Preparation Of Carbon Quantum Dots Research Articles

A green method for the preparation of carbon quantum dots from yellow lupin peel waste for spectrofluorometric determination of nirmatrelvir

The COVID-19 pandemic has highlighted the urgent need for effective antiviral agents. One such promising drug is nirmatrelvir (NIRMA), which has demonstrated the ability to inhibit viral replication and reduce hospitalization and mortality rates. In the field of analytical chemistry, carbon quantum dots (CQDs) derived from fruit peel waste have gained attention for their eco-friendly and cost-effective properties. In this study, CQDs were synthesized from the peel biomass waste of yellow lupin and utilized for the spectrofluorometric determination of NIRMA in pharmaceutical tablets. The proposed method offers simplicity and speed compared to existing methods. The synthesis process involved washing and grinding the peel waste, followed by heating in propylene glycol and purification using a dialysis membrane. The resulting CQD solution showed fluorescence at an emission wavelength of 411 nm upon excitation at 325 nm. The validation of the method, including linearity, range, limit of detection and quantification, accuracy, precision, and robustness, was conducted following ICH guidelines. The fluorescence intensities exhibited a linear relationship with increasing NIRMA concentration in the range of 15–150 µg/mL. The limit of detection found to be 4.0 μg/mL, with %relative standard deviations ≤ 1.46. This spectrofluorometric method represents a novel approach for the determination of NIRMA using CQDs derived from yellow lupin peel waste.

Rapid aqueous preparation of carbon quantum dots and their application as nanozyme for the detection of hydrogen peroxide and uric acid

A green and rapid method was developed to synthesize a series of carbon quantum dots (Fe,N/CQDs, Fe,S/CQDs, S,N/CQDs and Fe,S,N/CQDs) through thermal decomposition using persimmon frost as a carbon source. All the synthesized CQDs have peroxidase-like activity, and the comparision of their steady-state kinetic parameters inferred that the peroxidase-like activity of Fe,S,N/CQDs is superior to those of Fe,S/CQDs and Fe,N/CQDs. Furthermore, Fe,S,N/CQDs exhibited good affinity towards 3,3′,5,5′-Tetramethylbenzidine (TMB) and H2O2 compared to natural horseradish peroxidase (HRP) and other nanozymes. In theory, uric acid (UA) can produce H2O2 with the catalysis by uricase. Fe,S,N/CQDs could catalyze the breakdown of H2O2 to produce reactive oxygen species (ROS), which can oxidize TMB (colorless) to oxTMB (blue). Based on the nanozyme-catalyzed oxidation of TMB, a simple and sensitive colorimetric sensor was developed for the quantitative analysis of H2O2 and UA. Low limit of detection (0.73 μM), wide linear range (1–80 μM) and good repeatability were obtained. The sensor was also demonstrated for the determination of UA in biological samples and satisfactory results were obtained.

Preparation of carbon quantum dots and their application in the detection of vitamin B2.

A novel metal-doped carbon quantum dot, zinc-chlorine co-doped carbon quantum dots (Zn/Cl-CQDs), has been developed for the fluorescent probe detection of vitamin B2 and the analysis of the correlation properties of this carbon quantum dot and vitamin B2. Stability experiments demonstrate that Zn/Cl-CQDs possess good fluorescence properties under alkaline conditions. However, when vitamin B2 is added into Zn/Cl-CQDs, the fluorescence intensity decreases sharply, indicating that the fluorescence sensor shows rapid and sensitive detection of vitamin B2 under the static quenching. Lastly, the use of Zn/Cl-CQDs in the detection of vitamin B2 tablets and vitamin B2-rich fruits resulted in recovery rates of 98.2% and 100.6%, respectively. Therefore, this method can be well applied to the detection and analysis of vitamin B2, and has great development prospects in the pharmaceutical industry and food monitoring fields.

