Fluorescent Polymer Films Research Articles

Counter‐Propagating Evanescent Illumination Super‐Resolution Chip

Super‐resolution chip (SRC) made of fluorescent polymer film and polygon film waveguide can realize subdiffraction imaging. However, the propagation losses of evanescent waves impose a serious restriction on imaging performance. Meanwhile, the required redundant raw images hinder the imaging speed. Multiple‐azimuths evanescent illumination at the same time can efficiently increase the illumination intensity and uniformity, and reduce the number of required raw images. But, the experimental realization is impeded by the complex spatial frequency mixing problem. Herein, an SRC microscopy method with counter‐propagating evanescent illumination is demonstrated, which circumvents the influence of complex spatial frequency mixing, and efficiently enhances the reconstructed results. Meanwhile, the proposed method reduces the number of required raw images by half and saves the image acquisition time, which benefits the imaging speed enhancement of the SRC microscopy system and promotes its future practical application.

Aiegen-based fluorescent polymer films with tunable Janus luminescence and structural color

Fluorescent polymer films (FPFs) doped with aggregation-induced emission luminogens (AIEgens) have attracted great attention of scientists for their potential to solve the aggregation-caused quenching effect of traditional fluorescent molecules. Here, to rich the information and enhance the function of FPFs, AIEgens (DCDPP-2TPA) doped FPF was placed in the middle of two different inverse opal photonic crystals (IOPCs), whose photonic band gaps matched with the FPF's red and blue region respectively. Owing to the regulation effect of the IOPCs, tunable Janus luminescence and structural color depending on the viewing angle were achieved. Through designing complex patterns in FPFs, encrypted information can be decoded simply by ultraviolet light. More importantly, the decoded information displays different luminescent colors on each side, and the luminescence on each side is tunable with viewing angles. The “sandwich” structure can be used in most daily environments. Its unique property of variable Janus emissions and structural colors endow the structure with highly safe anti-counterfeiting performance.

Facile preparation of fluorescent non-conjugated polymer films with tunable multicolor photoluminescencevialayer-by-layer assembly

Fluorescent non-conjugated polymer films of poly(acrylic acid)/polyethylenimine are prepared by the layer-by-layer assembly, and these films exhibit tunable multicolor photoluminescence and sensitive response to metal ions.

Cellulose-based fluorescent films with anti-counterfeiting and UV shielding capabilities enabled by enamine bonds

Based on the enamine reaction, the cellulose-based (CAA-PEA) UV shielding film was prepared by solvent pouring.

Measuring dimensionality of cell-scaffold contacts of primary human bone marrow stromal cells cultured on electrospun fiber scaffolds.

The properties and structure of the cellular microenvironment can influence cell behavior. Sites of cell adhesion to the extracellular matrix (ECM) initiate intracellular signaling that directs cell functions such as proliferation, differentiation, and apoptosis. Electrospun fibers mimic the fibrous nature of native ECM proteins and cell culture in fibers affects cell shape and dimensionality, which can drive specific functions, such as the osteogenic differentiation of primary human bone marrow stromal cells (hBMSCs), by. In order to probe how scaffolds affect cell shape and behavior, cell-fiber contacts were imaged to assess their shape and dimensionality through a novel approach. Fluorescent polymeric fiber scaffolds were made so that they could be imaged by confocal fluorescence microscopy. Fluorescent polymer films were made as a planar control. hBSMCs were cultured on the fluorescent substrates and the cells and substrates were imaged. Two different image analysis approaches, one having geometrical assumptions and the other having statistical assumptions, were used to analyze the 3D structure of cell-scaffold contacts. The cells cultured in scaffolds contacted the fibers in multiple planes over the surface of the cell, while the cells cultured on films had contacts confined to the bottom surface of the cell. Shape metric analysis indicated that cell-fiber contacts had greater dimensionality and greater 3D character than the cell-film contacts. These results suggest that cell adhesion site-initiated signaling could emanate from multiple planes over the cell surface during culture in fibers, as opposed to emanating only from the cell's basal surface during culture on planar surfaces.

