Search Results (3,002)

Benefiting from tunable emission from ultraviolet to near-infrared windows, long luminescence lifetimes, and exceptional photostability, rare earth (RE)-doped nanomaterials overcome the limitations of conventional dyes and quantum dots, enabling deep-tissue, high-resolution, and low-background imaging. As multifunctional fluorescent probes, RE-doped nanomaterials are driving the development of next-generation biomedical imaging. This review summarizes recent advances in the structural design of RE-doped nanomaterials, surface engineering for biocompatibility, and targeting strategies for improved performance, and highlights their integration into advanced imaging modalities, including NIR-I/II fluorescence, FLIM, PAI, super-resolution STED, multimodal FL/MRI/CT, X-ray-excited luminescence, and persistent luminescence. Meanwhile, mechanistic insights, material innovations, and comparative advantages are discussed. Furthermore, challenges related to quantum yield, scalable synthesis, imaging resolution, and clinical translation are considered, while future directions—centered on multifunctional probe design, NIR-II imaging, and AI-assisted data analysis—are proposed, offering a versatile platform for precise multimodal imaging with significant potential to advance early diagnosis, personalized therapy, and clinical applications. Full article

Nineteen monoterpene indole alkaloids, including twelve new ones, were successfully isolated and identified from the stems and leaves of Uncaria hirsuta (Havil.). The planar structures were elucidated by nuclear magnetic resonance (NMR), high-resolution mass (HRMS), and ultraviolet (UV) analyses. The absolute configurations of new compounds were determined using electron circular dichroism calculations in conjunction with NMR calculations. The acetylcholinesterase inhibitory activity of the isolated compounds was evaluated in vitro. In further biological evaluation, the isolated compounds were evaluated for their neuroprotective effects on HT22 neuronal cells. Six compounds demonstrated significant protective activity. Their intracellular reactive oxygen species (ROS) levels were measured using the DCFH-DA fluorescent probe, which markedly attenuated glutamate-induced ROS accumulation. The results not only enrich the knowledge on the structural diversity of monoterpene indole alkaloids but also offer substantial evidence for further pharmacological exploration. Full article

Contemporary iterations of avian phylogenies based on multiple genome sequence assemblies assign three major clades: Palaeognathae (mostly ratite birds), Galloanseres (land and waterfowl) and the largest group—Neoaves. The latter two are sister clades representing subdivisions of Neognathae, while Neoaves further subdivide into Columbaves (pigeons/doves/cuckoos/bustards, etc.), Mirandornithes (flamingos/grebes), Telluraves (“higher land birds”, including finches) and the newly recognized Elementaves (e.g., penguins/pelicans/hummingbirds/swifts/cranes/shorebirds). Molecular studies provide clade information, likely divergence timings and a framework from which gross genomic (chromosomal) changes may be mapped. In this review, we consider the patterns of chromosome change that have occurred throughout all avian clades thus far examined, citing studies from standard karyotyping through molecular cytogenetics to whole genome assemblies. Standard karyotyping led to the realization that most chromosomes (particularly the microchromosomes and dot chromosomes) could not be distinguished by classical means. Indeed, cross-species comparisons were difficult, even among the macrochromosomes, because of indistinct banding patterns. Based on fluorescence (or fluorescent) in situ hybridization (FISH), comparative genomics was thence progressed considerably by cross-species chromosome painting (Zoo-FISH) for the macrochromosomes and interspecific mapping of bacterial artificial chromosome (BAC) probes for the microchromosomes. A key finding was that the most studied species, the chicken, fortuitously, has a genomic organization somewhat akin to that of the ancestral karyotype and tends to be the standard from which all others are measured. A notable exception is the fusion of basal chromosome 4 with a smaller chromosome that convergently appears in some other Galliformes, at least one goose and one dove species. While some groups such as Falconiformes (falcons, etc.) and Psittaciformes (parrots, etc.) underwent extensive interchromosomal change, most, broadly speaking, retain a basic karyotype that differs little from bird to bird. Many, e.g., Passeriformes (finches, songbirds, etc.) and Columbiformes (pigeons, doves), do this despite multiple intrachromosomal rearrangements. The complete karyotype and fully established chromosome-level genome assembly of the chicken allow full integration of DNA sequence assembly with karyotype. They further permit cytogenetic studies to be performed using genome assemblies alone alongside cutting-edge long-read sequencing and optical mapping without the need for chromosome preparation. The classic ZW sex-determination system of birds is easily visible in most Neognathae species, but intrachromosomal change in the sex chromosomes is faster than in the autosomes; indeed, there are numerous examples of autosomal fusions and new sex chromosomes formed. Sex chromosomes aside, the classic avian karyotype represents a very successful mode of genome organization established before the emergence of the dinosaurs and perpetuated to this day in their only living descendants. Full article

