High Fluorescence Efficiency Research Articles

Fluorescence imaging-guided cancer photothermal therapy using polydopamine and graphene quantum dot-capped Prussian blue nanocubes.

In recent years, imaging-guided photothermal tumor ablation has attracted intense research interest as one of the most exciting strategies for cancer treatment. Herein, we prepared polydopamine and graphene quantum dot-capped Prussian blue nanocubes (PB@PDA@GQDs, PBPGs) with high photothermal conversion efficiency and excellent fluorescence performance for imaging-guided cancer treatment. Transmission electron microscopy (TEM), UV-vis absorption spectroscopy (UV-vis), fluorescence spectroscopy, and X-ray photoelectron spectroscopy (XPS) were employed to characterize their morphology and structures. The photothermal conversion efficiency and therapeutic effect were evaluated in vitro and in vivo. Results revealed that this nanoagent had excellent biocompatibility and enhanced the photothermal effect compared to blue nanocubes (PBs) and polydopamine-capped Prussian blue nanocubes (PB@PDA, PBPs). Therefore, our study may open a new path for the production of PB-based nanocomposites as theranostic nanoagents for imaging-guided photothermal cancer treatment.

High fluorescence efficiency of dual-wavelength white OLED with NPB emission and triplet annihilation

A high-efficiency fluorescent dual-wavelength white organic light-emitting diode (WOLED) was fabricated with a single emission layer (EML) comprising ITO/MoO3/NPB/Spiro-Pye:DCJTB/Bphen/LiF/Al. OLEDs with a 2 nm-thick MoO3 showed a 6% decrease in the operating voltage and a 14% increase in the external quantum efficiency (EQE). The NPB emission that occurred near the NPB/EML interface was investigated with a carrier blocking layer containing Ir(ppy)3 and Ir(piq)3. Excess electrons in the EML affected the emission of NPB, even at a low voltage of 4 V. The maximum luminescence, current efficiency, and power efficiency of the WOLED were 21,070 cd/m2, 18.09 cd/A, and 8.77 lm/W, respectively. A high EQE of 8.16% was achieved, which exceeded the theoretical limit of 5% for all-fluorescent OLEDs.

Miniaturized modular-array fluorescence microscopy.

Fluorescence live-cell imaging allows for continuous interrogation of cellular behaviors, and the recent development of portable live-cell imaging platforms has rapidly transformed conventional schemes with high adaptability, cost-effective functionalities and easy accessibility to cell-based assays. However, broader applications remain restrictive due to compatibility with conventional cell culture workflow and biochemical sensors, accessibility to up-right physiological imaging, or parallelization of data acquisition. Here, we introduce miniaturized modular-array fluorescence microscopy (MAM) for compact live-cell imaging in flexible formats. We advance the current miniscopy technology to devise an up-right modular architecture, each combining a gradient-index (GRIN) objective and individually-addressed illumination and acquisition components. Parallelization of an array of such modular devices allows for multi-site data acquisition in situ using conventional off-the-shelf cell chambers. Compared with existing methods, the device offers a high fluorescence sensitivity and efficiency, exquisite spatiotemporal resolution (∼3 µm and up to 60 Hz), a configuration compatible with conventional cell culture assays and physiological imaging, and an effective parallelization of data acquisition. The system has been demonstrated using various calibration and biological samples and experimental conditions, representing a promising solution to time-lapse in situ single-cell imaging and analysis.

Modified triazine-based carbon nitride as a high efficiency fluorescence sensor for the label-free detection of Ag+

Abstract

Highly selective and sensitive detection towards cationic Cu2+ and Fe3+ contaminants via an In-MOF based dual-responsive fluorescence probe