Transparent and fluorescent breath figure arrays prepared from end-functionalized copolymers

Fluorescent and transparent polymer films with exquisite micro-structures are ideal candidates for anti-counterfeiting tags. However, it is still a great challenge to embed such properties in one breath figure array due to the restriction of the film-forming ability of polymers. In this work, we designed and synthesized fluorescent copolymers from styrene and 1-pyrenylmethyl methacrylate (PYMMA) and studied their self-assembly behaviors via the breath figure method. The significance of end groups and topologies have been investigated in detail. Novel hexagonal breath figure arrays with high transparency are formed at extremely low concentration (down to 0.06 mg/mL). The breath figure arrays display blue honeycomb pattern when irradiated by ultraviolet light. Breath figure arrays with such special optical properties demonstrated an ideal solution for anti-counterfeiting tags. Besides, this work demonstrates the significance of polymer architecture on the morphology of breath figure arrays and may enlighten the polymer design for a broad range of applications. • Fluorescent copolymers were designed and synthesized for self-assembly by the breath figure method. • A highly regular breath figure array can be formed at polymer concentration of as low as 0.06 mg/mL. • Transparent and fluorescent breath figure arrays are potential for anti-counterfeiting. • Effects of end groups and topologies of polymers on the morphology of breath figure arrays were studied.

Sustainable fabrication of N-doped carbon quantum dots and their applications in fluorescent inks, Fe (III) detection and fluorescent films

N-doped CQDs are efficiently fabricated with a green synthesis avenue, and exhibit huge potential in anticounterfeit application as the fluorescent ink, a smart fluorescent sensor towards ionic detection, and fluorescent polymer films. • One-step hydrothermal strategy is devised for synthesizing N-doped CQDs from garlic skins. • The obtained water-soluble N-doped CQDs exhibit a strong cyan luminescence with a quantum yield of ∼9%. • The CQDs present huge potential in anticounterfeit application as the fluorescent ink. • The CQDs show highly sensitive and selective determination of cations as a smart fluorescent sensor. • The PVA/CQDs film gives high visible transparency and nearly 100% UV-blocking ratio. In this work, the highly fluorescent N-doped carbon quantum dots (CQDs) were successfully synthesized via a simple hydrothermal method by using garlic skins (GSs) as the sole carbon source. The resultant N-doped CQDs with excitation-dependent emission demonstrates remarkable quantum yield of ∼9% and superior fluorescence stability. Their strong cyan-emission character upon irradiation with UV light (365 nm) reveals their huge potential in anticounterfeit field as the fluorescent ink. Owing to the fluorescence quenching resulted from the tightly chelating of Fe 3+ to the surface of N-doped CQDs, the CQDs can be applied a functional sensor for the detection of Fe 3+ , and the limit of detection is estimated as 4.44 μM. Furthermore, the CQDs is dispersed into poly (vinyl alcohol) (PVA) matrix to make PVA/CQDs composite film. The unique optical properties of CQDs are inherited by the PVA/CQDs film, giving intensive cyan fluorescence and high visible transparency, as well as nearly 100% UV-blocking ratio in the UV region.

In-situ formation of fluorophore cross-linked micellar thick films and usage as drug delivery material for Propranolol HCl

Polyethylene glycol monomethyl ether–block-poly(glycidyl methacrylate)-block-poly[2-(diethylamino)ethyl methacrylate] triblock copolymer was synthesized to prepare self-assembled micron sized films via a novel approach named as “phase separated micellar self assembly method”. Liquid-air interface self assembly method via slow solvent evaporation was used to obtain micellar films. Cross-linking of polymer films was carried out by diffusion of fluorophore cross-linker into polymer solution from subphase. In-situ micellar formation was triggered via driven forces such as molecular interactions and slow evaporation of solvent. Thiazolo[5,4-d]thiazole based cross-linker fluorophores containing alkali subphases were used to prepare highly fluorescent cross-linked micellar films. Micellar morphologies of the films were characterized with SEM while the cross-sections of fluorophore cross-linked films were observed with TEM analysis to examine diffusion of the dye as nano-sized particles into the polymer film. Convenience and usability of the micellar films as drug delivery material were demonstrated with Propranolol HCl release via UV–Vis spectroscopic studies. Optical properties of the films before and after drug release were determined via photoluminescence spectroscopy to be able to sense the completion of the drug release process. Swelling and shrinkage properties of the films were also determined in different pH values. These highly fluorescent polymer films have great potential as drug delivery materials and biomedical sensing applications.