Facile synthesis of carbon dots by the hydrothermal carbonization of avocado peels and evaluation of the photocatalytic property

The preparation of carbon quantum dots (CQDs) from agricultural waste sources stands out as a significant type of biomass-based nanomaterials. This is primarily because of their minute size, exceptional water solubility, lack of toxicity, and impressive stability. Here, carbon quantum dots (CQDs) were successfully prepared by a one-step hydrothermal method using the waste from Avocado peels and only water as solvent. Physicochemical properties of the CQDs were characterized by UV–vis, PL, FTIR, XRD, SEM, TEM, and HRTEM. The diameter of the CQDs was found to satisfy the quantum size effect and this was also supported by the reduced graphitization. The CQDs were used for the removal of methyl orange (MO), a common anionic dye, from an aqueous solution. The effectiveness of MO removal was directly related to the pH and the amount of the nanomaterial used. Under optimal experimental conditions, with a 7.5 mg catalyst dose, a 120-minute reaction time, and a pH of 10, the maximum degradation of MO (78 %) was achieved.

Effect of CQDs doping on the properties of RuO2–TiO2/Ti anode

Phenol is a harmful substance that can cause pathological changes in animals or human body, and its degradation has become a research hotspot at present. This paper innovatively proposed the preparation of carbon quantum dots by microwave enhancement technology, the preparation of RuO2–TiO2-CQDs/Ti composite coating anode by thermal decomposition method, and studied the electrocatalytic degradation process of organic wastewater containing phenol. The surface morphology of the anode was observed by XPS, TEM and SEM. Electrochemical workstation was used to characterize the electrocatalytic performance of the anode, and high performance liquid chromatography was used to determine the degradation process. The results show that the doping of CQDs can produce a large number of vacancy defects on the surface of the composite coating, and the addition of CQDs can increase the loading of Ru element on the surface of the coating during anode preparation. With the increase of CQDs content, the crack width and depth of coating surface decrease gradually, and the crystal size decreases. Doping of CQDs can effectively improve the surface charge capacity and corrosion resistance of anode. Compared with the traditional RuO2–TiO2/Ti anode, the removal efficiency of phenol and COD at the RuO2–TiO2-CQDS/Ti composite coating electrode was increased by 102% and 55.7% respectively within 1 h. This study makes full use of the high specific surface area and excellent electrocatalytic performance of carbon quantum dots, which provides a new idea for the mineralization of high concentration phenol in Ru–Ti electrode.

Preparation of carbon quantum dots from ionic liquid modified biomass for the detection of Fe3+ and Pd2+ in environmental water

A new type of green carbon quantum dots (ILB-CQDs) was prepared by hydrothermal method using ionic liquid as a modifier and grape skin as carbon source, and was obtained from hydrogen-bonded lattice structure ionic liquid preparation, which makes the CQDs in a ring-like stable structure with a stability period of more than 90 day. There is also the catalytic effect of the ionic liquid on cellulose, which makes the prepared CQDs show good advantages, such as uniform particle size, high quantum yield (26.7%), and very good fluorescence performance. This is a smart material for the selective detection of Fe3+ and Pd2+. It has a detection limit of 0.001 nM for Fe3+ and 0.23 µM for Pd2+ in pure water. It has a detection limit of 3.2 nmol/L for Fe3+ and 0.36 µmol/L for Pd2+ in actual water, both of which meet the requirements of WHO drinking water standards. And there is to achieve more than 90% of water restoration effect.

Facile two-step synthesis of nickel nanoparticles supported on 3D porous carbon frameworks as an effective electrocatalyst for urea and methanol oxidation

The design and development of facile and environmentally-friendly methods to prepare low-cost, high-activity electrocatalysts are desirable for the development of fuel cells. In our study, a high-efficiency anodic electrocatalyst for the oxidation of urea and methanol based on nickel nanoparticles supported on three-dimensional porous carbon frameworks (Ni/3DPCFs) was designed by an innovative and simple method. This innovative method is based on the preparation of carbon quantum dots (CQDs) and nickel ions (Ni2+) adsorbed on its surface by microwave-assisted synthesis, followed by pyrolysis. The method is notable for simultaneously preparing Ni2+ and CQDs and not requiring a stabilizer, surfactant, or organic solvent. The results of scanning and transmission electron microscopy (SEM and TEM) revealed that the CQDs were converted to 3DPCFs by pyrolysis and nickel nanoparticles (NiNPs) were formed on the surface. The prepared electrocatalyst showed high efficiency for the oxidation of urea and methanol in alkaline media. The electrocatalytic activity of Ni/3DPCFs showed the maximum anodic current density of 102.5 and 153.8 mA/cm2 for urea and methanol oxidation, respectively. This method can provide a simple and novel approach to producing various metallic nanoparticles supported on 3DPCFs as electrocatalysts by two-step microwave-assisted synthesis and pyrolysis without using toxic reagents and surfactants.