Effective recognition and detection of heavy metal Cu2+ and Fe3+ ions from water are highly desirable because of their serious harms to human health and environmental safety. However, the existing detection techniques are still high cost, time-consuming and highly demanding for operators. As an alternative approach to address this issue, an indium-based MOF labeled as In-MOF of 1 with high water stability and opposite charges to Cu2+ and Fe3+ ions was successfully prepared and deployed as optical sensor to sense target analytes, according to our previous work. Prominently, this anionic framework exhibits high photoluminescence property and excellent fluorescence quenching response to target analytes with high selectivity, sensitivity and detection limits of 3.88 ppb for Cu2+, 4.2 ppb for Fe3+ ions, respectively, both of which have been confirmed to be ultro-low values among all reported MOFs-based photochemical sensors. Furthermore, the quick and accurate probing capability of 1 also has been proved even under the interference of dozens of anions or cations. The possible photoluminescence and fluorescence quenching mechanisms were studied in detail, revealing that rapid coordination reactions between free imidazole nitrogen and carboxyl oxygen atoms of the framework (Lewis basic sites) and the metal ions of Cu2+/Fe3+ (Lewis acid sites) should be proposed to be the key reason for high efficiency fluorescence quenching.

2-(Dimesitylboryl)phenyl-Substituted [2.2]Paracyclophanes Featuring Intense and Sign-Invertible Circularly Polarized Luminescence.

We have disclosed a new type of [2.2]paracyclophanes that contain a 2-(dimesitylboryl)phenyl and a N,N-disubstituted amino groups at two different phenyl rings. They show intense circularly polarized luminescence combining high fluorescence efficiency (ΦF) and luminescence dissymmetry factor (|glum|), which are up to 0.93 and 1.73 × 10-2, respectively. In addition, the pseudo-meta derivatives display solvent-induced CPL sign inversion owing to the solvent-dependent excited-state dynamics.

A Visual Leaf Zymography Technique for the In Situ Examination of Plant Enzyme Activity under the Stress of Environmental Pollution.

This study established a high-efficiency fluorescence quenching approach for the in situ visualization and modeling of the spatial distribution of xylanase, β-glucosidase, and phosphatase activities in plant leaves under pollution stress (namely, the leaf zymography technique, LZT). In the LZT, a membrane saturated with an enzyme-specific fluorescent substrate on the leaf surface was incubated and the fluorescence image generated on the membrane under ultraviolet light was recorded. An image-based modeling method for restoring the morphological traits of the true image by reducing noise was developed to ensure the accurate estimation of enzyme activities. The LZT could simultaneously measure 48 samples within 2 h, with good reproducibility. The results obtained by the LZT were comparable to those obtained by a conventional biochemical analysis method and presented low-cost and convenient advantages. This paper explains the theoretical basis required to investigate the realistic application of the LZT for assessing ecotoxicity in large-scale monitoring.

Perovskite Nanocrystal Fluorescence-Linked Immunosorbent Assay Methodology for Sensitive Point-of-Care Biological Test

Summary Quantitative fluorescence immunoassay is a vital and convenient method in point-of-care (POC) testing for food safety and clinical healthcare. However, current marking materials, from organic luciferin to quantum dots, still lack the requirement of increasing need for multiple targets of interest because of their too broad emission. Here, a new label material, perovskite nanocrystals (Pe-NCs), with a narrower photoluminescence spectrum is reported, and a sensitive and quantitative immunoassay method named the perovskite nanocrystal fluorescence-linked immunosorbent assay is preliminarily demonstrated. The key point of realizing water-dispersed and stable Pe-NCs was addressed by functionalizing with hydroxyl groups. The fluorescent probes (perovskite antibody) were constructed via electrostatic adsorption with narrow full-width at half-maximum (∼18 nm), laying the foundation for future study of multi-target detection. Both indirect competitive immunity and sandwich immunoassay were successfully demonstrated. This work provides a possible label material for POC tests and may open up a promising avenue of next-generation immunoassay.

A review on rare earth (Ce and Er)-doped zinc oxide nanostructures

Diverse nanostructures of ZnO are one of the most studied materials. ZnO nanostructures possess several favourable properties such as good transparency, strong room-temperature luminescence, high electron mobility, wide band gap, chemical and photochemical stability, etc. These properties make them an interesting material for using in new light-emitting devices, solar cells, bio-sensors and as photocatalysts. They are generally of very low toxicity. ZnO nanostructures are an emerging material for next-generation. Doping is considered an effective way to enhance the properties of ZnO for various applications. In this framework, the doping of RE ion in ZnO is of great importance due to signs of tuneable luminescence and ferromagnetism at room temperature. RE ions are extensively used as activators in different host materials due to their high fluorescence efficiencies and very narrow line fluorescence bands. The ferromagnetism property of RE doped ZnO nanostructures is another such property which has drawn a great interest. These nanostructures find applications in magneto-optical device applications i.e. communications, storage, quantum computation etc. This review provides an overall study of the synthesis of Ce and Er doped ZnO nanostructures from various methods, and their properties and applications in different fields of industry.

