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Wavelength-dependent surface plasmon coupling electrochemiluminescence biosensor based on sulfur doped carbon nitride quantum dots for K-RAS gene detection
摘要： Although graphite phase carbon nitride quantum dots (GCN QDs) showed some advantages in the electrochemiluminescence (ECL) analytical research, the low ECL efficiency limited the potential sensing application. Herein, we synthesized sulfur doped graphite phase carbon nitride quantum dots (S-GCN QDs) to fabricate a sandwich sensor based on amplified surface plasmon coupling ECL (SPC-ECL) mode. Sulfur doping can change the surface states of QDs effectively and produced new element vacancy. As a result, the ECL efficiency of S-GCN QDs was 2.5 times over GCN QDs. Furthermore, compared with the big gap between the ECL peak of GCN QDs (620 nm) and the absorption peak of Au NPs, the doped sulfur elements in S-GCN QDs generated new ECL emission peaks at 555 nm, which was closed to the absorption peak of Au NPs at 530 nm. Due to the wavelength-dependent surface plasmon coupling effect, the ECL peak of S-GCN QDs at 555 nm had greater amplitude of enhancement in the sensing system. The proposed biosensor can quantify the K-RAS gene from 50 fM to 1 nM with a limit of detection (LOD) of 16 fM. We were the first to provide insight into the role of wavelength-dependent surface plasmon coupling in enhancing the sensitivity of ECL biosensor.
关键词： wavelength-dependent surface plasmon coupling effect,sulfur doped GCN QDs,K-RAS gene,Electrochemiluminescence
更新于2025-09-16 10:30:52
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Effective tuning of isotropic and anisotropic properties of quantum dots and rings by external fields
摘要： The combined effects of intense THz laser field, magnetic field and in-plane electric field on electronic states and intraband optical properties of single isotropic quantum dots and rings are investigated using the non-perturbative Floquet theory in the high-frequency limit. Here we show that the change of the electric field direction for fixed values of intense THz laser field parameter can recover the degeneracy of the excited states and the dipole-allowed transition intensities in a quantum dot. Additionally, it is shown that in isotropic quantum rings the intense THz laser and the in-plane electric field create unusual Aharonov-Bohm oscillations. For fixed values of the intense THz laser field parameter, the amplitudes of Aharonov-Bohm oscillations can be effectively tuned by changing the electric field direction. Furthermore, for fixed values of the electric field strength and the laser field parameter the intraband optical properties can be effectively tuned by changing the electric field direction. Therefore, it can be asserted that circular quantum dots or circular rings in the intense THz laser field are equivalent to anisotropic quantum dots or rings respectively, and the electric field direction effectively tunes the single-electron energy spectrum and intraband optical properties of these structures.
关键词： External electric and magnetic fields,Isotropic and unisotropic properties of QDs and QRs,Intraband optical properties of QDs and QRs,Intense THz laser field
更新于2025-09-12 10:27:22
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Tuning the optical properties of CdSe quantum dot using graphene nanocomposite
摘要： Graphene semiconductor quantum dots (G-QDs) nanocomposites have attracted a lot of scienti?c interest. They have promising properties which allow them to be a good choice for photoelectric devices. G-QDs nanocomposites are prepared chemically by thermal decomposition of organometallic complex. Synthesis procedures were performed in the absence and presence of graphene in order to study its in?uence on the optical properties of the quantum dots (QDs) precisely. Various experimental techniques were utilized to study the morphology, crystal structure and the optical properties of the as-prepared materials using X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and UV/visible spectrophotometer. This paper will discuss the coupling between graphene and QDs showing the quenching of QDs emission, slowing rate of particle growth, increasing stock shift and enhancing the particle size distribution.
关键词： Semiconductor quantum dots,QDs emission,G-QDs nanocomposites
更新于2025-09-12 10:27:22
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Cost-Effective and Semi-Transparent PbS Quantum Dot Solar Cells Using Copper Electrodes
摘要： PbS quantum dots (QDs) have gained significant attention as promising solution-based materials for third generation of photovoltaic (PV) devices thanks to their size-tunable bandgap, air stability and low-cost solution processing. Gold (Au), despite its high cost, is the standard electrode in the conventional PbS QDs PV architecture due to its perfect alignment with valence levels of PbS QDs. However, to comply with manufacturing requirements for scalable device processing, alternative cost-effective electrodes are urgently required. Here, we employed interface engineering approach and deposited poly(3-hexylthiophene-2,5-diyl) (P3HT) as a hole transport layer on 1,2-Ethanedithiol (EDT)-capped PbS QDs in order to adjust the valence band of QDs with the work function of inexpensive copper (Cu) electrode. In fact, this is the first report of Au-free PbS QDs PV system employing the conventional device structure. Our Cu-based device shows a maximum power conversion efficiency (PCE) of 8.7% which is comparable with that of the Au-based device (10.2 %). Interestingly, the P3HT-based device shows improved stability with relatively 10% PCE loss after 230 h under continuous illumination. Moreover, using ultrathin Cu electrode, a semi-transparent PbS QDs PV is fabricated with a remarkably high average visible transparency (AVT) of 26% and a PCE of 7.4%.
