Search Results (2,723)

The acquisition of kinetic data in QD-based PL sensing methodologies has been revealed to be an auspicious alternative in applying these nanomaterials in analytical chemistry, enabling enhanced discrimination and quantification of analytes, even in complex sample matrices. The accessibility of kinetic measurements, which use routine laboratory instrumentation, is a significant advantage that increases the practicality of this methodology. The simple acquisition of these kinds of second-order data combined with chemometric analysis can ensure accurate results in environmental, biomedical, and food monitoring applications. These developments emphasize the vital importance of kinetic approaches in increasing sensitivity, improving analyte discrimination, and making the application of QDs in complex samples possible. Full article

This study evaluates the potential of quantum dots (QDs) as a marking method for Mediterranean fruit flies (Ceratitis capitata) (Medfly) in comparison to traditional fluorescent powder. As a highly destructive pest impacting a wide variety of fruit crops, an effective marking technique is essential for improving the biological understanding and management of Medflies, including control strategies like the Sterile Insect Technique (SIT). Through multiple controlled experiments, we examined the effects of QDs and fluorescent powder markers on Medfly flight ability, marker retention rates, and marker durability and stability under diverse storage conditions. Fluorescent powder demonstrated consistently high reliability across all parameters, whereas QDs showed reduced retention, particularly when applied to pupae, and had a more pronounced negative effect on flight ability. This was illustrated by the field trials, which did not recapture any of the QD-marked flies, highlighting the current limitations in QD application methods. Additionally, fluorescent powders outperformed QDs in both long-term storage conditions and short-term stability tests. These findings indicate that while QDs possess potential as marking agents, further refinement of application techniques is required to achieve comparable efficacy to fluorescent powders in pest management contexts. Full article

Nanotechnology, particularly quantum dots (QDs), has ushered in a transformative era in the pharmaceutical and medical industries, offering notable opportunities for nanoscale advancements. These nanoscale particles, known for their exceptional optical properties and quantum confinement, have emerged as indispensable tools in cancer drug delivery and bioimaging. This review delves into various drug conjugation techniques with QDs, including covalent linking, non-covalent conjugation, click chemistry, disulfide linkage, and pH-sensitive linkage. Each method provides distinct advantages, such as enhanced stability, reversibility, specificity, and controlled drug release. Moreover, QDs have demonstrated significant promise in oncology by efficiently delivering drugs to cancerous tissues while minimising systemic toxicity. Investigations into their applications in different cancers, such as blood, brain, cervical, breast cancers, etc., reveal their efficacy in targeted drug delivery, real-time imaging, and improved therapeutic outcomes. However, challenges such as potential toxicity, stability, pharmacokinetics, and targeting specificity must be addressed to fully harness the benefits of QDs in cancer therapy. Future research should focus on developing biocompatible QDs, optimising conjugation techniques, and elucidating their safety profiles and long-term effects in biological systems. Overall, QDs represent a promising frontier in cancer treatment, offering multifaceted capabilities that hold the potential for enhanced therapeutic outcomes and reduced side effects across various cancers. Full article

Colloidal quantum dots (QDs) have emerged as promising materials for the development of infrared photodetectors owing to their tunable band gaps, cost-effective manufacturing, and ease of processing. This paper provides a comprehensive overview of the fundamental properties of quantum dots and the operating principles of various infrared detectors. We review the latest advancements in short-wave infrared (SWIR), mid-wave infrared (MWIR), and long-wave infrared (LWIR) detectors employing colloidal quantum dots. Despite their potential, these detectors face significant challenges compared to conventional infrared technologies. Current commercial applications are predominantly limited to the near-infrared and short-wave bands, with medium- and long-wave applications still under development. The focus has largely been on lead and mercury-based quantum dots, which pose environmental concerns, underscoring the need for high-performance, non-toxic materials. Looking forward, the development of large array and small pixel detectors and improving compatibility with readout circuits are critical for future progress. This paper discusses these hurdles and offers insight into potential strategies to overcome them, paving the way for next-generation infrared sensing technologies. Full article

