Search Results (96)

Quantum Dots (QDs) are small semiconductor nanoparticles (<10 nm) with strong, relatively stable, and tunable luminescent properties, which are increasingly applied in the sensing and detection of various analytes, including metal ions, biomarkers, explosives, proteins, RNA/DNA fragments, pesticides, drugs, and pollutants. In this review, we critically assess recent developments and advancements in luminescent QD-based sensors from an analytical perspective. We collected, tabulated, and analyzed relevant data reported in 124 peer-reviewed articles. The key analytical figures of merit, including the limit of detection (LOD), excitation and emission wavelengths, and size of the particles were extracted, tabulated, and analyzed with graphical representations. We calculated the geometric mean and median LODs from those tabulated publications. We found the following geometric mean LODs: 38 nM for QD-fluorescent-based sensors, 26 nM for QD-phosphorescent-based sensors, and an impressively low 0.109 pM for QD-chemiluminescent-based sensors, which demonstrate by far the best sensitivity in QD-based detection. Moreover, AI-based sensing methods, including the ATTBeadNet model, optimized principal component analysis(OPCA) model, and Support Vector Machine (SVM)-based system, were reviewed as they enhance the analytical performance of the detection. Despite these advances, there are still challenges that include improvements in recovery values, biocompatibility, stability, and overall performance. This review highlights trends to guide the future design of robust, high-performance, QD-based luminescent sensors. Full article

Point-of-care testing (POCT) has garnered widespread attention due to its rapid, convenient, and efficient detection capabilities, particularly playing an increasingly pivotal role in medical diagnostics and significantly improving the efficiency and quality of healthcare services. Nanozymes, as novel enzyme-mimicking materials, have emerged as a research hotspot owing to their superior catalytic performance, low cost, and robust stability. This review provides a systematic overview of the fundamental characteristics and classifications of nanozymes, along with various sensing strategies employed in POCT applications, colorimetric, electrochemical, fluorescent, chemiluminescent, and surface-enhanced Raman scattering (SERS)-based approaches. Furthermore, this review highlights innovative designs that enhance the sensitivity and accuracy of POCT across multiple domains, such as biomarker detection, environmental monitoring, and food safety analysis, thereby offering novel perspectives for the practical implementation of nanozymes in point-of-care diagnostics. Finally, this review analyzes current challenges in nanozyme-based POCT systems, including limitations in optimizing catalytic activity, ensuring nanozyme homogeneity, and achieving large-scale production, while proposing future development trajectories. Full article

Lab on Printed Circuit Boards (Lab-on-PCB) technology has emerged as a promising platform, offering miniaturization, integration, and cost-effective fabrication for a wide range of sensing applications. This review explores the most common optical detection techniques implemented on printed circuit boards (PCBs), including absorbance, fluorescence, and chemiluminescence, discussing their working principles, advantages, and limitations in the context of PCB-based sensing. Additionally, evanescent wave generation is considered as an alternative optical approach with benefits for specific applications. Elements such as excitation sources, photodetectors, and the distinguishing characteristics of each method are analyzed to provide a comprehensive, but concise, overview of the field. Emphasis is placed on how the PCB platform influences the performance, sensitivity, and feasibility of these detection methods, highlighting relevant design considerations. This work aims to provide a solid foundation for researchers interested in optical sensing within this technology, serving as a reference for future developments and applications in PCB-based optical detection. Full article

Conjugated polymers (CPs) have emerged as promising candidates for photodynamic therapy (PDT) in cancer treatment due to their high fluorescence quantum yield, excellent photostability, and remarkable reactive oxygen species (ROS) generation capability. This review systematically summarizes molecular design strategies to augment CP photosensitivity efficiency, including: (1) constructing donor–acceptor (D-A) alternating structures, (2) incorporating aggregation-induced emission (AIE) moieties, (3) employing heavy-atom effects, and (4) designing hyperbranched architectures. In addition, considering the limitations of monotherapy like tumor heterogeneity, we will further discuss the synergistic treatment strategies of CP-mediated PDT in combination with other therapeutic modalities, including photothermal therapy (PTT)-PDT, immunotherapy-PDT, chemotherapy-PDT, Chemiluminescence (CL)-PDT, diagnostic technology-PDT, and chemodynamic therapy (CDT)-PDT. These multimodal approaches leverage complementary mechanisms to achieve enhanced tumor eradication efficacy. Full article

