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Photoelectrochemical biosensor for hydroxymethylated DNA detection and T4-β-glucosyltransferase activity assay based on WS2 nanosheets and carbon dots
摘要： 5-Hydroxymethylcytosine (5hmC) plays an important role in switching genes on and off in mammals, and it is implicated in both embryonic development and cancer progression. Herein, a novel photoelectrochemical (PEC) biosensor was developed for 5hmC detection based on WS2 nanosheets as the photoactive material and boronic acid functionalized carbon dots (B-CDs) for signal amplification unit. This biosensor can also be used for T4-β-glucosyltransferase (β-GT) activity assessment. Firstly, WS2 nanosheets and gold nanoparticles (AuNPs) were immobilized on an ITO electrode surface. Then probe DNA was immobilized on this electrode surface via Au-S bond. Afterwards, the complementary DNA containing 5hmC was then captured on the modified electrode surface by hybridization. Subsequently, β-GT transferred glucose from uridine diphosphoglucose to the hydroxyl groups of the 5hmC residues. After glycosylation, B-CDs could further be immobilized on the modified electrode surface resulting in a strong photocurrent. The PEC biosensor afforded high selectivity, excellent sensitivity and good reproducibility, with detection limits of 0.0034 nM and 0.028 unit/mL for 5hmC and β-GT, respectively. Results demonstrate that the photoelectrochemical strategy introduced here based on WS2 nanosheets and B-CDs offers a versatile platform for hydroxymethylated DNA detection, β-GT activity assessment and β-GT inhibitor screening.
关键词： Photoelectrochemical biosensor,DNA hydroxymethylation,β-Glucosyltransferase,WS2 nanosheets,carbon dots
更新于2025-09-09 09:28:46
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Environmentally benign conversion of waste polyethylene terephthalate to fluorescent carbon dots for “on-off-on” sensing of ferric and pyrophosphate ions
摘要： The increasing production of waste polyethylene terephthalate (PET) is a growing problem worldwide. Environmentally benign conversion of waste PET to valuable materials remains a substantial challenge. In this paper, we developed a green route to reuse waste PET for low-cost synthesis of fluorescent carbon dots (CDs) via air oxidation followed by hydrothermal treatment in aqueous H2O2 solution. No expensive, corrosive, or toxic reagents, or severe conditions were required in the synthetic process. The resultant CDs possessed abundant oxygenous groups and unique photoluminescence (PL) properties, which showed a highly selective and sensitive detection of ferric ion (Fe3+) through a PL quenching effect (on-off). The fluorescence of CDs quenched by Fe3+ could be restored specifically with pyrophosphate anion (PPi), rendering the CDs/Fe3+ sensor promising for PPi detection (off-on). The linear ranges for Fe3+ and PPi detections were 0.5–400 and 2–600 μM, and the limit of detections (LODs) were 0.21 and 0.86 μM, respectively. The sensing system applied for Fe3+ and PPi assays in real water samples and human urine achieved good results. After detailed investigations, a possible electron transfer process was proposed for explaining the “on-off-on” sensing mechanism.
关键词： Waste polyethylene terephthalate,Carbon dots,Environmentally benign conversion,Sensing,Ferric and pyrophosphate ions
更新于2025-09-09 09:28:46
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High-fluorescent carbon dots (CDs) originated from China grass carp scales (CGCS) for effective detection of Hg(II) ions
摘要： Carbon dots (CDs) as a kind of environment-friendly fluorescent nanomaterial has been actively studied because of wide and potential applications, such as bioimaging and biosensors. It is worth mentioning that preparing CDs from the recycling of carbonaceous waste has received considerable research interest. We proposed a simple carbon dots synthesis technique, that is, using China grass carp scales (CGCS) as original and green materials by a one-step microwave hydrothermal method to prepare CDs. Since the mercury ion has strongly sulphophile, S atoms display higher thermodynamic affinity and faster integrating process with Hg2+ ions. Due to the presence of large amount of cysteine-containing sulfhydryl groups, the obtained CGCS-CDs can be used as a specific fluorescence probe for detecting Hg2+ ions. Subsequently, CGCS-CDs were characterized by HR-TEM, XRD, FT-IR and XPS analyses. The optical properties of CGCS-CDs were elucidated by fluorescence and UV–vis spectra. Additionally, the effects of pH values and salt concentrations on optical properties of CGCS-CDs were also researched by fluorescence spectra. Under optimal conditions, the decrease of fluorescence intensity displays a good linear relationship with allowable Hg2+ ion detection concentration range of 0.014–30 μmol/L and a limit of detection (LOD) of 0.014 μmol/L is acquired. Meanwhile, the effect of other metal ions on the detection of Hg2+ ions by using CGCS-CDs as fluorescence probe was studied, suggesting that the CGCS-CDs could be an excellent fluorescence probe for the detection of Hg2+ ions. Eventually, the CGCS-CDs were proven to be low toxicity and applied for Hg2+ ions detection in lake water and cosmetic, demonstrating their potential towards diverse applications.
