Fluolab荧光爱好者周刊（第三十二期）
ACS Omega
Noncovalent Interaction-Based Probe Design for PET-Facilitated Fluorescence Sensing of Synthetic Cannabinoids
Due to the structural diversity and rapid iteration of synthetic cannabinoids (SCs), their detection presents a challenging issue. Here, based on the structure and physicochemical property analysis of a typical SC, MDMB-CHMICA, four fluorescent probes were designed by introducing the recognition groups and fluorescence regulation groups on carbazole. It is found that the electron-withdrawing and conjugation-extending effect of the nitro group reduced the LUMO energy level and thereby narrowed the HOMO–LUMO energy gap, resulting in a red-shift of the fluorescence emission. As a result, the intramolecular charge transfer mechanism of the probe helps to lead to stronger fluorescence with a greater charge transfer distance. Two probes with stronger fluorescence show multiple noncovalent interactions with MDMB-CHMICA and efficient fluorescence quenching sensing through photoinduced electron transfer. This study is expected to shed light on the exploration of fluorescent probes from the analytes’ physicochemical nature and would be helpful for new psychoactive substance detection.
Analytical and Bioanalytical Chemistry
Dual DNA recycling amplification-assisted CRISPR/Cas12a cleavage for dual-channel ratiometric fluorescence biosensing of kanamycin antibiotic
Fluorescence biosensors hold significant importance for testing antibiotic residues which seriously endanger public health. However, how to adopt appropriate strategies to address the false result disadvantage involved in traditional single-channel biosensors is still a great challenge. Meanwhile, too much attention focused on designing signal amplification strategies of biosensors unavoidably decreases their detection efficiency. Herein, we combined the designed dual DNA recycling amplification strategy with CRISPR/Cas12a-mediated dual-channel signal output mode to successfully develop a novel ratiometric fluorescence biosensor for testing kanamycin (Kana) residues in complex sample matrices. The first recycling was formed from an exonuclease-assisted aptamer recognition reaction, which also triggered another cascade DNA recycling to amplify the release of the Cas12a activator. With the non-discrimination cleavage of Cas12a to cause reverse fluorescence changes of copper nanoclusters and an AMAC-labeled signal DNA, the ratiometric signal transduction strategy was constructed. Under optimal conditions, this biosensor could be applied for ultrasensitive testing of Kana antibiotics in a five-order of magnitude wide linear range with a low detection limit of 17.2 fg mL−1. Benefiting from the self-correction function of the ratiometric signal transduction mode, it showed promising practicality in lake water and milk samples with the relative error less than 4.9% to the standard ELISA results. Besides CRISPR/Cas12a-based fluorescence output efficiency improvement, this biosensor also excluded the complicated manipulations and expensive instruments required in traditional methods. Therefore, it provides a good choice for expanding the application of fluorescence biosensing technology for practical analysis application.
Aggregate
Fluorescence Color Gradient Immunochromatographic Assay for Highly-Sensitive, Quantitative, and Simultaneous Detection of Small-Molecule Pollutants
Rapid on-site screening of small-molecule pollutants in complex samples is essential but remains unachieved. In this study, we introduce a universal fluorescence color gradient immunochromatographic assay (FCGICA) utilizing dual-signal superposition to enable ultra-sensitive, wide-range, and simultaneous quantitative detection of multiple small molecules. A red fluorescent nanomembrane (GTQD@Si) is synthesized by the continuous self-assembly of multilayer quantum dots and a SiO2 shell on a graphene oxide surface. This nanomembrane exhibits high stability in complex environments and provides superior fluorescence along with a larger reactive interface for sensing. The integration of GTQD@Si with green fluorescent microspheres embedded in the test line generates a broad fluorescence color gradient based on variations in target molecule concentrations, thereby significantly enhancing the sensitivity, stability, and quantitative range of the immunochromatographic assay (ICA). By directly reading the ratio of red and green image signals, the proposed FCGICA enables simultaneous, high-sensitivity, and quantitative detection of three different types of small-molecule pollutants including fumonisin B1, imidacloprid, and clenbuterol within 15 min, with a detection range improved by 2–3 orders of magnitude compared with traditional methods. Moreover, the powerful practicality of FCGICA has been verified through comprehensive testing on various real samples, demonstrating its great potential in on-site detection of small molecules.