In this study, we developed a novel theranostic nanomedicine formulation that integrates multimodal imaging with controlled drug release in reactive oxygen species (ROS)-rich microenvironments. A fluorinated oxalate compound (FOC) was synthesized through a one-step condensation reaction between 1,1,1,3,3,3-hexafluoro-2-propanol and oxalyl chloride, characterized by ¹H, ¹³C, and ¹⁹F NMR spectroscopy. The FOC and luminophore-incorporated nanomedicine formulations reacted rapidly with hydrogen peroxide via the peroxyoxalate chemiluminescence (POCL) mechanism, producing strong chemiluminescence and inducing a notable 19-fold increase in ratiometric ¹⁹F NMR signal upon conversion to fluorinated alcohol (FAH), demonstrating promising potential for high-contrast ¹⁹F MRI in deep tissue. Following ROS stimulation, the chemical conversion from hydrophobic FOC to hydrophilic FAH led to the degradation of the nanomedicines, facilitating payload release. In vitro experiments with A-431 cancer cells under hypoxic conditions confirmed ROS-responsive drug release, evidenced by enhanced fluorescence from model luminophores. Additionally, doxorubicin-loaded FOC nanomedicines reduced cell viability to 32% under hypoxia while remaining non-toxic in normoxic conditions. These results indicate that FOC-based nanomedicine formulations provide a promising platform for combined chemiluminescence and ¹⁹F MRI with targeted therapeutic efficacy in ROS-rich inflammatory and cancerous tissues. Full article

This study evaluates the impact of PM2.5 exposure from wood combustion on reproductive health and fetal development using an experimental model in Sprague Dawley rats. The study was conducted in Temuco, Chile, where high levels of air pollution are primarily attributed to residential wood burning. A multigenerational exposure model was implemented using controlled exposure chambers with filtered (FA) and unfiltered (NFA) air. Second-generation (G2) female rats (n = 48) were exposed pregestationally (60 days) and gestationally (23 days) under four conditions: FA/FA, FA/NFA, NFA/FA, and NFA/NFA. PM2.5 concentration and composition were monitored using beta-ray attenuation and X-ray fluorescence spectrometry. Reproductive parameters, ovarian follicle counts, and hormonal levels were assessed via vaginal cytology, histological analysis, and chemiluminescence immunoassays. PM2.5 exposure disrupted estrous cyclicity (p = 0.0001), reduced antral and growing follicles (p = 0.0020; p = 0.0317), and increased post-implantation losses (p = 0.0149). Serum progesterone and estradiol levels were significantly altered (p < 0.05). Despite ovarian disruptions, fertility rates remained unchanged. These findings suggest that chronic exposure to wood smoke-derived PM2.5 adversely affects ovarian function and fetal growth without significantly impairing overall reproductive capacity. This study highlights the need for public health policies to mitigate wood smoke pollution. Full article

Biomolecular detection plays essential and irreplaceable roles in safeguarding human health, impeding the transmission of diseases, and augmenting the efficacy of treatments. The precise and specific identification of biomarkers holds profound significance for the early diagnosis, real-time surveillance, and targeted treatment of various diseases. In the initial phases of numerous diseases, the absence of distinct biomarkers in the bloodstream often leads to weak detection signals when using traditional immune detection methods such as enzyme-linked immunosorbent assays (ELISAs), chemiluminescence, and fluorescence chromatography. With the surge in research on surface plasmons, innovative approaches have recently emerged that combine surface plasmon resonance (SPR) with immunological detection techniques, reducing the detection sensitivity to 283 ag/mL, shrinking the sensor size to 2.228 µm², and shortening the detection time to 5.5 min. This review provides an overview of the theoretical foundations of surface plasmon resonance and immunoassays and then delves into the latest advancements in biosensors based on these principles, categorizing them according to their detection mechanisms and methodologies. Finally, we discuss future research directions, opportunities, and the challenges hindering the development of highly sensitive immuno-biochips. Full article

With the growing interest in nucleic acids and nanozymes, nucleic acid nanozymes (NANs) have emerged as a promising alternative to traditional enzyme catalysts, combining the advantages of nucleic acids and nanomaterials, and are widely applied in the field of biosensing. This review provides a comprehensive overview of recent studies on NAN-based biosensors. It classifies NANs based on six distinct enzymatic activities: peroxidase-like, oxidase-like, catalase-like, superoxide dismutase-like, laccase-like, and glucose oxidase-like. This review emphasizes how the catalytic activity of nanozymes is significantly influenced by the properties of nucleic acids and explores the regulatory mechanisms governing the catalytic activity of NANs. Additionally, it systematically reviews important research progress on NANs in colorimetric, fluorescent, electrochemical, SERS, and chemiluminescent sensors, offering insights into the development of the NAN field and biosensor applications. Full article