Green preparation of carbon quantum dots and its silver nanoparticles composite against carbapenem-resistant Acinetobacter baumannii

Green preparation of carbon quantum dots and its silver nanoparticles composite against carbapenem-resistant Acinetobacter baumannii

Green synthesis of carbon quantum dots toward highly sensitive detection of formaldehyde vapors using QCM sensor

In the present study, an eco-friendly method for the preparation of carbon quantum dots (CQDs) is demonstrated using hydrothermal treatment of laurel leaves. The optical and structural characteristics of the prepared CQDs are investigated using transmission electron microscopy (TEM), X-ray photoelectron (XPS), fluorescent and UV–visible spectroscopies, Fourier transform infrared (FTIR), and X-ray diffraction (XRD). The quartz crystal microbalance (QCM) sensor designed and modified with CQDs is capable of detecting formaldehyde vapors in the presence of other interfering chemical-vapor analytes. The changes in the frequency of the QCM sensor are linearly correlated with the injected formaldehyde concentrations. The sensing properties of formaldehyde, including sensitivity and reversibility, are investigated. Detection of formaldehyde in the presence of humidity is carefully discussed for home or workplace room environment use. The adsorption kinetics of various VOCs vapors are also calculated and discussed.

Bio-derived graphitic carbon quantum dot encapsulated S- and N-doped graphene sheets with unusual battery-type behavior for high-performance supercapacitor

Electrochemical supercapacitors (ECs) have increased large attention in recent years due to their faster charging and discharging process, large specific capacity, and high power density. Herein, we designed the preparation of carbon quantum dots (CQDs), and N-/S-doped CQDs, encapsulated within graphene sheets via a lemon-juice-derived sustainable route for high-performance positive electrode material in supercapacitor application. The as-prepared electrodes revealed an unusual battery-type behavior due to the presence of large number of O-/N-/S-containing functional groups within the graphitic network of the CQDs-graphene composite, which enhances the redox-active sites. The specific capacities were obtained for CQDs, N-doped, and S-doped CQDs at 284, 181, and 125 mAh/g at 1 A/g current density. The S-doped CQDs delivered 94.5% capacitance retention over 10,000 cycles with 98% Coulombic efficiency. The real-time symmetric supercapacitor was constructed using as-prepared S-doped CQDs with an operated potential window of 1.4 V. The constructed symmetric supercapacitor shows high specific capacity, energy, and power densities of 21.7 mAh/g (55.7 F/g at 1 A/g), 15.2 Wh/kg, and 700 W/kg, respectively. The outstanding electrochemical results are based on the easy formation of heteroatom doped S and N-CQDs to enhance the better electronic/ionic motion.

Efficient ethanol solvothermal synthesis of high-performance nitrogen-doped carbon quantum dots from lignin for metal ion nanosensing and cell imaging

The preparation of carbon quantum dots (CQDs) with excellent photoluminescence (PL) properties from biomass is a hot research topic. Herein, nitrogen-doped CQDs (N-CQDs) from lignin (C-source) using diethylenetriamine (DETA) as an N-source were synthesized via a facile, green, and large-scale solvothermal approach. The as-synthesized N-CQDs in ethanol (N-CQDs-ET) exhibit unique structures with abundant N-doping (~7.2%), rich functional groups (especially CO and pyrrolic-N), high degree of graphitization, and uniform particle size (~5.0 nm). The N-CQDs-ET have excellent QL properties with high quantum yield, superior fluorescence stability, and long fluorescence lifetime, all of which are much better than N-CQDs obtained from a traditional hydrothermal process. The N-CQDs-ET display excellent sensitivity for Fe3+ and Co2+ detection with a good linear correlation ranging from 0.27 to 250 μM and 0.45–500 μM, respectively. In addition, the N-CQDs-ET exhibit excellent biocompatibility and multicolored cell imaging ability, showing great potential applications in biosensors.