Applied Organometallic Chemistry
Zn (II) Complexes Synthesized With Salamo-Type Ligand as a Highly Efficient Sensor to Detect MnO4− in Aqueous Solution
Herein, Three Salamo-type Zn (II) complexes [Zn2(L)(μ-OAc)]·CH3OH (1), [Zn4(L)2]Cl2 (2), Zn4(L)22 (3) is synthesized as the fluorescence probe for ultrasensitive detection of MnO4− in aqueous solution. The structure analysis shows that complex 1 is a binuclear structure, while complexes 2 and 3 is a symmetric tetranuclear structure. Three complexes exhibited high stability of fluorescence intensity in aqueous solvent. The detection limit is 8.8, 12.8 and 13.8 μM. The anions involved in coordination in complex 1 undergo structural changes due to their different coordination modes compared with complexes 2 and 3, resulting in better detection performance than the other two complexes. Zn (II) complexes have good selectivity and applicability for the determination of MnO4− in aqueous solutions. At the same time, the sensing effect in the real water samples was also detected. In addition, the fluorescence recognition mechanisms of three complexes for the detection of the above analytes were explored in detail.
Biomaterials Advances
A multi-modal embolic gel system for long-term fluorescence imaging and photothermal therapy
Gel embolic agents are increasingly recognized for their versatility in minimally invasive vascular interventions. However, their application in real-time imaging, post-operative monitoring, and thermal treatment remains underexplored. In this study, we present a novel transcatheter injectable nanoclay-alginate (NCA) gel embolic agent integrated with indocyanine green (ICG) for dual fluorescence imaging and thermal ablation. The NCA/ICG embolic gel exhibits excellent shear-thinning properties, transcatheter injectability, and mechanical stability. Furthermore, the mechanism to enhance fluorescence for real-time imaging enhancement and extended post-operative monitoring was discussed. A 28-day fluorescence persistence shows the NCA/ICG gel's long-lasting fluorescent signal, which was significantly stronger and longer compared to current clinically used ICG aqueous solution. Furthermore, the gel can effectively convert near-infrared (NIR) laser energy into heat for potential photothermal therapy. The biocompatibility and enhanced antibacterial properties further highlight the potential clinical benefits of this embolic agent as a multifunctional agent for vascular embolization.
ChemistryEurope
Fluorescent Probe for δ-Cyclodextrin Enables Guest Encapsulation Studies via an Indicator Displacement Assay
A molecular probe that partially unfolds and exhibits fluorescence enhancement upon binding to δ-cyclodextrin (δ-CD) is presented. Its implementation in a fluorescence indicator displacement assay to test the binding of various guest to δ-CD is demonstrated.
ChemistrySelect
Fluorescent Nanoprobe Based on Ex_g-C₃N₄ for Highly Selective and Fast-Response Aluminum Detection in Water Samples
A novel fluorescent nanoprobe based on Ex_g-C₃N₄ for detecting Al3+ is proposed. Ex_g-C3N4 fluorescent nanoprobe can rapidly and selectively detect Al3+ in water with a detection limit of 5.75 nM and 10 s response time. A portable fluorescent test strip for the rapid detection of Al3+ is successfully developed based on Ex_g-C₃N₄, which can rapidly and conveniently detect Al3⁺ ion in solution.
Dyes and Pigments
Facile synthesis of dual-ligand Eu-MOF for ratiometric fluorescence and smartphone-assisted visual detection of Al3+
In this study, a neoteric dual-ligand europium metal-organic framework (Eu-MOF) was synthesized by a simple one-pot method for visual detection of Al3+. The Eu-MOF was prepared with 2,5-dihydroxyterephthalic acid (H2DHT) and dipicolinic acid (DPA) as dual-ligand and Eu3+ ions as a metal node, also denoted as Eu–H2DHT/DPA. Benefitting from the specific coordination of Al3+ by hydroxyl group of the ligand H2DHT, the emission at 515 nm derived from H2DHT increased significantly through an excited-state intramolecular proton transfer (ESIPT) mechanism. However, the emission at 620 nm from Eu3+ changed slightly which was used as the reference signal. The Eu–H2DHT/DPA probe exhibited clearly recognizable color change from orange-red to yellow-green with the increasing Al3+ concentration. In conjunction with smartphone to read color hue, the sensitive visual quantitative detection of Al3+ was realized. Moreover, the feasibility of detection of Al3+ in real water samples was verified. This study offers a sensitive and convenient route in the design and fabrication of novel fluorescence ratiometric probe with self-calibration model for detection of contaminants in practical water samples.