Background/Objectives: Aldo–keto reductase isoforms AKR1C1–3 and 17β-hydroxysteroid dehydrogenase 1 and 2 (17β-HSD1 and 17β-HSD2) are key enzymes in steroid metabolism and validated targets in hormone-dependent cancers. Methods: In this study, Δ¹⁵- and 15β-substituted estrone derivatives were evaluated as inhibitors of AKR1C1–3 and 17β-HSD1 using enzymatic assays, cell viability assaysand computational modeling. Cellular uptake of the fluorescent estrone-based inhibitor was investigated using confocal microscopy. Results: The Δ¹⁵-estrone derivative showed potent and selective inhibition of 17β-HSD1 in the low nanomolar range, while 15β-O-propargyl and 15β-azide derivatives exhibited dual inhibitory activity against 17β-HSD1 and AKR1C2. The Δ¹⁵- and 15β-azide derivatives reduced cell viability in hormone-dependent breast, endometrial, and ovarian cancer cell lines in the sub- to low-micromolar range. A BODIPY-labeled 15β-O-propargyl analogue retained submicromolar inhibitory potency toward 17β-HSD1, representing the first fluorescent estrane-based inhibitor with preserved biological activity. Confocal microscopy confirmed efficient cellular uptake and predominant cytosolic localization in MCF-7 cells. Conclusions: These findings identify Δ¹⁵- and 15β-modified estrone derivatives as promising single- and dual-target inhibitors and introduce a fluorescent probe suitable for investigating intracellular steroid metabolism in hormone-dependent malignancies. Full article

Three kinds of nitrogen-doped carbon quantum dots (N-CQDs) were successfully fabricated through a one-pot hydrothermal reaction at 180 °C for 12 h. L-lactic acid served as the carbon precursor, while three phenylenediamine isomers (o-phenylenediamine, m-phenylenediamine, p-phenylenediamine) were employed as nitrogen dopants, yielding samples denoted as OPD-LA, MPD-LA, and PPD-LA. All as-prepared N-CQDs presented uniformly dispersed spherical nanostructures, with average particle sizes of 8.2 nm (OPD-LA), 9.3 nm (MPD-LA), and 10.5 nm (PPD-LA). Abundant surface functional groups, including hydroxyl, carboxyl, amino, and amide moieties, endowed these N-CQDs with outstanding water solubility and tailorable fluorescence emission. The maximum emission wavelengths were centered at 550 nm, 505 nm, and 450 nm for OPD-LA, MPD-LA, and PPD-LA, respectively, exhibiting excitation-independent emission positions yet excitation-dependent intensity. MPD-LA delivered the highest fluorescence quantum yield of 9.59%, and the incorporation of lactic acid significantly elevated the quantum yield of all samples. The N-CQDs maintain high fluorescence intensity and favorable stability within the pH range of 4–11, possessing outstanding salt resistance and stable storage performance for six months. Their fluorescence was effectively quenched upon exposure to Fe³⁺, with a linear detection range of 10–100 μM and a low limit of detection (LOD) of 1.49 μM. These lactic acid-derived N-CQDs hold great promise as functional fluorescent probes for Fe³⁺ sensing applications. Full article

As the growing presence of antibiotic residues in environmental water bodies poses an increasing risk to ecological safety and human health, developing simple and efficient methods for the targeted detection of antibiotics is of particular importance. In this study, we propose a simple method for the one-step hydrothermal synthesis of N, S-co-doped carbon dots (N, S-CDs) using disulfide bonds from discarded badminton shuttlecocks. We investigated the effects of different synthesis temperatures on its performance and confirmed the method’s excellent performance in detecting tetracycline (TC) concentrations, with results demonstrating that varying synthesis temperatures affect the degree and distribution of carbonization, thereby influencing fluorescence intensity. Consequently, employing N, S-CDs-180, which exhibits optimal photoluminescence properties, as the sensing probe for the detection of TC solutions at varying concentrations yielded an excellent linear equation for fluorescence quenching and the detection limit is 1.963 mg/L. Additionally, the fluorescence stability of N,S-CDs-180 was investigated in laboratory water, tap water, seawater, lake water, and industrial wastewater, all of which demonstrated exceptional environmental adaptability. Furthermore, a systematic investigation into the target selectivity of N, S-CDs-180 toward various antibiotics revealed that this material exhibits a sensitive quenching response specifically to tetracycline-class antibiotics while showing no quenching effect on non-tetracycline antibiotics, collectively indicating that the as-prepared N, S-CDs can serve as potential fluorescent probes for the highly selective detection of tetracycline-class antibiotics in complex aqueous systems. Full article

