Fluorescence Emission Intensity Research Articles

AIE‐Based Sensor Combination for Oleic Acid/Elaidic Acid Discriminating and Sensing

AbstractTwo aggregation induced emission molecules (TPE‐MZ and QM‐Py‐TPE) have been synthesized and characterized. Similar to conventional AIE based molecules, both molecules displayed good sensitivity towards water fraction and viscosity of dispersing medium. The fluorescent emission intensity of TPE‐MZ gradually reduced with increasing concentration of oleic acid and elaidic acid within the range of 0.2–5 mM. The inflection points of TPE‐MZ fluorescent emission maximum for oleic acid and elaidic acid were observed at 1.40 and 0.80 mM, respectively. The corresponding inflection points of QM‐Py‐TPE were 1.80 and 2.00 mM for oleic acid and elaidic acid, respectively. Sensor combination (TPE‐MZ:QM‐Py‐TPE=2 : 1) emitted pink and yellow fluorescence in elaidic and oleic acid. Fluorescent emission ratio of I646/I508 of sensor combination displayed acceptable linear relationship (R2=0.9826) with concentration of oleic acid (within the concentration of 4 mM). Thus, the sensor combination was capable of oleic acid and elaidic acid naked‐eye discriminating and quantitively sensing.

Imaging of intracellular mitochondrial membrane potential with a highly photostable NIR fluorescent probe

Mitochondrial membrane potential (ΔΨm) participated in important physiological processes such as ATP synthesis, ion exchange, and plays an important role in maintaining normal life activities of cells. Herein, we synthesized a fluorescent probe EDXB (3-ethyl-2-(2-(6-methoxy-2,3-dihydro-1H-xanthen-4-yl) vinyl) benzothiazol-3-ium iodide) with positive charge, which targets mitochondria by electrostatic attraction. The probe has twisted intramolecular charge transfer (TICT) characteristics, resulting in near-infrared fluorescence emission enhanced with the increase of viscosity, when the probe falls off from the mitochondrial membrane to the low-viscosity cytoplasmic aqueous phase, the fluorescence emission intensity is weakened. Therefore, the EDXB exhibited favorable targeting. In addition, EDXB also has good anti-bleaching and pH stability, which enables it to accurately feedback the change of ΔΨm. In the experiment, the intracellular imaging of EDXB certificated mitochondrial depolarization (decrease of ΔΨm) during various cell injury events including cell inflammation, apoptosis and mitophagy. We expect EDXB to be a useful tool for the analysis of ΔΨm changes.

Supramolecular assemblies with aggregation-induced emission for in situ active imaging-guided photodynamic therapy of cancer cells

Photodynamic therapy (PDT) has attracted widespread attention as a novel non-invasive anticancer approach. However, the diminished photosensitivity and limited oxygen exposure caused by the aggregation of traditional photosensitizers greatly impair its overall therapeutic efficacy. Herein, a series of water-soluble aggregation-induced emission luminogens (AIEgens) with triphenylamine as skeleton were synthesized and exhibited bright Near-infrared (NIR) emission and strong reactive oxygen species (ROS) generation. Through host-guest complexation between the multicharged triphenylamine units on AIEgens and cucurbit[10]uril (CB[10]) host molecule, supramolecular nanoassemblies were constructed and exhibited negligible phototoxicity to normal cells due to their limited oxygen contact. In contrast, the efficient release of AIEgens from nanoassemblies through competitive binding of overexpressed peptides in cancer cells with CB[10], enabled the full exploitation of the photosensitivity of AIEgens to produce highly efficient ROS, achieving selective ablation of cancer cells. Moreover, due to the restriction of intramolecular motion (RIM) upon anchored on organelle membranes through electrostatic interactions, the cationic AIEgens with weak fluorescence in physiological environment exhibited intense fluorescence emission, thus realizing imaging-guided PDT. This work may open up an avenue for the development of simple and feasible smart responsive nanomaterials for cancer treatment using supramolecular host-guest complexation strategy.

