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Tuning the Functional Groups on Carbon Nanodots and Antioxidant Studies
摘要： Carbon nanodots (CNDs) have shown good antioxidant capabilities by scavenging oxidant free radicals such as diphenyl-1-picrylhydrazyl radical (DPPH?) and reactive oxygen species. While some studies suggest that the antioxidation activities associate to the proton donor role of surface active groups like carboxyl groups (–COOH), it is unclear how exactly the extent of oxidant scavenging potential and its related mechanisms are influenced by functional groups on CNDs’ surfaces. In this work, carboxyl and the amino functional groups on CNDs’ surfaces are modified to investigate the individual influence of intermolecular interactions with DPPH? free radical by UV-Vis spectroscopy and electrochemistry. The results suggest that both the carboxyl and the amino groups contribute to the antioxidation activity of CNDs through either a direct or indirect hydrogen atom transfer reaction with DPPH?.
关键词： carbon nanodots,radical scavenging,electro-chemistry,functional groups,antioxidation,charge transfer
更新于2025-11-19 16:56:35
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AIP Conference Proceedings [Author(s) 2ND INTERNATIONAL CONFERENCE ON CHEMISTRY, CHEMICAL PROCESS AND ENGINEERING (IC3PE) - Yogyakarta, Indonesia (14 August 2018)] - Enhanced photocatalytic activity of WO3 nanoparticles loaded with carbon
摘要： Enhanced photocatalytic activity of WO3 was attempted by carbon nanodots (C-dots) loading. C-dots were prepared using citric acid and urea for enhancing photocatalytic activity of WO3. Physicochemical character of C-dots was studied by fluorescence spectrophotometry and for the modified WO3, evaluation was studied by using x-ray diffraction (XRD) and scanning electron microscope (SEM). Effect of varied citric acid: urea ratio to photocatalytic activity was evaluated in methylene blue photodegradation. Increasing photocatalytic activity was achived by higher intensity in blue color range that obtained by higher urea molar ratio. Kinetics of reaction obey pseudo-first order and pseudo-second order reaction. Reaction reached 80% MB degradation for an hour treatment for 50mM of methylene blue solution.
关键词： photocatalytic activity,methylene blue photodegradation,WO3 nanoparticles,carbon nanodots
更新于2025-11-14 15:15:56
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Synthesis of Carbon Nanodots from Cellulose Nanocrystals Oil Palm Empty Fruit by Pyrolysis Method
摘要： Biomass such as cellulose is one of the most common abundant organic materials on the Earth. Biomass has carbon chain that could be an excellent choice for the fabrication of carbon materials. Cellulose nanocrystal is nano-sized cellulose and could become the potential source in fabricating carbon nanodots that are affected by pyrolysis temperature. In fact, the size and temperature are essentially important to synthesize the carbon nanodots. This research is contributed to synthesize this material, and to investigate the effect of temperature. The percentage of cellulose nanocrystals and carbon nanodots obtained are less than 50%. Carbon nanodots are synthesized by pyrolysis method and cellulose nanocrystals are fabricated by membrane method. TEM analysis shows that cellulose nanocrystals are nano-sized. Under UV light source, the samples show fluoroscencing colours i.e. blue to green. From this research it can be concluded that the temperature affects the characteristics of carbon nanodots produced by pyrolysis method.
关键词： Pyrolysis,Cellulose Nanocrystals,Fluorescent,Carbon Nanodots
更新于2025-09-23 15:23:52
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Spectroelectrochemical operando method for monitoring a phenothiazine electrografting process on amide functionalized C-nanodots/Au hybrid electrodes
摘要： Phenothiazine derivatives are extensively explored dye molecules, which present interesting electrochemical and optical properties. In recent years, the possibility of transforming some phenothiazines in their aryl diazonium salt derivatives has been proved, what allows them to be electrochemically reduced and electrografted onto conductive surfaces. This is a smart way to modify these surfaces and enable them with specific functionalities. In order to better comprehend the electrografting process and consequently have a higher control of it, in this work we have carried out an exhaustive study by operando UV–Vis spectroelectrochemistry of the electrografting of a phenothiazine aryl diazonium salt onto amide carbon nanodots. As a model of phenothiazine dye we have chosen Azure A. The electrografting onto carbon nanodots has been stablished by comparison with the results obtained on bare gold electrodes in this novel study. The presence of carbon dots improves the reversibility of the electrochemical process as derived from the results obtained by operando UV–Vis spectroelectrochemistry. In addition, to asses that the electrochemical process studied corresponds to the electrografting, the results have been compared to those obtained for the simple Azure A adsorption. This study shows the advantages of obtaining simultaneously the electrochemical and the spectroscopic evolution of an electron-transfer process in a single experiment, in a particular electrochemical reaction. This work could be the starting point for the study of the electrografting on other nanomaterials.