Human epidermal growth factor receptor 2 (HER2) remains the most recognized and clinically established molecular biomarker in gastric cancer; however, the regulatory mechanisms underlying its dysregulation are not fully understood. This study aimed to identify microRNAs associated with HER2 gene amplification, chromosome 17 centromere copy number increase (CNI), or alternative mechanisms driving HER2 protein overexpression. We analyzed 115 gastric cancer patients treated surgically at a single institution, with available material for immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and microRNA profiling. Among 11 candidate microRNAs, four demonstrated significant associations with HER2-related alterations. hsa-miR-128-3p expression was positively associated with HER2 gene amplification, while hsa-miR-145-5p expression showed an inverse relationship with centromere enumeration probe 17 (CEP17) signal count and correlated with membranous HER2 protein expression. hsa-miR-27b-5p expression was linked to CEP17 CNI, whereas hsa-miR-552-3p expression was associated with both increased HER2 amplification and CEP17 signal count. Importantly, hsa-miR-27b-5p upregulation independently predicted worse overall survival, whereas hsa-miR-128-3p upregulation independently predicted improved survival outcomes. These findings identify distinct microRNA signatures associated with HER2 pathway alterations and prognosis in gastric cancer, highlighting their potential as biomarkers and contributors to HER2-driven tumor biology. Full article

Nanotheranostics integrate theranostic functions onto a single nanoscale platform, and have become a new approach in precision medicine. Nanotheranostics rely on probes. However, traditional fluorescent probes often exhibit aggregation-caused quenching (ACQ) when loaded at high concentrations onto nanocarriers, severely limiting their imaging performance. Aggregation-induced emission agents (AIEgens) offer a solution to this long-standing problem through their ability to enhance fluorescence during aggregation. This mini-review systematically outlines nanotheranostic systems based on aggregation-induced emission (AIE). We first introduce the basic mechanism of AIE (the limitation of molecular internal motion) and its advantages over traditional fluorescent probes. Then, we discuss the design strategies of AIE nanoprobes according to the types of nanocarriers (including liposomes, polymer nanoparticles, and self-assembling systems). Additionally, we emphasize the disease-specific AIE nanotheranostic designs tailored for pathological microenvironments such as tumors, neurodegenerative diseases, and inflammatory diseases. Finally, we conduct an in-depth analysis of the current challenges hindering clinical translation, and propose future AIE nanotheranostic technologies applicable to clinical practice and the direction for personalized medicine. Full article

Genetically encoded voltage indicators (GEVIs) have long promised optical access to membrane potential, yet their adoption has lagged significantly behind genetically encoded calcium indicators. A central but underappreciated reason is that the metrics used to evaluate and compare GEVIs—fractional fluorescence change (ΔF/F), kinetics, and signal-to-noise ratio—rest on an assumption that is frequently violated: that GEVI fluorescence reflects a single underlying process. In this perspective, we argue that GEVI signals are composite optical measurements, arising from the superposition of voltage-dependent fluorescence, intracellular and nonresponsive signal, background, and contributions from neighboring cells. Under these conditions, ΔF/F is not a measure of sensor sensitivity but a contrast metric whose value depends on baseline fluorescence composition, optical sampling, and imaging configuration. This reinterpretation has two key consequences. First, it explains a substantial source of variability in GEVI performance that is currently attributed to noise or experimental inconsistency. Second, and more importantly, it reveals that the complexity of GEVI signals is not a limitation to be minimized but a resource to be exploited. By resolving composite signal components, GEVIs can report multiplexed physiological variables, expose hidden conformational states of voltage-sensing domains, probe membrane organization, and reveal intracellular and intercellular electrical coupling. We propose that realizing the full potential of GEVIs requires treating ΔF/F not as a gold standard for sensor performance, but as one interpretable component of a richer optical measurement whose structure encodes multiple layers of cellular physiology. Full article

