Search Results (347)

Copper ions play essential roles in biological systems, but they can cause toxicity following dysregulation or excessive accumulation. In addition, environmental overexposure to Cu²⁺ can lead to serious agricultural and ecological issues. Accurate detection of Cu²⁺ is therefore critical in both medical diagnostics and environmental monitoring. Fluorescent proteins (FPs), which are widely used in molecular and cell biology, have been suggested as attractive modalities for metal ion detection owing to their biocompatibility and specific responsiveness to metal ions. The fluorescence emission of FPs is efficiently quenched by Cu²⁺ in a reversible manner, suggesting the potential to develop Cu²⁺-responsive biosensors. To develop highly sensitive and selective Cu²⁺ biosensors based on FPs, an understanding of Cu²⁺ binding to FPs is crucial, along with FP engineering guided by structural analysis. In this study, the molecular properties of FPs and their fluorescence responses to metal ions were reviewed. The crystal structures of FPs complexed with Cu²⁺ were analyzed, revealing both specific and nonspecific Cu²⁺ binding modes. This structural analysis provides insights into the potential of engineering FPs to enhance sensitivity and selectivity for Cu²⁺ detection. Full article

Copper is an important environmental pollutant that poses a significant threat to human health and environmental safety. Therefore, the development of methods for detecting Cu²⁺ is of great significance. A novel fluorometric/colorimetric dual-mode sensor for detecting Cu²⁺ was synthesized by Schiff base reaction using fluorescein hydrazide and 8-hydroxyjulonidine-9-carboxaldehyde as raw materials. Cu²⁺ could form a complex with the probe in a stoichiometric ratio of 1:1. Within 1 min, the fluorescence of the probe rapidly quenched at 540 nm, and the absorbance reached a stable state at 452 nm. The color of the solution changed from light yellow to yellow, achieving real-time and visual detection of Cu²⁺. This probe exhibited exceptional selectivity for Cu²⁺. Within the range of 0–12 μM, the fluorescence intensity of the probe demonstrated a strong linear correlation with the concentration of Cu²⁺ (R² = 0.994), with a detection limit of 0.22 µM. In the ultraviolet colorimetric method, when the Cu²⁺ concentration reached 14 μM, the absorbance stabilized (R² = 0.996), and the detection limit for Cu²⁺ was determined to be 0.38 µM. Furthermore, this probe enabled reversible detection of Cu²⁺, and its performance in real water sample analysis and cellular bioimaging was proven to be highly satisfactory. Full article

Copper ions (Cu²⁺), indispensable in physiological processes yet toxic at elevated concentrations, require sensitive on-site monitoring. Here, a portable fluorescent sensing film (Y-CDs@BCM) was fabricated by anchoring yellow-emitting carbon dots (Y-CDs) into bacterial cellulose films, which enables rapid and sensitive detection of Cu²⁺ in complex real-world samples. The yellow fluorescent carbon dots (Y-CDs) were synthesized with the aid of o-phenylenediamine and 1-octyl-3-methylimidazolium tetrafluoroborate as precursors, exhibiting excellent fluorescence stability. The fluorescence of Y-CDs was selectively quenched by Cu²⁺ via the inner filter effect (IFE), allowing quantitative analysis with superior sensitivity compared to existing methods. By adding bacterial cellulose (BC) as a solid support, aggregation-induced fluorescence quenching was effectively reduced, and sensor robustness and portability were improved. Through smartphone-based colorimetric analysis, the Y-CDs@BCM sensor enabled rapid, visual interpretation of Cu²⁺ detection (within 1 min). Furthermore, cell viability and in vivo assays confirmed the biocompatibility of Y-CDs, indicating their suitability for biological imaging. This work presents an environmentally friendly, reliable, and practical method for on-site Cu²⁺ monitoring, emphasizing its broad application potential in food safety control and environmental analysis. Full article