Highly sensitive colorimetric and fluorescence “Turn On” sensing of hydrazine via restriction in intramolecular vibrations of AIEE active fluorophore
Hydrazine (N2H4), a B2 toxin, harms the environment due to its extensive use in industries. Because of its lethal hypertoxicity and carcinogenicity, there is a crucial need to identify and quantify hydrazine. For this purpose, we developed a colorimetric and fluorometric probe MFB for sensitive and selective detection of hydrazine (N2H4). The mefenamic acid-derived benzamide MFB was easily synthesized by coupling reagent through a single step. Fluorescent probe MFB shows the extraordinary aggregation-induced emission enhancement (AIEE) characteristics with the formation of aggregates. The DLS analysis was performed to determine the aggregates particle size and interaction with probe MFB. The probe MFB exhibits a strong emission wavelength at 444 nm in aggregated state. Furthermore, the probe MFB has selectively detected the hydrazine (N2H4) through a blockage of semi-photoinduced electron transfer and restricted intramolecular vibrations mechanism with the lowest possible detectable amount of 47.3 nM. The interaction of MFB with hydrazine (N2H4) was verified by the UV–Visible and 1H NMR titration experiments. Moreover, theoretical studies like orbitals energy calculation and type of interactions were executed to support the experimental findings. Interestingly, the probe MFB was employed in both solution and solid states for the favourable detection of hydrazine (N2H4) in real-time analysis including drinkable water, beverages, industrial wastewater, soil samples, mung bean sprouts and artificial urine samples.
A multifunctional ratiometric fluorescence sensing platform for Salicylaldehyde, DPA, Al3+, and Pb2+ in water samples
Developing multifunctional sensing platform for recognizing various toxic substances in water samples is essential for public safety. Salicylaldehyde is widely used in fine chemicals such as spices, pharmaceuticals, pesticides, dyestuffs and metal chelating agents. 2, 6-pyridinedicarboxylic acid (DPA), the main component of bacterial spores, is regarded as the most important biomarker for anthrax detection. Excessive exposure to Al3+ is associated with health risks such as Alzheimer's and Parkinson's diseases. Pb2+, a significant environmental pollutant, can lead to various health issues including muscle paralysis, anemia, and memory and mental health concerns. This work develops a dual-emission hybrid SiQDs@ZIF-8@Eu3+@HPU-14 for ratiometric detection of SA, DPA, Al3+ and Pb2+. Due to the enhanced emission at 484 nm and quenched emission at 618 nm, SiQDs@ZIF-8@Eu3+@HPU-14 has a low detection limit of 138 nM for SA. Besides, the emission at 618 nm could be enhanced by trace DPA and quenched by large concentration of DPA (LOD = 0.637 nM). The addition of Al3+ and Pb2+ in SiQDs@ZIF-8@Eu3+@HPU-14-SA solution could bring about distinct fluorescence responses, allowing the ability of SiQDs@ZIF-8@Eu3+@HPU-14-SA to distinguish Al3+ (LODAl3+ = 321 nM) and Pb2+ (LODPb2+ = 158 nM). Furthermore, a logical gate system and sensing film as well as a new microfluidic sensor-array platform were designed, offering intelligent and portable sensing prospects. This work introduces innovative ideas for synthesizing sophisticated hybrid materials with integrated sensing functionalities applied in water environment.
Intermetallics
Development of rapid analysis technique for Al, Nb, and Cr in TiAl alloys using X-ray fluorescence
TiAl alloy is a lightweight heat-resistant material that is used in turbine wheels in automotive turbochargers and turbine blades in aircraft engines. If the composition of the molten metal can be analyzed during melting (rapid analysis) and controlled within the standard by composition adjustment, it is effective in reducing the ingot scrap. Therefore, in this study, we present to develop rapid analysis technique using XRF through the making of high-precision standard sample and calibration curve. The standard sample was made by combining CCIM and PAM. Using the standard sample, the calibration curve was made that could be used in the range of 27mass% to 34mass% of the Al composition. We had developed the rapid analysis technique that could narrowly control the Al composition to within the upper and lower limits of 0.2mass% with respect to the target Al composition.
Inorganic Chemistry
Synergistic Photochromism, Fluorescence Switching, and Photomagnetism of Three Mn(II) Complexes Based on a Thiazolothiazole Extended Viologen Derivative
Multifunctional photochromic hybrid materials have attracted great attention due to their wide prospects in information storage, molecular switches, and sensors. Herein, three new photochromic coordination polymers (CPs) with paramagnetic Mn2+ ions, namely [Mn2(TTVP)(m-BDC)2] (1), [Mn3(TTVP)(p-BDC)3(H2O)2]·0.5H2O (2), and [Mn(TTVP)(H2O)4]·(4,4′-BPC)·2H2O (3) have been synthesized (TTVP = 2,5-bis(pyridinium-4-yl)thiazolo[5,4-d]thiazole propionate, m-H2BDC = isophthalic acid, p-H2BDC = terephthalic acid, 4,4′-H2BPC = 4,4′-diphenyldicarboxylic acid). Interestingly, under Ultraviolet (UV) light irradiation, these compounds exhibit distinct photochromic performances due to photoinduced electron transfer (PIET) between aromatic carboxylic acids and TTVP, as validated by spectroscopic and structural analyses. The coloration kinetics and final states are finely tuned by modulating the number and strength of weak interactions between electron donors (EDs) and electron acceptors (EAs). Furthermore, these complexes exhibit photoinduced magnetization enhancement at room temperature, while complexes 2 and 3 exhibit reversible fluorescence modulation during the coloration-decoloration cycles. The introduction of photoregulated fluorescent and magnetism into PIET photochromic compounds presents a promising approach for the development of multifunctional materials, holding potential for a range of applications.
