way for the sensitive protein detection.

A pioneering CuBTABB-MOF/rGO composite customized electrode is fabricated and utilized as a sensor towards identifying bisphenol A (BPA) in a phosphate buffer solution of pH 7.0. The composite is characterized by FTIR, Raman spectroscopy, XRD, SEM, EDX, HRTEM, and XPS to study its structural and morphological properties. Compared with Cu-BTABB-MOF and Cu-BTABB-MOF@GO, the Cu-BTABB-MOF@rGO modified electrode is more sensitive and selective to BPA due to a strong interaction between them. The developed Cu-BTABB-MOF@rGO modified electrode exhibits good sensitivity (6.95 × 10

Development of novel nanomaterial-based co-reactant is highly desired for enhancing ECL intensity and widespread analytical applications. Herein, we report the distinct role of amine-functionalized carbon quantum dots (f-CQDs) as a co-reactant, for the first time, augmenting the ECL property of Ru(bpy)32+ and demonstrating for biopharmaceutical (butein) detection. Unlike conventional co-reactants like tripropylamine (TPrA), 2-(dibutylamino)ethanol (DBAE), and pristine CQDs, the f-CQDs as a co-reactant yield superior ECL of Ru(bpy)32+. More importantly, the ECL intensity is independent of types of noble metals, metal oxide surfaces, and dissolved oxygen. Notably, the ECL intensity of Ru(bpy)32+–f-CQDs is linearly quenched with an increased concentration of butein, whereas no changes were observed with conventional co-reactants. ECL functionality of Ru(bpy)32+–f-CQDs has no interference with other similar phytochemicals and antioxidants. Enhanced selectivity is observed due to the formation of polyaminoquinone-like structures, which is confirmed by in situ spectroelectrochemical (UV–vis) and FT-IR studies. The present result envisaged that f-CQDs could be an alternative co-reactant for TPrA/DBAE, raising the ECL of Ru(bpy)32+ suitable for analytical studies.

Over the past few decades, electrochemiluminescence (ECL) has been used as a powerful analytical tool for in vitro diagnosis due to its promising potential in light-emitting and, which has greatly promoted recent for biosensor studies. Plenty of research articles on the ECL technique have been published by various researchers around the globe. On the other hand, studies on the coupling of ECL sensing strategies with other techniques are recently getting widespread attention. ECL strategies have been effectively coupled with scanning electrochemical microscope (SECM), flow injection analysis (FIA), and capillary electrophoresis. These coupled techniques have been effectively employed for various health care applications. Among these techniques, FIA coupled ECL sensing strategies have been designated as the most emerging technique, especially sensing of clinical samples. This critical review discusses the vibrant developments in FIA-ECL, the mechanism of ECL, the design of FIA-ECL, and highlights the application of FIA-ECL for the detection of immunoassays, catecholamines, antioxidant compounds, choline, tetracyclines, and pharmaceutical drugs. The current review will pave the way for the design and development of FIA-ECL for efficient point-of-care applications.

In electrochemiluminescence (ECL) studies, Tris (bipyridine)ruthenium(II) chloride (Ru(bpy)32+) and its derivatives have been used as primary luminophores since 1972. The flexible solubility in both aqueous and non-aqueous medium and the remarkable intrinsic properties like chemical, optical and desirable electrochemical behavior drives the researcher to use Ru(bpy)32+ and its derivatives as highly active ECL probes in modern analytical science. Novel surface modification of Ru(bpy)32+ based ECL platforms are highly useful in the selective and sensitive detection of biomolecules, DNA analysis, immunoassays detection, and imaging of the biologically important molecules in cells and tissue of living organisms. This chapter discusses and highlights the most significant works in Ru(bpy)32+ based ECL properties of reaction mechanisms and their applications.

Though luminol is one of the most prominent and extensively studied luminophores in ECL studies, only H2O2 has been widely used as a co-reactant. This limits the variety of applications because of the short-time radical stability and low quantum efficiency. In the present work, we identified dicyclohexylamine (DCHA) as a new and highly efficient anodic co-reactant in ECL for the luminol molecule. The electrochemical and ECL behavior of the luminol/DCHA system was studied on a simple bare GCE surface, which results in two anodic ECL peaks at the potential region of +0.38 and +0.94 V vs Ag/AgCl. The evidence of (DCHA•+) and O2•- generated in the system was detected via flat-cell electron spin resonance (ESR) spectroscopy experiments at ∼20 °C. Using the bimodal ECL system, the highly sensitive detection of luminol was achieved with the detection limit down to 1.5 pM. Further, a homebuilt electrochemiluminescent detector coupled with a flow injection analysis (ECL-FIA) system was adopted to detect the DCHA contaminant in harvested honey, which achieved higher detection and sensitivity under the optimized experimental conditions. DCHA was detected in the range of 10 nM to 100 μM with the detection limit of 2 nM (S/N = 3). The present findings of new luminol/DCHA ECL signals produced a strong ECL emission, which leads to a greater potential to meet the fast-developing analytical application of a luminol-based ECL system.

