Fluorescence Pattern Research Articles

Effect of pyridyl position on constructing acid-base dual-responsive fluorophores with ESIPT and AIE characteristics

Exceedingly large Stokes shift solid-state fluorescent materials with acid/base dual responses are promising for potential practical applications. However, their realization is extremely challenging because of the difficulty in designing molecules possessing these functionalities simultaneously. Herein, three pyridyl-modified 2-(2-hydroxyphenyl)benzothiazole (HBT) isomers (o-Py-HBT, m-Py-HBT, and p-Py-HBT) were rationally designed with a pyridyl group located at ortho, meso, and para positions relative to the phenolic hydroxyl (-OH), respectively. These compounds are both excited-state intramolecular proton transfer (ESIPT)- and aggregation-induced emission (AIE)-active. The intrinsic –OH and introduced pyridyl moiety were exploited as base- and acid-responsive units, respectively. Among the three HBT isomers, m-Py-HBT exhibited the most significant emission shift upon acidic stimuli. Theoretical calculations confirmed that the prominent intramolecular charge transfer of the protonated keto-tautomer of m-Py-HBT accounts for the trifluoroacetic acid-induced bathochromic shift of ∼33 nm. In addition, it was concluded that intramolecular H-bonding strength and –OH acidity jointly affected the base response. Finally, m-Py-HBT was successfully applied for the fabrication of trichromatic fluorescent patterns upon acid or base stimulation, exhibiting great application potential for encrypted pattern production. The exploration of structure-property correlations provides experimental and theoretical guidance for designing and developing multi-stimuli responsive solid-state molecular switches.

Detailed visualization of settlement and early development in Leptastrea purpurea reveals distinct bio-optical features

Sexually produced juvenile scleractinian corals play a key role in the adaptation process of coral reefs, as they are considered to possess an innate plasticity and thus can adjust to changing environmental parameters within a certain range. In this study we investigated in detail the early life stages of the brooding species Leptastrea purpurea to identify, categorize and visualize the critical steps of the complex transformation process from a swimming coral larva to a sessile coral recruit and later to a coral colony. For that, we performed settlement experiments using previously known cues: cycloprodigiosin (CYPRO) and crustose coralline algae (CCA) as well as novel cues: crude extracts of Pseudoalteromonas espejiana and P. piscicida to identify a general, cue-independent settlement pathway. We monitored the development of L. purpurea over 12 months using bright field and fluorescence microscopy. Also we identified the fluorescence signals of L. purpurea with confocal microscopy at four crucial development steps: (A) swimming larva, (B) metamorphosing larva, (C) coral recruit and (D) adult coral. Our methodological approach allowed us to observe an ontogenetic shift of fluorescence signals which provokes the hypothesis that certain fluorescence patterns might be connected to distinct sequential functions in the early life cycle of scleractinian corals. Our observations showed great similarities to the early development of other brooding and spawning corals, making L. purpurea a prospective candidate to be used as a model organism for coral research. Furthermore, our in-depth picture series provides a robust monitoring reference for coral nurseries or field applications and demonstrates the potential of fluorescence as an indicator to instantly determine the growth stage of a developing coral recruit.

ATM-SPARK: A GFP phase separation-based activity reporter of ATM.

The kinase ataxia telangiectasia mutated (ATM) plays a key role in the DNA damage response (DDR). It is thus essential to visualize spatiotemporal dynamics of ATM activity during DDR. Here, we designed a robust ATM activity reporter based on phosphorylation-inducible green fluorescent protein phase separation, dubbed ATM-SPARK (separation of phases-based activity reporter of kinase). Upon ATM activation, it undergoes phase separation via multivalent interactions, forming intensely bright droplets. The reporter visualizes spatiotemporal dynamics of endogenous ATM activity in living cells, and its signal is proportional to the amount of DNA damage. ATM-SPARK also enables high-throughput screening of biological and small-molecule regulators. We identified the protein phosphatase 4 that blocks ATM activity. We also identified BGT226 as a potent ATM inhibitor with a median inhibitory concentration of~3.8 nanomolars. Furthermore, BGT226 sensitizes cancer cells to the radiomimetic drug neocarzinostatin, suggesting that BGT226 might be combined with radiotherapeutic treatment. ATM-SPARK achieves large dynamic range, bright fluorescence, and simple signal pattern.

