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Zn2+ leakage and photo-induced reactive oxidative species do not explain the full toxicity of ZnO core Quantum Dots
摘要： Metal oxide nanoparticles (NPs), and among them metal oxides Quantum Dots (QDs), exhibit a multifactorial toxicity combining metal leaching, oxidative stress and possibly direct deleterious interactions, the relative contribution of each varying according to the NP composition and surface chemistry. Their wide use in public and industrial domains requires a good understanding and even a good control of their toxicity. To address this question, we engineered ZnO QDs with di?erent surface chemistries, expecting that they would exhibit di?erent photo-induced reactivities and possibly di?erent levels of interaction with biological materials. No photo-induced toxicity could be detected on whole bacterial cell toxicity assays, indicating that ROS-dependent damages, albeit real, are hidden behind a stronger source of toxicity, which was comforted by the fact that the di?erent ZnO QDs displayed the same level of cell toxicity. However, using in vitro DNA damage assays based on quantitative PCR, signi?cant photo-induced reactivity could be measured precisely, showing that di?erent NPs exhibiting similar inhibitory e?ects on whole bacteria could di?er dramatically in terms of ROS-generated damages on biomolecules. We propose that direct interactions between NPs and bacterial cell surfaces prime over any kind of intracellular damages to explain the ZnO QDs toxicity on whole bacterial cells.
关键词： Cell surface damages,Nanotoxicity,ZnO Quantum Dots,Photo-induced reactive oxygen species,Metal oxide nanoparticles
更新于2025-09-23 15:21:01
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One-step synthesis of strongly confined, defect-free and hydroxy-terminated ZnO quantum dots
摘要： This paper reports the production of strongly con?ned ligand-free, defect-free, hydroxy-terminated ZnO quantum dots with a mean diameter of 1.9 nm, by radio frequency atmospheric pressure microplasma. Systematic characterization is performed to understand the surface chemistry of ZnO quantum dots. Photoluminescence studies show strong con?nement effect on emission with only ultraviolet (UV) emission without any defect-related visible emission. Emission is again tested after eighteen months and con?rms the QDs long-term emission stability. The mechanism responsible for this UV emission is also discussed and originates from OH-related surface terminations.
关键词： band alignment,quantum con?nement,defect-free,photoluminescence,hydroxy-terminated ZnO quantum dots
更新于2025-09-19 17:13:59
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Triple stimuli-responsive ZnO quantum dots-conjugated hollow mesoporous carbon nanoplatform for NIR-induced dual model antitumor therapy
摘要： Aiming at the inef?ciency and toxicity in traditional antitumor therapy, a novel multifunctional nanoplat-form was constructed based on hollow mesoporous carbon (HMC) to achieve triple stimuli response and dual model antitumor therapy via chemo-photothermal synergistic effect. HMC was used as an ideal nanovehicle with a high drug loading ef?ciency as well as a near-infrared (NIR) photothermal conversion agent for photothermal therapy. Acid-dissoluble, luminescent ZnO quantum dots (QDs) were used as the proper sealing agents for the mesopores of HMC, conjugated to HMC via disul?de linkage to prevent drug (doxorubicin, abbreviated as Dox) premature release from Dox/HMC-SS-ZnO. After cellular endocytosis, the Dox was released in a pH, GSH and NIR laser triple stimuli-responsive manner to realize accurate drug delivery. Moreover, the local hyperthermia effect induced by NIR irradiation could promote the drug release, enhance cell sensitivity to chemotherapeutic agents, and also directly kill cancer cells. As expected, Dox/HMC-SS-ZnO exhibited a high drug loading capacity of 43%, well response to triple stimuli and excellent photothermal conversion ef?ciency g of 29.7%. The therapeutic ef?cacy in 4T1 cells and multicellular tumor spheroids (MCTSs) demonstrated that Dox/HMC-SS-ZnO + NIR had satisfactory chemo-photothermal synergistic effect with a combination index (CI) of 0.532. The cell apoptosis rate of the combined treatment group was more than 95%. The biodistribution and pharmacodynamics studies showed its biosecurity to normal tissues and synergistic inhibition effect to tumor cells. These distinguished results indicated that the Dox/HMC-SS-ZnO nanoplatform is potential to realize ef?cient triple stimuli-responsive drug delivery and dual model chemo-photothermal synergistic antitumor therapy.
