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Facile ultrasonic synthesized NH2-carbon quantum dots for ultrasensitive Co2+ ion detection and cell imaging
摘要： The amine decorated carbon quantum dots (NH2-CQDs) were synthesized through ultrasonic method from graphite rods derived CQDs and ammonia hydroxide and utilized as the sensing probes for cobalt (II) ions and nucleic acids. The sensing technique was investigated to be the fluorescence quenching effect, which demonstrated linear relationship between cobalt (II) ions concentration and the emission intensity deviation ratio in the concentration range of 50 nM to 40 μM with the detection limit of 12 nM. In brief, this sensitive and selective detection method was confirmed to demonstrate high potential in cobalt (II) ions detection in real samples and nucleic acid sensing in biological cells.
关键词： Nucleic acid sensing,Carbon quantum dots (CQDs),Cobalt sensor
更新于2025-11-19 16:56:42
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Growth Process and CQDs-modified Bi4Ti3O12 Square Plates with Enhanced Photocatalytic Performance
摘要： Bi4Ti3O12 square plates were synthesized via a hydrothermal route, and their growth process was systematically investigated. Carbon quantum dots (CQDs) were prepared using glucose as the carbon source, which were then assembled on the surface of Bi4Ti3O12 square plates via a hydrothermal route with the aim of enhancing the photocatalytic performance. XRD (X-ray powder diffraction), SEM (scanning electron microscopy), TEM (transmission electron microscopy), UV-vis DRS (diffuse re?ectance spectroscopy), XPS (X-ray photoelectron spectroscopy), FTIR (Fourier transform infrared spectroscopy), PL (photoluminescence) spectroscopy, EIS (electrochemical impedance spectroscopy) and photocurrent spectroscopy were used to systematically characterize the as-prepared samples. It is demonstrated that the decoration of CQDs on Bi4Ti3O12 plates leads to an increased visible light absorption, slightly increased bandgap, increased photocurrent density, decreased charge-transfer resistance, and decreased PL intensity. Simulated sunlight and visible light were separately used as a light source to evaluate the photocatalytic activity of the samples toward the degradation of RhB in aqueous solution. Under both simulated sunlight and visible light irradiation, CQDs@Bi4Ti3O12 composites with an appropriate amount of CQDs exhibit obviously enhanced photocatalytic performance. However, the decoration of excessive CQDs gives rise to a decrease in the photocatalytic activity. The enhanced photocatalytic activity of CQDs-modi?ed Bi4Ti3O12 can be attributed to the following reasons: (1) The electron transfer between Bi4Ti3O12 and CQDs promotes an ef?cient separation of photogenerated electron/hole pairs in Bi4Ti3O12; (2) the up-conversion photoluminescence emitted from CQDs could induce the generation of additional electron/hole pairs in Bi4Ti3O12; and (3) the photoexcited electrons in CQDs could participate in the photocatalytic reactions.
关键词： photocatalytic mechanism,photodegradation of RhB,CQDs@Bi4Ti3O12 composites,Bi4Ti3O12 square plates,CQDs
更新于2025-11-19 16:46:39
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A novel photoelectrochemical biosensor for the sensitive detection of dual microRNAs using molybdenum carbide nanotubes as nanocarriers and energy transfer between CQDs and AuNPs
摘要： Herein, a novel photoelectrochemical (PEC) biosensor was developed for the ultrasensitive detection of dual microRNAs (miRNAs), with the detection being based on energy transfer (ET) between carbon quantum dots (CQDs) and gold nanoparticles (AuNPs). The PEC platform consisted of a CQDs@Mo2C nanotube modified ITO electrode. Two hairpin probes (H1 and H2) carrying the Au NPs were used “switch off” and “switch on” the PEC signal of the CQDs, with a close approach of the tagged AuNPs to the CQDs quenching the PEC signal. The introduction of different miRNAs (miRNA-159b and miRNA-166a) altered the interparticle distance between the AuNPs and CQDs, thereby affecting the intensity of the PEC response. This approach allowed the highly sensitive detection of both miRNA-159b and miRNA-166a. The linear range of the biosensor for miRNA-159b and miRNA-166a detection were 0.5–5000 fM, with low detection limits of 0.15 fM and 0.21 fM, respectively. To our knowledge, this is the first reported CQDs-based ET biosensor for the PEC detection of dual miRNAs. Results suggest that this approach offers a promising platform for the ultrasensitive detection of multiple miRNAs.