Reusable, Ultrasensitive, Patterned Conjugated Polyelectrolyte-Surfactant Complex Film with a Wide Detection Range for Copper Ion Detection.

Conjugated polyelectrolytes (CPEs) are emerging as promising materials in the sensor field because they enable high-sensitivity detection of various substances in aqueous media. However, most CPE-based sensors have serious problems in real-world application because the sensor system is operated only when the CPE is dissolved in aqueous media. Here, the fabrication and performance of a water-swellable (WS) CPE-based sensor driven in the solid state are demonstrated. The WS CPE films are prepared by immersing a water-soluble CPE film in cationic surfactants of different alkyl chain lengths in a chloroform solution. The prepared film exhibits rapid, limited water swellability despite the absence of chemical crosslinking. The water swellability of the film enables the highly sensitive and selective detection of Cu2+ in water. The fluorescence quenching constant and the detection limit of the film are 7.24 × 106 L mol-1 and 4.38 nM (0.278 ppb), respectively. Moreover, the film is reusable via a facile treatment. Furthermore, various fluorescent patterns introduced by different surfactants are successfully fabricated by a simple stamping method. By integrating the patterns, Cu2+ detection in a wide concentration range (nM-mM) can be achieved.

Production and Patterning of Fluorescent Quantum Dots by Cryogenic Electron-Beam Writing.

Graphene quantum dots (GQDs) have emerged as a promising type of functional material with distinguished properties. Although tremendous effort was devoted to the preparation of GQDs, their applications are still limited due to a lack of methods for processing GQDs from synthesis to patterning smoothly. Here, we demonstrate that aromatic molecules, e.g., anisole, can be directly converted into GQD-containing nanostructures by cryogenic electron-beam writing. Such an electron-beam irradiation product exhibits evenly red fluorescence emission under laser excitation at 473 nm, and its photoluminescence intensity can be easily tuned with the electron-beam exposure dose. Experimental characterizations on the chemical composition of the product reveal that anisole undergoes a carbonization and further graphitization process during e-beam irradiation. With conformal coating of anisole, our approach can create arbitrary fluorescent patterns on both planar and curved surfaces for concealing information or anticounterfeiting applications. This study provides a one-step method for production and patterning of GQDs, facilitating their applications in highly integrated and compact optoelectronic devices.

Correlation Between Indocyanine Green Fluorescence Patterns and Grade of Differentiation of Hepatocellular Carcinoma: A Western Prospective Cohort Study.

Background. Most of the available evidence on the use of indocyanine green (ICG) fluorescence in clinical practice consists of articles published by surgeons of the Asian-Pacific area. We performed a prospective cohort study to assess the patterns of ICG fluorescence in Western hepatocellular carcinoma (HCC) counterparts.Methods. From April 2019 to January 2022, a total of 31 consecutive patients who underwent laparoscopic liver resection (LLR) for superficial HCC were enrolled in this prospective study. All patients underwent laparoscopic staging with both laparoscopic ultrasound (LUS) and ICG fluorescence imaging.Results. A total of 38 hepatocellular carcinomas (HCCs) were enrolled: 23 superficial (surfacing at the liver's Glissonian capsule), 5 exophytic, 5 shallow (<8mm from the hepatic surface) and 5 deep (>10mm from the hepatic surface). The detection rate with preoperative imaging (abdominal CT/MRI), LUS, ICG fluorescence and combined modalities (ICG and LUS) was 97.4%, 94.9%, 89.7% and 100%, respectively. The five deep seated lesions underwent ultrasound-guided laparoscopic thermal ablation. The other 33 HCCs were treated with minimally invasive liver resection. Intraoperative ultrasound patterns were registered for each single nodule resected. The ICG fluorescence pattern was classified in two types: total fluorescence (all the tumoral tissue showed strong and homogeneous fluorescence), n = 9/33 (27.3%), and non-total fluorescence (partial and rim fluorescence), n = 24/33 (72.7%). There was a statistical correlation between ICG patterns and grade of differentiation. Almost all lesions with uniform fluorescence pattern were well-differentiated HCCs (G1-G2), while partial and rim-type fluorescence pattern were more common among moderately and poorly differentiated HCCs (G3-G4) (88.9% vs 11.1%, 37.5% vs 62.5%, P = .025, respectively).Conclusions. ICG fluorescence imaging could be used to identify early the grade of HCC, ie intraoperatively, thus influencing the intraoperative treatment.