International Journal of Molecular Sciences
What Can Fluorescence Tell Us About Wine?
Rapid and cost-effective measurements of the autofluorescence of wine can provide valuable information on the brand, origin, age, and composition of wine and may be helpful for the authentication of wine and detection of forgery. The list of fluorescent components of wines includes flavonoids, phenolic acids, stilbenes, some vitamins, aromatic amino acids, NADH, and Maillard reaction products. Distinguishing between various fluorophores is not simple, and chemometrics are usually employed to analyze the fluorescence spectra of wines. Front-face fluorescence is especially useful in the analysis of wine, obviating the need for sample dilution. Front-face measurements are possible using most plate readers, so they are commonly available. Additionally, the use of fluorescent probes allows for the detection and quantification of specific wine components, such as resveratrol, oxygen, total iron, copper, hydrogen sulfite, and haze-forming proteins. Fluorescence measurements can thus be useful for at least a preliminary rapid evaluation of wine properties.
Journal of Cluster Science
Pyridine and Cyclohexylamine Fluorescence Paper Sensors Based on Two cubane-type Cu4I4 Clusters
A cubane-type Cu4I4 cluster 3-PhPy4Cu4I4 (1) was designed and synthesized (3-PhPy = 3-phenylpyridine). The cluster was characterized by elemental analysis, X-ray diffraction, FTIR and UV-Vis spectroscopic analysis. Single-crystal X-ray diffraction revealed that cluster 1 presents a supramolecular interlocking chain structure. Similar cluster 4-PhPy4Cu4I4 (2) was also prepared and re-determined. The TD-DFT calculations reveal that their UV-Vis absorption and luminescence originate from the hybrid [(X + M)LCT] excited states. Based on the cluster 1, a paper-based sensor (1) was prepared through a composite process, it shows a remarkable PL quenching response for pyridine (Py) / cyclohexylamine (CYA) detection with good selectivity. Using this sensor, an amazing sensing speed of T90 = 5 s was achieved for the detection of Py and T90 = 10 s for CYA. In the fluorescence sensing response of these two volatile organic compounds, their maximum fluorescence quenching efficiency reached outstanding 98%. The sensor (2) based on cluster 2 also demonstrated similar fluorescence sensing performance for selective detection of Py or CYA.
Journal of Clinical Medicine
Overcoming Barriers in Neurosurgical Education: Introducing a Simulator for Insular Glioma Resection with Fluorescence Imaging (SIGMA)
Background and Objectives: Realistic surgical simulation models are essential for neurosurgical training, particularly in glioma resection. We developed a patient-specific simulation model designed for fluorescence-guided glioma resection, providing an anatomically accurate and reusable platform for surgical education. While insular gliomas were used as an example, the model can be adapted to simulate gliomas in other brain regions, making it a versatile training tool. Methods: Using open-source 3D software, we created a digitally reconstructed skull, brain, and cerebral vessels, including a fluorescent insular glioma. The model was produced through additive manufacturing and designed with input from neurosurgeons to ensure a realistic and reusable representation of the Sylvian fissure and bone structures. The simulator’s educational effectiveness and usability were evaluated by two senior physicians, four assistant physicians, and six medical students using actual microsurgical instruments. Assessments were based on subjective and objective criteria. Results: Subjective evaluations, using a 5-point Likert scale, showed high face and content validity. Objective measures demonstrated strong construct validity, accurately reflecting the participant’s skills. Medical students and resident neurosurgeons showed marked improvement in their learning curve over three attempts, with progressive improvement in performance. Conclusions: This simulation model addresses advanced neurosurgical training needs by providing a highly realistic, cost- effective, and adaptable platform for fluorescence-guided glioma resection. Its effectiveness in enhancing surgical skills suggests significant potential for broader integration into neurosurgical training programs. Further studies are warranted to explore its applications in different glioma localizations and training settings.
Journal of Vinyl and Additive Technology
Can lead content be measured by handheld X-ray fluorescence spectroscopy to meet REACH regulation?
