Green, simple and quick melamine sensing assays for highly efficient detection of melamine down to nM level have been reported. Biopolyphenols (rutin & curcumin) were used as reducing and stabilizing ...agents for the synthesis of silver nanoparticles (AgNPs). The synthesis of AgNPs was confirmed by FTIR, UV–Visible, XRD and HRTEM-EDS analysis. The biopolyphenols reduced AgNPs were well dispersed and spherical in shape. However, the presence of melamine in the reaction medium disrupted their synthesis. This may be attributed to interaction of melamine with Ag+ ions and biopolyphenols. At low concentration of melamine, pale red colored solution was obtained owing to formation of aggregated mass of AgNPs, whereas, at high concentration of melamine, colorless solution was obtained indicating disruption in synthesis of AgNPs. The presented protocol was proposed in light of optical responses, UV–Visible plots and HRTEM-EDS analysis. Using the sensor assays, good limit of detection, 0.01 ppm (79 nM) and 0.24 ppm (1900 nM) by Ag-Rutin and Ag-Curcumin respectively, were obtained. The detection limits offered by both sensing assays were quite lower than safety level recommended by regulatory bodies (20 μM in the USA and EU, 8 μM for infant formula in China). The sensing assays displayed good selectivity as well as sensitivity. The proposed sensor was successfully deployed for detection of melamine in raw milk samples.
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•One-pot colorimetric melamine sensing assays.•Green, simple and quick melamine detection down to nM level.•The proposed sensing assays offer highly sensitive and selective detection of melamine.•The so developed sensing assay require no expensive and complicated instruments.
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•Misuse of veterinary drug, Clenbuterol as growth promoters in humans and livestock.•A comprehensive discussion on usage of nanosensors to detect clenbuterol in food samples.•The ...application of nano-sensors for real sample analysis has been discussed.•The limit of detection and recovery percentage values of each nanosensor has been compared.
Veterinary drugs which are primarily meant for livestock treatment have now been categorised under potential food contaminant due to its unregulated usage and abuse. Their over usage by animal workers lead to production of contaminated animal-based food products which contain veterinary drug residues. These drugs are also misused as growth promoters to enhance the muscle to fat ratio in human body. This review highlights the misuse of such a veterinary drug; Clenbuterol. In this review, we have comprehensively discussed the usage of nanosensors to detect clenbuterol in food samples. Colorimetric, fluorescent, electrochemical, SERS and electrochemiluminescence are major categories of nanosensors that have been utilized for this purpose. The mechanism through which these nanosensors detect clenbuterol have been discussed in detail. The limit of detection and recovery percentage values of each nanosensor have been compared. This review will impart significant information on various nanosensors for clenbuterol detection in real samples.
Perovskite-structured Bismuth ferrite (BiFeO
3
) nanoparticles as a novel heterogeneous catalyst were designed by an auto combustion route using a different chelating agent and calcination ...temperature. The effect of different chelating agents like disaccharide (sucrose), α-hydroxy acid (citric acid, tartaric acid), amide (urea) and calcination (150–750 °C) temperature on structure and the catalytic performance of BiFeO
3
have been analyzed. The catalytic performance of BiFeO
3
has been increased by modifying its synthesis with the addition of suitable organic compound and calcination. BiFeO
3
synthesized without the use of chelating agent gave very poor yield, i.e., 36.89%. The augmented effect of the chelating agent on the catalytic performance of BiFeO
3
was obtained in the order of blank < tartaric acid < sucrose < urea < citric acid, whereas the enhancing effect of calcination temperature in the order 150 °C < 450 °C < 550 °C < 650 °C > 750 °C. The calcination temperature results in augmentation in yield of approximately 30% with model reaction on increasing temperature from 150 to 650 °C. Different calcination temperatures (150–750 °C) have been employed to obtain single phase BiFeO
3
nanoparticles. All synthesized BiFeO
3
nanoparticles were fully characterized by FT-IR; XRD; VSM; BET; TGA; XPS and Raman spectroscopy. For the very first time ever we have used them as a recyclable magnetic nanocatalyst in the formation of highly substituted dihydro-2-oxypyrrole by using one-pot, three-component reaction of DMAD, aniline and formaldehyde in methanol at room temperature with 63–88% yield. All the synthesized oxypyrroles have been characterized by various spectroscopic techniques.
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•Fluorescent chemosensor for TNP detection in multiple solvent systems.•Triaryl substituted imidazoles FONPs afforded TNP detection in aqueous medium.•The chemosensor has been ...synthesized through one-pot route without tedious work-ups.•The so developed chemosensors enabled highly selective detection of TNP.