关键词： Semi-transparent,Solar cell,Copper,Cost-effective,P3HT,PbS QDs
更新于2025-09-12 10:27:22
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Quantum-enhanced tunable spin-valley dependent excitonic second harmonic generation in molybdenum disulfide quantum dots
摘要： Developing a robust system with a strong tunable nonlinear second harmonic generation (SHG) is desirable. In this work, we calculate SHG arising from the excitonic states of monolayer molybdenum disulfide quantum dots (MoS2 QDs) with a parabolic confinement potential within massive Dirac fermion model using the density matrix formalism. We theoretically demonstrate that MoS2 QDs can exhibit a giant and tunable Spin-Valley dependent excitonic SHG, which can be tuned from 0 to ～107 pm/V and realized by biasing nanostructured gates or by position-dependent doping. Remarkably, the strength of SHG response is more than two orders of magnitude higher than that in monolayer MoS2. Furthermore, robust excitonic effects together with strong spin-valley coupling in monolayer transition metal dichalcogenides quantum dots (TMDC QDs), which are tunable depending on the strength of the quantum confinement, make them as a promising candidate for ultrathin nonlinear optical materials with large nonlinearities. We believe that this study could spark interest in the nonlinear optical properties of TMDC QDs and open up a variety of new avenues for versatile novel 2D nonlinear photonics and optoelectronic nanodevices.
关键词： second harmonic generation,spin-valley coupling,TMDC QDs,excitonic nonlinear optical properties
更新于2025-09-12 10:27:22
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Electrostatic Repulsion Controls Efficiency of Cu‐free Click‐Reaction with Azide‐Modified Semiconductor Quantum Dots
摘要： Determination of factors influencing the efficiency of conjugation of various molecules with colloidal semiconductor quantum dots (QDs) is an important step toward their biomedical application. We have utilized controlled strain promoted [3+2] azid-alkyne cycloaddition (SPAAC) as an instrument for studying the influence of charge interaction between QDs and molecules on the efficiency of their conjugation. Azide-modified polymer-encapsulated core-shell CdSe/ZnS QDs, bicyclononyne(BCN)-modified JOE dye and BCN-BHQ1(Black Hole Quencher 1)-modified oligonucleotide duplex were used as model objects for conjugation. Strong surface negative charge of carboxylic QDs was shown to suppress efficient conjugation with negatively charged dsDNA or JOE dye (2',7'-dimethoxy-4',5'-dichloro-fluorescein) molecules. Utilization of zwitter-ionic QDs with reduced surface charge allows significantly enhance the efficiency of QDs conjugation with dsDNA.
关键词： bioconjugation,QDs,click-chemistry,zeta potential,SPAAC
更新于2025-09-12 10:27:22
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Electrochemiluminescence Resonance Energy Transfer between Ru(bpy) <sub/>3</sub><sup>2+</sup> and CdZnSe@ZnSe Quantum Dots for Ovarian Cancer Biomarker Detection
摘要： Herein, an enhanced electrochemiluminescence resonance energy transfer (ECL-RET) from Ru(bpy)3 2+ to the core/shell CdZnSe@ZnSe quantum dots (CdZnSe@ZnSe QDs) was first designed for ovarian cancer biomarker analysis. The TiO2 metal-organic frameworks (TiO2 MOFs) was used as promoter because of its unique semiconductor structure and high loading ability for Ru(bpy)3 2+. Additionally, Envision complex with numerous horseradish peroxidase (HRP) was employed to immobilize CdZnSe@ZnSe QDs, the acceptor of ECL-RET, which further improved the ECL emission of CdZnSe@ZnSe QDs. Concretely, reactive oxygen species (ROS), for instance, O2 ?? and OH?, were firstly yielded due to the catalytic ability of HRP to H2O2, and then the electron from O2 ?? or hole from OH? injection into the CdZnSe@ZnSe QDs, triggering an extremely strong ECL response of CdZnSe@ZnSe QDs. On the basis of all above features, a highly effective ECL-RET biosensor was elaborately established to detect the targets in the range of 1.00×10-6?1.00×102 ng/mL with low detection limit of 3.30×10-1 fg/mL (S/N=3). This work opened up a new avenue for developing high-performance ECL-RET biosensors and demonstrated the high potential of the new biomarker in clinical ovarian cancer screening.
