Nanotechnology最新文献

All-inorganic metal halide perovskite materials exhibit high photoluminescence quantum yields (PLQYs), broad emission bands, and tunable luminescence-attributes that confer great potential for white light applications. However, reports on Cd-based perovskites for efficient white light emission remain scarce. Here, the hydrothermal synthesis of Pb²⁺/Mn²⁺co-doped Rb₃Cd₂Cl₇ perovskite crystals, in which the substitutions of Cd²⁺by Pb²⁺or Mn²⁺form the luminescent centers of [PbCl₆]⁴^-and [MnCl₆]⁴^-for white emission, is reported. Doping with Pb²⁺enables a deep-blue emission at 443 nm with anti-thermal quenching and a maximum PLQY of 58.58%, attributed to the formation of confined exciton around [PbCl₆]⁴^-. Concurrently, Mn²⁺ion doping induces energy transfer toward intrinsic self-trapped exciton (STE) states to [MnCl₆]⁴^-, yielding intense yellow emission at 588 nm with a maximum PLQY of 137.79%. This emission is attributed to the intrinsic Cd-related STEs, combined with the generation of local exciton magnetic polarons (LEMPs) through ferromagnetic (FM) Mn²⁺-Mn²⁺interactions, via assistance of the coupling with the 245.3 cm^-1phonon mode in Rb₃Cd₂Cl₇: Mn²⁺. The co-emission of^PbCE and LEMP, from the interaction of Pb²⁺and Mn²⁺centers, achieved a PLQY of 75.4% for white light emission. The white light-emitting diodes exhibit an excellent color rendering index of 94.1, which is exceptional among recent devices compared to those based on Cd. This underscores its potential for significant applications in the optoelectronic field and offers a new alternative material for perovskite blue and white LEDs.

Recently, symmetry-broken ground states, such as correlated insulating states, magnetic order and superconductivity, have been discovered in twisted bilayer graphene (tBLG) and twisted trilayer graphene (tTLG) near the so-called magic angles. Understanding the magnetic order in these systems is challenging, however, as atomistic methods become extremely expensive near the magic angle and continuum approaches fail to capture important atomistic details. In this work, we develop an approach to incorporate short-ranged Hubbard interactions self-consistently in a continuum model. In addition, we include long-ranged Coulomb interactions, which are known to be important when doping the flat bands of tBLG and tTLG. Therefore, for the first time, magnetic order in moiré graphene multilayers is self-consistently explored in a continuum model with atomistic detail. With this approach, we perform a systematic analysis of the magnetic phase diagram of tBLG as a function of doping level and twist angle, near the magic angle. Our results are consistent with previous perturbative atomistic Hartree+U calculations. Furthermore, we investigated magnetic order of tTLG, which were found to be similar to those in tBLG. In the future, the developed continuum model can be utilized to investigate magnetic ordering tendencies from short-range exchange interactions in other moiré graphene multilayers as a function of doping, twist angle, screening environment, among other variables.

Metal halide perovskites generally present functional properties such as ferroelectricity and ferroelasticity, forming nano domains which dictate most of their physical properties. Crystalline changes in the nanoscale, including heat-induced domain rearrangements, are generally responsible for the appearance of structural defects. This is valid for bulk and surface but is especially relevant in nanomaterials, where charge traps lead to degradation in perovskites, reducing the lifetime and compromising their use in solar cells. The growth of oriented nano domains, on the other hand, does not only improve perovskite-based solar cells efficiency and lifetime, but can be potentially used to tailor conductivity and optical emission, opening new possibilities for applications in optoelectronic devices. Studying phase transitions, defect formation and nano domain dynamics in perovskites is challenging, requiring techniques capable of probing crystals with high strain sensitivity and good spatial resolution. In situ and operando experiments, for instance, are difficult to perform using traditional techniques which require severe sample preparation. Recent developments in synchrotron x-ray sources, with the emergence of instruments able to offer small x-ray beams with improved photon flux and coherence, can bring new insights into the field. This review focuses on x-ray methods for the study of perovskite basic properties, enlightening possible multi-technique experiments which are currently available in large scale facilities.

