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oe1(光电查) - 科学论文

130 条数据
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  • Lard detection using a tapered optical fiber sensor integrated with gold-graphene quantum dots

    摘要： In this paper, we reported the detection of lard using tapered optical fiber integrated with graphene quantum dot (GQD). Two different sensors were fabricated and tested, one coated with GQD only as sensing element, the other was coated with gold (Au)-GQD to be tested with lard concentration ranging from 20% till 100%. The GQD coated sensor obtained a sensitivity of 0.034/a.u.% at fluorescence emission peak 652 nm. Meanwhile the Au-GQD sensor, obtained higher sensitivity at 0.042/a.u.% with peak fluorescence emission at 680 nm. The proposed sensor shows a great potential of using sensor in detection of lard for future advancement of food technology.

    关键词： Fiber sensor,Fluorescence,Lard,Tapered fiber,Graphene quantum dots

    更新于2025-09-19 17:13:59

  • Highly biocompatible graphene quantum dots: green synthesis, toxicity comparison and fluorescence imaging

    摘要： Graphene quantum dots (GQDs) have tremendous potential in biological imaging due to their bright visible photoluminescence mission. However, the tedious preparation procedures and potential toxicity of GQDs greatly limit their application in biological field. Here, highly biocompatible GQDs (HGQDs) have been successfully prepared only by glucose in aqueous solution. Compared with GQDs prepared from conventional methods (CGQDs), the cytotoxicity of HGQDs reduced by more than 60%, and the flow cytometric analysis of the normal cells treated with HGQDs showed that the early and late apoptotic rate reduced by more than 72% and 40%, respectively. In vitro fluorescence imaging showed that both cells and bacteria could be imaged by HGQDs, and the morphology of cells and bacteria could be kept to a maximum extent. A long-term in vivo study revealed that no obvious organ (heart, liver, spleen, lung and kidney) damage or lesions were observed, and the blood–brain barrier (BBB) could be overcome, which provides the possibility for treatment and diagnosis of brain-related diseases. With adequate studies of biocompatibility, both in vitro and in vivo, HGQDs may be considered for further biological application.

    关键词： biocompatibility,biological application,fluorescence imaging,Graphene quantum dots

    更新于2025-09-19 17:13:59

  • Robot path planning with two-axis positioner for non-ideal sphere-pipe joint welding based on laser scanning

    摘要： The conversion and degradation of organic pollutants remain challenges relating to environmental science. Herein, we report the carbonization of organic pollutants (4-nitrophenol, 4-NP) toward metal-free nitrogen-doped graphene quantum dots (N-GQDs) using a one-pot solvothermal route. The resultant N-GQDs demonstrate excellent activity for the catalytic conversion of 4-NP to 4-aminophenol (4-AP) when exposed to near infrared (NIR) light because of their excellent upconverted photoluminescence and photothermal conversion ability. The NIR-enhanced reduction efficiency of 4-NP to 4-AP not only originates from the enhanced collisions between N-GQDs and 4-NP due to photothermal-increased Brownian movement of molecules, but also comes from the accelerated transfer rate of electrons produced by the photoexcitation of N-GQDs under NIR irradiation. The N-GQDs display excellent photostability and remain high activity even after five cycles of reuse. Such conversion of organic pollutants to highly efficient metal-free carbocatalysts has significant importance in relevance of the industrial production of aniline and paracetamol.

    关键词： organic pollutants,metal-free photocatalysts,4-nitrophenol reduction,nitrogen-doped graphene quantum dots,NIR-enhanced catalytic activity

    更新于2025-09-19 17:13:59

  • ZrO2 Nanoflowers Decorated with Graphene Quantum Dots for Electrochemical Immunosensing

    摘要： In present work, hybrid nanostructures of graphene quantum dots decorated zirconia (GQDs@ZrO2) synthesized by facile one-pot hydrothermal method and utilized as an efficient electrochemical sensing probe. The hydrothermal method involved carbonization of citric acid into GQDs and growth of ZrO2 NPs, simultaneously. The electron microscopic images visualized nanoflower structure of GQDs@ZrO2 nanostructures having an average diameter of 17–3.5 nm. X-ray photoelectron spectroscopic, zeta potential, UV-visible and fluorescence characterizations have validated the existence of ZrO2 NPs and GQDs in the synthesized GQDs@ZrO2 nanostructures. The GQDs@ZrO2 hybrid prevented re-stacking of GQDs and provided adequate availability of functional groups and high electron transport rate, which resulted in improved electrochemical biosensing performance. The oxygen moieties associated with the GQDs@ZrO2/ITO electrode offer an excellent environment for covalent attachment of antibodies. Fabricated BSA/anti-OTA/GQDs@ZrO2/ITO immunosensor revealed enhanced biosensing parameters such as detection range of 1–20 ng/mL, the sensitivity of 5.62 μA mL/ng cm2, limit of detection of 0.38 ng/mL and an average of 95% recovery of ochratoxin-A from the spiked coffee sample.