Improved fluorescence stability for Fe3O4/silica @fluorescein/dense silica structure with double shell

The dyes-doped silica particles have been attracting considerable attention because of their applications in various fields such as anti-counterfeiting, biological imaging, sensor technology, microarrays and optical computing. However, it still remains a challenge to a long-term stable fluorescence property of the dyes-doped silica particles, particularly in simulated biological condition, aroused from the leakage of the dyes out of the silica particles. In this work, Fe3O4/silica @fluorescein/dense silica core/shell/shell nanoparticles were synthesized by a two-step procedure. We demonstrate that such a core/shell/shell architecture can improve the fluorescence stability in aqueous solution at room temperature and high temperature due to the protection of dense silica. The findings should make an important contribution to the synthesis of fluorescent nanoparticles with high stability and fluorescence efficiency.

A reversible vapor-responsive fluorochromic molecular platform based on coupled AIE–ESIPT mechanisms and its applications in anti-counterfeiting measures

In this work, a series of 2-(2-hydroxyphenyl)benzothiazole (HBT) derivatives with an aggregation-induced emission–excited state intramolecular proton transfer (AIE-ESIPT) dual mechanism was synthesized. We systematically investigated their optical properties in solution, aqueous suspension, and the solid state. The fluorescence properties of these five compounds were highly dependent on the solvent environment. Particularly, DMSO and DMF were found to significantly promote deprotonation of the phenolic hydroxyl and favor fluorescence emission from the phenolic anion. The Keto or Enol forms generally could be transformed to phenolic anions with the aid of base in solution. The results from aggregation-induced emission enhancement (AIEE) and red-shifted AIE clearly illustrated the evolution process of the fluorescence spectra, indicating that the three luminescent species in the solution were transformable. The systematic investigation demonstrated that the desired fluorescence could be generated for HBT derivatives by varying the solvents or adding additives, such as base or water, to the solution. Because of the synergistic effect of AIE and ESIPT, these fluorophores exhibited high solid-state quantum yields and large Stokes shifts. These dyes also featured high photostability and tunable emission spectra covering most of the visible light region. Single crystal studies and theoretical calculations elucidated the luminescent properties. When loaded on filter paper, the HBT-based dyes exhibited high-efficiency fluorescence visualization and reversible solid-state luminescence switching under alternating amine and acid vapor treatments. These dyes were used on banknotes for anti-counterfeiting measures, demonstrating the practical applications of these molecules as security inks.

N,N-Dimethyl-Substituted Boron Ketoiminates for Multicolor Fluorescent Initiators and Polymers

In this contribution, an efficient synthesis strategy of multicolor fluorescent N,N-dimethyl-substituted boron ketoiminates (NBKI) was presented. The introduction of dimethylamino group as donor and NOBF2 moiety as acceptor with variously tunable substituents led to the formation of D (donor)−π–A (acceptor) system in NBKI molecules, which exhibited a high fluorescence efficiency and a significant red shift of absorption/emission in solution. NBKI molecules were applied in the synthesis of multicolor fluorescent ATRP initiators (i-NBKI 1–4) and RAFT initiator (i-NBKI 5), as well as multicolor fluorescent PS, PMMA, PDBA, or PEG-based homopolymers/copolymers. It was demonstrated that PEG-based polymers showed effective fluorescence emission, good water solubility, and great potential in biological applications. This work bridges the gap in current organoboron compounds and multicolor fluorescent polymerization initiators and related fluorescent polymers/copolymers by utilizing D−π–A design. It may shed light on the downstream applications in next-generation multicolor fluorescent probes/devices.