Rapid assessment of acetophenone using an anti-interfering triple-emission Ln3+-functionalized HOF@MOF sensor

The development of high-performance sensors for rapidly detecting acetylacetone (AP) in water samples is necessary because its release into the environment can result in many vital problems for human health and environment. Herein, we first designed a hybrid by integrating HOF with ZIF-8 through a sequential growth strategy. By separately introducing blue-emitting SiQDs and green- and red-emitting Tb3+ and Eu3+ into ZIF-8 and HOF, the resultant ZIF-8@SiQDs@HOF@Eu3+@Tb3+ comprised three emission peaks at 484, 545 and 620 nm, all of which could be employed as switch-off responsive peaks to low concentrations of AP with a detection limit of 0.79 ppm. However, in environments with high concentrations of AP, a turn-on signal at 484 nm was observed. Thereupon, the ratiometric fluorescence intensity of the ternary emission varied within different concentration ranges, accompanied by the fluorescence color evolution from red to salmon to plum to purple to final blue. Moreover, a portable sensing film was fabricated for rapid warning, sensitive and visual determination of AP in complicated environments. Therefore, this triple-emission sensor with wide color variations and strong anti-interference advantages could promote further research to improve the selectivity, sensitivity and inherent self-correction of multimodal fluorescence detection and the ease of sensing operation.

Study on the Performance of Deep Red to Near-Infrared pc-LEDs by the Simulation Method Considering the Distribution of Phosphor Particles.

Effectively utilizing deep red to near-infrared (DR-NIR) phosphors to achieve the optimal performance of NIR phosphor-converted white LEDs (DR-NIR pc-wLEDs) is currently a research hotspot. In this study, an optical model of DR-NIR pc-wLEDs with virtual multilayer fluorescent films was established based on the Monte Carlo ray-tracing method. Different gradient distributions of the particles were assigned within the fluorescent film to explore their impact on the optical performance of pc-LEDs. The results show that, for the case with single-type particles, distributing more DR-NIR particles far from the blue LED chip increased the overall radiant power. The distribution of more DR-NIR particles near the chip increased the conversion ratio from blue to DR-NIR light. The ratio of the 707 nm fluorescence emission intensity to the 450 nm excitation light intensity increased from 1:0.51 to 1:0.28. For multiple-type particles, changes in the gradient distribution resulted in dual-nature changes, leading to a deterioration in the color rendering index and an increase in the correlated color temperature, while also improving the DR-NIR band ratio. The reabsorption caused by the partial overlap between the excitation band of the DR-NIR particles and the emission band of the other particles enhanced the radiant power at 707 nm. Distributing DR-NIR phosphor particles closer to the chip effectively amplified this effect. The proposed model and its results provide a solution for the forward design of particle distributions in fluorescent films to improve the luminous performance of DR-NIR pc-wLEDs.

Photophysical Response of Propranolol in Biomimetic Micellar Media of Alkyltrimethylammonium Bromide Surfactants: Effect of pH and Alkyl Chain Length.

The photophysical behavior of a β-blocker drug propranolol (PPL) in micellar environments, formed by alkyltrimethylammonium bromide surfactants viz.; Cetyltrimethylammonium bromide (CTAB), Tetradecyltrimethylammonium bromide (TTAB), and Dodecyltrimethylammonium bromide (DTAB), has been investigated through fluorescence and UV-visible spectroscopic techniques at pH levels of 3.5, 7.4, and 10.4. The impact of pH on the critical micelle concentration (cmc) and micropolarity of micelles were assessed using pyrene as a photophysical probe. The cmc values were found to be lower at pH 10.4 compared to pH 7.4 and pH 3.5. Fluorescence emission intensities of PPL at 323nm, 338nm, and 352nm were significantly influenced by pH, hydrophobic alkyl chain length of surfactants, and their concentrations. Quenching experiments with Cetylpyridinium chloride (CpCl) indicated the localization of charged and uncharged forms of PPL within micelles, with quenching constant (Ksv) values dependent on alkyl chain length and pH. At pH < pKa, PPL is positioned near the Stern layer, whereas at pH 10.4, its naphthalene moiety resides near the hydrophobic micellar core. UV spectroscopy showed that the charged form of PPL interacted with micelles only above cmc, while the neutral form interacted even below the cmc. Density Functional Theory (DFT) reveals the HOMO of the surfactants to be localized on the hydrocarbon chains, and the LUMO localized around the quaternary ammonium unit. Upon complexation with PPL, both HOMO and LUMO shifted to the drug, thereby decreasing energy levels. The findings are explained based on weak noncovalent interactions, further supported and analyzed through Reduced Density Gradient (RDG) and Noncovalent Interaction (NCI) methods, confirming synergistic non-covalent interactions in surfactant-PPL complexes.