    关键词： Biosensor,Ochratoxin A,Electrochemical,Graphene Quantum Dots,Zirconia

    更新于2025-09-19 17:13:59

  • Interfacial modification using ultrasonic atomized graphene quantum dots for efficient perovskite solar cells

    摘要： Tin dioxide (SnO2) is a promising electron transport material to replace traditional titanium dioxide (TiO2) for fabricating efficient planar perovskite solar cells (PSCs). However, in order to realize process compatibility and larger scale device, low temperature solution processed SnO2 is normally used, which generates numerous trap states in ETL layer and directly affects the device performance. Here, an interfacial modification strategy proposed, depositing an ultrasonic atomized ultrathin graphene quantum dots (GQDs) layer between tin dioxide (SnO2) and perovskite layer. Ultrasonic atomized deposition can effectively prevent the damage of the surface chemical properties of SnO2 by aqueous solution. Additionally, we demonstrate that the GQDs change the surface property of SnO2 film, and optimized the charge transport capability in SnO2 and perovskite interface. Correspondingly, we obtained a significant power conversion efficiency (PCE) improvement for CH3NH3PbI3-based PSCs from 13.61% to 16.54% and reached a highest steady-state PCE over 16%. We believe that the interfacial modification engineering by means of ultrasonic atomizing process is a promising tactic to obtain efficient perovskite solar cells.

    关键词： Interface modification,SnO2,Ultrasonic atomizing,Perovskite solar cells,Graphene quantum dots

    更新于2025-09-19 17:13:59

  • Additive‐free electrophoretic deposition of graphene quantum dots thin films

    摘要： The electrophoretic deposition (EPD) of graphene-based materials on transparent substrates is highly potential for many applications. Several factors can determine the yield of EPD process, such as applied voltage, deposition time, and particularly the presence of dispersion additives (stabilizers) in the suspension solution. This study presents an additive-free EPD of GQDs thin films on Indium Tin Oxide (ITO) glass substrate and studies the deposition mechanism with the variation of the applied voltage (10 – 50 V) and deposition time (5 – 25 min). It is found that due to the small size (~3.9 nm) and high content of deprotonated carboxylic groups, the GQDs form a stable dispersion (zeta potential of about –35 mV) without using additives. The GQDs thin films can be deposited onto ITO with optimal surface morphology at 30 V in 5 min (surface roughness of approximately 3.1 (±1.3) nm). In addition, as-fabricated GQDs thin films also possess some interesting physico-optical properties, such as a double-peak photoluminescence at about 417 and 439 nm, with ca. 98% visible transmittance. This low cost and eco-friendly GQDs thin film is a promising material for various applications, e.g. transparent conductors, supercapacitors, and heat conductive film in smart windows.

    关键词： visible transparency,graphene quantum dots,thin film,electrophoretic deposition,additive free

    更新于2025-09-19 17:13:59

  • Fluorine-containing graphene quantum dots with a high singlet oxygen generation applied for photodynamic therapy

    摘要： Recently, graphene quantum dots (GQDs) have been extensively studied in biomedical areas such as bio-imaging, bio-sensing and photothermal therapy due to their superior optical and physiochemical properties compared to traditional organic biomarkers. Application of GQDs in photodynamic therapy (PDT) has been explored since 2014, but currently the main challenges are inadequate singlet oxygen (1O2) quantum yield (QY), poor solubility and biocompatibility. Herein, we report on the synthesis of a new kind of fluorine-containing GQDs (F-GQDs) by an oxidative cutting method using fluorinated graphite as the raw material. The as-synthesized F-GQDs sample demonstrates an average particle size of 2.1 nm with the fluorine doping content of 1.43%. The F-GQDs have a more excellent water solubility and biocompatibility than the GQDs, and emit strong green fluorescence at 365 nm excitation with the relative fluorescence QY of 13.72%. Moreover, the fluorescence imaging effect as well as photodynamic activity successfully tested in both in vitro HepG2 cell line model and a 3D multicellular spheroids model that mimics the tumour microenvironment. Further studies using UV-visible spectroscopy through the degradation of water-soluble 9,10-anthracenediyl-bis(methylene) dimalonic acid(ABDA) demonstrate that the F-GQDs sample generate 1O2 efficiently (QY = 0.49) under a visible light irradiation. Compared to non-fluorinated GQDs, the as-reported F-GQDs manifest to be a more promising photosensitizer for image-guided PDT.