Hydrogen peroxide (H₂O₂), a common oxidant present in the environment, food, and biological systems, has wide-ranging applications. While H₂O₂ is generally considered non-toxic, prolonged or repeated exposure to high concentrations can be harmful, making its accurate detection crucial in environmental monitoring, food safety, healthcare, and other fields. This review delves into the recent advancements in H₂O₂ detection methods, with a particular focus on chemosensors. We comprehensively summarize the fundamental principles of various chemosensor principles (e.g., colorimetric, fluorescence, chemiluminescence, electrochemical, and chemiresistive approaches), active materials, and diverse applications. Additionally, we discuss the current challenges and future prospects in this field, emphasizing the need for innovative materials and advanced sensing technologies to meet the growing demand for highly sensitive, accurate, reliable, real-time, and cost-effective H₂O₂ detection solutions. Full article

Nanozymes represent a new generation of artificial enzymes that combine nanomaterial properties with catalytic activities similar to those of natural enzymes. It has significant advantages in catalytic efficiency, selectivity, and stability, leading to increasing interest in their application in aqueous environments. Since the discovery of enzyme-like activity in Fe₃O₄, more and more iron-based nanozymes have been utilised for the detection and removal of pollutants. Iron is a non-toxic, low-cost transition metal, and this property makes iron-based nanozymes more compatible with safety requirements in aqueous environmental applications. Although iron-based nanozymes have demonstrated significant advantages in the water environment field, the relevant research is still in its infancy. Therefore, it is of great practical significance to systematically summarise the latest applications of iron-based nanozymes in the water environment. This paper describes the common methods of synthesising iron-based nanozymes. In addition, the applications of iron-based nanozymes in detecting pollutants and pollutant removal are reviewed. It was found that the removal of pollutants by iron-based nanozymes was mainly achieved through the reactive oxygen species, whereas the recognition of pollutants primarily depended on the reactions of iron-based nanozymes, such as colour development, fluorescence, and chemiluminescence. Finally, we highlight the challenges and future prospects for the application of iron-based nanozymes in water environments. In summary, this paper systematically summaries and discusses the common synthesis methods of iron-based nanozymes and their applications in the aquatic environment, with a view to providing new ideas for overcoming the limitations of traditional pollutant detection and removal methods and realising the high-quality development of iron-based nanozymes in water environment. Full article

This research targets the need for eco-friendly strategies in the synthesis of bioactive materials, addressing the importance of valorization of vegetal waste. This study focuses on developing biohybrids containing biomimetic lipid vesicles and phytosynthesized gold–silver chloride nanoparticles (AuAgCl NPs) derived from Achillea millefolium L. extract. By leveraging the natural antioxidant and antimicrobial properties of the plant, the research proposes a sustainable approach to creating materials with potential biomedical applications. The biomimetic membranes were loaded with chlorophyll a, a natural spectral marker. Three types of bioactive materials (biohybrids) were developed by varying the lipid vesicle/AuAgCl NP ratio. Optical (UV-Vis, fluorescence emission, FTIR), structural (XRD), elemental (EDX, XPS), and morphological (TEM) studies were performed to characterize the bio-developed materials. The hydrophobic/hydrophilic characteristics of the samples were investigated by measuring the water contact angle, and their size was estimated by DLS and TEM. Zeta potential measurements were used to evaluate the physical stability of phyto-developed particles. Antioxidant properties of phyto-particles were investigated through the chemiluminescence technique. The obtained biomaterials exhibited high antioxidant activity and antiproliferative activity against HT-29 and B-16 cancer cells. Therapeutic index values were calculated for each biohybrid. Additionally, the bio-prepared hybrids revealed biocidal action against Staphylococcus aureus and Enterococcus faecalis. The phyto-developed biomaterials are promising in biomedical applications, particularly as adjuvants in cancer therapy. Full article

Blowoff limits are essential in establishing the combustor operating envelope. Hence, there is a great demand for practical aero-engines to extend the blowoff limits further. In this work, the behavior of non-premixed swirling flames under fuel flow rate oscillations was investigated experimentally close to its blowoff limits. The methane flame was stabilized on the axisymmetric bluff body and confined in a square quartz enclosure. External acoustic forcing at 400 Hz was applied to the fuel flow to induce a fuel mass flow rate fluctuation (FMFRF) with varying amplitudes. A high-speed burst-mode laser and cameras ran at 20 kHz for OH*-chemiluminescence (CL), CH₂O-, and SO₂-PLIF measurements, offering the visualization of the two-dimensional flame structure and heat release distribution, temporally and spatially. The results show that the effect of FMFRF is predominantly along the central axis without altering the time-averaged flame structure and blowoff transient. However, the blowoff limits are extended due to the enhanced temperature and longer residence time induced by FMFRF. This work allows us to explore the mechanism of flame instability further. Full article

