- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Fluorescence detection of Escherichia coli on mannose modified ZnTe quantum dots
摘要： Rapid detection and identification of Escherichia coli (E.coli) is essential to prevent its quickly spread. In this study, a novel fluorescence probe based on ZnTe quantum dots (QDs) modified by mannose (MAN) had been prepared for the determination of E.coli. The results showed that the obtained QDs showed excellent selectivity toward E.coli, and presented a good linearity in range of 1.0 × 105~1.0 × 108 CFU/mL. The optimum fluorescence intensity for detecting E.coli was found to be at pH 7.0 with a temperature of 25 oC and incubation time of 20 min. Under these optimum conditions, the detection limit of E.coli was 4.6 × 104 CFU/mL. The quenching was discussed to be a static quenching procedure, which was proved by the quenching efficiency of QDs decreased with the temperature increasing.
关键词： Fluorescence intensity,Mannose,ZnTe quantum dots,Probe,Escherichia coli
更新于2025-09-11 14:15:04
-
Smartphone-based three-channel ratiometric fluorescent device and application in filed analysis of Hg2+, Fe3+ and Cu2+ in water samples
摘要： Determination of metal ions in water samples, especially harmful heavy metal like mercury or essential elements like iron and copper, is an important work in environmental monitoring. Herein, we report a smartphone-based three-channel ratiometric fluorescence device for simultaneous determination of Hg2+, Fe3+ and Cu2+ in environmental samples on site. It was based on the fluorescence quench mechanism of Hg2+, Fe3+ and Cu2+ to three kinds of doped carbon quantum dots, which were prepared by pyrolysis methods using ammonium citrate, citric acid + 1,10-phenanthroline, and EDTA + thiourea as initial materials, respectively. By using a multivariate calibration method, the mutual interference among Hg2+, Fe3+ and Cu2+ can be corrected. Under the optimized conditions, the limits of detection for Hg2+, Cu2+ and Fe3+ are 3, 0.5, and 30 nM, respectively. The proposed device offers the advantage of portability, sensitivity and reliability for field analysis.
关键词： Smartphone,Heavy ions,Portable device,Carbon quantum dots,Ratiometric fluorescence,Triple-channel
更新于2025-09-11 14:15:04
-
High performance phototransistors with organic/quantum dot composite materials channels
摘要： Nanomaterials, especially quantum dots, have become one of the most great potential channel transport layer materials in the field of photo detection mainly due to their particular light absorption characteristics. However, there are still many disadvantages such as low carrier transport capability possibly attributable to the discontinuity nature of materials. Therefore, particular phototransistors with pentacene/CdSe@ZnS QDs composite materials channels have been prepared by simply blending and spin-coating 6,13-Bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene) and QDs solution in weight ratio of 3:1. The particular device architecture with organic/quantum dot composite materials channels effectively combined the high carrier mobility advantage of organic semiconductors with the strong absorption characteristic of quantum dots in specific optical band regions and further overcame the low conductivity shortcomings of pure quantum dot materials. The device with particular pentacene/CdSe@ZnS QDs composite channel exhibited excellent electrical and optical properties with current switch ratio Ion/off of 104, carriers mobility of ~0.161 cm2/V, photosensitivity P of 105, responsivity R of 0.33 mA/W and detectivity D of 1.48 ? 1011 Jones at drain voltage of (cid:0) 35 V and light intensity of 1.6 mW/cm2, respectively, indicating that this composite, as one of the most promising channel transport layer material candidates for photodetector, provides one chance to improve the characteristic of photodetector transistors just by using hybrid channel technology.
关键词： Solution method,Quantum dots,Photodetectors,Composite materials,Organic thin film transistors
更新于2025-09-11 14:15:04
-
Interface‐Sliding‐Induced Graphene Quantum Dots Transferring to Fullerene‐Like Quantum Dots and Their Extraordinary Tribological Behavior
摘要： Carbon materials such as diamond, fullerene, graphene, and carbon nanotubes possess superior chemical and physical properties, which are widely used in various applications. Especially, since fullerene-like carbon is successfully converted to graphene during sliding, the sliding-induced microstructure transfer between carbon-based materials should be given more attention. Here, the tribological behaviors of graphene-based materials is investigated under the load of 196 N and the rotational speed of 1450 rpm using a four-ball wear machine under deionized water. Results show that the friction coefficient continuously decreases with increasing sliding time and the wear scar diameter is just about 0.224 mm. Remarkably, graphene is severely ripped and loses its lubrication performance during sliding. Sliding induces graphene quantum dots converting to fullerene quantum dots, which would cooperate with the sliding-reduced fullerene-like structures containing WO2 nanocrystals and sulfurized isobutene as extreme pressure lubricant additives instead of graphene to achieve low friction and wear. This work confirms that the low friction and wear under high load and fast rotation have a close relation to the microstructure transfer of interfacial carbon-based materials, rather graphene, and provide practical approach for investigating the tribological behaviors of carbon-based materials.