Green preparation of carbon quantum dots with wolfberry as on-off-on nanosensors for the detection of Fe3+ and l-ascorbic acid

A green and facile hydrothermal synthesis approach is proposed for the preparation of nitrogen-doped carbon quantum dots (N-CQDs) with wolfberry. These N-CQDs were developed as a highly sensitive fluorescent ‘on-off-on’ switch sensor for the sensing of Fe3+ and l-ascorbic acid (AA). The N-CQDs displayed superior fluorescence characteristics of CQDs with a quantum yield up to 22%. The N-CQDs were demonstrated to selectively react with Fe3+, leading to fluorescence quenching effect, which was successfully used for the detection of Fe3+ with a limit of detection at 3 μmoL•L−1. The addition of AA is supposed to repair the surface defects, and result in the fluorescence recovery. Based on this effect, the strategy of ‘on-off-on’ detection of AA was established with a limit of detection at 1.8 μmoL•L−1. Furthermore, the practical application of the detection of Fe3+ lake water and AA in medical tablet was demonstrated, promising an effective and efficient ‘on-off-on’ nanosensor with low-cost, green synthesis for Fe3+ and AA detection.

Preparation of carbon quantum dots from corn straw and their application in Cu2+ detection

Water-soluble carbon quantum dots were hydrothermally produced using corn straw as the starting material and nitric acid solution as solvent, then they were introduced as fluorescent probes for the detection of Cu2+. High-resolution transmission electron microscopy and X-ray diffraction showed that the carbon quantum dots were spherical amorphous particles with a diameter of 5 nm. The surface functional groups of carbon quantum dots were observed via Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy. A new approach for Cu2+ detection was designed using carbon quantum dots based on fluorescence quenching. Linear relationships between the fluorescence variation and the Cu2+ level (1 mg·L-1 to 20 mg·L-1 and 20 mg·L-1 to 500 mg·L-1) were obtained, with coefficients of determination of 0.9960 and 0.9923, respectively. The Cu2+ detection limit was 4.26 mg·L-1. The probable quenching principle between Cu2+ and the carbon quantum dots was attributed to charge transfer.

Biomass‐derived Carbon Quantum Dots – A Review. Part 1: Preparation and Characterization

AbstractThe preparation of nanostructured carbon materials from chosen biomass through hydrothermal carbonization and pyrolysis processes by optimizing the reaction conditions is one of the bases for applying the product in certain of the development activities. The finished product more or less reflects the raw material and the way of preparation. Among the many products, carbon quantum dots (CQDs) have gained importance due to their bolstered characteristics and facile preparation. CQDs are zero‐dimensional (0D) nanomaterials which attracted attention in the recent past due to their excellent water solubility, unique optical properties, good electrical conductivity, eco‐friendliness, and biocompatibility. Small‐sized CQDs offer high surface area per unit volume, strong tunable fluorescence, photo‐luminescent emissions, and semiconducting properties. In this paper, identification of ideal raw materials, process parameters being followed in the preparation of CQDs through hydrothermal carbonization and pyrolysis techniques, and the properties of the resultant CQDs commensurate with the nature of process are reviewed.

Synthesis and Surface Engineering of Carbon Quantum Dots by Electrical Discharges Generated Inside and in Contact with Liquid

