Thiosemicarbazide functionalized carbon quantum dots as a fluorescent probe for the determination of some oxicams: application to dosage forms and biological fluids

Efficient and eco-friendly detection of gabapentin using nitrogen-doped carbon quantum dots: an analytical and green chemistry approach

This study presents the development of an eco-friendly and highly selective mitrogen-doped carbon quantum dot based sensor (N-CQDs) for the detection of gabapentin - a commonly misused drug. A detailed characterization of N-CQDs spectral features and their interaction with gabapentin is provided. The optimal conditions for sensing, including pH value, buffer volume, N-CQDs concentration, and incubation time, were established. The results showed excellent fluorescence quenching at 475 nm (λex = 380 nm) due to the dynamic quenching mechanism, and the sensor demonstrated excellent linearity in the 0.5-8.0 μg mL-1 concentration range with correlation coefficients of more than 0.999, a limit of detection (LOD) of 0.160 and limit of quantification (LOQ) of 0.480 μg mL-1. The accuracy of the proposed sensor was acceptable with a mean accuracy of 99.91 for gabapentin detection. In addition, precision values were within the acceptable range, with RSD% below 2% indicating good repeatability and reproducibility of the sensor. Selectivity was validated using common excipients and pooled plasma samples. The proposed sensor accurately estimated gabapentin concentration in commercial pharmaceutical formulations and spiked plasma samples, exhibiting excellent comparability with previously published methods. The 'greenness' of the sensing system was evaluated using the Analytical GREEnness calculator, revealing low environmental impact and strong alignment with green chemistry principles with a greenness score of 0.76. Thus, the developed N-CQDs-based sensor offers a promising, eco-friendly, and effective tool for gabapentin detection in various situations, ranging from clinical therapeutics to forensic science.

Recent Applications of Quantum Dots in Pharmaceutical Analysis

Nanotechnology has emerged as one of the most potential areas for pharmaceutical analysis. The need for nanomaterials in pharmaceutical analysis is comprehended in terms of economic challenges, health and safety concerns. Quantum dots (QDs)or colloidal semiconductor nanocrystals are new groups of fluorescent nanoparticles that bind nanotechnology to drug analysis. Because of their special physicochemical characteristics and small size, QDs are thought to be promising candidates for the electrical and luminescent probes development. They were originally developed as luminescent biological labels, but are now discovering new analytical chemistry applications, where their photo-luminescent properties are used in pharmaceutical, clinical analysis, food quality control and environmental monitoring. In this review, we discuss QDs regarding properties and advantages, advances in methods of synthesis and their recent applications in drug analysis in the recent last years.

Eco-Friendly High-Performance Thin-Layer Chromatography Method for the Determination of Tenoxicam in Commercial Formulations

There is a dearth of information in the literature regarding environmentally benign high-performance thin-layer chromatography (HPTLC) methods to determine tenoxicam (TNX). Therefore, designing and validating an HPTLC method to detect TNX in commercial tablets and capsules was the goal of this investigation. The green mobile phase utilized was the combination of ethanol/water/ammonia solution (50:45:5 v/v/v). The TNX was quantified at a wavelength of 375 nm. The proposed method's greenness profile was established using the Analytical GREEnness (AGREE) approach. The proposed methodology for determining TNX was linear in the range of 25-1400 ng/band. The proposed methodology for measuring TNX was accurate (% recoveries = 98.24-101.48), precise (% RSD = 0.87-1.02), robust (% RSD = 0.87-0.94), sensitive (LOD = 0.98 ng/band and LOQ = 2.94 ng/band), and environmentally friendly. The AGREE scale for the present methodology was derived to be 0.75, indicating an outstanding greenness profile. TNX was found to be highly stable under acidic, base, and thermal stress conditions. However, it completely decomposed under oxidative stress conditions. Commercial tablets and capsules were found to have 98.46 and 101.24% TNX, respectively. This finding supports the validity of the current methodology for measuring TNX in commercial formulations. The outcomes of this work showed that the proposed eco-friendly HPTLC methodology can be used for the routine analysis of TNX in commercial formulations.

Sulfur and nitrogen co-doped carbon quantum dots as fluorescent probes for the determination of some pharmaceutically-important nitro compounds

In this study, highly fluorescent sulfur and nitrogen co-doped carbon quantum dots (SN-CQDs) were synthesized by a simple one-pot hydrothermal method using thiosemicarbazide and citric acid as starting materials. Various spectroscopic and microscopic techniques were applied to characterize the prepared SN-CQDs. The synthesized SN-CQDs' maximum fluorescence emission was obtained at 430 nm after excitation at 360 nm. Rifampicin (RFP), tinidazole (TNZ), ornidazole (ONZ), and metronidazole (MNZ) all quantitatively and selectively quenched the SN-CQDs' native fluorescence, which was the base-for their-spectrofluorimetric estimation without the need for any tedious pre-treatment steps or high-cost instrumentation. SN-CQDs demonstrated a "turn-off" fluorescence response to RFP, TNZ, ONZ, and MNZ over the ranges of 1.0-30.0, 10.0-200.0, 6.0-200.0, and 5.0-100.0 μM with detection limits of 0.31, 1.76, 0.57, and 0.75 μM and quantitation limits of 0.93, 5.32, 1.74, and 2.28 μM respectively. The suggested method was successfully used to determine the investigated drugs in their commercial dosage forms. The method was further extended to their determination in spiked human plasma samples, with satisfactory mean % recoveries (99.44-100.29) and low % RSD values (< 4.52). The mechanism of fluorescence quenching was studied and discussed. The suggested method was validated in accordance with ICH recommendations.

Cation-π aggregation-induced white emission of moisture-resistant carbon quantum dots: a comprehensive spectroscopic study

Controlling mechanisms involved in the aggregation of carbon quantum dots (CQDs) can lead to new application developments for these quantum dot materials. In this study, an unusual aggregation-induced white emission of CQDs with strong intrinsic green emission is reported. Due to the deprotonation/protonation of the surface functional groups during the aggregation of CQDs induced by pH variations of the solution through the addition of sodium hydroxide, and hydrophobic interactions between CQDs, it results in the formation of aggregated CQDs through an avalanche-like process. Our results suggest that sodium hydroxide not only plays a critical role in the formation of strong cation-π interactions, but also polishes the surface of CQDs, leading to the formation of the aggregated CQDs. The aggregated CQDs present excellent dispersibility characteristics in water. Moreover, optical studies suggest a combined aggregation mechanism in the presence of both J-type and H-type aggregation monoliths involved in forming the aggregated CQDs. The findings obtained from the deconvolution of the as-synthesized CQDs can perceptively elucidate the cation-π aggregation process.