Optical nonreciprocity and nonreciprocal devices such as optical diodes have broad and promising applications in various fields, ranging from optical communication to signal process. Here, we propose a magnet-free nonreciprocal scheme based on the four-wave mixing (FWM) effect in semiconductor quantum dots (SQDs). Via controlling the directions of the coupling fields, the probe field can achieve high transmission in the forward direction within a certain frequency range due to the FWM effect. And the transmission of the probe field in the backward direction undergoes significant reduction, as the FWM effect is absent. The calculation results show a wide nonreciprocal transmission window with isolation greater than 12 dB and insertion loss lower than 0.08 dB. The influences of the Rabi frequencies of the coupling fields, the medium length, and the decay rates on the nonreciprocal propagation of the probe field are also studied, showing the requirements of these parameters for good nonreciprocal performances. Our work may offer an insight for developing optical nonreciprocal devices based on the FWM process and the SQD system. Full article

Methyl orange (MO) is an organic synthetic dye widely used in laboratory and industrial applications. In laboratory settings, it serves as an acid–base indicator due to its distinct color change in both acidic and alkaline environments. Industrially, it is primarily utilized in the textile industry for its ultraviolet (UV) absorption properties. However, the discharge and leakage of methyl orange into the environment can cause severe ecological damage and pose potential carcinogenic and teratogenic risks to human health. Therefore, detecting and quantifying the concentration of methyl orange in various matrices is crucial. This study reports the synthesis of graphene quantum dots (GQDs) from orange peel as a precursor, using ethanol and dimethylformamide (DMF) as solvents. Cyan (c-GQDs) and yellow (y-GQDs) graphene quantum dots were synthesized through a bottom-up hydrothermal method. The difference in color is attributed to the redshift caused by the varying ratio of pyridine nitrogen to pyrrole nitrogen. These GQDs exhibited notable optical properties, with c-GQDs emitting cyan fluorescence and y-GQDs emitting yellow fluorescence under UV light. To investigate fluorescence quenching effects, nine commonly used dyes were tested, and all were found to quench the fluorescence of y-GQDs, with methyl orange having the most significant effect. The fluorescence quenching of orange peel-derived GQDs in the presence of methyl orange is attributed to poor dispersion in DMF solution. Additionally, the GQDs possess high specific surface area, abundant surface functional groups, and excellent electronic conductivity, which contribute to their effective fluorescence quenching performance. The average thickness of y-GQDs (the vertical dimension from the substrate upwards) was 3.51 nm, confirming their graphene-like structure. They emitted yellow fluorescence within the wavelength range of 450–530 nm. Notably, a significant linear correlation was found between the concentration of methyl orange and the fluorescence intensity of y-GQDs (regression coefficient = 0.9954), indicating the potential of GQDs as effective sensing materials for organic pollutant detection. Full article

Ultrafast fiber lasers have shown exceptional performance across various domains, including material processing, medical applications, and optoelectronic communication. The semiconductor saturable absorber mirror (SESAM) is a key enabler of ultrafast laser operation. However, the narrow wavelength range and limited modulation depth of conventional SESAMs pose challenges to further advancing ultrafast fiber laser technology. To address these limitations, we explored the integration of guided mode resonance (GMR) effects to enhance light–matter interaction within the absorption layer. By incorporating subwavelength dielectric film gratings onto the cap layer of SESAMs, we excited GMR and formed a microcavity structure in conjunction with the distributed Bragg mirror (DBR). This design significantly improved the absorption efficiency of InAs quantum dots. The experimental results demonstrate that the modulation depth of the SESAM increased from 6.7% to 17.3%, while the pulse width was reduced by 2.41 times. These improvements facilitated the realization of a high-quality, stable ultrafast fiber laser. This study not only broadens the application potential of ultrafast lasers in diverse fields but also offers a practical pathway for advancing SESAM technology toward industrial-scale deployment. Full article

In this paper, we demonstrate a broadband and simultaneous waveguide array light source based on water-soluble CdSe/ZnS quantum dots (QDs). We initially measure the fluorescence intensity for various cladding solution concentrations along the fiber axis to assess their impact on the propagation loss; the experimental results show that the fluorescent intensity decreases with fiber length, with higher concentrations showing a more pronounced decrease. Then, we showcase a synchronous QD light source in an optofluidic chip that fluoresces in red, green, and blue (RGB) within a microfluidic channel. Finally, a 3 × 3 QD array of a fluorescent display on a single PDMS chip is demonstrated. The QD waveguide represents a compact and stable structure that is readily manufacturable, making it an ideal light source for advancing high-throughput biochemical sensing and on-chip spectroscopic analysis. Full article