In this paper electrical discharge plasma in liquid was used for synthesis of carbon NPs. In addition, targeted changes of the NPs surface properties could be selectively achieved via treatment of as-prepared NPs by a gas-liquid interfacial discharge produced in contact with the colloidal solution. For synthesis a high-voltage spark discharge was ignited in the solution between two graphite electrodes immersed in water. The discharge in contact with liquid was generated between a stainless-steel capillary electrode served as cathode and the surface of the liquid. The discharge was ignited by applying the high voltage of 3.6 kV using a dc power supply with argon flowing through the capillary tube. The discharge current was kept constant in the range of 1 - 5 mA [1, 2].The composition, morphology and optical properties of the synthesized and plasma treated NPs were studied by TEM, EDX, PL, FTIR, Raman and ultraviolet–visible spectroscopy The NPs obtained by the spark discharge in water looked like isolated spherical NPs with the average diameter about 3 nm as it followed from the TEM analysis. The HRTEM images of separate particles revealed that particles are crystalline and the measured interplanar distances were found to be 2.06 Å that correspond to the reflections between (111) planes in carbon having diamond-like structure. The SAED analysis further proved the formation of diamond-like structures with admixture of orthorhombic carbon phases, while the rings corresponding to graphitic structure were absent in the SAED patterns.For the further studies of the prepared C NPs Raman and XRD techniques were used. The Raman spectrum contained two distinct peaks: narrow G-band near 1578 cm-1 attributable to the ordered graphite and the broadened D-band at 1349 cm-1 which is associated with disodered carbon and the presence of a carbon sp3 defects in the prepared C-NPs. It should be noted that the D-band is rather broad thus covering the range 1310-1320 cm-1, typical to the diamond and orthorhombic carbon structures.Analogically, the results of the X-ray diffraction studies exhibited the broad peak in the region 20-40˚, so-called halo, indicated a presence of small particles with various carbon phases in the sample. Nevertheless, the diamond-like phases, observed in TEM measurements most probably are presented in the sample but only as very small particles that are produced through the condensation mechanism. It is known that NPs in electrical discharge are formed through two competing mechanisms namely via the condensation of the evaporated electrode material that are atoms, ions and small clusters with their subsequent growth into the NPs; and in result the destroying of the electrodes with the formation of the particles of much larger sizes. For the Raman studies, the colloid was deposited onto the substrate, and thus larger and better crystallized particles with graphite structure formed by the second route were dominant that can explain the contradiction of Raman and TEM results.To modify the properties of NPs, the colloidal solution of C NPs synthesized by spark discharge was treated by reactive non-equilibrium gas-liquid discharge plasma contacting with the solution. The results of these studies showed that different surface chemistry activated in different solutions could be due to different reactions induced by plasma electrons at the plasma–solution interface compared to plasma–water one. Changing the surface groups is believed to be effective in improvement of photoluminescence properties of the synthesized C-dots.Thus, the EDL technique has been demonstrated to be suitable for the preparation of carbon quantum dots with sizes 2-5 nm and narrow size distribution that are the part of the requirements for practical applications. In addition, a treatment of NPs by reactive non-equilibrium gas-liquid discharge plasma contacting with a colloidal solution can offer great opportunities for the NPs surface engineering and an improvement of the photoluminescent properties. Carbon NPs with size less than 10 nm – so called quantum dots due to their excellent biocompatibility, chemical inertness, and size-selective photoluminescence properties may find increasing applications in modern biotechnology as more suitable alternatives to the traditional semiconductor quantum dots.The work was supported by the National Academy of Sciences of Belarus under project Convergence 2.4.06.[1] A. Nevar, N. Tarasenka, M. Nedelko, N. Tarasenko Carbon Lett. – 2020 https://doi.org/10.1007/s42823-020-00147-9.[2] V.S. Burakov, V.V Kiris, M.I. Nedelko, N.N. Tarasenka, A.A. Nevar, N. V. Tarasenko, Eur. Phys. J. Appl. Phys., 79 10801 (2017)

A green path to extract carbon quantum dots by coconut water: Another fluorescent probe towards Fe3+ ions

In recent years, carbon quantum dots (CQDs) have been of great enthrallment in the fluorescent probe field. Carbon precursors with interesting physicochemical properties may be derived from natural sources. In this research, for the first time, coconut water has been used as a source of carbon to prepare blue fluorescent CQDs without any modification and functionalization. The preparation of CQDs is very simple and cost-effective, when compared with other conventional techniques. The reaction parameters temperature and pH were varied to obtain monodispersed spherical CQDs with an average grain size of ∼5nm. The CQDs exhibit blue emission with a wavelength of 487nm with an excitation wavelength of 390nm and are used for Fe3+ ions detection. Fe3+ ions have been observed to quench the fluorescence intensity of the CQDs than other heavy metals. In the presence of Fe3+ ions, the fluorescent CQDs are quenched due to the interaction of CQDs and Fe3+ ions. A spectroscopic result shows that Fe3+ ions can be observed within a concentration of 0–700μM, as well as the detection limit is 0.30μM. The CQDs provide a unique pathway for potential application in the environmental monitoring of heavy metal ions.

