Search Results (194)

Decentralized diagnostics is undergoing a transformative shift from qualitative screening to high-precision quantification, driven by the clinical demand for rapid, point-of-care (POC) syndromic triage. Multiplexed lateral flow immunoassays (mLFIAs) serve as the foundational platform for this transition. However, their performance is limited by systemic factors such as fluidic lag, conjugate depletion, and spectral crosstalk. This review evaluates recent advances in engineered nanomaterials and artificial intelligence (AI)-driven detection as the dual pillars of next-generation multiplexing. The review covers different types of nanomaterial reporters—such as multicolor quantum dots, surface-enhanced Raman scattering nanotags, upconversion nanoparticles, surface-modified magnetic nanoparticles, and fluorescent nanodiamonds—that help address analytical challenges in lateral flow assays. We then discuss AI and machine learning methods, including convolutional neural networks, support vector machines, random forests, and transfer learning, that convert raw multi-channel signals into useful clinical data. Finally, we highlight the main challenges that still need to be addressed before these platforms can become WHO-ASSURED-compliant POC devices. The combination of engineered nanomaterial reporters and computational intelligence is transforming lateral flow assays into quantitative tools that can provide lab-quality clinical information at the POC. Full article

A dual-mode electrical–optical nanocomposite hydrogel is developed by integrating carboxyl-modified upconversion nanoparticles (UCNPs-COOH) and quaternized chitosan (CQAS) into a polyacrylamide (PAAm) covalent network. The hydrogel exhibits high optical transparency (>90% in the visible region), excellent mechanical properties (fracture strain of 1742%, tensile strength of 0.85 MPa, toughness of 6.57 MJ/m³), and robust adhesion to various substrates. The synergistic covalent–noncovalent hybrid network enables efficient energy dissipation, while CQAS-enhanced dispersion of UCNPs significantly improves upconversion luminescence intensity and stability, as evidenced by prolonged fluorescence lifetime from 0.564 ms to 0.691 ms at 539 nm. Leveraging distinct electrical and optical signal transduction pathways, the hydrogel functions as a highly sensitive resistive strain sensor with multistage gauge factors up to 13.85 and excellent cyclic stability over 1200 loading–unloading cycles at 100% strain for human motion monitoring. It also serves as a ratiometric optical pH sensor over a broad range (pH 1–13) based on phenolphthalein-sensitized upconversion luminescence, with excellent repeatability. By integrating real-time resistance responses with optical readouts within a single soft material, this work demonstrates a reliable dual-mode sensing strategy for simultaneous mechanical and chemical monitoring, holding promise for wearable electronics, smart healthcare, and environment-responsive sensing systems. Full article

Rare earth elements (REEs), located in the IIIB group of the periodic table, can be detected in very small quantities by sensitive detection techniques. REE labeling technologies utilize fluorescent labeling, magnetic labeling, atomic fluorescence labeling, fluorescence resonance energy transfer (FRET) labeling and radiolabeling. Widely used immunoassays related to REE-labeled technologies include time-resolved fluorescence immunofluorescence assay (TRFIA), inductively coupled plasma–mass spectrometry (ICP–MS)-based immunoassays, mass spectrometry flow-through (CyTOF), and upconversion nanoparticles (UCNPs). REE-labeled immunoassays have been widely used in various fields, such as biological analysis, biomarker detection and analysis of food detection techniques, as these assays can use low quantities of biological tissue, exhibit stability, can label materials, lack radioactivity and show multidetection capability. To provide researchers with a deeper understanding of the immunoassay technique used to label rare earth elements, this paper reviews its labeling principle, detection technology, and application. Full article

Upconverting nanoparticles, which transform low-energy infrared radiation into high-energy visible or UV light, show great potential in today’s technology. High-quality upconversion colloid (UCC) consisting of lanthanide-based nanoparticles with a diameter of ~10 nm was obtained using a combination of two processes: high-temperature coprecipitation and hydrothermal treatment in an autoclave. The UCC was then PEGylated with PEG-alendronate (PEG-Ale) to facilitate its dispersion in aqueous cell culture media intended for in vitro cell uptake assays. The surface modification of the nanoparticles increased both the colloidal stability in water and the upconversion emission by mitigating surface quenching. UCC@Ale-PEG was characterized by transmission and scanning electron microscopy, dynamic light scattering, and fluorescence microscopy detecting upconversion photoluminescence emission. The results of an in vitro assay revealed that this new generation of UCC can be internalized by various cell types, including epithelial cells and macrophages, upon several hours of exposure, suggesting broad application potential of this type of UCC in biomedicine, bioengineering, and environmental sciences. Full article