蛍光性水センサーの創製と水分可視化用蛍光性フィルムの開発

蛍光性水センサーの創製と水分可視化用蛍光性フィルムの開発

Fluorescent polymer films based on photo-induced electron transfer for visualizing water.

As fluorescent materials for visualization, detection, and quantification of a trace amount of water, we have designed and developed a PET (photo-induced electron transfer)-type fluorescent monomer SM-2 composed of methyl methacrylate-substituted anthracene fluorophore-(aminomethyl)-4-cyanophenylboronic acid pinacol ester (AminoMeCNPhenylBPin) and achieved preparation of a copolymer poly(SM-2-co-MMA) composed of SM-2 and methyl methacrylate (MMA). Both SM-2 and poly(SM-2-co-MMA) exhibited enhancement of the fluorescence emission with the increase in water content in various solvents (less polar, polar, protic, and aprotic solvents) due to the formation of the PET inactive (fluorescent) species SM-2a and poly(SM-2-co-MMA)a, respectively, by the interaction with water molecules. The detection limit (DL) of poly(SM-2-co-MMA) for water in the low water content region below 1.0 wt% in acetonitrile was 0.066 wt%, indicating that poly(SM-2-co-MMA) can act as a PET-type fluorescent polymeric sensor for a trace amount of water in solvents, although it was inferior to that (0.009 wt%) of SM-2. It was found that spin-coated poly(SM-2-co-MMA) films as well as 15 wt% SM-2-doped polymethyl methacrylate (PMMA) films produced a satisfactory reversible fluorescence off–on switching between the PET active state under a drying process and the PET inactive state upon exposure to moisture, which is demonstrated by the fact that the both the films are similar in hydrophilicity to each other from the measurement of the water contact angles on the polymer film surface. Herein we propose that PET-type fluorescent polymer films based on a fluorescence enhancement system are one of the most promising and convenient functional dye materials for visualizing moisture and water droplets.

Development of highly sensitive fluorescent sensor and fluorescent sensor-doped polymer films for trace amounts of water based on photo-induced electron transfer

A highly sensitive fluorescent sensor for trace amounts of water based on photo-induced electron transfer (PET) has been developed and the PET-type fluorescent sensor-doped polymer films for moisture and water droplets were prepared.

Facile preparation of fluorescent carbon quantum dots from denatured sour milk and its multifunctional applications in the fluorometric determination of gold ions, in vitro bioimaging and fluorescent polymer film

In the present study, the multifunctional applications of food waste derived carbon quantum dots (CQD) have been demonstrated. The results obtained from the absorption and fluorescence spectroscopic analysis affirmed the superior photophysical property of the prepared CQD. X-ray diffraction (XRD), Fourier transformed infra-red spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) studies further confirmed the crystallographic phase and surface functional groups present in the CQD. The ultrafine size of the CQD is established from the high-resolution transmission electron microscope (HR-TEM) micrographs with the grain size of 2−4 nm. The excellent fluorescence property of the CQD is utilised to detect trace levels of Au3+ ions by simply mixing aqueous dispersion of CQD with ascorbic acid (AA). The sensing mechanism is based on the reduction of Au3+ to gold nanoparticles (AuNPs) by AA and the subsequent AuNPs induced fluorescence quenching of CQD by synergistic static quenching and inner filter effect. The CQD/AA probe could selectively detect Au3+ ion as low as 0.95 μM. The cytotoxicity of the CQD toward U-251 MG glioblastoma cell revealed that the CQD did not possess any significant cytotoxicity. The application of CQD in bioimaging of cells is ascertained by fluorescence microscopic analysis. Furthermore, fluorescent polymer films were prepared by incorporating CQD within the polymer matrix (poly-vinyl-alcohol).