Lead compounds have long been the most commonly used stabilizers for PVC products, but they are classified as toxic to reproduction category 1A, and their use is restricted in Europe. To promote recycling, the European Union adopted Regulation (EU) 2023/923, which permits the use of recycled rigid PVC (PVC-U) containing up to 1.5% w/w of lead in specific products. This study compares the results obtained from two different handheld X-Ray Fluorescence (HHXRF) devices on samples with known composition, also considering the matrix effect. This kind of evaluation is still missing in the literature. The measurements from both HHXRF devices show that the lead content falls within the 13% of relative inaccuracy range specified for lead in IEC 62321-3-1:2013, the standard currently used for determining lead in electrotechnical products. To assess whether the matrix effect can influence the measurements, two samples were produced by altering only the content of titanium dioxide. The results from both instruments were not significantly different, considering the 13% inaccuracy. In conclusion, HHXRF could be an effective method to determine the lead concentration in its usual dosage in the PVC-U matrix. In case of inconclusive results based on this range, it is recommended to analyze the sample with another, more accurate technique, such as ICP.
Journal of Analytical Atomic Spectrometry
The occurrence and sources of Ni in ambient air particulates using synchrotron radiation based X-ray fluorescence and X-ray absorption near edge structure
Nickel (Ni) is a transition metal widespread in the environment, and derives from both natural sources and industrial activities. In turn, environmental nickel pollution may be linked to these natural and anthropogenic sources including sea spray, industrial processes, commercial products (fuels), and agriculture waste burning. High concentrations of Ni in the ambient air might cause acute, chronic, and noxious effects on human health, and are known to induce in particular carcinogenic effects. The present work aims at investigating the presence and related concentration of Ni and its species in ambient air particulates using a combination of laboratory and advanced X-ray synchrotron radiation-based techniques. For this purpose, suspended particulate matter (SPM) and fine particulate matter with an aerodynamic diameter equal to or less than 2.5 μm (PM2.5) were collected from residential and industrial areas of Cairo, Egypt using an established air sampler setup. The quantitative elemental results indicate remarkably high concentrations of Ni in the ambient air particulates, ranging from 20 to 30 ng m−3, which, for most samples, are higher than the annual allowance thresholds as indicated by the World Health Organization (WHO) and in the air quality standard of the European Union. Elemental maps of nickel were acquired to unravel its spatial distribution on the filters carrying the ambient air particulates. Complementary X-ray absorption near edge structure (XANES) spectroscopy at the Ni K-edge (8333 eV) was used to determine Ni speciation. Together with linear combination fitting, our results demonstrate that Ni species at the industrial area is predominantly found under its divalent oxidation state in the studied ambient air particulates.
Materials Today Bio
pH-responsive nanovesicles capable of remodeling the tumor microenvironment enable activatable near-infrared-II fluorescence image-guided enhanced radiotherapy
Traditional radiotherapy (RT) lacks the precision to distinguish between tumor and normal tissues, leading to inevitable X-ray-induced side effects in patients. Therefore, it is crucial to develop integrated imaging and therapeutic modalities that can reduce side effects on surrounding healthy tissues while enhancing susceptibility to tumor tissues. In this study, we developed a pH-responsive nanodrug (AuNRs-Mn3O4-Ag2S Ve) by self-assembling the second near-infrared (NIR-II, 950–1700 nm) fluorescent probe Ag2S quantum dots (QDs), multifunctional nanozyme Mn3O4 nanoparticles (NPs), and radiosensitizer gold nanorods (AuNRs) into a single nanoplatform via an emulsion process. This nanodrug enables precise tumor localization for accurately guided RT and multi-angle sensitization of RT. Upon intravenous administration, the nanodrug disintegrates in the tumor area due to the pH-sensitive polymer P4VP, releasing Ag2S QDs which are specifically activated by the acidic environment, thereby “turning on” the NIR-II fluorescence signal. The optimal timing of the NIR-II fluorescence signal within the tumor region after intravenous injection was investigated, providing a reference for guided RT. In vitro and in vivo experiments confirmed the efficient enhancement of tumor radiosensitization by AuNRs and Mn3O4 NPs. The specific imaging modality that transitions the fluorescence signal from “off” to “on” has been successfully implemented, addressing the limitations of conventional RT and enhancing radiosensitivity. The integration of imaging and therapeutic approaches in this study presents a promising modality for image-guided tumor RT.