关键词： MicroRNA detection,AuNPs,Photoelectrochemistry,Energy transfer,CQDs@Mo2C
更新于2025-11-14 17:03:37
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Synthesis of folic acid conjugated photoluminescent carbon quantum dots with ultrahigh quantum yield for targeted cancer cell fluorescence imaging
摘要： Folic acid functionalized carbon quantum dot (FA-CQD) with ultrahigh quantum yield (50%) were synthesized by one-pot hydrothermal route using citric acid. The synthesized CQDs were characterized by fluorescence spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS) and X-ray diffraction. The cell viability of about 95% and 97% were obtained for MTT assay of the CQDs and FA-CQDs toward MCF-7 cells after 24 h of incubation respectively. The FA-CQDs were successfully applied for targeted imaging of cervical cancer (type HeLa) and human breast adenocarcinoma (type MCF7) cells using fluorescence microscope.
关键词： HeLa cancer cell,Ultra high quantum yield CQDs,MCF-7 cancer cell,Fluorescence imaging,Targeted cancer imaging
更新于2025-09-23 15:19:57
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Nitrogen/sulfur-co-doped carbon quantum dots: a biocompatible material for the selective detection of picric acid in aqueous solution and living cells
摘要： Here, a fast and eco-friendly one-pot hydrothermal technique is utilized for the synthesis of nitrogen/sulfur-co-doped fluorescent carbon quantum dots (NS-CQDs) from a simple precursor of citric acid (CA) and thiosemicarbazide (TSC). The obtained NS-CQDs exhibited strong blue emission under UV light, with fluorescence quantum yield (QY) of ~37.8%. The Commission internationale de l’eclairage (CIE) coordinates originated at (0.15, 0.07), which confirmed the blue fluorescence of the synthesized NS-CQDs. Interestingly, the prepared NS-CQDs were successfully used as a selective nanoprobe for the monitoring of environmentally hazardous explosive picric acid (PA) in different nitro- and non-nitro-aromatic derivatives of PA. The mechanism of the NS-CQDs was also explored, and was posited to occur via the fluorescence resonance electron transfer (FRET) process and non-fluorescent complex formation. Importantly, this system possesses excellent biocompatibility and low cytotoxicity in HeLa cervical cancer cells; hence, it can potentially be used for PA detection in analytical, environmental, and pathological applications. Furthermore, the practical applicability of the proposed sensing system to pond water demonstrated the feasibility of our system along with good recovery.
关键词： Feasibility,PA,NS-CQDs,Cytotoxicity,Fluorescent probe,Synthesis
更新于2025-09-23 15:19:57
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Preparation of triplea??responsive porous silica carriers and carbon quantum dots for photodynamica??chemo therapy and cell multicolor imaging
摘要： Photosensitive carbon quantum dots (CQDs) provide a new route to treat cancer owing to their ability to produce singlet oxygen. In this paper, pH/redox/enzyme-responsive porous silica-based carriers with CQDs were constructed for photodynamic-chemical combination therapy. Porous silica (pSiO2) sample presents uniform sphere with center-radial channels, which is favorable for drug loading and delivery. The CQDs with size of 2.5 nm were synthesized and have the excellent ability to generate singlet oxygen. After loading CQDs and drug molecules, the channels of pSiO2 carrier were blocked with hyaluronic acid (HA)/chitosan (CHI) layer. The disulfide bonds conjugating HA to the surface of pSiO2 carrier would achieve redox-responsive drug release while breaking disulfide bonds and HA/CHI layer could endow the pSiO2 carrier enzyme/pH responsive drug release. The prepared pSiO2 carriers display low cytotoxicity and good biocompatibility for multicolor imaging and photodynamic-chemo therapy.