Lanthanide hydrogen-bonded organic frameworks (Ln-HOFs) integrating luminescent and proton-conductive properties hold significant promise for multifunctional sensing and energy applications, yet their development remains challenging due to the difficulty of balancing structural stability and functional diversity. In this context, this study successfully synthesized a novel neodymium(III)-based hydrogen-bonded framework material, formulated as {Nd(H₂O)₃(4-CPCA)[H(4-CPCA)]∙H₂O}ₙ (SNUT-15), via hydrothermal assembly using 1-(4-carboxyphenyl)-4-oxo-1,4-dihydropyridazine-3-carboxylic acid (H₂(4-CPCA)) as the ligand. Single-crystal X-ray diffraction analysis revealed a rare two-dimensional hydrogen-bonded bilayer structure stabilized by π-π stacking interactions and intermolecular hydrogen bonds. Hirshfeld surface analysis further corroborated the structural characteristics of this material. Moreover, leveraging the superior luminescent properties of lanthanide elements, this crystalline material exhibits dual functionality: selective fluorescence quenching toward Fe³⁺, La³⁺, and Mn²⁺ (with detection limits of 1.74 × 10⁻⁴, 1.88 × 10⁻⁴, and 3.57 × 10⁻⁴ mol·L⁻¹, respectively), as well as excellent proton conductivity reaching 7.92 × 10⁻³ S cm⁻¹ under conditions of 98% relative humidity and 353 K (80 °C). As a multifunctional neodymium(III)-based HOF material, SNUT-15 demonstrates its potential for applications in environmental monitoring and solid-state electrolytes, providing valuable insights into the rational design of lanthanide-containing frameworks. Full article

This study systematically explored the interaction mechanisms between two KRAS G12C inhibitors (Sotorasib and Adagrasib) and human serum albumin (HSA) via UV-vis spectroscopy, fluorescence spectroscopy, three-dimensional fluorescence spectroscopy, and molecular docking methods. The experimental findings demonstrated that both drugs caused static quenching of HSA fluorescence, with binding constants of 13.64 × 10³ M⁻¹ (Sotorasib) and 63.67 × 10³ M⁻¹ (Adagrasib), demonstrating significant selectivity differences in their binding affinities. UV spectral analysis demonstrated distinct microenvironmental perturbations: Sotorasib and Adagrasib induced a shift (∆λ = 7 nm and ∆λ = 8 nm, respectively) at 211 nm, consistent with altered polarity in HSA’s binding pockets. Fluorescence spectroscopy confirmed a 1:1 binding stoichiometry, with Stern-Volmer analysis validating static quenching as the dominant mechanism. Three-dimensional fluorescence spectra further highlighted Adagrasib’s stronger conformational impact, reducing tyrosine and tryptophan residue fluorescence intensities by 16% (Peak 1) and 10% (Peak 2), respectively, compared to Sotorasib. Molecular docking revealed divergent binding modes: Sotorasib occupied Sudlow Site I via three hydrogen bonds and hydrophobic interactions (∆G = −24.60 kJ·mol⁻¹), whereas Adagrasib bound through one hydrogen bond and hydrophobic forces (∆G = −30.92 kJ·mol⁻¹), with stability differences attributed to structural characteristics. This study uses multispectral technology and molecular docking to reveal the binding mechanism of Sotorasib and Adagrasib with HSA, providing a theoretical basis for designing highly targeted albumin nanocarriers. The strong binding properties of Adagrasib and HSA may reduce the toxicity of free drugs, providing direction for the development of long-acting formulations. Full article

Elevated levels of homocysteine (Hcy) are associated with various pathological conditions including atherosclerosis, hypertension, and cardiovascular diseases. In this work, quantum-dot-based molecularly imprinted hydrogels (QD@MIHs) were developed by integrating L-cysteine-modified ZnS quantum dots (QDs)with highly selective molecular imprinting technology for rapid homocysteine detection. The QD@MIPHs were fabricated using a dual-functional monomer system (acrylamide and methacrylic acid) through surface coating of the Hcy molecularly imprinted polymer gel onto the QDs. Under optimal conditions, the response time of the QD@MIPHs for Hcy detection was 5 min. When the Hcy concentration ranged from 0.1 to 10.0 μM, the fluorescence quenching of the QD@MIHs showed a good linear relationship with Hcy concentration (R² = 0.9972), with a corresponding detection limit of 0.027 μM. In addition, the constructed QD@MIPHs showed no significant response to other interfering substances, demonstrating the high selectivity of the prepared material. Practical sample analysis revealed that the recovery rates of Hcy ranged from 94.34% to 104.1%, with relative standard deviations (RSD, n = 3) between 3.56% and 7.17%. This study provides a novel tool and method for rapid Hcy detection with significant potential in biomedical diagnostics and preventive-healthcare applications. Full article