关键词： CdZnSe@ZnSe QDs,TiO2 MOFs,Envision complex,ECL-RET,ovarian cancer biomarker
更新于2025-09-12 10:27:22
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Detection of lead Using Thioglycolic Acid Capped ZnSe and ZnSe@ZnS core-shell Quantum Dots
摘要： Herein, we proffer a sensitive and selective sensor using ZnSe and ZnSe@ZnS quantum dots (QDs), for detection of toxic metal ions at nm level. It has been found that the TGA capped ZnSe and ZnSe@ZnS QDs were apparently sensitive to Pb2+ ions as perceptible from their fluorescence quenching measurements. However, in case of few common heavy metal ions such as Zn2+, Co2+, Fe2+, , Mg2+, Cu2+, Ni2+ and Cd2+ ions, negligible quenching compared to Pb2+ ions was noted. Hence, we have successfully detected Pb2+ ions in aqueous solutions based on the photoluminescence (PL) spectroscopy. The observed linearity range was from 10 NM to 100 nM for both Pb2+ ions. An alternative QD based sensor for the spectroscopic detection, and concentration quantification of Pb2+ ions is proposed.
关键词： Metal ions,Photoluminescence,Thioglycolic acid,Quantum dots,Core-shell QDs
更新于2025-09-12 10:27:22
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Cadmium sulfide quantum dots impact Arabidopsis thaliana physiology and morphology
摘要： The differential mechanisms of CdS QDs (Quantum Dots) and Cd ion toxicity to Arabidopsis thaliana (L.) Heynh were investigated. Plants were exposed to 40 and 60 mg L-1 for CdS QDs and 76.9 and 115.2 mg L-1 CdSO4·7H2O and toxicity was evaluated at 5, 20, 35 (T5, T20, T35) days after exposure. Oxidative stress upon exposure was evaluated by biochemical essays targeting non-enzymatic oxidative stress physiological parameters, including respiration efficiency, total chlorophylls, carotenoids, ABTS and DPPH radicals reduction, total phenolics, GSH redox state, lipid peroxidation. Total Cd in plants was measured with AAS. Root and leaf morphology and element content were assessed in vivo utilizing low-vacuum Environmental Scanning Electron Microscopy (ESEM) with X-ray microanalysis (EDX). This integrated approach allowed identification of unique nanoscale CdS QDs toxicity to the plants that was distinct from CdSO4 exposure. The analyses highlighted that CdS QDs and Cd ions effects are modulated by the developmental stage of the plant, starting from T20 till T35 the plant development was modulated by the treatments, in particular CdS QDs induced early flowering. Both treatments induced Fe accumulation in roots, but at different intensities, while CdS QDs was associated with Mn increase into plant leaf. CdSO4 elicited higher levels of oxidative stress compared with QDs, especially the former treatment caused more intense respiration damages and reduction in chlorophyll and carotenoids than the latter. The two types of treatments impact differently on root and leaf morphology.
关键词： oxidative stress,morphology,Arabidopsis thaliana,Iron,ESEM/EDX,CdS QDs
更新于2025-09-12 10:27:22
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CsPbBr3 quantum dots assisted crystallization of solution-processed perovskite films with preferential orientation for high performance perovskite solar cells
摘要： The performance of hybrid perovskite solar cells (PSCs) is significantly influenced by the crystallization and morphology of perovskite films. Herein, a novel method of CsPbBr3 quantum dots (QDs) assisted nucleation is applied to prepare high quality solution-processed methylammonium lead iodide (MAPbI3) films by employing CsPbBr3 QDs as an additive into diethyl ether anti-solvent. The appropriate amount of CsPbBr3 QDs can act as effective heterogeneous nucleation centers, leading to the formation of smooth and pinhole-free perovskite films with increased grain size. Furthermore, the growth direction of MAPbI3 grains is regulated by CsPbBr3 QDs, exhibiting preferential orientation of (110) plane. Therefore, the MAPbI3 films with CsPbBr3 QDs modification show reduced defects and increased carrier lifetime. As a result, the champion PSC with a maximum power conversion efficiency (PCE) up to 20.17% is achieved and 85% of its initial PCE is maintained after aging 1000 hours at room temperature under a relative humidity of 50%. This work demonstrates a feasible way to prepare high quality perovskite films for optoelectronic applications.
关键词： preferred orientation,heterogeneous nucleation centers,perovskite solar cells,CsPbBr3 QDs
更新于2025-09-12 10:27:22