Materials Chemistry and Physics
Surface porosity-boosted fluorescence performance of N,N′-Bis(salicylidene)-1,3-propanediamine nanoparticles for thiabendazole detection: Sensing mechanism by DFT
Cluster-assembled materials based on small organic molecules (SOMs) have attracted much attention as appropriate platforms for different functional explorations due to their large surface-to-volume ratio. However, the self-association propensity of SOMs induces increased surface energy, surface passivation, and altered surface tension, limiting their large-scale applications. Suitable structural modification would be attempting this issue to achieve the highest level of surface stability. To this end, we fabricate SOMs-based fluorescent organic nanoparticles (ONPs) using N,N′-Bis(salicylidene)-1,3-propanediamine (BSPD); its surface stability and porosity were modified by introducing Na+ ions in BSPD-ONPs. Results from FTIR, UV–vis, Raman, XRD, and SEM show that there is enhanced crystalline behavior observed with the presence of Na; the micrographs obtained from atomic force microscopy (AFM) before and after introducing Na showed an improved surface morphology of BSPD-ONPs with highly ordered granulated particles with a size of 25 nm. Which is observed as, with the involvement of Na+ ions, the roughness of the particles reduced from 258 nm to 33 nm, and the average density of 0.560/μm increased to 1.136/μm2, indicating that the increased compactness of the particles and the improvement of the photophysical character. These surface-modified ONPs acted as a high-performance turn-on fluorescence sensor towards thiabendazole (TBZ) detection (detection limit of 6.4 × 10−4 μM) in aqueous solution. The sensing mechanism of TBZ by BSPD-ONPs/Na was proposed by analyzing molecular energies involved in host-guest interaction through DFT, showing that the TBZ-recognition system works by a metal ion-induced hyperconjugation effect between the localization of σ electrons of the imine group in BSPD and sp2 nitrogen at the imidazole and thiazole rings of TBZ, which resulted in an elevated fluorescence emission.
Methods
RNA aptamer-induced fluorescence enhancement for NADH monitoring in cellular environment
Cellular redox homeostasis is tightly regulated by the oxidation–reduction reactions of nicotinamide metabolites, including NAD(H) and NADP(H), which serve as essential cofactors in enzymatic processes related to energy metabolism. Monitoring intracellular NADH levels is therefore of significant interest. Most chemosensor designs to date rely on fluorescence turn-on mechanisms triggered by NADH oxidation, but these reaction-based sensors are inherently limited by NADH concentration and reaction kinetics. While NADH exhibits intrinsic fluorescence, its low quantum yield has led to the development of redox-sensitive substrates that emit fluorescence upon NADH oxidation. Here, we report an alternative fluorescence enhancement strategy based on an NADH-binding RNA aptamer. The interaction between NADH and a 49-base-pair RNA aptamer induces a 1.4-fold increase in fluorescence emission in vitro and an 1.8-fold increase in live-cell imaging. This fluorescence enhancement arises from aptamer-induced structural rigidity, analogous to the mechanism by which 4-(p-hydroxybenzylidene)-5-imidazolidinone (HBI) enhances fluorescence in green fluorescent protein. Using our aptamer-based assay, we established a live-cell fluorescence emission assay for real-time monitoring of cellular NADH dynamics.
New Biotechnology
Screening assay for polyester hydrolyzing microorganisms using fluorescence-labeled poly(butylene adipate)
Despite recent advances, there is still a demand for more efficient enzymes hydrolyzing synthetic polymers. Automated high throughput screening strategies of microorganisms from different environments could yield novel enzymes but require specific methods for detection of polymer hydrolysis in complex matrices. Here, 5-carboxy-fluorescein (5-FAM) was covalently coupled to poly(butylene adipate) (PBA) and blended at 1 %, 5 % and 10 % w/w concentrations with non-labeled PBA. Hydrolysis of PBA by the Thc_Cut1 cutinase from Thermobifida cellulosilytica was confirmed via quantification of the released monomers 1,4-butanediol and adipic acid, weight loss and FTIR analysis. Upon incubation with Thc_Cut1, hydrolysis of all three fluorescent labeled PBA blends lead to a clear fluorescence increase of up to 4000 RFU while no signal change was detected for the blank and for heat-inactivated enzyme (signal below 500 RFU). In a next step, as a model organism Pichia pastoris expressing the identical cutinase was cultivated in the presences of labeled PBA. Despite the complex matrix, a fluorescence increase of up to 500 RFU was observed for P. pastoris expressing the enzyme while no significant signal change was seen for the control strain (lacking Thc_Cut1 expression). Likewise, extracellular enzymes from the fungi Fusarium solani and Alternaria alternata hydrolyzed labeled PBA leading to fluorescence increases of 1328 and 1187 RFU. This indicates that 5-FAM covalently coupled to polymers could be used for development of simple and high throughput screening platforms to identify polymer decomposing microorganisms and enzymes.