Degradable fluorescent sensors present a promising portable approach for heavy metal ion detection, aiming to prevent secondary environmental pollution. Additionally, the excessive intake of ferric ions (Fe³⁺), an essential trace element for human health, poses critical health risks that urgently require effective monitoring. In this study, we developed a thermally degradable fluorescent hydrogel sensor (Eu-CDs@DPPG) based on europium-doped carbon dots (Eu-CDs). The Eu-CDs, synthesized via a hydrothermal method, exhibited selective fluorescence quenching by Fe³⁺ through the inner filter effect (IFE). Embedding Eu-CDs into the hydrogel significantly enhanced their stability and dispersibility in aqueous environments, effectively resolving issues related to aggregation and matrix interference in traditional sensing methods. The developed sensor demonstrated a broad linear detection range (0–2.5 µM), an extremely low detection limit (1.25 nM), and rapid response (<40 s). Furthermore, a smartphone-assisted LAB color analysis allowed portable, visual quantification of Fe³⁺ with a practical LOD of 6.588 nM. Importantly, the hydrogel was thermally degradable at 80 °C, thus minimizing environmental impact. The sensor’s practical applicability was validated by accurately detecting Fe³⁺ in spinach and human urine samples, achieving recoveries of 98.7–108.0% with low relative standard deviations. This work provides an efficient, portable, and sustainable sensing platform that overcomes the limitations inherent in conventional analytical methods. Full article

A novel ruthenium(II) complex, [RuCl₂(η⁶-p-cymene)(bph-κN)] (1), was synthesized and structurally characterized using FTIR and NMR spectroscopy. Density functional theory (DFT) calculations supported the proposed geometry and allowed for comparative analysis of experimental and theoretical spectroscopic data. The interaction of complex 1 with human serum albumin (HSA) and calf thymus DNA was investigated through fluorescence quenching experiments, revealing spontaneous binding driven primarily by hydrophobic interactions. The thermodynamic parameters indicated mixed quenching mechanisms in both protein and DNA systems. Ethidium bromide displacement assays and molecular docking simulations confirmed DNA intercalation as the dominant binding mode, with a Gibbs free binding energy of −34.1 kJ mol⁻¹. Antioxidant activity, assessed by EPR spectroscopy, demonstrated effective scavenging of hydroxyl and ascorbyl radicals. In vitro cytotoxicity assays against A375, MDA-MB-231, MIA PaCa-2, and SW480 cancer cell lines revealed selective activity, with pancreatic and colorectal cells showing the highest sensitivity. QTAIM analysis provided insight into metal–ligand bonding characteristics and intramolecular stabilization. These findings highlight the potential of 1 as a promising candidate for further development as an anticancer agent, particularly against multidrug-resistant tumors. Full article

Elevated [CO₂] enhances light interception and carboxylation efficiency in plants. The combined effects of [CO₂] and photosynthetic photon flux density (PPFD) on stomatal morphology, leaf anatomy, and photosynthetic capacity in tomato seedlings remain unclear. This study subjected tomato seedlings (Solanum lycopersicum Mill. cv. Jingpeng No.1) to two [CO₂] (ambient [a[CO₂], 400 µmol·mol⁻¹] and enriched [e[CO₂], 800 µmol·mol⁻¹]) and three PPFD levels (L; low[Ll: 200 µmol·m⁻²·s⁻¹], moderate[Lm: 300 µmol·m⁻²·s⁻¹], and high[Lh: 400 µmol·m⁻²·s⁻¹]) to assess their interactive impacts. Results showed that e[CO₂] and increased PPFD synergistically improved relative growth rate and net assimilation rate while reducing specific leaf area and leaf area ratio. Notably, e[CO₂] decreased stomatal aperture (−13.81%) and density (−27.76%), whereas elevated PPFD promoted stomatal morphological adjustments. Additionally, Leaf thickness increased by 72.98% under e[CO₂], with Lm and Lh enhancing this by 10.79% and 41.50% compared to Ll. Furthermore, photosynthetic performance under e[CO₂] was further evidenced by improved chlorophyll fluorescence parameters (excluding non-photochemical quenching). While both e[CO₂] and increased PPFD Photosynthetic performance under e[CO₂] was further evidenced by improved chlorophyll fluorescence parameters (excluding non-photochemical quenching). Moreover, e[CO₂]-Lh treatment maximized total dry mass and seedling health index. Correlation analysis indicated that synergistic optimization of stomatal traits and leaf structure under a combination of e[CO₂] and increased PPFD enhanced light harvesting and CO₂ diffusion, thereby promoting carbon assimilation. These findings highlight e[CO₂]-Lh as an optimal strategy for tomato seedling growth, providing empirical guidance for precision CO₂ fertilization and light management in controlled cultivation. Full article