Novel fluorescent chemosensors with a triaryl-substituted imidazole (TAI) moiety were synthesized, which exhibited strong fluorescence. These fluorescent chemosensors allowed highly sensitive and selective detection of nitroaromatic explosive, trinitrophenol (TNP). The TAI were successfully transformed to fluorescent organic nanoparticles (FONPs) in aqueous medium using re-precipitation method thus enabling fluorescent based detection of TNP in aqueous medium also. We hereby present simple and selective chemosensors that are highly sensitive towards TNP and not-sensitive towards interfering analytes. In light of Stern-Volmer plots, Benesi–Hildebrand plots and 1H NMR titrations; it was confirmed that there exist competent interactions between the chemosensors and TNP. A detailed study revealed that synergistic effect of photo-induced electron transfer, electrostatic interaction and inner filter effect resulted in fluorescence quenching of chemosensors on the addition of TNP. The compounds are practically applicable for sensing TNP in real environmental samples as they gave good sensing response towards TNP in pH range of 5–9. Fluorescent test strips were fabricated which allowed effective on-site visual detection of explosive compound (TNP). To the best of our knowledge, this chemosensor represents the first example of TNP detection in aqueous medium using FONPs of TAI.
In this study, a novel rhodamine-based optically and electrochemically active chemosensor, integrated with a p-DMAC moiety, demonstrated extremely selective identification of Au3+ ions relative to ...other metal species, including (Li+, Na+, K+, Ba2+, Ca2+, Mg2+, Co2+, Mn2+, Zn2+, Pb2+, Ni2+, Fe2+, Hg2+, Fe3+, Cd2+, Pd2+, Al3+, Cr3+, Cu2+, and nitrate salt of Ag+). These compounds demonstrated a novel and outstanding aggregation-induced emission enhancement (AIEE) behavior by aggregating in DMF/H2O medium. Furthermore, the degree of quenching was varying linearly with a Au3+ concentration from 0 to 40 nM, with a lower detection limit by RH-DMAC nanoaggregates of 118.79 picomolar (40.35 ppm). The Stern–Volmer plots, Job’s plot, Benesi–Hildebrand plot, 1H NMR titrations, ESI-mass, and FTIR all revealed significant interactions between the sensor and Au3+. Moreover, the proposed electrochemical sensor afforded a linear correlation before the peak current and concentration of Au3+ in the range of 0–40 nM, with a detection limit of 483.73 pM or 164.36 ppt (by cyclic voltammetry method) and 298.0 pM or 101.24 ppt (by the Differential Pulse Voltammetry method). Furthermore, the proposed sensing assay was used to measure Au3+ ion in spiked water samples (tap, drinking, waste, and river water), achieving acceptable accuracy and precision with high recovery rates. Furthermore, RH-DMAC-coated fluorescence paper test strips were designed for on-site Au3+ detection. Apart from this, the use of smartphone-based RGB (Red Green Blue) color analysis shortened the operating process, accelerated the detection technique, and provided a novel methodology for the instantaneous, real-time examination of Au3+ in real water samples.
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•Synthesis of four different novel anthracene-incorporating pyrimidinone/thione derivatives using one-pot synthetic route.•The synthesis is carried out in the presence of magnetically ...responsive sulphonated magnesium ferrite (MgFe2O4@SO3H).•The desired pure products were isolated in excellent yield (up to 98.2%) within a short duration of time (7–28 min).•The organic fluorophore exhibited AIEE characteristics with the formation of nanoaggregates in H2O-DMF mixture.•High efficiency, facile magnetic recoverability and reusability are the highlighting features of the prepared nanocatalyst.
Four new anthracene-incorporated pyrimidinones/thiones based fluorophores have been fabricated via a highly efficient, facile and simple one-pot synthetic approach. The synthesis of these organic fluorophores was nicely catalysed by the designed magnetically retrievable sulphonic acid tethered magnesium ferrite nanocatalyst. In the presence of nanocatalyst and ethanolic media, the desired products were isolated in excellent yields (up to 98.2 %) and within short duration of reaction time (7–28 min). Apart from this, the manufactured nanocatalyst was also characterized well with several characterization techniques such as Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Vibrating sample magnetometer (VSM), High resolution transmission electron microscopy (HR-TEM), X‐ray Photoelectron Spectroscopy (XPS) and Brunauer–Emmett–Teller (BET). The advantageous features of the designed catalyst include its smooth recovery, via externally applied magnetic forces, and its subsequent reusability (up to five cycles), highly stable nature, high efficiency and cost-effectiveness. Additionally, the prepared anthracene-incorporated pyrimidinones/thiones based fluorophores exhibited nano-aggregation induced emission enhanced behaviour, with the formation of nano-aggregates, in H2O-DMF medium.