Identification of the Backsheet Type of Silicon Photovoltaic Modules from Encapsulant Fluorescence Images

Feasibility of the identification of backsheet (BS) composition of field-aged Si photovoltaic (PV) modules based on the analysis of characteristic patterns of UV-excited fluorescence (UVF) of ethylene vinyl acetate copolymer encapsulant is shown. The approach includes BS identification by vibrational spectroscopies and the formation of a database of BS-related characteristic UVF patterns. A multivariate principal component analysis of the UVF images of unknown samples combined with the UVF pattern database allows the BS type to be identified only from UVF images. The geometric place of particular samples in the principal component plots is indicative of the general degradation status of PV modules. The proposed method can be applied for high-throughput noncontact characterization of solar PV plants.

A Non-Intrusive Fluorescent Pattern for Internal Microscale Strain Measurements Using Digital Image Correlation

A Non-Intrusive Fluorescent Pattern for Internal Microscale Strain Measurements Using Digital Image Correlation

Development of serial X-ray fluorescence holography for radiation-sensitive protein crystals.

X-ray fluorescence holography (XFH) is a powerful atomic resolution technique capable of directly imaging the local atomic structure around atoms of a target element within a material. Although it is theoretically possible to use XFH to study the local structures of metal clusters in large protein crystals, the experiment has proven difficult to perform, especially on radiation-sensitive proteins. Here, the development of serial X-ray fluorescence holography to allow the direct recording of hologram patterns before the onset of radiation damage is reported. By combining a 2D hybrid detector and the serial data collection used in serial protein crystallography, the X-ray fluorescence hologram can be directly recorded in a fraction of the measurement time needed for conventional XFH measurements. This approach was demonstrated by obtaining the Mn Kα hologram pattern from the protein crystal Photosystem II without any X-ray-induced reduction of the Mn clusters. Furthermore, a method to interpret the fluorescence patterns as real-space projections of the atoms surrounding the Mn emitters has been developed, where the surrounding atoms produce large dark dips along the emitter-scatterer bond directions. This new technique paves the way for future experiments on protein crystals that aim to clarify the local atomic structures of their functional metal clusters, and for other related XFH experiments such as valence-selective XFH or time-resolved XFH.

Two-pot synthesis of unsymmetrical hetero[7]helicenes with intriguing optical properties

A two-pot synthesis of unsymmetrical hetero[7]helicenes from commercially available substrates has been established. Combining the acid-mediated annulation with the electrochemical domino reaction (oxidative hetero-coupling/dehydrative cyclization sequence) in a single protocol afforded oxaza[7]helicenes with up to 45% overall yield. The photophysical properties of these [7]helicenes have been studied, and their absorption and fluorescence patterns were explained by DFT calculations.

Versatile Red-Emissive Carbon Dots for Smart Textiles and Fluorescence Sensing

Red-emissive carbon dots (RCDs) were facilely synthesized from o-phenylenediamine and catechol in ethanol through a hydrothermal method. The produced RCDs showed a triplet fluorescence emission around 597, 647, and 707 nm, respectively. The eco-friendly fluorescent pigment was prepared by dispersing RCDs into poly(vinylpyrrolidone) for smart textiles. Bright and stable fluorescent patterns on the cotton fabrics were successfully created by a screen-printing technique. Based on the pH-sensitive color change of RCDs, reversible volatile acid/amine-responsive RCD-patterned smart textiles and paper indicators were also constructed, respectively. Furthermore, fluorescence-sensing platforms were developed for MnO4– using an inner-filter-effect approach. It was found that the present RCDs could be used for the quantitative detection of MnO4– in the range of 0–7 μM in aqueous solution and for practical water sample analysis with satisfactory recovery results.