Organic Geochemistry
Nanometer-scale relationships between sedimentary organic matter molecular composition, fluorescence, cathodoluminescence, and reflectance: The importance of oxygen content at low thermal maturities
Molecular characterization of sedimentary organic matter (SOM), termed macerals, is a common goal when seeking to understand petroleum generation as well as other geologic processes in deep time. However, unambiguous measurement of discrete macerals is challenging due to the small size of organic particles in sedimentary rocks, the proximity of different organic matter types to one another, mineral-organic matter interactions, and maceral mixing that occurs during SOM isolation prior to ex situ analysis. The recent advent of infrared spectrometers capable of nanometer-scale resolution and the application of these technologies to geologic samples has enabled advances in rapid, in situ molecular characterization of SOM allowing for insights into paleoenvironmental processes, such as organic matter productivity and preservation, among others. Here we employ one such technology, optical photothermal infrared (OPTIR) spectroscopy, to map SOM functional group distributions at 500-nm resolution in a sample from the Lower Cretaceous Sunniland Limestone of the South Florida Basin. Examined fields of view include occurrences of amorphous organic matter (AOM), inertinite, micrinite, solid bitumen, telalginite, and vitrinite. OPTIR data from these macerals are compared against traditional organic petrographic data from the same organic grains including fluorescence intensity and white light reflectance as well as against cathodoluminescence response, an emerging organic petrographic approach. Maceral oxygen content (using carbonyl functional group abundance as a proxy) is observed to vary widely between maceral types but correlates strongly with fluorescence and cathodoluminescence intensity as well as against reflectance. These findings highlight the important role that oxygen content plays in determining the optical properties of SOM and further demonstrate the ability of OPTIR to discriminate subtle molecular differences between SOM types.
Pharmaceutics
Carbon Dots as a Fluorescent Nanosystem for Crossing the Blood–Brain Barrier with Plausible Application in Neurological Diseases
Background/Objectives: The development of effective therapies for brain disorders is highly correlated with the ability of drugs or nanosystems to cross the blood–brain barrier (BBB), which has been limited. Recently, carbon dots (CDs) have been receiving attention to be used as BBB-crossing theranostic agents due to their inherent advantages, such as low size, excellent biocompatibility, high quantum yield (QY), tunable fluorescence, high drug loading, and relatively easy synthesis at low cost. The aim of this study was to design CDs with precisely controlled fluorescence properties for advanced bioimaging and an in-depth assessment of BBB permeability. Methods: CDs were synthesized using a microwave-assisted approach, optimized through microwaves’ irradiation time, and employing citric acid, urea, and sodium fluoride as precursors. The optimized sample was labeled as NF-CD. Results: A comprehensive physicochemical, photoluminescence, and biological characterization revealed the ability of NF-CD to diffuse across a neuromimetic-BBB model, mainly due to their small size (average diameter of 4.0 ± 1.1 nm), exhibiting excitation-dependent fluorescence in the blue and green wavelengths, high biocompatibility and QY, and exceptional photostability. Conclusions: Owing to the exceptional fluorescence characteristics and biological compatibility, NF-CD presents promising opportunities in theranostic applications, particularly in brain-targeted bioimaging, nanocarrier-based drug and immunotherapy delivery, early-stage diagnostics, and personalized medicine. NF-CD’s ability to cross the BBB further underscores the relevance of pioneering nanomaterial-based strategies for neurological disorder diagnostics and precision-targeted therapeutic interventions. Overall, this research contributes to the broader field of nanotechnology-driven biomedical advancements, fostering innovations in neurological diagnostics and therapeutic delivery systems.