Plasmonic nanostructures have been widely employed to improve upconversion luminescence performance; however, their impact on excitation pathways under multi-wavelength excitation is not yet fully understood. In this work, we constructed hybrid systems composed of gold nanorod arrays and NaYF₄:Yb³⁺/Ln³⁺ (Ln = Er³⁺, Tm³⁺) upconversion nanoparticles to systematically investigate upconversion behavior under dual-wavelength excitation at 808 and 976 nm. Contrary to the expected synergistic enhancement, our experimental results demonstrate that dual-wavelength excitation in the plasmonic hybrid structures produces different responses of upconversion emission. Measurements dependent on excitation power, along with the analysis of emission intensity ratio, indicate that plasmonic coupling under dual-wavelength excitation significantly enhances dissipative pathways that compete with upconversion processes. Notably, these effects strongly depend on the intrinsic energy-level structure of the lanthanide ions. In the Er³⁺-doped system, excitation at 808 nm facilitates population of higher-lying excited states, but the overall upconversion gain remains limited. In contrast, in the Tm³⁺-doped system, plasmonic coupling markedly amplifies stimulated emission and cross-relaxation processes, causing rapid depletion of high-energy state populations and substantial suppression of luminescence. These findings elucidate the competition between upconversion and dissipation processes governing plasmon-assisted upconversion under dual-wavelength excitation and provide a physical foundation for manipulating upconversion luminescence using multiple wavelengths. Full article

Rare-earth-doped upconversion nanoparticles (UCNPs) exhibit upconversion luminescence upon excitation with infrared light and have been extensively utilized in the field of biosensing. In this study, a UCNPs-based biosensor with porous silicon (PSi) as the substrate was developed for the first time, enabling the detection of target DNA molecule concentration. First, a PSi substrate was prepared via electrochemical etching and subsequently functionalized to enable target DNA molecules to immobilize onto the inner walls of the PSi substrate’s pores. Then, UCNPs-labeled probe DNA molecules hybridized with the target DNA molecules, enabling indirect attachment of UCNPs to the inner walls of the PSi substrate. Subsequently, the sample surface is irradiated with a 980 nm laser. Upconversion fluorescence images of the sample, both before and after the biological reaction, are captured using an image acquisition device. Image processing software is employed to calculate the average change in grayscale values, enabling the determination of the molecular concentration of target DNA. The limit of detection (LOD) of this method for target DNA molecular concentration is 86 pM, demonstrating that it enables low-cost, highly sensitive, rapid, and convenient biological detection of target DNA molecules. Full article

Next-generation therapeutic devices will rely on an intelligent integrated system that consolidates multiple functions into a single platform. These individual chemical components exhibit diverse physicochemical properties, demonstrating multifunctional characteristics. In this review, we focus on how the distinctive properties of upconversion nanoparticles (UCNPs), achieved via refined preparation methods, unlock novel functionalities in biomedical applications. Specifically, features such as near-infrared excitation, deep-tissue penetration, low autofluorescence, and tunable multicolor emission endow UCNPs with substantial potential in fields including deep-tissue imaging, targeted drug delivery, and photodynamic therapy. This article systematically reviews recent advances in the design and functionalization of UCNPs, elucidating their role in facilitating the development of integrated diagnostic and therapeutic platforms and fostering the establishment of intelligent responsive treatment systems. Finally, we address current technical challenges—including uniformity in large-scale production, long-term biosafety, and in vivo metabolic mechanisms—and provide insights into future interdisciplinary integration, clinical translation pathways, and their potential role in personalized medicine. Full article

As the global food industry expands and consumers demand higher food safety and quality standards, high-throughput detection technology utilizing digital intelligent optical sensors has emerged as a research hotspot in food testing due to its advantages of speed, precision, and non-destructive operation. Integrating cutting-edge achievements in optics, electronics, and computer science with machine learning algorithms, this technology efficiently processes massive datasets. This paper systematically summarizes the construction principles of intelligent optical sensors and their applications in food inspection. Sensors convert light signals into electrical signals using nanomaterials such as quantum dots, metal nanoparticles, and upconversion nanoparticles, and then employ machine learning algorithms including support vector machines, random forests, and convolutional neural networks for data analysis and model optimization. This enables efficient detection of target substances like pesticide residues, heavy metals, microorganisms, and food freshness. Furthermore, the integration of multiple detection mechanisms—including spectral analysis, fluorescence imaging, and hyperspectral imaging—has significantly broadened the sensors’ application scenarios. Looking ahead, optical sensors will evolve toward multifunctional integration, miniaturization, and intelligent operation. By leveraging cloud computing and IoT technologies, they will deliver innovative solutions for comprehensive monitoring of food quality and safety across the entire supply chain. Full article