An evaluation of plant ploidy is an important task in breeding and biotechnology. Current methods of ploidy assessment (flow cytofluorometry and microscopy) are time-consuming and costly, and not applicable to real-world agricultural conditions. We developed an automated method for ploidy assessment based on fluorescence microscopy, which aims to accelerate and reduce the cost of plant ploidy analysis. The method is based on the automated selection of plant nuclei in fluorescence micrographs, followed by analysis of nuclear area, fluorescence intensity of the Hoechst DNA-binding probe, and nuclear geometry (circularity, roundness, solidity). The study was conducted on monocotyledonous and dicotyledonous plants with known genome sizes. Triticum aestivum Wt (6n, hexaploid) and Temp (4n, tetraploid) are monocotyledonous, and Capsella bursa-pastoris (4n, tetraploid) and Capsella rubella (2n, dT/iploid) are dicotyledonous. A simple fluorescent staining protocol combined with automated analysis using our ImageJ macro enables reliable separation of both monocotyledonous and dicotyledonous plants by genome size with an accuracy close (for dicots) or comparable (for monocots) to flow cytofluorometry. For ploidy separation in monocots, the most sensitive parameters are fluorescence intensity, nucleus area, and circularity. For ploidy separation in dicots, the most sensitive parameters are nucleus area, fluorescence intensity, and circularity. Full article

Elucidating structure–activity relationships in semiconductor photocatalysis has been significantly impeded by the inherent limitations of ensemble-averaged characterization techniques, which obscure the spatiotemporal heterogeneity intrinsic to catalytic surfaces. Single-molecule fluorescence microscopy (SMFM) surmounts this bottleneck by offering nanometer-scale spatial resolution coupled with the capacity to resolve single-turnover events. Herein, we provide a comprehensive overview of the State-of-the-Art applications of fluorogenic probe-coupled SMFM in deciphering the microscopic mechanisms governing photocatalysis. We begin by delineating the operational principles of total internal reflection fluorescence (TIRF) microscopy and categorizing the response mechanisms of three distinct classes of fluorogenic probes: oxidative (e.g., Amplex Red, APF), reductive (e.g., Resazurin, DN-BODIPY), and acidic (e.g., furfuryl alcohol, thiophene) reporters. Subsequently, we highlight seminal studies wherein SMFM has been leveraged to visualize facet-dependent charge separation on model photocatalysts—including TiO₂, BiOBr, and InSe—to map the dynamic activity associated with surface defects and to precisely locate active sites during photoelectrochemical water splitting. Finally, we critically assess the prevailing technical challenges, such as limitations in probe specificity and background interference, while offering a perspective on prospective avenues for methodological refinement. This review is intended to serve as a methodological cornerstone for advancing mechanistic understanding in photocatalysis and for guiding the rational design of high-performance catalysts. Full article

Capillary electrophoresis (CE) has proven to be an effective technique for aptamer selection. Here, we directly integrated the separation advantages of CE into a live-cell system, thereby establishing an integrated and highly efficient CE-Cell-SELEX screening model for bone microvascular endothelial cells (BMECs) without the need for negative selection. The selection progress was monitored through quantitative real-time fluorescence PCR (qRT-PCR) analysis, which yielded 7 candidate sequences from the amplified library after four rounds of selection. Flow cytometry analysis demonstrated that aptamer T-24 exhibited high affinity for BMECs, with a Kd of 111.86 ± 18.36 nM. Owing to its high affinity and specificity, coupled with its small molecular weight and non-immunogenicity, T-24 holds great potential as a biological probe for the identification and isolation of BMECs. Furthermore, molecular docking was performed by MOE 2022 software to validate the candidate sequences and assist in the identification process. The CE-Cell-SELEX method eliminates the need for negative screening and traditional elution, greatly reduces the screening cycle, and may provide a valuable reference system for the early diagnosis and precise treatment of femoral head ischemia. Full article