Cancer is a global health concern. Various therapeutic approaches, including chemotherapy, photodynamic therapy, and immunotherapy, have been developed for cancer treatment. Silica nanoparticles, quantum dots, and metal–organic framework (MOF)-based nanomedicines have gained interest in cancer therapy because of their selective accumulation in tumors via the enhanced permeability and retention (EPR) effect. However, bare nanoparticles face challenges including poor biocompatibility, low stability, limited drug-loading capacity, and rapid clearance by the reticuloendothelial system (RES). Gels with unique three-dimensional network structures formed through various interactions such as covalent and hydrogen bonds are emerging as promising materials for addressing these challenges. Gel hybridization enhances biocompatibility, facilitates controlled drug release, and confers cancer-targeting abilities to nanoparticles. This review discusses gel–nanoparticle hybrid systems for cancer treatment developed in the past five years and analyzes the roles of gels in these systems. Full article

To develop a highly efficient and environmentally friendly flame-retardant system, ionic liquids (ILs) have recently emerged as promising candidates. However, the addition of ILs into emulsion paint disrupts emulsion stability, leading to rapid demulsification due to electrostatic effects. Herein, IL–silica capsules were developed using a soft-template method. These capsules can be directly added to an acrylic emulsion paint system as flame-retardant additives. Incorporating 5 wt% IL–silica capsules into the system and coating it on fabric reduced flammability by 53% compared to untreated fabric. This work provides a novel and practical approach to enhance flame retardancy in emulsion paint systems without compromising their stability. Full article

We propose a simple and innovative configuration consisting of a quantum dot and micro-optical resonator that emits single photons with good directionality in a plane parallel to the substrate. In this device, a single quantum dot is placed as a light source between the slits of a triangular split-ring micro-optical resonator (SRR) supported in an optical polymer film with an air-bridge structure. Although most of the previous single photon emitters in solid-state devices emitted photons upward from the substrate, operation simulations confirmed that this configuration realizes lateral light emission in narrow regions above, below, left, and right in the optical polymer film, despite the absence of a light confinement structure such as an optical waveguide. This device can be fabricated using silica-coated colloidal quantum dots, focused ion beam (FIB) lithography, and wet etching using an oxide layer on a silicon substrate as a sacrificial layer. The device has a large tolerance to the variation in the position of the SRR in the optical polymer film and the height of the air-bridge. We confirmed that Pt-SRRs can be formed on the optical polymer film using FIB lithography. This simple lateral photon emitter is suitable for coupling with optical fibers and for fabricating planar optical quantum solid-state circuits, and is useful for the development of quantum information processing technology. Full article

This study investigates the synthesis and photoluminescent properties of carbon quantum dots (CQDs) derived from Actinidia deliciosa using the hydrothermal method. The effect of concentration and pH on the composition, structure, and optical properties of CQDs was analyzed using characterization techniques such as TEM, EDS, FTIR, UV-Vis, and photoluminescence (PL) spectroscopy. The CQDs exhibited particle sizes ranging from 1 to 10 nm, with a graphitic structure and oxygen-containing functional groups, as identified by FTIR bands corresponding to OH, C=O, and C=C. The stability analysis revealed particle agglomeration over 30 days, increasing the size up to <40 nm. Regarding the optical properties, the CQDs displayed absorption peaks at 225 and 280 nm and a bandgap of ~3.78–3.82 eV. The PL characterization demonstrated tunable emission from violet to green, depending on the excitation wavelength. CQDs synthesized at an acidic pH of 2 exhibited enhanced luminescence due to protonation effects, whereas an alkaline pH led to a reduction in emission intensity. The hydrothermal method enabled a simple and eco-friendly synthesis, using water as the sole solvent, yielding stable CQDs with a luminescence lifespan exceeding 30 days. Their optical and electronic properties make them promising candidates for photocatalysis, heavy metal detection, and bioimaging applications. Full article