Green synthesis of carbon quantum dots from corn stalk shell by hydrothermal approach in near-critical water and applications in detecting and bioimaging

Carbon quantum dots (CQDs) have diverse outstanding properties and potential application, but there are not many reports on the preparation of CQDs from agricultural waste without any addition of chemical reagent. Herein, a facile, economical and environmental route was developed for green synthesis of CQDs from corn stalk shell by hydrothermal approach in near-critical water. It’s worth noting that this method converted the biomass, which is regarded as agricultural wastes, into the carbon nano-materials with brilliant potential. The prepared CQDs present the great fluorescence property, the remarkable stability and biocompatibility, demonstrating this method is appreciate to produce the CQDs. The as-prepared CQDs can be employed in detecting and bioimaging domain, displaying distinctive potential for application. The superiorities of low-cost, renewability and sustainability drive the synthesis and applications of CQDs derived from biomass.

Quenching photoluminescence of Carbon Quantum Dots for detecting and tracking the release of Minocycline

This work reports the preparation of Carbon Quantum Dots via one-step microwave-assisted synthesis, to be employed for the determination of Minocycline antibiotic. Linear relationship was observed between photoluminescence quenching of CQDs and Minocycline concentration between 0.28–30.39 μM. UV–vis and PL Spectroscopy revealed that PL decrease arise from Inner Filter Effect. Selectivity studies were conducted to evaluate interference of various compounds on MC detection. In addition, Minocycline was loaded on Chitosan-grafted-oligomeric Lactic Acid microspheres, to be used as a drug carrier of Minocycline. Thereafter, CQDs were used to determine loading capacity, encapsulation efficiency, and cumulative drug release of Minocycline-loaded microspheres. Optimum samples showed loading capacity between 14.1–26.344 %, and encapsulation efficiency between 34.48–64.37%. CHS-g-OLA2 sample showed diminished burst release, and 50 % cumulative drug release during 4 days. Mathematical modelling showed that CHS-g-OLA2 sample follows Higuchi kinetic model, which describes the release of drug from swellable matrix by diffusion.

The Kuzbass Basin coals as a raw material for the preparation of carbon quantum dots

The article discusses a promising method for producing carbon quantum dots (C-dots) from coal. Coal grades A (anthracite), K (coking), OS (lean-sintered) were used as raw materials. The separated particles were investigated by X-ray diffraction and optical methods of analysis. The interplanar distances in C-dots and the phase ratio in the samples are determined. The intrinsic absorption region was determined from the optical spectra and the band gap of the obtained C-dots was estimated. Lines of photoluminescence were found in the UV and visible ranges.

Preparation of carbon quantum dots- quinic acid for drug delivery of gemcitabine to breast cancer cells

Carbon quantum dots (CQDs) have undergone extensive research and proved to have the potential to act both as drug delivery vehicles and imaging agents. Quinic acid is an antioxidant that has shown anticancer activity through apoptosis-mediated cytotoxicity in breast cancer cells. Besides, it has demonstrated a strong affinity for selectins, which are angiogenesis factors increased in breast cancer tissue. In this study, Nitrogen-doped CQDs were prepared via hydrothermal method. The resulting nanoparticles were conjugated with Quinic acid as targeting agent toward breast cancer cells. Characterization of the resulting nanoparticles included TEM, SEM, Zeta potential, FTIR, EDX, MAP, UV–Visual, and Fluorescent spectroscopy. Gemcitabine was loaded on the resulting nanoparticles through electrostatic interactions. Cell viability was evaluated via MCF7 cell line. In-vivo imaging and biodistribution studies were conducted in breast cancer cells growing in mice. Taken together, Quinic acid conjugated N-CQDs exhibited promising properties such as excellent luminescent properties and high tumor accumulation, suggesting that they could be excellent candidates as multifunctional theranostic agents.