关键词： Azure A,Electrografting,Diazonium salt,Carbon nanodots,Spectroelectrochemistry
更新于2025-09-23 15:22:29
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Controlling the fluorescence and room-temperature phosphorescence behaviour of carbon nanodots with inorganic crystalline nanocomposites
摘要： There is a significant drive to identify alternative materials that exhibit room temperature phosphorescence for technologies including bio-imaging, photodynamic therapy and organic light-emitting diodes. Ideally, these materials should be non-toxic and cheap, and it will be possible to control their photoluminescent properties. This was achieved here by embedding carbon nanodots within crystalline particles of alkaline earth carbonates, sulphates and oxalates. The resultant nanocomposites are luminescent and exhibit a bright, sub-second lifetime afterglow. Importantly, the excited state lifetimes, and steady-state and afterglow colours can all be systematically controlled by varying the cations and anions in the host inorganic phase, due to the influence of the cation size and material density on emissive and non-emissive electronic transitions. This simple strategy provides a flexible route for generating materials with specific, phosphorescent properties and is an exciting alternative to approaches relying on the synthesis of custom-made luminescent organic molecules.
关键词： room temperature phosphorescence,photoluminescence,heavy atom effect,carbon nanodots,nanocomposites
更新于2025-09-23 15:22:29
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Fabrication and photoluminescent properties of Tb3+ doped carbon nanodots
摘要： Carbon nanodots (CNDs) doped with Tb ions were synthesized using different synthetic routes: hydrothermal treatment of a solution containing carbon source (sodium dextran sulfate) and TbCl3; mixing of CNDs and TbCl3 solutions; freezing-induced loading of Tb and carbon-containing source into pores of CaCO3 microparticles followed by hydrothermal treatment. Binding of Tb ions to CNDs (Tb-CND coupling) was confirmed using size-exclusion chromatography and manifested itself through a decrease of the Tb photoluminescence lifetime signal. The shortest Tb photoluminescence lifetime was observed for samples obtained by hydrothermal synthesis of CaCO3 microparticles where Tb and carbon source were loaded into pores via the freezing-induced process. The same system displays an increase of Tb photoluminescence via energy transfer with excitation at 320–340 nm. Based on the obtained results, freezing-induced loading of cations into CNDs using porous CaCO3 microparticles as reactors is proposed to be a versatile route for the introduction of active components into CNDs. The obtained CNDs with long-lived emission may be used for time-resolved imaging and visualization in living biological samples where time-resolved and long-lived luminescence microscopy is required.
关键词： freezing-induced loading,Tb3+ doping,photoluminescence,hydrothermal treatment,Carbon nanodots,CaCO3 microparticles
更新于2025-09-23 15:21:01
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Rapid detection of tryptamine by optosensor with molecularly imprinted polymers based on carbon dots-embedded covalent-organic frameworks
摘要： A rapid optosensing detection method for tryptamine (TRY) based on one-pot surface-imprinting synthesis methods has been developed. The optosensor consists of molecularly imprinted polymers (MIPs) based on carbon dots (CNs)-embedded covalent-organic frameworks (COFs). The principle of operation depends on adsorbents providing a large number of accessible recognition sites with high affinity and specificity, to achieve both a rapid uptake of and high capacity for TRY. After removing the template molecules, the desired molecular cavities were selected and fixed in a distinct manner to provide a defined chemical microenvironment for the reversible binding of the TRY target molecules. The optosensing system relied on the linear relationship between the fluorescence intensity of the TRY-imprinted polymers and the concentration of TRY in the range of 0.025–0.4 mg kg-1 with a detection limit of 7 μg kg-1. The system was used for efficiently detecting TRY in meat samples with recovery values from 91.42% to 119.80%.
关键词： covalent organic frameworks,meat,molecularly imprinted polymers,tryptamine,carbon nanodots
更新于2025-09-19 17:15:36
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Control of the size and luminescence of carbon nanodots by adjusting ambient pressure in laser ablation process
摘要： A femtosecond pulse laser was used to fabricate carbon nanodots (CDs), of which the particle size and photoluminescence (PL) properties could be effectively controlled by adjusting ambient pressure. By increasing the reaction pressure, the particle size of CDs gradually decreased and finally reached less than 1 nm at 4 MPa. Simultaneously, the fluorescence intensity of the CDs first increased and then decreased by further increasing the pressure. By examining the PL dynamics and the chemical structure of the CDs, we found that the PL change of products was attributed to the quantity change of functional groups attached to the CDs due to the surface area change of the carbonic core.