关键词： Sulfhydryl group,Microwave hydrothermal,Nanoscale sensing,Mercury,Carbon dots (CDs),China grass carp scales (CGCS)
更新于2025-09-09 09:28:46
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Microalgae biochar-derived carbon dots and their application in heavy metal sensing in aqueous systems
摘要： This research seeks a coupled solution for managing the large amounts of biochar produced by microalgae biofuel production, and the necessity for novel, economic and accurate heavy metal sensing methods. Therefore, this study evaluated the transformation of microalgae biochar (MAB) into carbon dots (Cdots) and their subsequent application as heavy metal ion sensors in aqueous systems. The experimental phase included the transformation of MAB into microalgae biochar-derived carbon dots (MAB–Cdots), MAB–Cdot characterisation and the evaluation of the MAB–Cdots as transducers for the detection of four heavy metal ions (Pb2+, Cu2+, Cd2+, and Ni2+). MAB–Cdot fluorescence was stable over a wide range of pH and resistant to photo-bleaching, making them suitable as fluorescence probes. The MAB–Cdot fluorescence was quenched by all of the metal ions and displayed different quenching levels. Depending upon the ions involved, MAB–Cdots were used to detect the presence of heavy metal ions from concentrations of 0.012 μM up to 2 mM by measuring the reduction in fluorescence intensity. Neutral and slightly alkaline pHs were optimal for Cu2+ Ni2+ and Pb2+ heavy metal quenching. To quantify the concentration of the heavy metal ions, linear and logarithmic functions were used to model the MAB–Cdot fluorescence quenching. The sensing mechanism was determined to be reversible and purely collisional with some fluorophores less accessible than the others. This work demonstrated the ability to produce Cdots from microalgae biochar, examined their application as a transducer for detecting heavy metal ions in aqueous systems and paves the way for novel sensing systems using MAB-Cdots.
关键词： Heavy metal ion,Carbon dots,Renewable nanomaterials,Quenching,Biochar,Microalgae,Fluorescence sensors
更新于2025-09-09 09:28:46
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Nickel ion detection by imidazole modified carbon dots
摘要： Nickel ions (Ni2+) were detected by a new imidazole modified carbon dots (CDs) based on fluorescence quenching method. Structural characterization of CD-imidazole quantum dots were accomplished by transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR). Spectroscopic properties were characterized by ultraviolet absorption spectrum and fluorescence spectrum. Ni2+ concentration showed good linear relationship with fluorescence quenching efficiency in the range of 6-100 mM (R = 0.99) and the limit of detection (LOD) was 0.93 mM. Imidazole modified CDs have strong selectivity of Ni2+ compared with other metal ions in aqueous solution. These results demonstrated that the fluorescence sense platform based on imidazole modified CDs can be applied to Ni2+ detection in environment.
关键词： Nickel ions,Fluorescence quenching,Carbon dots-imidazole quantum dots
更新于2025-09-04 15:30:14
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Systematic Toxicity Evaluations of High-Performance Carbon “Quantum” Dots
摘要： Carbon dots (CDots) in a general structure of small carbon nanoparticles with various surface passivation schemes have emerged to represent a new class of carbon nanomaterials in now a rapidly advancing and expanding research field. Among various synthesis methods, the use of pre-processed and selected small carbon nanoparticles for deliberate chemical functionalization of the particle surface with organic molecules have produced high-performance and structurally better defined CDots. Specifically, small organic molecules 2,2'-(ethylenedioxy)bis(ethylamine) and 3-ethoxypropylamine were used for the effective surface passivation of the carbon nanoparticles via chemical functionalization to yield CDots that are brightly fluorescent and also structurally ultra-compact, amenable to various desired cell imaging applications. Thus, a systematic evaluation of these CDots on their cytotoxicity profiles is necessary, and performed in this study by using a diverse selection of cell lines. Also for fluorescence imaging, CDots were modified with their encapsulating selected organic dyes for much enhanced red/near-IR fluorescence emissions. These modified CDots with the dyes as guest were also evaluated for their cytotoxicity profiles. The results suggest that the CDots without and with the guest dyes are generally nontoxic to the selected cell lines, further supporting the notion that CDots can be used as high-performance yet nontoxic bioimaging agents.