A new approach for visual and colorimetric detection of glutathione (GSH) in an aqueous solution has been developed that is extremely simple and rapid. The designed biosensor SL1 used is simple to ...make and utilize, with the additional benefits of being cost-effective. By changes in absorption intensity as well as colorimetrically, it shows superb selectivity and ultrasensitivity towards GSH over other amino acids and biomolecules. Based on the information provided above, we developed an approach to determine GSH qualitatively and quantitatively using UV spectrophotometer, paper based test strips, and visually, respectively. A satisfactory linear relationship may be achieved from 0.26 to 52 μM with a detection limit (LOD) of 63 nM and detection quantitation (LOQ) 210 nM. Moreover, the high recovery rates for human blood serum samples demonstrated that the proposed colorimetric technique is practicable, straightforward, and ultrasensitive, with a prominent application in regular biosample analysis.
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•Open chain conjugated azomethine derived optical biosensor is developed for the detection of biomarker glutathione.•An effective, ultrasensitive, and selective colorimetric biosensor was established for GSH.•The determination of GSH using UV–Vis spectroscopy, paper based test strips and naked eye has also be done.•A good linear relationship was obtained from 0.26 to 52 μM with a limit of detection of 63 nM.•The proposed method is also successfully applied for the detection of GSH in human blood serum sample.
Silver-doped zirconium ferrite (A
x
Z
1-x
FO, x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1) nanoparticles (NPs) have been successfully synthesised by utilising the facile auto-combustion approach. The ...synthesis of NPs has been confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope with energy-dispersive spectrometer (SEM-EDS), high-resolution transmission electron microscope (HR-TEM) and Brunauer-Emmett-Teller (BET) analytical techniques. The magnetic and optical properties of synthesised A
x
Z
1-x
FO NPs have been investigated using a vibrating sample magnetometer (VSM) and UV-Visible spectroscopy, respectively. Additionally, herein the prepared magnetic NPs have been utilised for the photodegradation of hazardous colouring agents, namely, Chromotrope-FB (Chr-FB) and Ponceau-BS (PBS). The prepared NPs, particularly A
x
Z
1-x
FO, (x = 0.8), showed excellent photoresponse for photodegradation of Chr-FB and PBS having a % degradation of 99.77% for Chr-FB and 99.21% for PBS in just 40 and 45 min, respectively, under solar irradiation. The photocatalytic degradation has been determined by the electron-hole mechanism in which the electrons are transferred from the valence band to the conduction band of the photocatalyst's surface and combined with oxygen or water to form radicals. It has been found that the
radical played a significant role in the photodegradation of Chr-FB and PBSs in the presence of A
x
Z
1-x
FO, (x = 0.8). In addition, UV-Visible spectroscopy and mass spectrometry were used to analyse the degradation process. Moreover, the photocatalyst A
x
Z
1-x
FO (x = 0.8) achieved notable stability and reusability, thus making it an effective catalyst for environmental pollutant degradation.
Herein alkali metal (Na/K) doped graphitic carbon nitride (g-C3N4) was fabricated using a facile one-pot route. The as synthesized three materials; bulk g-C3N4 (CN-B), K doped g-C3N4 (K-CN-300) and ...Na doped g-C3N4 (Na-CN-x) were well characterized using various characterization techniques. CN-B, K-CN-300 and Na-CN-x modified glassy carbon electrode were used as electrochemical nitrite sensor. Among them Na-CN-300 showcased impressive electrochemical current response under optimized condition. The Na doping into CN-B enhanced the electrochemical response of CN-B towards nitrite detection. The fabricated sensor exhibits excellent electrochemical performance and gave linear response for nitrite concentration range of 10 μM to 2 mM with LOD of 1.9 μM. Moreover the sensor displayed impressive selectivity, sensitivity and reproducibility, which are qualities of a good sensor material. In an attempt to fabricate disposable electrochemical sensor, Na-CN-300 was applied on a screen printed electrode and its stability was tested for 30 days. The proposed sensor was deployed for detection of nitrite in real samples (water and food), representing its possibilities for real-time analysis.
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•A facile one-pot route for synthesis of alkali metal (Na/K) doped graphitic carbon nitride•The electrochemical sensor enabled highly selective detection of nitrite over other analytes.•The sensor allowed detection of nitrite in food and water samples.
Food safety concerns have been haunting the human population since ancient times. There have been instances when the food safety was compromised which lead to deteriorating effects on human health ...and other living creatures. Globally the annual incidence of food-borne illness has been estimated to affect 5–10% of the world population in the developed countries; however its number is way higher in developing countries. Biotoxins are one of the prevailing food contaminants. They are lethal to humans and vary in severity based on their interaction to target sites. The objective of this review is to provide a broad overview of the origin and toxicity of the biotoxins. In addition this review highlights the utilization of nanosensors for biotoxin detection. This review provides details of various nanomaterials that are utilized in designing of these nanosensors and their possible interaction with biotoxins during detection.