    关键词： singlet oxygen,photodynamic therapy,biocompatibility,fluorine-containing,graphene quantum dots

    更新于2025-09-19 17:13:59

  • N-Doped Graphene Quantum Dots Supported by Carbon Nanotubes Grown on Carbon Clothes for Lithium Storage

    摘要： Graphite has been widely used as an anode material for commercial lithium-ion battery applications because of its excellent stability and low cost. However, graphite-based anodes need to improve the energy storage capacities to meet the increasing power demands of next-generation technologies. Here, we have developed a class of novel and ?exible electrode materials that consist of N-doped graphene quantum dots supported by carbon nanotubes grown on carbon cloth (denoted as CC/CNT@N-GQD). Such architecture synergistically combines the advantages of three dimensions/one dimension substrates and zero dimension N-GQDs. It greatly improves the electron/ion transport kinetics of N-GQDs, resulting in attractive electrochemical performance in terms of high reversible capacity and excellent rate capability. Moreover, the annealing temperature plays an important role in the control of N-doping types of CC/CNT@N-GQD. CC/CNT@N-GQD anodes annealed at 500 °C have a high content of pyridinic N, exhibiting a very excellent rate capability and cycling stability, as exempli?ed by a capacity of 2.88 mAh cm?2 at 4 mA cm?2 and a reversible capacity of 3.63 mAh cm?2 after 150 cycles at 0.19 mA cm?2.

    关键词： carbon nanotubes,carbon cloth,lithium storage,annealing temperature,pyridinic N,N-doped graphene quantum dots

    更新于2025-09-19 17:13:59

  • Silver nanoparticles on graphene quantum dots as nanozyme for efficient H <sub/>2</sub> O <sub/>2</sub> reduction in a glucose biosensor

    摘要： In this work, we developed graphene quantum dot-supported silver nanoparticles (AgNPs@GQDs) as Nanozyme for efficient electrocatalytic reduction of H2O2. We applied this composite material in a glucose oxidase-based glucose sensor, by drop casting a mixture of AgNPs@GQDs and chitosan (CS) on glassy carbon electrodes (GCE). Various conditions such as thickness of the AgNPs@GQDs/CS film, pH and temperatures were optimized. The proposed sensor presented excellent selectivity and sensitivity, a linear dependence on glucose concentration in the range 0.1–10 mM and a limit of detection of ca. 0.01 mM.

    关键词： hydrogen peroxide reduction,electrochemical sensor,graphene quantum dots (GQDs),silver nanoparticles (AgNPs),glucose oxidase (GOx)

    更新于2025-09-19 17:13:59

  • Cu2+-mediated Fluorescence Switching of Graphene Quantum Dots for Highly Selective Detection of Glutathione

    摘要： As a short peptide containing active thiol group, glutathione (GSH) participates in many cellular reactions, so it is of great significance to detect cellular GSH. In this work, amino-rich graphene quantum dots (GQDs) were synthesized, which could coordinate with copper ions (Cu2+) and yield aggregation-induced fluorescence quenching. However, GSH owns stronger coordination ability with Cu2+, so that GSH could promote the dissociation of Cu2+ from the surface of GQDs, and then led to the fluorescence recovery of GQDs. In BR buffer medium at pH 6.8, GSH was able to gradually recover the fluorescence of GQDs (1 μg/mL) that was quenched by Cu2+ (250 μmol/L), which could be finished within 20 min. Additionally, the recovery degree of fluorescence was linear to the concentration of GSH in the range of 20─500 μmol/L with a detection limit of 3.4 μmol/L. This method was applicable to the detection of GSH in cell lysate by the switchable function of Cu2+ to improve the selectivity.

    关键词： Graphene quantum dots,Fluorescence switching,Copper ions,Glutathione

    更新于2025-09-19 17:13:59