关键词： graphene quantum dots (GQDs),fullerene,sulfurized isobutene (SIB),tribological,graphene
更新于2025-09-11 14:15:04
-
Highly Efficient and Stable White Light‐Emitting Diodes Using Perovskite Quantum Dot Paper
摘要： Perovskite quantum dots (PQDs) are a competitive candidate for next-generation display technologies as a result of their superior photoluminescence, narrow emission, high quantum yield, and color tunability. However, due to poor thermal resistance and instability under high energy radiation, most PQD-based white light-emitting diodes (LEDs) show only modest luminous efficiency of ≈50 lm W?1 and a short lifetime of <100 h. In this study, by incorporating cellulose nanocrystals, a new type of QD film is fabricated: CH3NH3PbBr3 PQD paper that features 91% optical absorption, intense green light emission (518 nm), and excellent stability attributed to the complexation effect between the nanocellulose and PQDs. The PQD paper is combined with red K2SiF6:Mn4+ phosphor and blue GaN LED chips to fabricate a high-performance white LED demonstrating ultrahigh luminous efficiency (124 lm W?1), wide color gamut (123% of National Television System Committee), and long operation lifetime (240 h), which paves the way for advanced lighting technology.
关键词： light-emitting diodes,stability,paper,quantum dots,perovskites
更新于2025-09-11 14:15:04
-
Dot size variability induced changes in the optical absorption spectra of interdiffused quantum dot systems
摘要： In this work, we have quantified the effects of dot size variability on the interband optical absorption spectra of interdiffused III–V quantum dot (QD) systems through analytical models which agree well with experimental data. The variability function induced due to inhomogeneous nature of dot size distribution has been considered to be Gaussian in nature, where individual dots have been assumed to be lens-shaped having inhomogeneous material composition inside the dot. This is necessary to consider any realistic interdiffused system. Such an assumption is not in line-up with the conventional methodologies reported earlier on the subject, where the QD composition was considered to be homogeneous, presenting an ideal or quasi-ideal situation which may be applicable only for dot structures in absence of interdiffusion. Moreover, for the first time, the effects of dot size variability and interdiffusion on the optical spectra of QD systems have been analysed in the same platform. The effects of dot size deviation, QD aspect ratio, core group III content inside the dot, standard deviation, and so on, on the optical absorption spectra have been demonstrated.
关键词： Dot size variability,III–V semiconductors,Optical absorption spectra,Interdiffusion,Quantum dots
更新于2025-09-11 14:15:04
-
A novel approach to coat silica on quantum dots: Forcing decomposition of tetraethyl orthosilicate in toluene at high temperature
摘要： The coating of silica (SiO2) on quantum dots (QDs) has been widely studied, because SiO2 can protect QDs from the damages of moisture, radiation, and heat. Conventional SiO2 coating methods for QDs are usually performed in aqueous or emulsion solutions, which require the addition of water for the hydrolysis of SiO2 precursors and lead to the photoluminescence (PL) quenching of QDs. To address this issue, a novel SiO2 coating approach on single particle level was developed by the thermally forcing decomposition of tetraethyl orthosilicate in toluene. The CdSe/CdS/ZnS:Al@SiO2 nanoparticles (NPs) were prepared without decreasing the original PL quantum yield (QY), which exhibited much better photo and thermal stability in comparison with uncoated CdSe/CdS/ZnS:Al QDs. Furthermore, due to the natural formation of silanol groups on the SiO2 shell, CdSe/CdS/ZnS:Al@SiO2 NPs present not only good solubility but also excellent room temperature stability in phosphate buffer saline solution for several months.