Dual mode colorimetric-fluorescent sensor for highly sensitive and selective detection of Mg2+ ion in aqueous media

A novel dual-mode colorimetric and fluorescent probe was designed and synthesized based on the reaction of 1,10-phenanthroline and 8- hydroxyquinoline, 5-(1H-imidazole [4,5-f] [1,10]phenanthrolin-2-yl)quinolin-8-ol (PHQ), for detection of Mg2+ ion. The probe was characterized by FT-IR, UV–Vis and 1H NMR techniques. The PHQ sensor displays outstanding sensitivity and selectivity toward Mg2+ over other cations via fluorescence quenching at 300 nm and color change from colorless to yellow. A very important aspect of the presented ligand is its very high fluorescence efficiency over individual precursors 1,10-phenantroline and 8-hudroxyquinoline. Addition of Mg2+ ion to PHQ led to a color change with a significant bathochromic shift in the λmax of the absorption band and made naked eye detection possible. The experimental results as performed by Job’s method revealed a 2:1 stoichiometry of PHQ/Mg2+ ratio. The sensor exhibited high selectivity and sensitivity toward Mg2+ ions in the presence of adverse anions and cations and the detection limit was found to be 33 nM 1H NMR and quantum calculations DFT and TDDFT were used to determine the type of interactions between the PHQ and Mg2+.

High-Efficiency Fluorescence through Bioinspired Supramolecular Self-Assembly.

Peptide self-assembly has attracted extensive interest in the field of eco-friendly optoelectronics and bioimaging due to its inherent biocompatibility, intrinsic fluorescence, and flexible modulation. However, the practical application of such materials was hindered by the relatively low quantum yield of such assemblies. Here, inspired by the molecular structure of BFPms1, we explored the “self-assembly locking strategy” to design and manipulate the assembly of metal-stabilized cyclic(l-histidine-d-histidine) into peptide material with the high-fluorescence efficiency. We used this bioorganic material as an emissive layer in photo- and electroluminescent prototypes, demonstrating the feasibility of utilizing self-assembling peptides to fabricate a biointegrated microchip that incorporates eco-friendly and tailored optoelectronic properties. We further employed a “self-encapsulation” strategy for constructing an advanced nanocarrier with integrated in situ monitoring. The strategy of the supramolecular capture of functional components exemplifies the use of bioinspired organic chemistry to provide frontiers of smart materials, potentially allowing a better interface between sustainable optoelectronics and biomedical applications.

Facile and highly effective synthesis of nitrogen-doped graphene quantum dots as a fluorescent sensing probe for Cu2+ detection

Nitrogen-doped graphene quantum dots (N-GQDs) with high blue fluorescence efficiency were synthesized by the hydrothermal method from p-Phenylenediamine and p-Coumaric acid. The N-GQDs possess several superiorities, most significantly in excellent solubility and superior photostability. Besides, the as-prepared N-GQDs exhibit a uniform size distribution with a diameter of about 3.8 ± 0.5 nm. After dispersing the N-GQDs in water, the formed aqueous solution still presents a stable and homogeneous phase even after 2 months at room temperature. The N-GQD dispersion was further utilized as sensing probes for the selective detection of copper ions (Cu2+), which is realized by the photoluminescence (PL) quenching of N-GQDs after adding Cu2+. The detection limit for Cu2+ was found to be 57 nM L−1, with superior selectivity in the presence of other commonly interfering metal ions. The presented results in this study provide a facile and high-efficiency method for synthesizing N-GQDs, with ultra-high detectivity and selectivity for Cu2+ detection, offering numerous opportunities for the development of biosensing, bioimaging, environment monitoring, and others.

Designing highly fluorescent, arylated poly(phenylene vinylene)s of intrinsic microporosity

The design of new arylated poly(phenylene vinylene) with high fluorescence efficiency (from AIE) and intrinsic microporosity (from SBET) is described.

Remarkable mechanofluorochromism and low efficiency-off electroluminescence from a fully aromatic D-A cruciform emitter

Two-dimensional aryl center-crossed cruciforms generally exhibit the strongly twisted conformation and the spatial separation of frontier molecular orbitals, which can render the emitters destructible packing structures and high solid-state fluorescence efficiency. In the current work, we design and synthesize a benzene-centered cruciform emitter (DOT) with two adjacent phenyloxadiazoles and two adjacent triphenylamines starting from commercially available chemicals. Single crystal analysis indicates that DOT molecules loosely pack together in a twisted conformation and weak inter-molecular interactions. Upon mechanical grinding, the crystalline DOT is changed into an amorphous state, accompanying with a remarkable (56 nm) mechanofluorochromism (MFC). In view of the crossed donor and acceptor structure and the strong solid-state fluorescence, the non-doped electroluminescence (EL) devices with the structures ITO/HATCN/NPB or TAPC/DOT/TPBi/LiF/Al are fabricated. The devices efficiently emit 500 nm green EL with the low turn on voltage of 2.7 V and the low efficiency roll-off. Thus, we have provided a feasible synthetic strategy for various isomers and analogues of fully aromatic benzene-centered D‒A cruciforms and demonstrated a new class of candidates for MFC and EL materials.