Recently, the numerical simulation of solar cells has attracted tantamount scientific attention in the photovoltaic community because it saves on research time and resources before the actual fabrication of the devices in the laboratories. Despite significant advancements in the fabrication of quantum dot-sensitized solar cells (QDSSCs), the power conversion efficiency (PCE) is still low when compared to other solar cells such as perovskite. This efficiency gap poses a substantial challenge in harnessing the full potential of QDSSCs for widespread adoption in renewable energy applications. Enhancing the efficiency of QDSSCs is imperative for their commercial viability and widespread deployment. In this work, SCAPS-1D was used in the simulation of QDSSCs. The solar cell with a general configuration of FTO/TiO₂/PbS/HTL/Au was investigated. In the device, PbS quantum dots were inserted as the absorber layer, TiO₂ as the electron transport layer (ETL), gold as the back contact, and the following inorganic materials, i.e., copper (I) iodide (CuI), copper (I) oxide (Cu₂O), cadmium zinc telluride selenide (CZTSe), copper iron tin sulfide (CFTS), and copper zinc tin sulfide selenide (CZTSSe) were tested as HTL materials, and FTO acted as the conductive substrate. The best HTL material (CZTSSe) exhibited a PCE of 22.61%, with a fill factor (FF) of 84.67%, an open circuit voltage (V_oc) of 0.753 V, and a current density (J_sc) of 35.48 mA cm⁻². This study contributes to the field by employing SCAPS-1D simulations to optimize QDSSCs, exploring novel inorganic HTL materials for these solar cells and identifying CZTSSe as a promising low-cost HTL that significantly enhances both the performance and commercial viability of QDSSCs. Full article

The controlled functionalization of graphene is critical for tuning and enhancing its properties, thereby expanding its potential applications. Covalent functionalization offers a deeper tuning of the geometric and electronic structure of graphene compared to non-covalent methods; however, the existing techniques involve side reactions and spatially uncontrolled functionalization, pushing research toward more selective and controlled methods. A promising approach is 1,3-dipolar cycloaddition, successfully utilized with carbon nanotubes. In the present work, this method has been extended to graphene flakes with low defect concentration. A key innovation is the use of a custom-synthesized ylide with a protected amine group (Boc), facilitating subsequent attachment of functional molecules. Indeed, after Boc cleavage, fluorescent dyes (Atto 425, 465, and 633) were covalently linked via NHS ester derivatization. This approach represents a highly selective method of minimizing structural damage. Successful functionalization was demonstrated by Raman spectroscopy, photoluminescence spectroscopy, and confocal microscopy, confirming the effectiveness of the method. This novel approach offers a versatile platform, enabling its use in biological imaging, sensing, and advanced nanodevices. The method paves the way for the development of sensors and devices capable of anchoring a wide range of molecules, including quantum dots and nanoparticles. Therefore, it represents a significant advancement in graphene-based technologies. Full article

Quantum dot light-emitting diodes (QLEDs) based on high-color-purity blue quantum dots (QDs) are crucial for the development of next-generation displays. I-III-VI type QDs have been recognized as eco-friendly luminescent materials for QLED applications due to their tunable band gap and high-stable properties. However, efficient blue-emitting I-III-VI QDs remain rare owing to the high densities of the intrinsic defects and the surface defects. Herein, narrow-band blue-emissive CuAlSe₂/Ga₂S₃/ZnS QDs is synthesized via a facile strategy. The resulting QDs exhibit a sharp blue emission peak at 450 nm with a full width at half maximum (FWHM) of 35 nm, achieved by coating a double-shell structure of Ga₂S₃ and ZnS, which is associated with the near-complete passivation of Cu-related defects (e.g., Cu vacancies) that enhances the band-edge emission, accompanied by an improvment in photoluminescence quantum yield up to 69%. QLEDs based on CuAlSe₂/Ga₂S₃/ZnS QDs are fabricated, exhibiting an electroluminescence peak at 453 nm with a FWHM of 39 nm, a current efficiency of 3.16 cd A⁻¹, and an external quantum efficiency of 0.35%. This research paves the way for the development of high-efficiency eco-friendly blue QLEDs. Full article