Hypoxia-induced radioresistance remains a major obstacle in non-small cell lung cancer (NSCLC) radiotherapy. This study investigates whether artificially activating mitochondrial reverse electron transfer (RET) can enhance radiosensitivity in NSCLC by triggering oxidative stress. An in vitro hypoxia/reoxygenation (H/R) model was established in A549 cells to assess reactive oxygen species (ROS) levels, mitochondrial function, and metabolic alterations using fluorescence probes, flow cytometry, confocal microscopy, and targeted metabolomics. Mitochondrial complex inhibitors and dimethyl succinate (DM-S) were employed to validate the RET mechanism, and radiosensitivity was evaluated through clonogenic survival, apoptosis assays, and γ-H2AX staining. In vivo, A549 tumor-bearing mice received high oxygen (95% O₂) combined with DM-S and localized irradiation (4 Gy); tumor growth, histopathology, and immunohistochemistry were examined. H/R triggered substantial mitochondrial ROS production via complex I-mediated RET, dependent on a high mitochondrial membrane potential and electron transport chain imbalance, with succinate accumulation serving as a key metabolic switch. Exogenous DM-S exacerbated H/R-induced oxidative damage, DNA fragmentation (8-OHdG elevation, mtDNA integrity loss), and mitochondrial network disruption. H/R combined with DM-S significantly enhanced in vitro radiosensitivity, reducing clonogenic survival and increasing apoptosis to 53.4% ± 1.9% versus 10.3% ± 1.2% with irradiation alone. In vivo, the combination therapy markedly suppressed tumor growth, induced apoptosis and oxidative lipid damage (4-HNE), alleviated hypoxia (reduced HIF-1α), and showed no overt toxicity. These findings demonstrate that activating mitochondrial RET effectively enhances radiosensitivity in NSCLC. Succinate metabolism is a critical therapeutic target, and combining high oxygen with a succinate analog represents a promising radiosensitization strategy for hypoxic tumors. Full article

In prokaryotes, translation initiation orchestrates protein synthesis through a network of dynamic interactions among the ribosome, mRNA, initiator tRNA^fMet, and initiation factors (IFs). Traditional approaches that rely on radioactive labeling or surface immobilization are hindered by inherent safety risks and methodological constraints. We present a fluorescence-based analytical platform that integrates microscale thermophoresis (MST) as a unified, multiparametric toolkit for comprehensive interrogation of bacterial translation initiation at the molecular level. By systematically applying MST to a panel of fluorescently labeled components—initiator tRNA^fMet, mRNAs, and initiation factors—we quantify assembly pathways and equilibria as initiation progresses from simple bimolecular interactions to higher-order, multicomponent complexes. To broaden the fluorescence toolbox for ribosomal studies, we developed a robust BODIPY-labeling protocol for 70S ribosomes and confirmed preservation of structural integrity and function by nano differential scanning fluorimetry, stopped-flow kinetic assays, and peptide-synthesis activity tests. Our microscale fluorescent system facilitates probing initiation at a variety of steps, since the role of magnesium ions and initiation factors upon 30S initiation complex formation. The same platform can be applied to investigate the effects of different compounds on translation initiation, as demonstrated for a number of antibiotics, aptamers, and antimicrobial peptides. Using this approach, we determined the antibiotic streptomycin dissociation constant for both 30S and 70S ribosomes, which proved identical at 0.3 ± 0.1 μM, and demonstrated the effect of the antimicrobial peptide rumicidin-1 on translation initiation. Offering a cost-effective and high-sensitivity alternative to conventional methods, this approach advances mechanistic understanding of prokaryotic translation and provides a versatile framework for the discovery of novel protein synthesis inhibitors. Full article

In this study, bis-1,10-phenanthroline (Biphen) was synthesized via a hydrogen transfer-mediated coupling reaction in a single step. The resulting compound was demonstrated, for the first time, to function as a selective fluorescent probe for Ni²⁺ ions. The presence of Ni²⁺ at a 2:1 molar ratio of Biphen to Ni²⁺ results in complete fluorescence quenching, with a detection limit of 4.34 × 10⁻⁹ M in aqueous medium. Fluorescence is restored upon the introduction of a suitable chelating agent, producing an “on-off-on” fluorescence switching response. Furthermore, fluorescence co-localization studies demonstrate that Biphen functions as a mitochondria-targeted fluorescent probe with excellent cell membrane permeability, enabling rapid, reversible imaging and ultratrace detection of Ni²⁺ in mitochondria of live cells. Overall, this work demonstrates highly selective ultratrace detection of Ni²⁺ in both aqueous and biological environments, providing a promising platform for mitochondrial imaging and potential diagnostic applications. Full article