A highly sensitive colorimetric and fluorometric sensor for the detection of cyanide

Certain anions play a vital role in metabolic reactions in our body, but the cyanide ion is highly toxic and poisonous to humans, animals, and the environment even at extremely low concentrations. To detect CN−ions, a highly sensitive electron donor-π-acceptor molecular system (IC) was designed based on the carbazole electron donor and 1,3-indanedione electron acceptor. The IC molecular probe was synthesized through simple organic transformations with good yields and characterized by all spectroscopic methods, including single-crystal X-ray diffraction. The IC probe molecule absorbs in the UV–visible region (200–550 nm), and fluorescence emission encompasses 400–750 nm with LE and CT emission bands. A systematic study suggests that the addition of cyanide ions caused both longer wavelength absorption bands and CT fluorescence emission intensity to decrease. Cyanide ion detection can be visualized with the naked eye, where the yellow color of the IC probe solution changes to colorless upon adding cyanide ion solution. Both UV–visible and fluorescence emission spectral changes with the addition of cyanide ions are attributed to the nucleophilic addition of cyanide at the vinylic carbon, which is confirmed by the 1H NMR, HRMS and fluorescence lifetime studies. The cyanide ion detection limit of the IC has been estimated to be 0.43 µM, far below the WHO permissible limit for cyanide ion concentration in potable water, thus broadening the utility of the IC probe in detecting cyanide in Tapioca. A prototype TLC testing strip has been fabricated for the qualitative determination of cyanide in THF/water medium.

Solvent and media effects on the photophysics of cranad-2 and cranad-58

Alzheimer’s disease (AD) represents the most widespread form of age-related cognitive degeneration, characterized by long-term degenerative damage, cognitive dysfunction, and profound deficits in logical thinking, knowledge acquisition, and interpersonal communication. A principal biomarker of AD involves the emergence and aggregation of β-amyloid (Aβ). Cranad derivatives are fluorescent probes capable of detecting, quantifying, and imaging Aβ aggregates. In this work, the effect of solvent and microheterogeneous environments on the photophysical behavior of CRANAD-2 and CRANAD-58 was investigated employing a large solvent set and several microorganized systems. Both the absorption and fluorescence spectra exhibit a substantial solvatochromic effect, resulting in significant Stokes shifts. Application of linear solvation energy relationships to correlate the fluorescence spectra maxima and the Stokes shift with microscopic solvent parameters suggests significant intramolecular charge transfer during the excitation, as corroborated by the increased dipole moment in the excited state. Generally, fluorescence quantum yields determined for CRANAD-2 exceed those of CRANAD-58 in most solvents, with low values in polar solvents and bigger values in non-polar solvents. Introduction of CRANAD-2 and CRANAD-58 into micellar and vesicular solutions notably augments the fluorescence emission intensity, accompanied by a blue shift in the fluorescence maxima. The fluorescence maxima values observed within microheterogeneous systems closely parallel those reported for interactions between CRANAD derivatives and soluble or aggregated Aβ amyloids which potentially constrains the efficacy of “in vivo” Aβ detection trials, because localization of CRANAD derivatives in non-polar microenvironments present in biological media could interfere with the detection of amyloid fibers.

Orthogonal Determination of Competing Surfactant Adsorption onto Single-Wall Carbon Nanotubes During Aqueous Two-Polymer Phase Extraction via Fluorescence Spectroscopy and Analytical Ultracentrifugation.

A combination of analytical ultracentrifugation (AUC) and fluorescence spectroscopy are utilized to orthogonally probe compositions of adsorbed surfactant layers on the surface of (7,5) species single-wall carbon nanotubes (SWCNTs) under conditions known to achieve differential partitioning in aqueous two-phase extraction (ATPE) separations. Fluorescence emission intensity and AUC anhydrous particle density measurements independently probe and can discriminate between adsorbed surfactant layers on a (7,5) nanotube comprised of either of two common nanotube dispersants, the anionic surfactants sodium deoxycholate and sodium dodecyl sulfate. Measurements on dispersions containing mixtures of both surfactants indicate near total direct exchange of the dominant surfactant species adsorbed to the carbon nanotube at a critical concentration ratio consistent with the ratio leading to partitioning change in the ATPE separation. By conducting these orthogonal measurements in a complex environment reflective of an ATPE separation, including multiple surfactant and polymer solution components, the results provide direct evidence for the hypothesis that it is the nature of the adsorbed surfactant layer that primarily controls partitioning behavior in selective ATPE separations of SWCNTs.