Development of novel nanomaterial-based co-reactant is highly desired for enhancing ECL intensity and widespread analytical applications. Herein, we report the distinct role of amine-functionalized carbon quantum dots (f-CQDs) as a co-reactant, for the first time, augmenting the ECL property of Ru(bpy)

A sensitive electrochemical method for riboflavin (RF) detection based on Ce–NiO nanostructures was developed using a hydrothermal assisted chemical route. The created several oxygen vacancies on Ce doping are considered as the key factor for the magnificent electrocatalytic behavior of the Ce–NiO sample. The same oxygen vacancies also play an important role in antibacterial applications. Hence dual behavior of this Ce–NiO sample was investigated: (i) RF sensing was characterized by XRD, SEM, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV) using [Fe(CN)6]3−/4− and phosphate buffer solution (PBS) for probing the binding interaction between the Ce–NiO and RF. The Ce ions doped into the NiO nanostructure exhibit an excellent performance towards the detection of RF over a wide linear range from 1 mM to 50 nM, with a detection limit of 0.676 nM (3σ/b). (ii) Investigation of antibacterial activity using both Gram negative and positive bacterial strains. The minimal inhibitory concentration and minimal bactericidal concentration against B. Subtilis is found to be 10 μg ml−1. The diameter of the zone of inhibition for B. subtilis and S. aureus is quantified to be 22 and 18 mm respectively. Our results confirmed that Ce-doped NiO nanomaterial is a useful platform for electrocatalytic and biomedical applications.

Developing a unique luminophores especially nanomaterial based quantum dots to enhance the quantum yield of ECL as well as selective sensing of heavy metal ions or biomarkers are really challenging research area in analytical chemistry. Herein, we demonstrate for the time that newly synthesized phosphorous doped carbon quantum dots (P-CQDs) utilized as a solid-state sensing platform for the detection of Cu2+ ion by ECL signal-on strategy using H2O2 as co-reactant. The average size of P-CQDs is 6.4 nm with spherical shape determined by HR-TEM. The FT-IR and XPS results confirm the presence of phosphorous doping in the CQDs. The electrochemical studies clearly revealed that the formation of OH radicals during the electro reduction of H2O2 which react with electrochemically generated P-CQDs anion radicals to produce excited state of P-CQDs and emit the light through reductive oxidation mechanism. The doping of phosphorus in CQDs alters the electronic state levels and produces more emissive sites in CQDs which generates more intense ECL signals than un-doped or pristine CQDs. Interestingly, ECL intensity of P-CQDs-H2O2 system is further enhanced linearly with each addition of Cu2+ ion and the detection limits of Cu2+ ion found to be 0.27 nM. The developed P-CQDs could be a promising luminophore for the fabrication of solid state ECL platform and more sensitive to determine Cu2+ ions.

It has been suggested that the presence of adsorbed impurities, such as capping agent or organic reaction products adsorbed on the metallic nanoparticles, severely affects the electrocatalytic activity of surface sensitive reactions. At least in some cases, these adsorbed impurities may alter the electronic nature of nanoparticles and thus alter the electrocatalytic activity. In this work, we report the synthesis of AuPt/C bimetallic nanoparticles (BNPs) supported on Vulcan carbon using the polyol method in the presence of different concentrations of polyvinylpyrrolidone (0.01, 0.1, and 1 %) as a capping agent and electrocatalytic activity of the synthesized AuPt/C BNPs. We found that the PVP adsorbs on the AuPt BNPs through C = O functional group, but not through the N-atom. The oxygen reduction reaction (ORR) activity and the methanol tolerance were evaluated on those PVP adsorbed AuPt/C BNPs catalysts. Remarkably, AuPt/C BNPs catalyst with 0.1 % PVP showed a balance of ORR electrocatalysis and methanol tolerance when compared to the PVP free AuPt BNPs. The adsorbed PVP on AuPt BNPs alters the electronic properties of the Pt through electronic interaction with Pt and also controls the surface geometry suitable to ORR, but not the methanol adsorption.