In this study, we have constructed a novel voltammetric sensor based on montmorillonite clay (MMT) incorporated with CeO₂ nanoparticles using a composite graphite paste electrode as a cross linker (MMT-CeO₂NPs/GPG-PE) for the trace determination of tadalafil (TAD) drug. The characterization of CeO₂ nanoparticles has been conducted using various analytical techniques, including X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. The morphology of the composite of CPG and MMT-CeO₂NPs/CPG was elucidated through scanning electron microscopy (SEM). The newly developed sensor (MMT-CeO₂NPs/CPG-PE) exhibited remarkable efficiency towards TAD oxidation using adsorptive stripping square-wave voltammetry (AdS-SWV) in Mcllvaine buffer solution (pH 8.0). A highly selective and sensitive method for TAD detection has been successfully …

A novel and sensitive fluorescence ratiometric method is developed for urea detection based  on the pH-sensitive response of two fluorescent carbon dot (CD) systems: R-CDs/methyl red (MR) and NIR-CDs/Cu²⁺. The sensing mechanism involves breaking down urea using the enzyme urease, releasing ammonia and increasing pH. At higher pH, the fluorescence of NIR-CDs is quenched due to the enhanced interaction with Cu²⁺, while the fluorescence of R-CDs is restored as the acidic MR converts to its basic form, removing the inner filter effect. The ratiometric signal (F₆₀₈/F₇₅₀) of the R-CDs/MR and NIR-CDs/Cu²⁺ intensities changed in response to the pH induced by urea hydrolysis, enabling selective and sensitive urea detection. Detailed spectroscopic and morphological investigations confirmed the fluorescence probe design and elucidated the sensing mechanism. The method exhibited excellent …

The monitoring of ziram levels is of vital importance due to its widespread application in agriculture and the possible risks it poses to human health and the ecosystem. This work proposes an innovative approach for the highly sensitive and selective sensing of ziram, a widely used dithiocarbamate fungicide, through the formation of copper dimethyldithiocarbamate Cu)DDC)₂ assisted dual quenching of red and blue emission carbon dots (R/NCDs and B/NSCDs). When ziram is added to a system containing copper-bound B/NSCDs and R/NCDs, the displacement of ziram zinc ions by copper ions leads to the formation of a yellow-colored Cu)DDC)₂ complex. This complex induces significant quenching of the fluorescence emissions from both types of carbon dots, consequently enhancing the sensitivity of the detection method. Comprehensive characterization of the R/NCDs and B/NSCDs was conducted using …

This study develops a novel fluorometric method for the sensitive and selective determination of urea, based on unique system comprising nitrogen doped red-emissive carbon dots (NRECDs), zinc-dithizone complex, and the urease enzyme. The underlying principle of this method relies on the pH increase resulting from the enzymatic breakdown of urea by urease. Initially, the fluorescence of the NRECDs is quenched by the red-colored zinc-dithizone complex. However, upon the addition of urea, the subsequent release of ammonia and the consequent rise in pH lead to the dissociation of the zinc-dithizone complex, causing a color change from red to yellow. This spectral shift eliminates the quenching effect, resulting in the restoration of the CDs’ fluorescence. The prepared NRECDs were comprehensively characterized using various spectroscopic techniques, including fluorometry, X-ray diffraction (XRD), X-ray 

Benzene, toluene, ethylbenzene and xylene are known to be lethal environmental contaminants that have carcinogenic and mutagenic influences in human being while styrene and benzaldehyde have a neurotoxic effect. In other hand, the constituents of air freshener considered as a probable source of volatile organic compound. In the present work, a solid phase extraction and gas chromatography–mass spectrometry (GC-MS) technique has been optimized and applied to the fabric, carpet and air freshener samples to determine the trace amounts of benzene, toluene, ethylbenzene, xylene, styrene and benzaldehyde. The Supelclean TM ENVI TM-18 cartridge with dichloromethane extracting solvent were found to be the optimal procedures. The system presented excellent performance in terms of limit of detection (0.08-0.61 ng/mL), coefficient of determination (0.994-0.997), precision with the relative standard deviation values ranging from 0.05-2.57%. According to the results, the concentration of benzene, toluene, ethylbenzene, xylene, styrene and benzaldehyde in fresheners’ samples was found in the range 0.03-53.27, 0.03-7.12, 0.02-6.51, 0.05-96.44, 0.04-7.06 and 0.22-23.02, respectively. The excellent recovery values were also obtained up to 99.93%. The Supelclean TM ENVI TM- 18 GC-MS system was found to appropriate for the monitoring of analytes in fabric, carpet, air freshener samples, and other samples of the similar