N-Acetyl Cysteine-Cadmium Telluride NAC-CdTe QDs for Detecting the Damaged DNA in Cancerous Diseases

In this study water-soluble N-Acetyl Cysteine Capped-Cadmium Telluride QDs (NAC/CdTe nanocrystals) using N-acetyl cysteine as a stabilizer were prepared to investigate the utility of quantum dots (QDs) in distinguishing damaged DNA, (extracted from blood samples of leukaemia patients), from intact DNA (extracted from blood samples of healthy individuals) to be used for biosensing application. Based on the optical characterization of the prepared QDs, the XRD results revealed the formation of the NAC-CdTe-QDs with a grain size of 7.1nm. Whereas, the SEM test showed that the spherical size of the NAC-CdTe-QDs lies within 11~33nm. NAC-CdTe-QDs have superior PL emission properties at of 550nm and UV-Vis absorption peak at 300nm. The energy gap measurement through PL and UV–Vis was found to be 2.2eV and 2.3 eV, respectively. The interaction between the synthesized QDs and the extracted genomic DNA (both cancer damaged DNA and healthy undamaged DNA) was analysed optically, and compared to the normal reference DNA. The results showed a shift in the maximum fluorescence emission intensities (observed at 540nm nm for a damaged sample and 535 for a reference cell). Based on the obtained fluorescence results, the present study reached the conclusion that the prepared core/shell QDs could be employed as probes for diagnosing genetically disrupted DNA that is associated with malignant diseases from healthy DNA.

Charge reconstruction from simultaneous Fe coordination and P/O co-doping in g-C3N4 for efficient photo-reductive recovery of uranium(VI)

The risk of radionuclide leakage always threats ecological security and human health, making the recovery of uranium from nuclear wastewater a meaningful and urgent issue. However, the low-cost and efficient capture of uranium remains a challenge at present. In this study, a homemade photocatalyst of iron coordinated graphitic carbon nitride (g-C3N4) co-doped with phosphorus and oxygen (OPFCN), which was facilely synthesized through a novel one-step thermal polymerization method, exhibited superior photoelectric efficiency and photocatalytic activity towards the photo-reductive capture of uranium(VI). The simultaneous Fe coordination and P/O co-doping in framework of g-C3N4 played a synergistic effect in charge reconstruction, in which electrons migration driven by coordinated Fe and lone electron pairs delocalization from doped P/O enormously increased electron density and enhanced charge transfer, thus effectively promoting the separation of photogenerated charge carriers. The specific surface area, pore volume and average pore size of OPFCN reached 70.2 m2·g−1, 0.157 cm3·g−1 and 7.78 nm, respectively, exhibiting a trend increasingly beneficial for photocatalytic adsorption and mass transfer with successive introduction of Fe, P and O into original g-C3N4. With the simultaneous introduction of Fe, P and O, the optical absorption edge underwent a significant redshift and fluorescence emission intensity dropped by 75 % compared to that of CN, demonstrating the enhanced visible light capturing ability and significantly inhibited recombination of photogenerated charge carriers in OPFCN. As a result, a uranium capture rate of over 98 % was achieved with catalyst dosage of only 5:1 at pH 5 with OPFCN, demonstrating its competitive photo-reductive activity towards uranium(VI) uptake compared with previously reported g-C3N4-based photocatalysts. Meanwhile, OPFCN exhibited remarkable reusability and stability with even over 65 % uranium recovery rate and almost unchanged peak patterns in XRD and FT-IR in fifth reuse recycle. Additionally, it was demonstrated that e− and O2•− were the direct active species to realize the photoreduction of uranium(VI) over OPFCN, in which e− played the dominant role. The modification method of simultaneous Fe coordination and P/O co-doping would be expected to effectively promote the utilization of g-C3N4-based photocatalysts towards photo-reductive recovery of uranium(VI) from radioactive wastewater.