关键词： Carbon Dots,Cytotoxicity,Host-Guest
更新于2025-09-04 15:30:14
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Preparation of carbon dots decorated graphene/polyaniline composites by supramolecular in-situ self-assembly for high-performance supercapacitors
摘要： Supramolecular in-situ self-assembly is achieved to prepare carbon nanodots decorated graphene/polyaniline composites by adding β-cyclodextrin (β-CD) as the bonding agent in this work. With its unique structure, β-CD can form a supramolecular system with graphene oxide layers, generating the inclusion compound with aniline monomers, which makes the in-situ polymerization of polyaniline on the surface of graphene oxide. In the hydrothermal process, β-CD is carbonized to carbon nanodots anchored on the surface of reduced graphene oxide. The scanning electron microscopy (SEM) images show that the prepared reduced graphene oxide/carbon nanodots/polyaniline (RGO@CN/PANI) nanocomposites exhibit the micro morphology of a regular polyaniline particle array on the surface of graphene layers. The electrochemical tests demonstrate that the RGO@CN/PANI nanocomposites exhibit high specific capacitance (up to 871.8 F g-1 at 0.2A g-1), low charge transfer resistance (Rct), and presentable cycling performance (72% capacitance retention after 10000 cycles), indicating the satisfied performance for supercapacitors. The promising performance of RGO@CN/PANI can be attributed to the synergistic effect of RGO, carbon nanodots and PANI, as well as the regular microstructure in which the effective reaction area of polyaniline is increased and the rapid ion transport channel is provided.
关键词： β-cyclodextrin,supramolecular in situ self-assembly,Carbon dots modified Graphene,polyaniline
更新于2025-09-04 15:30:14
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Phosphorus and chlorine co-doped carbon dots with strong photoluminescence as a fluorescent probe for ferric ions
摘要： Usually, carbon dots (CDs) display a relatively weak fluorescence quantum yield (QY). In order to obtain brighter CDs, phosphorus and chlorine co-doped CDs (P,Cl-CDs) were prepared via hydrothermal treatment of maltose in the presence of phosphoric and hydrochloric acids. The new CDs are highly monodispersed in water solution, have high fractions of P (14.4 atomic%) and Cl (8.9 atomic%), and exhibited yellow fluorescence with a QY of 15%. This is higher than that of monoatomic doped CDs (8.7 and 9.3% for P-CDs and Cl-CDs, respectively). The P,Cl-CDs are highly photostable, and fluorescence is strongly (statically) quenched by Fe(III). Fluorescence decreases with increasing concentration of Fe(III) in the range from 0.1–8.0 μmol?L-1, with a 60 nmol?L-1 detection limit. The doped CDs are shown to be a viable nanoprobe for the fluorometric determination of Fe(III) in spiked serum and water samples.
关键词： Quantum yield,Phosphorus,Fluorescent probe,Chlorine,Co-doped carbon dots
更新于2025-09-04 15:30:14
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Preparation of water-soluble asphalt carbon dots and hyperchromic effect to Cr (VI)
摘要： Water-soluble asphalt carbon dots（W-CDs）was prepared from medium - temperature coal tar pitch as raw material, via mixed acid oxidation，alkali solubilization and acid precipitation method. It was observed that as-prepared W-CDs were irregular particles with good water dispersibility and the particle size was controlled by the pH of the acid precipitation solution by a polarizing microscope . Infrared spectroscopy confirmed that the surface of the W-CDs was functionalized by hydrophilic and color-promoting functional groups, which had good water solubility; the thermal weight loss proved to be good thermal stability below 200°C; the fluorescence spectrum proved that the fluorescence emission peak position of the carbon dots appears red shift with increase of excitation wavelength, with fluorescence conversion property, and its emission light intensity decreases, belonging to non-resonant fluorescence type of direct jump fluorescence; UV spectrum proves that the addition of W-CDs can be chromium (VI) CrO4 2- content The detection limit was increased from milligram to microgram; the molar absorptivity of CrO4 2- was increased by 4 times. The experimentally optimized W-CDs-ultraviolet-viscometry method for measuring CrO4 2- conditions: W-CDs to chromium ratio of 8:2, pH of 8, hexamethylenetetramine as a surfactant, and the solution was allowed to stand at room temperature for 45 min.
关键词： hyperchromic effect,Cr (Ⅵ),UV-vis spectrophotometry,Water-soluble asphalt carbon dots
更新于2025-09-04 15:30:14
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Time-resolved photoluminescence of pH-sensitive carbon dots
摘要： Time-resolved photoluminescence emission were performed to study the ? 100 ps time-scale photophysics of water soluble carbon dots (CDs) dispersed in different pH solutions. Excitation of the core and high-energy edge states at excitation wavelengths λex ￡ 350 nm produce hole-electron excitonic charge-carriers but do not yield any photoluminescence emission, implying efficient non-radiative recombination mechanisms for the charge-carriers. Using λex ~ 375 nm, surface fluorophores as well as low-lying edge-states are excited, producing emission over a broad range. However, the emission characteristics vary strongly depending on the pH condition and the choice of excitation wavelength. In particular, the edge state emission is abruptly extinguished at pH ≥ 5, which also marks the onset of deprotonation of surface-bound -COOH groups of the CDs, indicating that the -COO- anionic centers promote quenching of edge-state emission. Using λex ~ 450 nm, only the surface fluorophores are excited. The deprotonation of phenolic -OH group at pH>9 causes a sharp red-shift in the emission spectra at all excitation wavelengths. The pH-sensitive emission behavior of the CDs enable them to serve as optical pH sensors.
关键词： time-resolved spectroscopy,carbon dots,photoluminescence,pH-sensitive,optical pH sensors
更新于2025-09-04 15:30:14