关键词： SiO2,TEOS,stability,core/shell quantum dots,water solubility
更新于2025-09-11 14:15:04
-
The optical behavior of multi-emission quantum dots based on Tb-doped ZnS developed via solvothermal route
摘要： Quantum dots (QDs), semiconducting nanocrystals with exceptional photo-physical characteristics, have become one of the prevailing class of multifunctional nanodevices and imaging probes. The engineering of QD probes became an essential step for successful clinical applications in real-life. In this work, a water soluble and highly luminescent semiconducting QDs are developed via solvothermal route. Terbium was used as a dopant to replace the Zn in the ZnS nanocrystals. Various concentrations of Tb, from 0 to 6 at.%, was doped into the ZnS. The influence of Tb dopant on the crystal structure of the ZnS and diameter of the formed nanocrystals was investigated using X-ray diffraction and transmission electron microscopy. The optical properties were studied using the UV-Vis spectrophotometer, which showed a red shift of the optical band gap. The luminescence properties showed that the doping of ZnS with 6at.% of Tb ions resulted in a remarkable enhancement of the luminescence intensity and the quantum yield. This sample showed three distinctive light emissions (blue, green and red) when excited at 320 nm, 360 nm and 390 nm. The obtained results embarked that the developed QDs may be employed as efficient bio-imaging probe for practical clinical applications in real-life, which is confirmed in this article for the first time.
关键词： Bioimaging,Quantum dots,Structure,Luminescence,ZnS
更新于2025-09-11 14:15:04
-
Effect of doping mechanism on photogenerated carriers behavior in Cu-doped ZnSe/ZnS/L-Cys core-shell quantum dots
摘要： Cu-doped ZnSe/ZnS/L-Cys core–shell QDs are prepared by both nucleation doping and growth doping in an aqueous synthesis method. Transport of photogenerated free charge carriers (FCCs) in these Cu-doped QDs is probed via a combination of surface photovoltaic (SPV), photoacoustic (PA), and electric-field-induced SPV techniques, supplemented by the UV–VIS absorption spectrum and Raman spectrum. The results confirm that the two doping mechanisms result in different doping locations and microelectronic structures of the Cu-doped QDs. The distinctive microelectronic structure of the QDs prepared by nucleation doping, as compared with those prepared by growth doping, results in a number of favorable SPV characteristics. For example, the QDs prepared by nucleation doping exhibit a higher SPV response intensity at 600 nm because of a higher concentration of photogenerated FCCs. The ratio of the strongest SPV response and the strongest PA signal of the QDs prepared by nucleation doping is up to 2.41 times greater than those of the QDs prepared by growth doping. This is because the greater numbers of photogenerated FCCs in the QDs prepared by nucleation doping generate the PV effect rather than the PA effect that is caused by a nonradiative de-excitation process. The position of the shoulder peak of the SPV response at a long wavelength of the QDs prepared by nucleation doping is significantly red-shifted compared with that of the QDs prepared by growth doping, leading to a broader SPV response range in the visible region. The QDs prepared by nucleation doping have a more obvious donor feature than those prepared by growth doping.
关键词： photogenerated carriers,Cu-doped ZnSe/ZnS/L-Cys,quantum dots,photoacoustic,surface photovoltaic,nucleation doping,growth doping
更新于2025-09-11 14:15:04
-
Compact quantum dot surface modification to enable emergent behaviors in quantum dot-DNA composites
摘要： Quantum dot (QD) biological imaging and sensing applications often require surface modification with single-stranded deoxyribonucleic acid (ssDNA) oligonucleotides. Furthermore, ssDNA conjugation can be leveraged for precision QD templating via higher-order DNA nanostructures to exploit emergent behaviors in photonic applications. Use of ssDNA-QDs across these platforms requires compact, controlled conjugation that engenders QD stability over a wide pH range and in solutions of high ionic strength. However, current ssDNA-QD conjugation approaches suffer from limitations, such as the requirement for thick coatings, low control over ssDNA labeling density, requirement of large amounts of ssDNA, or low colloidal or photostability, restraining implementation in many applications. Here, we combine thin, multidentate, phytochelatin-3 (PC3) QD passivation techniques with strain-promoted copper-free alkyne-azide click chemistry to yield functional ssDNA-QDs with high stability. This process was broadly applicable across QD sizes (i.e., λem = 540, 560, 600 nm), ssDNA lengths (i.e., 10–16 base pairs, bps), and sequences (poly thymine, mixed bps). The resulting compact ssDNA-QDs displayed a fluorescence quenching efficiency of up to 89% by hybridization with complementary ssDNA-AuNPs. Furthermore, ssDNA-QDs were successfully incorporated with higher-order DNA origami nanostructure templates. Thus, this approach, combining PC3 passivation with click chemistry, generates ssDNA-PC3-QDs that enable emergent QD properties in DNA-based devices and applications.
关键词： ssDNA,click chemistry,DNA origami,quantum dots,fluorescence quenching
更新于2025-09-11 14:15:04