Physiology and Molecular Biology of Plants
Effects of cadmium (Cd) on photosynthetic characteristics and chlorophyll fluorescence parameters in the ornamental Plant Salvia splendens Ker-Gawl
Salvia splendens Ker-Gawl. (scarlet sage), widely used in urban landscaping, it is frequently exposed to cadmium (Cd) contamination resulting from industrial and vehicular emissions. However, its tolerance and adaptability to Cd stress remain poorly understood. A soil experiment was conducted to investigate the effects of Cd on the growth and the photosynthetic performance of S. splendens by measuring photosynthetic pigments, gas exchange and chlorophyll fluorescence parameters. Four weeks-seedlings were treated with 0 (CK), 0.5, 2.5, 5, 10, 25 and 50 mg·kg−1 Cd for 60 days. Results showed significant reductions in root length and biomass of leaves, stems, and roots, with shoot and root biomass notably decreasing by up to 46.3% and 28.5% at higher Cd levels, respectively. The translocation factor remained low (TF < 1.0), and the bioaccumulation factors (BCF < 1.0) decreased when Cd higher than 5 mg·kg−1, indicating limited Cd uptake. Cd stress (> 5 mg·kg−1) caused a decrease in Chl a and Chl b content, but increased the Chl a/b ratio, thereby disrupting photosynthesis and causing significant declines in photosynthetic parameters. Cd exposure (> 2.5 mg·kg−1) significantly decreased net photosynthetic rate (Pn) by 18.94–52.91%, stomatal conductance (Gs) by 35.77–58.53%, and transpiration rate (Tr) by 24.63–48.83%, accompanied by only a slight reduction in inter-cellular CO2 concentration (Ci) of just 7.0%, indicating non-stomatal factors in Pn decline. Cd concentrations (> 5 mg·kg−1) caused a reduction in initial fluorescence (Fo) by 7.44–31.58% and maximal fluorescence (Fm) measurements by about 20%, indicating damage to photosystem II (PSII). At 50 mg·kg−1, further decreases were observed in photochemical quenching (qP) by 40.31%, the quantum yield of photochemical energy dissipation (ΦPSII) by 44.77%, and the electron transport rate (ETR) by 25.11%, while non-photochemical quenching increased by 42.66%, signifying significant PSII inhibition and enhanced photoinhibition. Decrease in ΦPSII, along with the increase in the quantum yield of regulated non-photochemical energy loss in PSII (ΦNPQ) and the quantum yield of non-regulated energy loss in PSII (ΦNO) as Cd levels rise, indicates enhanced non-photochemical energy dissipation and greater photoinhibition. S. splendens shows high sensitivity to Cd stress, with reduced growth and disrupted photosynthesis, highlighting its potential as a bioindicator for Cd contamination in urban areas.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
A near-infrared fluorescence probe for sensing mitochondrial viscosity in cells and mice
Mitochondria play a critical role in providing energy to maintain cellular physiological functions. The viscosity in mitochondria is one of the important indicators of mitochondrial microenvironment. When mitochondrial viscosity increases, it often indicates the occurrence or development of certain diseases. Herein, a series of near-infrared (NIR) fluorescent probes (ZHY-1 ∼ 4) were developed to detect viscosity changes. After screening, we selected ZHY-2 for cellular imaging, since it had the largest fluorescence intensity enhancement (222 times) in response to viscosity compared to the other probes (ZHY-1, ZHY-3, ZHY-4). In addition, ZHY-2 responded to viscosity specifically, and was not affected by pH and other biological species. Also, the probe ZHY-2 had good biocompatibility and mitochondria-targeting ability. It has been applied to measure viscosity changes after stimulation of nystatin and rapamycin. Finally, using probe ZHY-2, we have achieved the real-time fluorescence imaging of viscosity during starvation, as well as in drug-induced liver injury mice.
Sensors
Research on the Transformer Failure Diagnosis Method Based on Fluorescence Spectroscopy Analysis and SBOA Optimized BPNN
The representative dissolved gases analysis (DGA) method for transformer fault detection faces many shortcomings in early fault diagnosis, which restricts the application and development of fault detection technology in the field of transformers. In order to diagnose early failure in time, fluorescence analysis technology has recently been used for the research of transformer failure diagnosis, which makes up for the shortcomings of DGA. However, most of the existing fluorescence analyses of insulating oil studies combined with intelligent algorithms are a qualitative diagnosis of fault types; the quantitative fault diagnosis of the same oil sample has not been reported. In this study, a typical fault simulation experiment of the interval discharge of insulating oil was carried out with the new Xinjiang Karamay oil, and the fluorescence spectroscopy data of insulating oil under different discharge durations were collected. In order to eliminate the influence of noise factors on the spectral analysis and boost the accuracy of the diagnosis, a variety of spectral preprocessing algorithms, such as Savitzky–Golay (SG), moving median, moving mean, gaussian, locally weighted linear regression smoothing (Lowess), locally weighted quadratic regression smoothing (Loess), and robust (RLowess) and (Rloess), are used to smooth denoise the collected spectral data. Then, the dimensionality reduction techniques of principal component analysis (PCA), kernel principal component analysis (KPCA), and multi-dimensional scale (MDS) are used for further processing. Based on various preprocessed and dimensionally reduced data, transformer failure diagnosis models based on the particle swarm optimization algorithm (PSO) and the secretary bird optimization algorithm (SBOA) optimized BPNN are established to quantitatively analyze the state of insulating oil and predict the durations of transformer failure. By using the mathematical evaluation methods to comprehensively evaluate and compare the effects of various algorithm models, it was found that the Loess-MDS-SBOA-BP model has the best performance, with its determination coefficient (R2) increasing to 99.711%, the root mean square error (RMSE) being only 0.27144, and the other evaluation indicators also being optimal. The experimental results show that the failure diagnosis model finally proposed in this paper can perform an accurate diagnosis of the failure time; the predicted time is closest to the true value, which lays a foundation for the further development of the field of transformer failure diagnosis.