Significant research accomplishments have been made so far for the development and application of ZnO nanomaterials in enhanced optical biodetection. The unparalleled optical properties of ZnO nanomaterials and their reduced dimensionality have been successfully exploited to push the limits of conventional optical biosensors and optical biodetection platforms for a wide range of bioanalytes. ZnO nanomaterial-enabled advancements in optical biosensors have been demonstrated to improve key sensor performance characteristics such as the limit of detection and dynamic range. In addition, all nanomaterial forms of ZnO, ranging from 0-dimensional (0D) and 1D to 2D nanostructures, have been proven to be useful, ensuring their versatile fabrication into functional biosensors. The employment of ZnO as an essential biosensing element has been assessed not only for ensembles but also for individual nanomaterials, which is advantageous for the realization of high miniaturization and minimal invasiveness in biosensors and biodevices. Moreover, the nanomaterials’ incorporations into biosensors have been shown to be useful and functional for a variety of optical detection modes, such as absorption, colorimetry, fluorescence, near-band-edge emission, deep-level emission, chemiluminescence, surface evanescent wave, whispering gallery mode, lossy-mode resonance, surface plasmon resonance, and surface-enhanced Raman scattering. The detection capabilities of these ZnO nanomaterial-based optical biosensors demonstrated so far are highly encouraging and, in some cases, permit quantitative analyses of ultra-trace level bioanalytes that cannot be measured by other means. Hence, steady research endeavors are expected in this burgeoning field, whose scientific and technological impacts will grow immensely in the future. This review provides a timely and much needed review of the research efforts made in the field of ZnO nanomaterial-based optical biosensors in a comprehensive and systematic manner. The topical discussions in this review are organized by the different modes of optical detection listed above and further grouped by the dimensionality of the ZnO nanostructures used in biosensors. Following an overview of a given optical detection mode, the unique properties of ZnO nanomaterials critical to enhanced biodetection are presented in detail. Subsequently, specific biosensing applications of ZnO nanomaterials are discussed for ~40 different bioanalytes, and the important roles that the ZnO nanomaterials play in bioanalyte detection are also identified. Full article

In this study, the soot formation and oxidation processes in different turbulent, pre-evaporated and partially premixed diesel surrogate flames are experimentally investigated. For this purpose, a piloted jet flame surrounded by an air co-flow is used. Starting from a defined diesel surrogate mixture, different fuel blends with increasing blending ratios of poly(oxymethylene) dimethyl ether (OME) are studied. The Reynolds number, equivalence ratio, and vaporization temperature are kept constant to ensure the comparability of the different fuel mixtures. The effects of OME addition on flame structures, soot precursors, and soot are investigated, showing soot reduction when OME is added to the diesel surrogate. Using chemiluminescence images of C₂ radicals (line of sight) and subsequent Abel-inversion, flame lengths and global flame structure are analyzed. The flame structure is visualized by means of planar laser-induced fluorescence (PLIF) of hydroxyl radicals (OH). The spatial distribution of soot precursors, such as polycyclic aromatic hydrocarbons (PAHs), is simultaneously measured by PLIF using the same excitation wavelength. In particular, aromatic compounds with several benzene rings (e.g., naphthalene or pyrene), which are known to be actively involved in soot formation and growth, have been visualized. Spatially distributed soot particles are detected by using laser-induced incandescence (LII), which allows us to study the onset of soot clouds and its structures qualitatively. Evident soot formation is observed in the pure diesel surrogate flame, whereas a significant soot reduction with changing PAH and soot structures can be identified with increasing OME addition. Full article

The specific detection of serum IgE antibodies specific to allergens (sIgE Abs) that can crosslink the plural high-affinity IgE receptor (FcεRIα) molecules on the surface of mast cells or basophils with a multivalent allergen can reduce the false-positive diagnoses observed in chemiluminescent and fluorescence enzyme immunoassays for type-I allergic patients. In this study, we detected sIgE Abs to the egg-allergen ovalbumin (OVA) and the wheat-allergen gluten in the sera of rats sensitized with each allergen using an amplified luminescence proximity homogeneous assay by crosslinking (AlphaCL). OVA and gluten were reacted with each sIgE Ab in the sera. Then, acceptor and donor beads labeled with the human FcεRIα were added to the reacted solution. The luminescence intensity for anti-OVA IgE Abs in the sera with the removal of IgG Abs was observed in five of seven (71.4%) of the sensitized rats, whereas no signals were observed in any of the unsensitized rats. The AlphaCL could also detect anti-gluten sIgE Abs in the sera of sensitized rats, but not of unsensitized rats. In conclusion, we successfully detected sIgE Abs in the sera of rats sensitized to two allergens using the AlphaCL. This detection method has the potential to be used as a new diagnostic tool for type-I allergic patients. Full article