Preparation and application of wormlike micelles generated from a rosin-based aggregation-induced emission surfactant through coordinating aggregation

Fluorescent nanomaterials have drawn considerable attentions due to their high fluorescence sensitivity, excellent signal stability and tunable luminescent properties. A bio-based aggregation-induced emission (AIE) surfactant (Sodium 4-(tetraphenylstyrene)maleate, MPA-TPE-Na) was prepared from rosin, which showed typical AIE characteristic, obvious solvatochromism and a large Stokes shift (>100 nm). AIE viscoelastic solutions were further prepared by complexing MPA-TPE-Na and cetyltrimethylammonium bromide (CTAB) through coordinating aggregation and their microstructure, fluorescence properties and viscoelasticities were investigated. The aggregates in the viscoelastic solutions were wormlike micelles. As the concentration of MPA-TPE-Na increased, the fluorescence intensity of the viscoelastic solutions increased, and their viscosity increased at first and then decreased. The fluorescence emission intensity of the viscoelastic solutions was barely affected by the change in pH. But reducing the pH could increase its viscosity. This system can specifically recognize Fe3+ without any organic solvent and has anti-interference ability. The present work provided a bio-based fluorescent nanomaterial and verified the feasibility of preparing aqueous AIE nanomaterials by modifying AIE groups with rosin skeleton.

Rapid enzyme-free detection of miRNA-21 in human ovarian cancerous cells using a fluorescent nanobiosensor designed based on hairpin DNA-templated silver nanoclusters

BackgroundCancer is known as one of the main non-communicable diseases and the leading cause of death in the new era. Early diagnosis of cancer requires the identification of special biomarkers. Currently, microRNAs (miRNAs) have attracted the attention of researchers as useful biomarkers for cancer early detection. Hence, various methods have been recently developed for detecting and monitoring miRNAs. Among all miRNAs, detection of miRNA-21 (miR-21) is important because it is abnormally overexpressed in most cancers. Here, a new biosensor based on silver nanoclusters (AgNCs) is introduced for detecting miR-21. ResultsAs a fluorescent probe, a rationally designed hairpin sequence containing a poly-cytosine motif was used to facilitate the formation of AgNCs. A guanine-rich sequence was also employed to enhance the sensing signal. It was found that in the absence of miR-21, adding a guanine-rich sequence to the detecting probe caused only a slight change in the fluorescence emission intensity of AgNCs. While in the presence of miR-21, the emission signal enhanced. A direct correlation was observed between the increase in the fluorescence of AgNCs and the concentration of miR-21. The performance of the proposed biosensor was characterized thoroughly and confirmed. The biosensor detected miR-21 in an applicable linear range from 9 pM to 1.55 nM (LOD: 2 pM). SignificanceThe designed biosensor was successfully applied for detecting miR-21 in human plasma samples and also in human normal and lung and ovarian cancer cells. This biosensing strategy can be used as a model for detecting other miRNAs. The designed nanobiosensor can measure miR-21 without using any enzymes, with fewer experimental steps, and at a low cost compared to the reported biosensors in this field.

Fast-Responsive HClO-Activated Near-Infrared Fluorescent Probe for In Vivo Diagnosis of Inflammatory Bowel Disease and Ex Vivo Optical Fecal Analysis.

Inflammatory bowel disease (IBD) is an idiopathic intestinal inflammatory disease, whose etiology is intimately related to the overproduction of hypochlorous acid (HClO). Optical monitoring of HClO in the living body favors real-time diagnosis of inflammatory diseases. However, HClO-activated near-infrared (NIR) fluorescent probes with rapid response and high inflammatory cell uptake are still lacking. Herein, we report an activatable acceptor-π-acceptor (A-π-A)-type NIR fluorescent probe (Cy-DM) bearing two d-mannosamine groups for the sensitive detection of HClO in early IBD and stool testing. Once reacted with HClO, nonfluorescent Cy-DM could be turned on within 2 s by generating a donor-π-acceptor (D-π-A) structure due to the enhanced intramolecular charge transfer mechanism, showing intense NIR fluorescence emission at 700 nm and a large Stokes shift of 115 nm. Moreover, it was able to sensitively and selectively image exogenous and endogenous HClO in the lysosomes of living cells with a detection limit of 0.84 μM. More importantly, because of the d-mannosamine modification, Cy-DM was efficiently taken up by inflammatory cells in the intestine after intravenous administration, allowing noninvasive visualization of endogenous HClO in a lipopolysaccharide-induced IBD mouse model with a high fluorescence contrast of 6.8/1. In addition, water-soluble Cy-DM has also been successfully applied in ex vivo optical fecal analysis, exhibiting a 3.4-fold higher fluorescence intensity in the feces excreted by IBD mice. We believe that Cy-DM is promising as an invaluable tool for rapid diagnosis of HClO-related diseases as well as stool testing.