Melanoma is one of the most aggressive skin cancers and requires innovative therapeutic strategies to overcome the limitations of conventional therapies. In this work, upconversion nanoparticles coated with mesoporous silica and functionalized with folic acid (UCNP@mSiO₂-FA) were developed as a targeted nanocarrier system for the delivery of doxorubicin (DOX). The UCNPs were synthesized via thermal decomposition, coated with mesoporous silica shells, and functionalized with folic acid (FA) to enable receptor-mediated targeting. DOX was then loaded into the mesoporous silica coating by adsorption, yielding UCNP@mSiO₂-FA-DOX. The different UCNPs were characterized for size, composition, colloidal stability, and loading and release of DOX. This comprehensive physicochemical characterization confirmed a high DOX loading efficiency and a slightly increased drug release under acidic conditions, mimicking the tumour microenvironment. In vitro assays using four melanoma cell lines (A375, B16-F10, MNT-1, and SK-MEL-28) revealed an excellent biocompatibility of UCNP@mSiO₂-FA and a significantly higher cytotoxicity of UCNP@mSiO₂-FA-DOX compared to unloaded UCNPs, in a dose-dependent manner. Cell cycle analysis demonstrated G2/M phase arrest after treatment with UCNP@mSiO₂-FA-DOX, confirming its antiproliferative effect. Overall, UCNP@mSiO₂-FA-DOX represents a promising nanoplatform for targeted melanoma therapy, combining active tumour targeting and enhanced anticancer efficacy. Full article

Up-conversion nanoparticles (UCNPs) are materials that convert near-infrared (NIR) photons into ultraviolet (UV) or visible emissions. To enhance their optical properties, UCNPs are often synthesized with oxide (Y₂O₃) or fluoride (NaYF₄) support matrices, useful for energy storage applications. In this study, NaYF₄-UCNPs were synthesized via coprecipitation and heat-treated at 400 °C. Then, a tetraethyl orthosilicate (TEOS) film was synthesized by the sol–gel technique at varying pH and temperatures from 25 °C to 80 °C. Characterization using scanning electron microscopy (SEM), X-ray diffraction (XRD), and confocal microscopy (CM) confirmed the up-conversion properties. These materials show promise for enhancing solar radiation density in polymer degradation. Full article

Heavy metal contamination in foodstuff poses a serious threat to food safety and human health; therefore, the development of toxic heavy metal detection methods is crucial. However, lots of these methods, based on traditional nanomaterials, have unavoidable limitations, such as high instrument cost, complicated operation procedures, or a long analysis time, which restrict their wide application in heavy metal detection. This review aims to conduct a systematic overview of major analytical methods using novel upconversion nanoparticles (UCNPs) for assessing heavy metal ions in complex food matrices in the context of food safety and show their potential application prospects when combined with big data and artificial intelligence. Due to their unique optical properties, good bio-compatibility, and tunable interfacial chemistry, UCNPs have shown significant detection advantages in the field of food heavy metal analysis. The review summarizes the progress of the application of UCNPs in heavy metal detection in food. Despite the development of new technologies such as artificial intelligence, and the continuous optimization and improvement of its own design, the wide application of UCNPs in food safety detection still has great potential for further development. Full article

Fluorescent nanoprobes operating in the NIR-II window have gained considerable attention for biomedical imaging because of their deep-tissue penetration, reduced scattering, and high spatial resolution. Their tunable optical behavior, flexible surface chemistry, and capacity for multifunctional design enable sensitive detection and targeted visualization of biological structures in vivo. This review highlights recent advances in the design and optical engineering of four widely studied NIR-II nanoprobe families: quantum dots, carbon dots, upconversion nanoparticles, and dye-doped silica nanoparticles. These materials were selected because they offer well-defined architectures, controllable emission properties, and substantial mechanistic insight supporting discussions of imaging performance and translational potential. Particular focus is placed on emerging strategies for activatable, targeted, and ratiometric probe construction. Recent efforts addressing biosafety, large-scale synthesis, optical stability, and early preclinical validation are also summarized to clarify the current progress and remaining challenges that influence clinical readiness. By outlining these developments, this review provides an updated and focused perspective on how engineered NIR-II nanoprobes are advancing toward practical use in biomedical imaging and precision diagnostics. Full article