Acute Maculopathy in a Patient with Positive Coxsackie A Immunoglobulin G Viral Titers

A 23-year-old healthy woman presented with vision loss in her left eye (OS) following a prodrome consisting of fever, malaise, and maculopapular rash on her chest and shins 3 weeks prior. Visual acuity OS was 20/100, and fundus examination revealed an elevated circular area in the left macula (A) without vitritis. Fluorescein angiography (B) demonstrated speckled fluorescence pattern and pooling consistent with a neurosensory detachment. OCT (C) illustrated outer retina intraretinal fluid, subretinal fluid, and a bacillary layer detachment (arrows). Serologic testing was positive for Coxsackie A immunoglobulin G titers (titers ranged from 1:800–1:1,600; reference < 1:100) (Magnified version of Figure A-C is available online at www.aaojournal.org).

Speckle contrast of interfering fluorescence X-rays

With the development of X-ray free-electron lasers (XFELs), producing pulses of femtosecond durations comparable with the coherence times of X-ray fluorescence, it has become possible to observe intensity-intensity correlations due to the interference of emission from independent atoms. This has been used to compare durations of X-ray pulses and to measure the size of a focusedX-raybeam, for example. Here it is shown that it is also possible to observe the interference of fluorescence photons through the measurement of the speckle contrast of angle-resolved fluorescence patterns. Speckle contrast is often used as a measure of the degree of coherence of the incident beam or the fluctuations of the illuminated sample as determined from X-ray diffraction patterns formed by elastic scattering, rather than from fluorescence patterns as addressed here. Commonly used approaches to estimate speckle contrast were found to suffer when applied to XFEL-generated fluorescence patterns due to low photon counts and a significant variation of the excitation pulse energy from shot to shot. A new method to reliably estimate speckle contrast under such conditions, using a weighting scheme, is introduced. The method is demonstrated by comparing the speckle contrast of fluorescence observed with pulses of 3 fs to 15 fs duration.

Diurnal Pattern of Sun-Induced Chlorophyll Fluorescence as Reliable Indicators of Crop Water Stress

Diurnal Pattern of Sun-Induced Chlorophyll Fluorescence as Reliable Indicators of Crop Water Stress

Eu2O3 microsphere luminescent material based on aerosol jet printing

In this paper, microsphere structural materials of europium oxide (Eu2O3) were prepared using the aerosol jet printing technique. Europium oxide powders were produced at different calcination temperatures for the comparisons of nanostructures and luminescence properties. The peak of the emission spectrum of Eu3+ is near 612 nm (red), which contributes to the three primary colors. As an important and typical rare earth oxide, Eu2O3 plays an important role in red phosphor materials and is an activator for the red phosphor. Rare earth oxides microsphere materials are widely used in modern industrial production, such as light, electricity, magnetism, mechanics, and machinery, because of their advantages of the small size effect and the surface effect. Eu2O3 microsphere nanomaterials possess the advantages of both rare earth oxides and microsphere materials, exhibiting excellent optical properties and laying a good foundation for the development of biomedical, electronic information photocatalysis and other industries. However, the existing preparation methods of Eu2O3 microsphere nanomaterials have shortcomings, including uncontrollable microparticle morphology and complicated experimental operations. The most important point is that the initial pattern of the phosphor cannot be customized, and a secondary process is needed to obtain the target pattern. This two-step process inevitably leads to the loss of material and production time. Under this background, this experiment attempts to prepare a microspherical Eu2O3 phosphor using aerosol jet printing (AJP) technology, which is an important attempt to improve the level of the luminescent performance and the customization level of the fluorescent initial pattern.

Advanced UV-fluorescence image analysis for early detection of PV-power degradation

Reliability and durability of photovoltaic modules are a key factor for the development of emerging PV markets worldwide. Reliability is directly dependent on the chemical and physical stability of the polymeric encapsulation materials. One method capable of detecting ageing effects of the polymeric encapsulant directly on-site is UltraViolet Fluorescence (UVF) imaging. This work deals with advanced imaging analysis of UVF images and the subsequent correlation to electrical parameters of PV modules, which were exposed to climate-specific, long-term, accelerated aging procedures. For establishing a correlation, a so called UVF area ratio was established, resulting from the typical fluorescence patterns of the encapsulant material, which arise due to stress impact (e.g., water vapor ingress, elevated temperature, irradiation) and aging/degradation processes. Results of the data analysis show a clear correlation of the UVF area ratios and the electrical parameters with increasing aging time. In particular, the relationship between power and series resistance could be confirmed by extensive long-term test series with different climate-specific aging processes. Assuming the same type of polymeric encapsulation and backsheet and a comparable climate, determining the UVF area ratio can be used to estimate the service life and electrical power dissipation of each module installed in a PV array.