关键词： CQDs,photodynamic-chemical combination therapy,controlling release,porous silica
更新于2025-09-23 15:19:57
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Superficial preparation of biocompatible carbon quantum dots for antimicrobial applications
摘要： Orange waste peel CQDs has been synthesized via simple hydrothermal method. The UV–visible spectrum shows near band edge absorbance and optical energy bandgap has been calculated as 3.44 eV and 5.60 eV. In addition, the antibacterial assay of CQDs was carried out against two kind of bacteria such as gram positive and gram-negative bacteria. It has been noted that the CQDs show good antibacterial activity towards the gram-negative bacterium Pseudomonas aeruginosa (ZOI: 30 mm). Antibacterial activity of natural waste CQDs was compared with chemically synthesized NPs and QDs.
关键词： Tauc’s plot,CQDs,Hydrothermal method,Electron microscopy,Antibacterial assay
更新于2025-09-23 15:19:57
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Green production of fluorescent carbon quantum dots based on pine wood and its application in the detection of Fe3+
摘要： Carbon quantum dots (CQDs) have novel applications as fluorescent nanomaterials in various fields. In this study, a green hydrothermal carbonisation (HTC) method is proposed to produce CQDs from pine wood (P-CQDs). The P-CQDs exhibited excellent fluorescence characteristics, with the optimal excitation wavelength being 330 nm and a corresponding emission wavelength of 447 nm. A blue light emission under ultraviolet light was observed and a typical graphene structure was seen in the HR-TEM images with a fringe spacing of 0.21 nm. Moreover, the mechanism of P-CQD formation during the HTC process was proposed. It was observed that P-CQDs demonstrated an aromatic polymer structure rich in oxygen-containing groups. This is because of the condensation, chain breaking, and chain forming reactions occurring among the hydrolytic products of the cellulose, hemicellulose, and lignin in pine wood. The fluorescence quenching results indicated that the P-CQDs selectively detected Fe3+ in an aqueous phase. This implies that these CQDs have broad application prospects for Fe3+ detection. More importantly, this signifies that the large-scale and low-cost production of CQDs and Fe3+ sensors will now be possible.
关键词： CQDs,Formation mechanism,Fluorescence characteristic,Fe3+ sensor,Pine wood
更新于2025-09-23 15:19:57
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Phytochemical properties and antioxidant activity of Echinops persicus plant extract: green synthesis of carbon quantum dots from the plant extract
摘要： Echinops persicus is a species of Echinops that can be found in Europe and western Asia especially in Iran. In this paper, the phytochemical properties of Echinops persicus were thoroughly investigated and studied. In this way, total amounts of flavonoid, tannins, phenols, carotenoids, saponins, alkaloids, and anthocyanin were measured by various analytical methods. The major phenolic and flavonoid content was found in the root acetone and flower ethanolic extract of the plant. Also, major saponins and carotenoid contents was found in root and leaf of the plant. These measurements were also performed for root, leaf, and flower of the plant in various solvent extracts. The results indicated that Echinops persicus is a rich source of secondary metabolites. Also, the plant extract demonstrated a considerable antiradical activity, which evaluated qualitatively as well as quantitatively. The largest capacity to neutralize DPPH radicals was found for root water extract of Echinops persicus plant. Finally, the possibility of the plant extract was evaluated for the green preparation of carbon quantum dots (CQDs). As-prepared CQDs were characterized by TEM, HRTEM, UV–Vis, XRD, and EDX analyses.
关键词： Antioxidant,Echinops persicus,Secondary metabolites,Green preparation of CQDs,Carbon quantum dots
更新于2025-09-23 15:19:57
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Graphene/HgTe Quantum-Dot Photodetectors with Gate-Tunable Infrared Response
摘要： Graphene-based vertical heterostructures are of interest as emerging electronic and optoelectronic devices. Here, we report the study of photovoltaic response from graphene/HgTe quantum-dot junction. The graphene/HgTe quantum-dot junction combines the high carrier mobility of graphene and tunable infrared optical absorption of HgTe colloidal quantum dots, which offers promising route for the next-generation infrared optoelectronics. We demonstrate that both the sign and magnitude of the short-circuit photocurrents and open-circuit voltages can be controlled by the applied gate voltage, which tunes the Fermi level and the interfacial built-in potential across the junction. The interfacial energy band diagram is deduced to provide the fundamental understanding of the essential physics behind the graphene/quantum-dot film junction.
关键词： graphene/HgTe CQDs junction,photovoltaic detection,interfacial photocarrier transport,gate-tunable photoresponse,infrared
更新于2025-09-19 17:13:59