关键词： laser ablation,ambient pressure,photoluminescence,particle size,carbon nanodots
更新于2025-09-19 17:13:59
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Intracellular pH-propelled assembly of smart carbon nanodots and selective photothermal therapy for cancer cells
摘要： A kind of smart carbon nanodots (CNDs) with pH response feature was prepared by one-pot hydrothermal treatment of citric acid and dicyandiamide, which was used for differentiation of cancer/normal cells and selective photothermal therapy (PTT) of cancer cells. When they were cultured with cells, they were highly internalized in the lysosomes of cells. Since the small-sized CNDs (about 5 nm) tends to form aggregation (as large as about 20 nm or even over) under the an acid condition (pH=4.7) due to the electrostatic attraction produced by surface protonation, relatively severer aggregation of the CNDs were observed in liver cancer cells (HepG2 cells) relative to normal ones (LO2 cells) due to a relative lower pH in the lysosomes of HepG2 cells, which endows them a new strong absorption band at longer wavelengths (450-900 nm) and a higher photothermal conversion efficiency (42.13 %), benefiting to differentiated PTT. The flow cytometric data indicates strong photothermal ablation (8 min, 509.6 mW/cm2) for cancer cells with assistance of these smart CNDs achieves 82 % death rate of cancer cells, while much less damageis observed on the normal cells (6.35 %). To the best of our knowledge, this is the first report about CNDs for selective PTT owing to their intrinsic property without assistance of any other targeting ligands. This smart CNDs is also available for other acid-responsive sensing systems and this study inspires us in the synthesis of near-infrared featured carbon materials.
关键词： supra-carbon nanodots,carbon nanodots,assembly,selective photothermal therapy
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Photoreduction in Optofluidic Hollow-Core Photonic Crystal Fiber
摘要： Optofluidic hollow-core photonic crystal fiber (HC-PCF) uniquely allows light to be guided at the centre of a microfluidic channel. The system maximizes the interaction of light with infiltrated chemicals and (nano)particles, offering unique opportunities for in-situ optical monitoring of a range of photochemical and catalytic reactions [1,2]. Our current goal is to extend this work to hybrid colloidal systems comprising a particulate light absorber and a molecular catalyst for photocatalytic fuel production [3]. Here we use HC-PCF microreactors to study novel light-absorbing particles for such systems: graphitic, N-doped, and amorphous carbon-nanodots (CNDs) that offer a unique combination of scalability, biocompatibility, water solubility, and stable optical properties [4]. To test the CNDs’ absorption- and electron-transfer properties, we combine them with the redox-active heterocycle methyl viologen dichloride (MV2+·2Cl-). Upon absorption of UV light, CNDs can transfer an electron to MV2+, whose reduction to the radical cation (MV?+) creates a strong optical absorption peak around 600 nm (Figs. 1(a,c)). An electron donor (EDTA) is added to the solution to quench the photo-induced holes in the CNDs [4]. The mixture was infiltrated into the core of a 30 cm long liquid-filled kagomé style HC-PCF (Fig. 1(b)), designed to guide in the wavelength range of the MV?+ absorption peak. To ensure a homogeneous excitation of the CNDs, a 5 cm long section of the fiber was side-illuminated by a UV lamp (λ = 365 nm). A supercontinuum source, launched into a guided mode, was used to monitor the absorption spectrum. Despite sample volumes of less than 50 nL, we obtain highly-reproducible time traces of the MV?+ absorption (Fig 1(d-e)). Unexpectedly, a significant initial time-delay of 135 s was observed in the reduction of MV2+, revealing the presence of a previously unknown activation process of the CNDs. The initial delay was found to depend on the functionalization of the CNDs, with delays for a -COOH group (81 s) being ca. three times shorter than those for NH2 (176 s) and NMe2 (204 s) groups. The subsequent reaction rate was found to be independent of the surface-group. Our unexpected results highlight the scope for urgently needed in-situ analysis of photocatalytic systems. Future experiments will include the use of surface-sensitive higher-order modes [5] to selectively probe the diffusion of reaction products within the optofluidic reactor.
关键词： Carbon-Nanodots,Photoreduction,Hollow-Core Photonic Crystal Fiber,Optofluidic,Photocatalytic
更新于2025-09-12 10:27:22