关键词： Chemo-photothermal synergistic therapy,Triple stimuli-responsive,Hollow mesoporous carbon nanoparticles,TEM-EDX mapping,ZnO quantum dots
更新于2025-09-19 17:13:59
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Photothermal amplified cathodic ZnO quantum dots/Ru(bpy)32+/S2O82- ternary system for ultrasensitive electrochemiluminescence detection of thyroglobulin
摘要： Herein, an ultrasensitive electrochemiluminescence (ECL) immunosensor based on a high performance probe of Nb2CTx MXene immobilized ZnO quantum dots (QDs) was constructed for Thyroglobulin (Tg) detection. ZnO QDs with good biocompatibility and catalytic property was for the first time utilized as coreaction accelerator in Ru(bpy)3 2+/S2O8 2- system and enhanced ECL signal. Specifically, ZnO QDs can facilitate S2O8 2- reduction to generate more SO4 ??, and then reacted with cathodic radical of Ru(bpy)3 2+, realizing 2-fold enhancement in ECL intensity. Additionally, Nb2CTx MXene possesses excellent properties and was used as prominent supporter, improving the loading capacity of Ru(bpy)3 2+ and ZnO QDs, and accelerating the electron transfer, resulting in ECL signal enhancement. Furthermore, Nb2CTx MXene acted as temperature controller and increased the electrode surface temperature by converting laser energy into heat, further amplified ECL signal. Because of the high sensitivity, good specificity and favorable stability, the proposed immunosensor realized sensitive detection of Thyroglobulin and had a great application prospect in bioanalysis and clinical diagnosis.
关键词： ZnO quantum dots,Photothermal amplification,Coreactant accelerator,Nb2CTx MXene,ECL immunosensor
更新于2025-09-19 17:13:59
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Field emission enhancement of composite structure of ZnO quantum dots and CuO nanowires by Al2O3 transition layer optimization
摘要： In this paper, ZnO quantum dots (QDs)-CuO nanowires (NWs) heterostructure was synthesized by a mild solution method. The Al2O3 transition layer were deposited on CuO NWs by surface modification engineering using atomic layer deposition (ALD) to increase the nucleation probability of ZnO QDs. The field emission properties of the composites were investigated. The results reveal that the CuO@Al2O3/ZnO QDs ternary heterostructures have the turn-on field of 2.82 V/μm and the field emission enhancement factor of 5798, which are superior to that of ZnO QDs-CuO NWs and pure CuO NWs. The improvement of field emission performance is mainly attributed to the decrease of the electron transport barrier at the interface and the increase of the oxygen vacancies, making it easier to transport electrons to ZnO QDs. The use of amorphous Al2O3 in the transition layer also effectively alleviates the lattice mismatch between ZnO QDs and the substrate. This study provides an effective method for enhancing the field emission performance of the core-shell nanomaterial device.
关键词： transition layer,field emission,composite structure,ZnO quantum dots
更新于2025-09-19 17:13:59
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[Lecture Notes in Electrical Engineering] Advances in Signal Processing and Communication Volume 526 (Select Proceedings of ICSC 2018) || Fabrication and Characterization of Photojunction Field-Effect Transistor
摘要： In this article, ZnO Quantum Dot (QD)-based photojunction ?eld-effect transistor (photo-JFET) has been fabricated for the detection of ultraviolet (UV) spectrum. The effects of photojunction between the ZnO Quantum Dots (QDs) and deep work function transparent MoO2 is analyzed under the illumination of UV. The illuminated optical power density acts as a ?oating gate for the JFET. The device was fabricated on a glass substrate using interdigitated electrodes (Ag) followed by ZnO QDs layer and MoO2. The dark current between source and drain was found minimum, 2.79 μA/cm2, in the case of photojunction as compared to the metal semiconductor metal (MSM)ZnO QDs photoconductor 19.32 μA/cm2 at an applied bias of 10 V. The reduction in dark current is attributed due to the effect of the junction formed between ZnO QDs and MoO2 with the recti?cation ratio of ~347. The MoO2 depletes the ZnO QDs channel between the electrodes and reduces the dark current which in turn helps to improved photodetector characteristics.
关键词： Schottky junction,Photo-JFET,ZnO quantum dots
更新于2025-09-10 09:29:36
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Blue Luminescent ZnO Nanoclusters Stabilized by Esterifiable Polyamidoamine Dendrimers and their UV-Shielding Applications
摘要： Zinc oxide quantum dots (QDs) were added to the water solutions of esterifiable polyamidoamine (PAMAMs) and the ZnO nanoclusters were prepared. The ZnO nanoclusters are stable in water and show bright blue fluorescence under UV lamp. TEM images showed that the ZnO nanoclusters consisted of numerous ZnO QDs. FTIR spectra of ZnO nanoclusters demonstrated the successful modification of ZnO QDs by the esterifiable polyamidoamine dendrimers. The UV-visible absorption spectra indicated that the ZnO nanoclusters exhibited wider and red-shifted comparing with ZnO QDs. The fluorescent spectra showed that the emission peaks at 404 nm of the ZnO QDs became weaker and a new emission peaks appeared at 330 nm after modifying the ZnO QDs with polyamidoamine dendrimers. The UV-visible transmittance spectra showed that the poly(vinyl alcohol)/ZnO nanoclusters film absorbed nearly 99 % of UV light at wavelengths between 200 and 240 nm while 75 % between 240 and 300 nm.
关键词： Poly(vinyl alcohol),Nanoclusters,ZnO quantum dots,UV-shielding,Polyamidoamine dendrimers
更新于2025-09-04 15:30:14