Nitrogen-doped carbon dots (NCDs) exhibiting superior fluorescence characteristics were synthesized employing o-phenylenediamine and 2-methylimidazole as precursors. The synthesized NCDs exhibited yellow photoluminescence with an excitation/emission maxima of 410/554 nm with a quantum yield of 28.41%. The presence of pyridinic N, pyrrolic N, graphitic N, and amino N functionalities on the NCDs’ surface provided strong evidence for the successful nitrogen doping of the carbon dots. Upon exposure to hydrogen peroxide (H₂O₂), the NCDs exhibited a significant reduction in fluorescence intensity, which could be restored by the addition of ascorbic acid (AA), demonstrating a quantitative relationship between ascorbic acid and fluorescence efficiency. A novel fluorescence “off–on” system utilizing these NCDs was developed for the quantification of AA. The sensing mechanism relies on H₂O₂-induced fluorescence quenching via the selective oxidation of the NCDs’ surface, followed by fluorescence restoration upon AA addition due to the reduction in surface defects. Meanwhile, further experiments confirmed that the quenching mechanism was static quenching. The NCDs demonstrated a limit of detection (LOD) of 0.605 μM for AA detection. The use of NCDs for AA sensing was validated through the analysis of commercially available beverages. This study aimed to establish a simplified method for ascorbic acid detection. The experimental findings indicated that the developed technique exhibited high accuracy in quantifying ascorbic acid. These findings suggest that the developed NCDs possess considerable potential as a multifunctional sensing tool for various analytical applications. Full article

Although α-amylase is crucial for postprandial glucose control, existing inhibitors present various side effects, necessitating the exploration of natural alternatives. The ability of sugarcane polyphenol (SP) to inhibit α-amylase remains unclear. This study assessed the inhibitory activity of SP via in vitro assays, circular dichroism (CD), fluorescence quenching, and stability analysis, while the mechanism of action was elucidated using molecular docking and molecular dynamics (MD). The results showed that the IC₅₀ of the SP was 0.841 ± 0.029 mg/mL, with proanthocyanidin-B1 (PC-B1) presenting the most potent effect (IC₅₀ = 0.504 ± 0.019 mg/mL). CD and barycentric mean (BCM) analysis indicated that the complexes might limit substrate binding. The mechanistic assessment showed that the polyphenols bonded to the active enzyme pockets to form stable complexes with reduced key residue fluctuations. In conclusion, SP, especially PC-B1, effectively inhibited α-amylase activity via structural regulation and molecular interactions, providing a theoretical basis for developing natural hypoglycemic agents. Full article

The novel benzanthrone derivative, 2-bromo-3-aminobenzo[de]anthracene-7-one (2-Br-3-NH₂BA), was synthesized and extensively characterized to investigate its photophysical behavior in various solvents. It was prepared through selective bromination of 3-aminobenzanthrone using N-bromosuccinimide in dimethylformamide at −20 °C. Featuring a donor–π–acceptor (D–π–A) structure, 2-Br-3-NH₂BA exhibits pronounced solvatochromism due to the intramolecular charge transfer (ICT) between the amino donor and the carbonyl acceptor groups. Optical measurements conducted in eight solvents of varying polarity revealed a significant bathochromic shift in both absorption and fluorescence emission, with emission maxima red-shifting by over 110 nm from non-polar to polar environments. Corresponding reductions in the optical band gap energies, as calculated from Tauc plots, further support solvent-induced electronic state modulation. Additionally, quantum yield analysis showed higher fluorescence efficiency in non-polar solvents, while polar solvents induced twisted intramolecular charge transfer (TICT), leading to emission quenching. These findings demonstrate the sensitivity of 2-Br-3-NH₂BA to environmental polarity, making it a promising candidate for color-tunable luminescent applications in optoelectronics and sensing. However, further studies in the solid state are required to validate its applicability in device architectures such as OLEDs. Full article

