Thiosemicarbazide functionalized carbon quantum dots as a fluorescent probe for the determination of some oxicams: application to dosage forms and biological fluids
Abstract:Highly fluorescent nitrogen and sulfur doped carbon quantum dots were synthesized via hydrothermal process using citric acid and thiosemicarbazide. The dots had an emission band at 415 nm (λex = 345 nm). The polarity of the studied drugs affects the method’s sensitivity.
“…In addition, SN-CQDs produced strong blue fluorescence when exposed to UV light, and the solution remained stable for about two weeks without alteration. The amino, carbonyl, and hydroxyl groups were found to be responsible for the SN-CQDs' excellent hydrophilicity and high fluorescence 41 , 52 . Figure 2 Fluorescence emission spectrum of SN-CQDs at 430 nm after excitation at 360 nm.…”
Section: Resultsmentioning
confidence: 99%
“…Due to their excellent photo-physical properties, high quantum yields, superior solubility, low toxicity, lowcost, and eco-friendly nature with strong fluorescence emission, carbon-quantum-dots (CQDs)-have piqued theinterest-of researchers in a variety of fields [34][35][36][37] . The top-down 38,39 and bottom-up 40 approaches-for synthesis-of CQDs have both been reported 41 . Larger carbon structures are divided into smaller ones during the top-down processes used to manufacture CQDs, such as electrochemical oxidation and laser ablation, which resulted in low yields and high costs.…”
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.
“…In addition, SN-CQDs produced strong blue fluorescence when exposed to UV light, and the solution remained stable for about two weeks without alteration. The amino, carbonyl, and hydroxyl groups were found to be responsible for the SN-CQDs' excellent hydrophilicity and high fluorescence 41 , 52 . Figure 2 Fluorescence emission spectrum of SN-CQDs at 430 nm after excitation at 360 nm.…”
Section: Resultsmentioning
confidence: 99%
“…Due to their excellent photo-physical properties, high quantum yields, superior solubility, low toxicity, lowcost, and eco-friendly nature with strong fluorescence emission, carbon-quantum-dots (CQDs)-have piqued theinterest-of researchers in a variety of fields [34][35][36][37] . The top-down 38,39 and bottom-up 40 approaches-for synthesis-of CQDs have both been reported 41 . Larger carbon structures are divided into smaller ones during the top-down processes used to manufacture CQDs, such as electrochemical oxidation and laser ablation, which resulted in low yields and high costs.…”
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.
“…To ensure the change in lifetime of the CQDs, lifetime study of both CQDs and CQDs+H2O were performed and it was come spectroscopic results confirmed that the quenching process is dynamic one. [70][71][72][73] FRET Process: It is a phenomenon that occurs between the excited state of the CQDs and the ground state of the quencher which may be organic molecules or inorganic analytes. [74] This phenomenon is applied in huge scale in different fields to detect various organic molecules, biologically important molecules, pesticides or inorganic metal ions which may be very important in sense of toxicity.…”
Carbon quantum dots (CQDs) are a new blooming carbon containing nanoparticles having size of less than 10 nm. They have wide range of application in the field of sensing of inorganic analytes, bio sensing, cell imaging, studying biological processes in living cells and also for drug delivery. These nanoparticles of carbon are playing important roles due to their interesting qualities like small particle size, biocompatibility, fluorescing, etc. Sometimes it shows excitation wavelength dependent, which may be more than 100 nm, and sometimes excitation wavelength independent fluorescent property. CQDs are highly photo stable (stable for hours), compared to the conventional fluorescent semiconductor quantum dots. To apply such carbon quantum dots, it is necessary to characterize the CQDs first. Most of the time they are characterized by photophysical and structural property using UV‐VIS spectroscopy, fluorescence spectrophotometry, FT‐IR, XRD, XPS, Raman spectroscopy, TCSPC, HRTEM, etc. In this review article we demonstrate how these tools are used to characterize newly synthesized CQDs, monitor the synthesis process along with finding its application in numerous fields.
“…For the purpose of determining TNX in pharmaceutical formulations, a few high-performance thin-layer chromatography (HPTLC) methods were also published. ,, An HPTLC method has also been reported to determine TNX in combination with piroxicam, celecoxib, and rofecoxib in the whole human blood and urine . Some voltammetry techniques were also used to detect TNX in dosage forms. , Some other approaches such as potentiometric, polarographic, indirect flow-injection spectrophotometry, reverse flow-injection method, fluorescence probe, colloidal gold strip sensor, and quantum dots as fluorescence probe have also been utilized to determine TNX, either alone or in combination with other NSAIDs in pharmaceutical preparations.…”
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.
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