This paper presents a wafer-scale NiO (a prototype Mott material)/ferroelectric heterostructure termed as ferroelectric Mott (FeMott), which is capable of room-temperature operations as a gate tunable electrical switch, in deep contrast with several existing Mott transistors that operate at around 70°C and are based on VO₂, which is the most widely used Mott material. Here, FeMott devices made using NiO illustrate a reversible insulator-metal transition (IMT), which was first investigated by Mott and referred as the first known Mott material. We show that integrating NiO with an yttrium-doped HfO₂(HfYO) ferroelectric layer enables electrical switching through an electrically induced IMT. This switching mechanism is attributed to the electronic interactions between NiO and HfYO, which possess a significant remanent polarization of 80μC cm^-2and a coercive electric field of 2.7 MV cm^-1at room temperature. The device exhibits a gate voltage control of the IMT starting at 1μV, resulting in a high ON/OFF ratio of five orders of magnitude.

Graphene is one of the most important carbon materials in the global trend of nanotechnology application and sustainable development. Beside liquid-phase exfoliation, solid-phase exfoliation, chemical vapour deposition and electrochemical methods, the most popular technology for large-scale production of graphene-based nanosheets is the chemical route of oxidation-reduction reactions. Chemical conversion of natural/artificial graphite into graphite oxide (GrO) requires a strong oxidation reaction, typically using manganese (VII) oxidant in improved Hummers methods, to generate numerous oxygen-containing functional groups on graphene planes in multilayer graphite structure. Ultrasonic exfoliation of hydrated multilayer GrO in water produces an aqueous dispersion of graphene oxide nanosheets (GO) for next reduction reaction, restoring conductiveπ-conjugated graphene domains in reduced GO (RGO). While green reducing agents like vitamin C and sugars are eco-friendly choices, highly alkaline solutions emerge as an efficient approach to synthesizing non-stacked RGO. Among strategies for preventing graphene restacking through hydrophobic force andπ-πinteraction, bioinspired supramolecular graphene-based materials are excellent to preserve and produce solution-processable nanostructures for a variety of applications. In this review, advancements in chemical oxidation and reduction reactions for synthesizing GO and RGO are highlighted, particularly mechanism of cascade design oxidation process using manganese (VII) oxidant, mechanism of GO reduction reaction using highly alkaline solutions, and the reversible self-assembly of graphene-based materials. Moreover, the review summarizes the conceptualization, density functional theory calculation and experimental syntheses of supramolecular hydration structures of graphene-based hydrogels, including multifunctional applications in aqueous dispersions, water purification, photocatalysis, biosensing, antibacterial hydrogels, polymer nanocomposites, nanostructured coatings and energy devices.

Ferroelectric field-effect transistors (FeFETs), a type of ferroelectric memory with a transistorbased structure, have attracted significant attention from integrated circuit researchers due to their compact device architecture, non-destructive readout capability, and elimination of additional selector devices. These advantages make FeFETs highly promising for achieving higher storage density and enabling computing-in-memory applications. For their practical industrial deployment, extensive studies have been conducted on device fabrication, circuit design, and reliability. Among the key challenges, enlarging the memory window (MW) while maintaining stability is critical, as it directly affects data accuracy and retention. In this work, we experimentally investigate the modulation of the memory window (MW) and interface defect density (N it ) in Zr-doped HfO 2 (HfZrO x )-based FeFETs under different polarization states of the ferroelectric gate dielectric. The results demonstrate that with progressively enhanced ferroelectric polarization, the MW expands, while the interface trap density is simultaneously suppressed, suggesting that robust polarization effectively inhibits the formation of interface defects and improves subthreshold swing characteristics of the device. Furthermore, TCAD simulations were conducted to systematically investigate the impact of various ferroelectric properties, including remanent polarization (P r ), saturation polarization (P s ) and variations in coercive field (E c ), on the memory characteristics of HfZrO x FeFETs. It was confirmed that higher polarization can alleviate the degradation caused by defects. In addition, an increase in P r and P s , together with a lower E c , enhances the surface potential difference, charge separation, and switching efficiency, thereby improving both the MW and the stability of the device. This study provides valuable insights for the development of reliable FeFET-based memory technologies.

As nanoscale luminescent semiconductors with wide-range access to many precursors, carbon dots (CDs) represent an extremely biofriendly structure with easy and low-cost preparation methods. In the meantime, antibiotic resistance is a global challenge that needs utmost attention for health. In the current study, luminescent CDs were prepared using the solvothermal treatment ofcitrus tangerinepeel-extract. With a bluish excitation-dependent emission, the amorphous CDs include C, O, Ca, and K elements. Biomass-based CDs showed reliable antimicrobial activity against various gram-positive and -negative bacteria. The antibacterial effects of CDs were evaluated and compared with some antibiotics that are routinely used for treatment of infection caused by these bacteria. Our results showed that the antibacterial effects of CDs were more effective than amikacin, gentamycin and ceftazidime in most of the bacterial cultures. It revealed somehow identical properties to that of imipenem, while a little bit worse bactericidal activity compared to ciprofloxacin and cefixime was obtained. In conclusion, the prepared CDs can be an effective alternative for antibiotics, although their side effects in the body have to be investigated.