Photodynamic therapy (PDT) is a highly selective, clinically approved, minimally invasive technique that effectively eliminates cancer cells. Its effectiveness is limited by poor light penetration into tissue and the hydrophobic nature of photosensitizers, highlighting the need for new approaches to treatment. Here, a theranostic upconversion nanoplatform, consisting of a NaYF₄:Yb,Er,Tm,Fe core and a NaHoF₄ shell codoped with Yb, Nd, Gd and Tb ions, was designed to enhance PDT outcomes by integrating multi-wavelength upconversion luminescence, T₂-weighted magnetic resonance imaging (MRI) and PDT. The synthesized core–shell upconversion nanoparticles (CS-UCNPs) were coated with new verteporfin (VP)-conjugated alendronate-terminated poly(N,N-dimethylacrylamide-co-2-aminoethyl acrylate) [Ale-P(DMA-AEA)] grafted with poly(ethylene glycol) (PEG). Under 980 nm NIR irradiation, CS-UCNP@Ale-P(DMA-AEA)-PEG-VP nanoparticles generated reactive oxygen species (ROS) due to the efficient energy transfer between CS-UCNPs and VP. In a pilot preclinical study, intratumoral administration of nanoparticle conjugates to mice, followed by exposure to NIR light, induced necrosis of pancreatic tumor and suppressed its growth. Full article

Flexible upconversion (UC) devices, owing to their unique combination of high–efficiency optical energy conversion and mechanical flexibility, have attracted increasing attention in the fields of optoelectronics, wearable devices, flexible displays, and biomedical applications. However, significant challenges remain in balancing optical performance, mechanical adaptability, long–term stability, and scalable fabrication, which limit their practical deployment. This review systematically introduces five representative upconversion mechanisms—excited–state absorption (ESA), energy transfer upconversion (ETU), energy migration upconversion (EMU), triplet–triplet annihilation upconversion (TTA–UC), and photon avalanche (PA)—highlighting their energy conversion principles, performance characteristics, and applicable scenarios. The article further delves into the flexible transition of upconversion devices, detailing not only the evolution of the luminescent layer from bulk crystals and nanoparticles to polymer composites and hybrid systems, but also the optimization of electrodes from rigid metal films to metal grids, carbon–based materials, and stretchable polymers. These developments significantly enhance the stability and reliability of flexible upconversion devices under bending, stretching, and complex mechanical deformation. Finally, emerging research directions are outlined, including multi–mechanism synergistic design, precise nanostructure engineering, interface optimization, and the construction of high–performance composite systems, emphasizing the broad potential of flexible UC devices in flexible displays, wearable health monitoring, solar energy harvesting, flexible optical communications, and biomedical photonic applications. This work provides critical insights for the design and application of high–performance flexible optoelectronic devices. Full article

In recent years, cadmium sulfide (CdS) has been widely investigated due to its excellent photocatalytic performance. However, its practical application in pollutant treatment is limited by its narrow photoresponse range and susceptibility to photocorrosion. Herein, we design a unique four-layer core–shell structure NaYF₄:Yb³⁺,Er³⁺@NaYF₄@CdS@Au (CSNPs@CdS@Au), with an inert NaYF₄ shell coating on NaYF₄:Yb³⁺,Er³⁺ (CNPs) to form NaYF₄:Yb³⁺,Er³⁺@NaYF₄ (CSNPs) and CdS depositing on CSNPs (CSNPs@CdS); Au nanoparticles are loaded on CdS (CSNPs@CdS@Au). Compared with CdS (9.81%), CSNPs (5.0%), CSNPs/CdS (6.9%), and CSNPs@CdS (81.0%), CSNPs@CdS@Au degrades 97.7% Rhodamine B (RhB) within 15 min, exhibiting superior photocatalytic performance, attributable to two key factors: (1) the NaYF₄ inert shell encapsulation amplifies upconversion (UC) luminescence intensity by suppressing surface quenching; and (2) the electron transfer between Au nanoparticles and CdS effectively promotes spatial separation of photogenerated charge carriers and increases reactive active sites. Additionally, after five degradation cycles, CSNPs@CdS@Au still maintains a 93.25% degradation rate for RhB, confirming its excellent stability. This remarkable stability is attributed to the uniquely designed multilayer core–shell architecture, which significantly enhances structural integrity through physical isolation effects. This study establishes a material preparation strategy for efficient photocatalytic pollutant degradation. Full article