Structure and Spectral Properties of Er3+-Doped Bismuth Telluride Near-Infrared Laser Glasses.

TeO2-Bi2O3-B2O3-ZnO laser glasses doped with Er3+ were synthesized through an optimized melt-quenching method. The absorption spectra at 808 nm LD pumping were studied. Various spectral tests and data analyses indicate that the maximum fluorescence emission intensity can be obtained when the Er3+ doping concentration reaches 2%. In this case, the emission cross-section can reach up to 9.12 × 10-21 cm2 and the gain coefficient at 1.55 μm is 6.17 cm-1. Simultaneously, the sample has a lower phonon energy in the high-frequency band at 1077 cm-1, which reduces the probability of non-radiative relaxation. The calculated energy transfer coefficient CD-A is 13.8 × 10-40 cm6/s, reflecting the high cross-relaxation probability of Er3+ in the sample, which promotes the luminescence of 1.55 μm and favors the emission in the near-infrared region. The comprehensive results demonstrate that the prepared Er3+-doped bismuth telluride laser glass can be used as a promising and high-quality gain material for near-infrared lasers.

Ratiometric fluorescence sensor for protamine and heparin based on N,P‐doped carbon dots and Eosin Y

AbstractA novel ratiometric fluorescent assay was proposed for protamine and heparin based on blue‐emitting N,P‐doped carbon dots (N,P‐CDs) and green‐emitting Eosin Y. The N,P‐CDs were prepared using arginine as carbon and nitrogen sources according to hydrothermal method with favorable luminescence intensity, photostability, and good reproducibility. And the N,P‐CDs were used as internal reference fluorescence molecules. The anionic Eosin Y was used as fluorescence signal molecule. Protamine with positive group could interact with Eosin Y through electrostatic effect, leading to the fluorescence quenching of Eosin Y. Upon the addition of heparin, heparin was combined with protamine with stronger affinity through electrostatic interactions and hydrogen bonds, which preventing the bonding of protamine with Eosin Y and obvious fluorescence emissions of Eosin Y at 538 nm could be observed. Meanwhile, the fluorescence signal of N,P‐CDs at 420 nm remained stable during the whole process. A good linear range between the fluorescence emission intensity ratio of I538/I420 was obtained for protamine from 0.01 to 40 μg/mL with a low detection limit of 5.6 ng/mL, and heparin from 0 to 35 μg/mL with a low detection limit of 2.5 ng/mL. Moreover, the method was further applied to detection of heparin with satisfactory results in fetal bovine serum samples.

Illuminating tetracycline: The role of metal coordination in fluorescence emission and its optical detection potential

Rapid on-site detection of antibiotics such as tetracycline (TC) is crucial for understanding their elusive environmental fate. Fluorescence-based strategies are promising owing to their sensitivity and ease of use. This study demonstrates that Al3+–TC coordination significantly enhances the intrinsic fluorescence of TC at excitation/emission wavelengths of 395/490 and 270/490 nm. The fluorescence emission intensity is proportional to the TC concentration between 0.005 and 7.5 μmol/L TC, which increases the detection sensitivity by 40 times compared with the commonly used absorption signals. Density functional theory calculations, when combined with the independent gradient model, indicate that the six-membered chelate ring in the octahedral Al3+–TC complex restricts molecular motion, along with two intramolecular hydrogen bonds formed between TC and water ligands. These factors lead to a narrowing of the energy gap between the highest occupied and lowest unoccupied molecular orbitals upon complexation with Al3+. Consequently, the enhanced molecular rigidity and facilitated electron transfer result in a significant increase in the fluorescence quantum yield. This captivating fluorescence response significantly enhances the proficiency of optical signals in detecting TC, thereby enriching future environmental monitoring systems with greater diversity and adaptability.