CRISPR-Cas proteins from bacteria are powerful tools for gene editing and molecular diagnostics. Expanding capacity of CRISPR to low cost, multiplexed assays of biomarkers is a key to future disease diagnostics, since multiple biomarker detection is essential for reliable diagnostics. Herein we describe a multiplexed assay in a 3D-printed 96-well plate with CRISPR-Cas13a immobilized in each well to target three circulating blood biomarker microRNAs (miRNAs 34c-5p, 200c-3p, and 30e-5p) for Alzheimer’s disease (ALZ). Immobilized Cas13a is equipped with different crRNAs complementary to each miRNA target. MiRNA binding to crRNA complements activates the collateral RNase activity of Cas13a, cleaving a quenched fluorescent reporter (RNaseAlert) with fluorophore and quencher connected by an RNA oligonucleotide to enable fluorescence measurements. We achieved ultralow limits of detection (LOD) of 0.74 fg/mL for miRNA 34c-5p, 0.70 fg/mL for miRNA 30e-5p, and 7.4 fg/mL for miRNA 200c-3p, with dynamic ranges from LODs up to about 1800 pg/mL. The accuracy of the assay was validated by spike-recovery studies and good correlation of levels of patient plasma samples vs. a referee method. This new approach provides selective, sensitive multiplex miRNA biosensing, and simultaneously accommodates analysis of standards and controls. Full article

Nitrogen and sulfur-co-doped carbon dots (N, S-CDs) were synthesized using a simple, eco-friendly hydrothermal technique with L-cysteine as the precursor. The synthesis approach produced highly water-dispersible, heteroatom-doped CDs with surface functional groups comprising amine, carboxyl, thiol, and sulfonic acid. Data analysis of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM) confirmed their amorphous nature, nanoscale dimensions (1–8 nm, average particle size of 2.6 nm), and surface chemistry. Optical examination revealed intense and pure blue fluorescence emission under UV excitation, with excitation-dependent emission behavior attributed to surface defects and heteroatom doping. The N, S-CDs were applied as fluorescent probes for detecting perfluorooctanesulfonic acid (PFOS), a notable component of the perfluoroalkyl substances (PFAS) family, demonstrating pronounced and concentration-dependent fluorescence quenching. A linear detection range of 3.33–20 µM and a limit of detection (LOD) of 2 µM were reported using the N, S-CDs probe. UV-Vis spectral shifts and dye-interaction investigations indicated that the sensing mechanism is regulated by non-covalent interactions, primarily electrostatic and hydrophobic forces. These findings confirm the potential of N, S-CDs to be used as effective optical sensors for detecting PFOS in environmental monitoring applications. Full article

A novel polyhedron-based anionic Er-MOF with three types of cages and abundant open metal sites (OMSs) and Lewis base sites (LBSs) has been successfully synthesized. The inorganic secondary unit possesses a rarely reported six-connected three-nucleated rare-earth cluster, and the overall framework shows a new (3,3,6)-connected topology. The Er-MOF has good fluorescence selectivity and anti-interference performance with Fe³⁺ and Cu²⁺. In addition, benefiting from the anionic framework, nanoscale cavity and small window size of the Er-MOF, the composite RhB@Er-MOF has been synthesized by in situ encapsulation of the cationic dye Rhodamine B (RhB). It can provide dual-emitting fluorescence that facilitates self-calibration in sensing. The RhB@Er-MOF has higher accuracy than the Er-MOF with regard to the fluorescence-selective and anti-interference performance of Fe³⁺ and quenching coefficient K_sv values of 1.97 × 10⁴ M⁻¹, which are attributed to its self-calibration function that can eliminate environmental interference. The fluorescence quenching mechanism was explained by our experiments and density functional theory (DFT) calculations. Furthermore, RhB@Er-MOF can achieve the visual and rapid selective detection of Fe³⁺ by a smartphone RGB color analysis application, resulting in the dual-signal output performance of the material. Full article