Low-temperature in situ preparation of Eu3+/Tb3+-doped CaMoO4/SrMoO4 nanoparticle thin films and their application in anti-counterfeiting.

Rare earth-doped metal oxide thin films exhibit remarkable potential for application in anti-counterfeiting, owing to their exceptional fluorescent properties. However, the existing fabrication techniques for these rare earth-doped luminescent thin films are predominantly complex and necessitate high-temperature conditions. In light of this issue, we present a low-temperature method for in situ fabrication of luminescent Ca1-xMoO4:Eux3+ and Sr1-xMoO4:Tbx3+ nanocrystal thin films by a solution deposition process. The developed method has the advantages of simple operation, rapid and low-temperature synthesis. The optimal chemical compositions of molybdate-based luminescent films are Ca0.90MoO4:Eu0.103+ and Sr0.90MoO4:Tb0.103+. Moreover, we evaluate the practical feasibility of luminescent nanoparticle films in the field of anti-counterfeiting by combining the unique fluorescent properties of rare earth ions and designing customized fluorescent patterns.

Correlation between Indocyanine Green Fluorescence Patterns and Grade of Differentiation of Hepatocellular Carcinoma: A Western Prospective Cohort Study

Correlation between Indocyanine Green Fluorescence Patterns and Grade of Differentiation of Hepatocellular Carcinoma: A Western Prospective Cohort Study

Lanthanide coordinated multicolor fluorescent polymeric hydrogels for bio-inspired shape/color switchable actuation through local diffusion of Tb3+/Eu3+ ions

Lanthanide coordinated multicolor fluorescent polymeric hydrogels (MFPHs) are quite promising for various applications because of their sharp fluorescence bands and high color purity. However, few attempts have been carried out to locally regulate their fluorescence switching or shape deforming behaviors, but such studies are very useful for patterned materials with disparate functions. Herein, the picolinate moieties that can sensitize Tb3+/Eu3+ luminescence via antenna effect were chemically introduced into interpenetrating double networks to produce a robust kind of lanthanide coordinated MFPHs. Upon varying the doping ratio of Tb3+/Eu3+, fluorescence colors of the obtained hydrogels were continuously regulated from green to orange and then red. Importantly, spatial fluorescence color control within the hydrogel matrix could be facilely realized by controlled diffusion of Tb3+/Eu3+ ions, producing a number of 2D hydrogel objects with local multicolor fluorescent patterns. Furthermore, the differential swelling capacities between the fluorescent patterned and non-fluorescent parts led to interesting 2D-to-3D shape deformation to give well-defined multicolor fluorescent 3D hydrogel configurations. Based on these results, bio-inspired synergistic color/shape changeable actuators were demonstrated. The present study provided a promising strategy to achieve the local fluorescence and shape control within lanthanide coordinated hydrogels, and is expected to be expanded for fabricating useful patterned materials with disparate functions.

Persistent ATP‐Concentration Gradients in a Hydrogel Sustained by Chemical Fuel Consumption

AbstractWe show the formation of macroscopic ATP‐concentrations in an agarose gel and demonstrate that these gradients can be sustained in time at the expense of the consumption of a chemical fuel. The approach relies on the spatially controlled activation of ATP‐producing and ATP‐consuming reactions through the local injection of enzymes in the matrix. The reaction‐diffusion system is maintained in a stationary non‐equilibrium state as long as chemical fuel, phosphocreatine, is present. The reaction‐diffusion system is coupled to a supramolecular system composed of monolayer protected gold nanoparticles and a fluorescent probe. As a result of this coupling, fluorescence signals emerge spontaneously in response to the ATP‐concentration gradients. We show that the approach permits the rational formation of complex fluorescence patterns that change over time as a function of the evolution of the ATP‐concentrations present in the system.