In recent decades, significant progress has been made in the development of quantum dots (QDs) as sensing materials in advanced sensor technology. This review discusses the brief history, significance, and advancements of QD-based gas sensors. Additionally, it emphasizes the integration of artificial intelligence (AI) and nanotechnology to enhance sensing performance. These advancements have resulted in improved selectivity, sensitivity, and overall performance. However, challenges such as reproducibility and environmental stability persist, requiring further investigation. Emerging innovations are actively addressing these limitations that aims for the wider implementation of QD-based gas sensors. Given their transformative potential, these materials could play a crucial role in industrial safety, medical diagnostics, and environmental monitoring.

Extracellular vesicles (EVs) are membrane bound nanoscale particles released by cells that contain molecular cargo reflective of their parental cell and can be found in many biofluids. The overexpression of EVs and EV-related protein markers has been linked to various diseased states, making them a promising tool for liquid biopsy-based disease diagnostics. Many complex diseases, like cancer, impact multiple markers simultaneously, and during early stages, are present at low concentrations. Current EV analysis technology is limited in sensitivity, multiplexing, and ease of use. We have developed a silver nanoparticle embedded membrane (sNEM) platform that utilizes the 3D structure of nitrocellulose membrane, metal-enhanced fluorescence (MEF)-based detection and a novel wax-based compartmentalization technique for highly sensitive multiplex EV protein detection from minimal sample volume. We compared various nanoparticle shapes, sizes, and metal types with fluorophores of different wavelengths to determine which provided optimal MEF-based detection with high sensitivity. Fluorescence intensity from FITC was much lower than that from Cy5 and was found to pronounce the effects of autofluorescence by 2 times. After selecting 30 nm silver nanoparticles at a concentration of 10⁹particles ml^-1and the Cy5 fluorophore based on greatest fluorescence enhancement, we then demonstrated its application for multiplexed detection of surface and intravesicular proteins directly from lysed EVs in both buffer and human plasma. In PBS, detection limits of 2-3 orders of magnitude lower than traditional ELISA were achieved. Directly from human plasma, detection limits of 1.97 × 10⁵EVs ml^-1, 1.94 × 10⁶EVs ml^-1, and 2.17 × 10⁴EVs ml^-1for TGF-β1, AKT1, and TSG101 were achieved. These results demonstrate the suitability of sNEM for highly sensitive, multiplexed detection of EV markers from complex biofluids for early diagnostics while offering advantages such as low reagent/sample consumption, scalability, reduced sample preparation, and ease of use.

Leishmaniasis, a vector-borne disease transmitted by phlebotomine sandflies and caused by protozoa of the genus Leishmania, constitutes a significant public health challenge, with approximately one million new cases reported annually. Current therapeutic options are constrained by issues related to toxicity, suboptimal efficacy, and elevated costs. This study details the formulation, lyophilization, physicochemical characterization, and in vitro assessment of poly(lactic acid) (PLA) nanoparticles encapsulating SB-83, a novel antileishmanial compound, with the aim of enhancing its therapeutic profile. The nanoparticles were prepared via the nanoprecipitation method, yielding spherical particles with mean diameters ranging from 146,4 to 239 nm. The lyophilization process was capable to obtain NPs with excellent stability and particle recovery and shows influence in SB-83 delivery. Encapsulation efficiency varied between 65% and 86%, contingent upon the specific preparation method. A sustained release of SB-83 from the nanoparticles was observed over a period of up to 96 hours. In vitro analyses confirmed the efficacy of SB-83-loaded nanoparticles against both promastigote and amastigote forms of Leishmania (L.) amazonensis, demonstrating a substantial increase in the selectivity index to 50% and a reduction in cytotoxicity toward macrophages by more than 85%. Collectively, these findings indicate that PLA nanoparticles loaded with SB-83 offer a promising drug delivery platform for the treatment of leishmaniasis, providing prolonged release, enhanced efficacy and selectivity against the parasite, and decreased adverse effects. These results underscore the potential of nanoparticle-based systems as innovative and effective therapeutic strategies for leishmaniasis.