Smartphone-based ratiometric fluorescence sensor for sensitive visual detection of H2O2 and glucose based on B-CDs-Ag NPRs-OPD ternary system

A straightforward and highly sensitive ratiometric fluorescence sensor comprising blue emissive carbon dots, silver nanoprisms, and o-phenylenediamine (B-CDs-Ag NPRs-OPD) was developed for the detection of H2O2 and glucose. Ag NPRs were etched into Ag+ ions upon exposure to H2O2, which caused non-fluorescent OPD to be oxidized and produce 2,3-diaminophenazine (DAP), resulting in intense yellow fluorescence emission at 555 nm. DAP can quench the B-CDs based on inner filter effect (IFE), leading to a decrease in their fluorescence intensity at 435 nm. Because glucose oxidase may catalyze the oxidation of glucose to produce H2O2, this approach can also be used to detect glucose. The unique triangular structure leads to the easy etching of the edge and tip of Ag NPRs by H2O2 into Ag+ ions, allowing for the high sensitivity of detection of H2O2 and glucose with limit of detection (LOD) of 0.12 μM and 0.6 μM, respectively. Furthermore, with the increase of the concentrations of H2O2 and glucose, a visible color shift from blue to yellow-green occurs, which can be detected using a smartphone's color recognition application that captures the RGB channel values of the image. Real-time and on-spot detection of H2O2 and glucose were achieved based on smartphone sensing platform, presenting vast potential for applications in various fields.

Phyto-Photodynamic Therapy of Prostate Cancer Cells Mediated by Yemenite 'Etrog' Leave Extracts.

Cancer therapy, from malignant tumor inhibition to cellular eradication treatment, remains a challenge, especially regarding reduced side effects and low energy consumption during treatment. Hence, phytochemicals as cytotoxic sensitizers or photosensitizers deserve special attention. The dark and photo-response of Yemenite 'Etrog' leaf extracts applied to prostate PC3 cancer cells is reported here. An XTT cell viability assay along with light microscope observations revealed pronounced cytotoxic activity of the extract for long exposure times of 72 h upon concentrations of 175 μg/mL and 87.5 μg/mL, while phototoxic effect was obtained even at low concentration of 10.93 μg/mL and a short introduction period of 1.5 h. For the longest time incubation of 72 h and for the highest extract concentration of 175 μg/mL, relative cell survival decreased by up to 60% (below the IC50). In combined phyto-photodynamic therapy, a reduction of 63% compared to unirradiated controls was obtained. The concentration of extract in cells versus the accumulation time was inversely related to fluorescence emission intensity readings. Extracellular ROS production was also shown. Based on an ATR-FTIR analysis of the powdered leaves and their liquid ethanolic extract, biochemical fingerprints of both polar and non-polar phyto-constituents were identified, thereby suggesting their implementation as phyto-medicine and phyto-photomedicine.

A smart insulation material achieving self-reporting and autonomous repairing against electrical and mechanical damages based on targeted controllable microcapsules

Under the long-term action of electrical and mechanical stresses, irreversible micro-damages, such as electrical trees and cracks tend to occur inside solid insulation materials, leading to insulation failures, which have no effective countermeasures. This study develops a multi-responsive, target-controlled microcapsule to endow the epoxy resin with dual functions of self-reporting and autonomous repair against internal damage even under strong electric fields without human intervention. A turn-on mechanism for self-reporting signals is designed, to be applicable to electrical tree damage inside an epoxy matrix. In situ UV emissions generated by the partial discharge during electrical treeing are employed to automatically cure the microcapsule core material released into the damaged channel. This triggers aggregation-induced emission (AIE) signals and simultaneously repairs the damaged matrix. The polyurethane hybrid shell filled with magnetic particles endows the microcapsules with magnetic response characteristics. Under the control of a directional magnetic field, the microcapsule is concentrated around the vulnerable areas, obtaining high fluorescence emission intensity under low doping content without affecting the matrix performance. This method enables the autonomous inspection and maintenance of electric equipment and electronic devices under live working and provides new insight into the bionic intelligence of electrical and electronic insulation materials.