This study presents a novel dual-modal approach for glutathione (GSH) detection using blue and yellow dual-emission carbon dots (BY-CDs) and bromothymol blue (BTB) at pH 8.0. The method employs both colorimetric and fluorometric detection modes, offering a new perspective on GSH quantification. BTB's blue coloration induces selective fluorescence quenching of the CDs' 610 nm emission peak, with minimal effect on the 445 nm peak. Upon GSH addition, the quinonoid structure (blue color) of BTB transforms to its benzenoid form (yellow color). This transformation triggers fluorescence restoration at 610 nm and significant quenching at 445 nm, enabling ratiometric fluorescence analysis (F₆₁₀/F₄₄₅). Concurrently, colorimetric detection is also ratiometric, based on measuring the ratio between the emerging yellow color peak (435 nm) and the decreasing blue color peak (618 nm) (A₄₃₅/A₆₁₈). The state-of …

For the first time, we introduce a novel disposable and ultrasensitive sensing electrode made up of nanosized ceria uniformly loaded carbon nanofibers (CeNPs@CNF) sol-gel nanoceramic film (CF) wrapped on eco-friendly and inexpensive pencil graphite rods (PGRs) to explore their electro-catalytic detection of the anticancer drug capmatinib (CMB). The as-prepared CeNPs@CNF hybrid nanocomposite was described by XRD, SEM, TEM, HRTEM, and EDX analysis. The CV study clearly demonstrated that, the disposable CeNPs@CNF-CF/PGRE sensor exhibited excellent redox activities in the ideal probe [Fe(CN)₆]^3-/4-. Due to the outstanding electrochemical properties, larger electrochemically active surface area, and tremendous electro-catalytic activity of CeNPs@CNF, the reduction current of CMB on the CeNPs@CNF-CF/PGRE sensor is considerably higher than that of bare PGRE. The detection conditions …

For the first time, we introduce a new disposable and ultrasensitive sensing electrode made up of nanostructured gold anchored porous carbon black (Au@PCB) sol–gel nanoceramic conductive film (CF) coated eco-friendly and inexpensive pencil graphite rods (PGRs) to explore their electro-catalytic sensing of dopamine (DA) in the absence and presence of uric acid (UA). X-ray diffraction (XRD) and scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDX) were used for evaluating the Au@PCB nanocomposite. The CV analysis revealed that the disposable Au@PCB-CF/PGRE sensor exhibited outstanding redox activities in the optimal probe [Fe(CN)₆]^3−/4−. The conductive Au@PCB nanocomposite exhibits exceptional electrochemical characteristics, a larger electrochemically active surface area, and remarkable electro-catalytic activity. As a result, the oxidation current of

Dual-emissive gold and silver nanoclusters stabilized by bovine serum albumin (BSA@Au-Ag NCs) were engineered for the precise and sensitive estimation of acrylamide (ACM). The probe demonstrated emissions at 630 nm and 405 nm upon excitation at 320 nm. Decreasing the fluorescence of the probe at 630 nm was observed upon cysteine (Cys) addition while the emission band at 405 nm experienced a slight increase. The introduction of ACM into the probe led to the recovery of fluorescence at 630 nm, while the fluorescence at 405 nm remained largely unaffected. This selective response provides a ratiometric method for determining ACM. A linear relationship between the response ratio (F₆₃₀/F₄₀₅) and ACM concentration was established in the range of 0.12–450 µM, with LOD of 0.03 µM. The fluorescent probe boasts several advantages, including a low LOD, robustness against interference, and …

In this work, an electrochemical platform was developed for detection of D-pencillamine utilizing highly responsive molecularly imprinted polymers (MIPs). This platform operates on a ratiometric principle and is constructed on nitrogen-doped porous carbon nanosheets (N-PCNS) derived from zeolite imidazolate frameworks (ZIF-12) in the presence of saturated solution of zinc sulfate. Subsequently, silver nanoparticles (Ag) were introduced onto the surface of N-PCNS/GCE to enhance conductivity and surface area, and serve as a standard signal. The MIP layer was formed on the Ag@N-PCNS/GCE surface through o-phenylenediamine (o-phen) electro-polymerization in the presence of the D-pencillamine (D-PAN) as a template. Detection of D-PAN relies on measuring I_D-PAN/I_Ag response ratio employing differential pulse voltammetry (DPV). This ratio exhibits a linear correlation with the concentration of D-PAN in …