Chemically-modulated turn-on fluorescence for rapid and visual discrimination of norepinephrine and epinephrine and its application for dopamine-β-hydroxylase detection

Monitoring the concentration of norepinephrine (NE), epinephrine (Ep) and dopamine-β-hydroxylase (DβH) is of great importance in studying and diagnosing related diseases. In this study, a simple chemically-modulated turn-on fluorescence strategy is proposed for rapid, selective and visual discrimination of trace NE and Ep. Herein, Ep is differentiated from other catecholamines via its fast fluorescence response in 1.0 M NaOH medium. Furthermore, NE is alkalized with 0.01 M NaOH and is then immediately triggered by polyethyleneimine to emit bright cyan fluorescence, whereas Ep and DA show no any fluorescence response. The fluorescence intensity of resultant solution is linearly proportional to the concentration of Ep and NE in the range of 50.0–10000.0 nM and 10.0–10000.0 nM, respectively. Moreover, NE and Ep as low as 500.0 nM can be fluorescently identified with naked-eye, which is convenient for rapidly preliminary diagnosis and self-test of hypercatecholaminism. Inspired by the catalytic property of DβH transforming DA into NE, the proposed strategy enables a simple and high-efficient fluorescence method to monitor DβH by using trace DA as substrate and directly quantifying NE. The method is simple, smart, highly efficient and eco-friendly, and has been applied to the rapid assay of NE, Ep and DβH in real samples.

A rapid-response and ratiometric fluorescent probe for nitric oxide: From the mitochondria to the nucleus in live cells

Nitric oxide (NO) is a very important signal molecule implicated in numerous physiological and pathological processes, and its detection is the key to understand these processes. For this reason, various fluorescent probes have been developed for detection analysis of NO. However, few rapid-response (<1 min) and ratiometric fluorescent probe are reported for real-time detection of short-time NO in biological systems. In this work, we report a rapid-response (within several seconds) and ratiometric fluorescent probe, RatioTr, which displays selective and sensitive detection of NO in solutions, and detections of exo- and endogenous NO in live RAW 264.7 cells. Unexpectedly, the probe RatioTr and its sensing product (p-Nus) display different cellular localizations, the mitochondria and the nucleus, which were demonstrated by co-stained experiments. The sensing process of RatioTr toward NO from mitochondria to nucleus was observed in live cells by confocal fluorescence images. Furthermore, the subcellular localizations were demonstrated by measurements of pKa and interaction of p-Nus and DNA. In the presence of a natural DNA, calf thymus DNA, RatioTr is more sensitive to NO (LOD = 2.8 nM). Therefore, due to the nucleus localization together with a high fluorescence efficiency in the nucleus, p-Nus is a good candidate of cell-permeant nucleic acid stain or a fluorescent probe for the nucleus.

Upgrade of laser pump time-resolved X-ray probes in Beijing synchrotron.

The upgrade of the laser pump time-resolved X-ray probes, namely time-resolved X-ray absorption spectroscopy (TR-XAS) and X-ray diffraction (TR-XRD), implemented at the Beijing Synchrotron Radiation Facility, is described. The improvements include a superbunch fill, a high-efficiency fluorescence collection, an efficient spatial overlap protocol and a new data-acquisition scheme. After upgrade, the adequate TR-XAS signal is now obtained in a 0.3 mM solution, compared with a 6 mM solution in our previous report. Furthermore, to extend application in photophysics, the TR-XAS probe is applied on SrCoO2.5 thin film. And for the first time, TR-XAS is combined with TR-XRD to simultaneously detect the kinetic trace of structural changes in thinfilm.