Highly Polarized Active Fluorescent Enhancement Polymer Film With Quantum Rods Aligned by Ink-Jet Printing

Fluorescent CdSe/CdS quantum rods (QRs) as a variation of quantum dots (QDs), have unique advantages of linearly polarized light emission with specific wavelength and small re-absorption. Therefore, QRs are usually aligned to become an active fluorescent enhancement film to replace the down-conversion material, yellow phosphors, in liquid crystal display (LCD) backlight module. However, most of the QRs alignment methods have their own limitations. In this work, we used the contact ink-jet printing (CIJP) to align QRs on flexible polymer substrate. With the QRs being printed, they will flow, automatically align along the printing direction, and be embedded in polymer substrates. Eventually, the ordered QRs become a flexible fluorescent film with better adhesiveness and high degree of polarization (DOP) of 45.2%.

High Lycopene of Tomato Fruit by Blue-Violet Fluorescent Polymer Film

農業分野に応用可能な蛍光色素として，ベンゾトリアゾール系青色蛍光色素が対応する5-カルボキシ-2-（4-ヒドロキシフェニル）-2H-ベンゾトリアゾールから合成した。この蛍光色素をポリカーボネートに含有させ押出成形機で青紫蛍光フィルムを作製した。その蛍光特性は，蛍光主波長が410 nm，蛍光量子収率74％の高効率な発光を示し，優れた耐光性も示した。この蛍光フィルムは，太陽光の下で紫外光を青紫光に波長変換することができることを分光放射光量計の測定で示した。この青紫蛍光フィルムをトマト栽培に使用することで，トマト果実のリコピン含量が著しく増加することを見いだした。また，このリコピン含量の増加は，果皮表面の色彩測定でも明らかになり，対照区（フィルムの無）の完熟トマトと比較して，色差△a*値で2～6増加することがわかった。

Emission-Color Control in Polymer Films by Memorized Fluorescence Solvatochromism in a New Class of Totally Organic Fluorescent Nanogel Particles.

In this work, a new class of totally organic fluorescent nanogel particles and their exceptionally specific behaviors based on their unique structures are introduced, which draws a sharp line from conventional fluorophore-doped and fluorophore-branched-type particles. The nanogel particles, the diameter of which could be controlled by adjusting reaction conditions, such as the solvent system, were spontaneously fabricated with a spherical shape by direct polymerization of non-heterocyclic aromatic compounds, such as 2,6-dihydroxyanthracene, 2,6-dihydroxynaphthalene, and 9,9-bis(4-hydroxyphenyl)fluorene with triazinane as the cross-linker. A fluorophoric moiety formed from a polymer main chain was realized in the particle, and consequently, the resultant content of the fluorophoric moiety was around 70-80 wt % per particle. The uniqueness and versatility of the particles can be emphasized by their good compatibility with various solvents due to their amphiphilic and ampholytic swelling properties, but also by their remarkable fluorescent solvatochromism in the dispersion state. Furthermore, these behaviors were preserved even in their polymer composite system. This study also demonstrates that various fluorescent polymer films can be fabricated with emission color control due to memorization of the solvatochromism phenomenon of the dispersed fluorescent nanoparticles.

Super‐Resolution Microscopy: On‐Chip Super‐Resolution Imaging with Fluorescent Polymer Films (Adv. Funct. Mater. 27/2019)

Super‐Resolution Microscopy: On‐Chip Super‐Resolution Imaging with Fluorescent Polymer Films (Adv. Funct. Mater. 27/2019)

Rationally-designed multi responsive fluorescent switching polymer films

Stimuli-responsive fluorescence switching is of great importance to fluorescence modulation in a wide range of applications, such as sensors, bioimaging, and displays. We report here multi-stimuli-responsive fluorescence switching behavior of a multifunctional polymer bearing oligoaniline, azobenzene, and fluorene groups synthesized via copolycondensation polymerization. This fascinating fluorescence switching behavior is originated from controlled conformational (oligoaniline) and geometric (cis↔trans of azobenzene) changes within a polymer chain upon multiple external stimuli, including potential, pH value, redox species, UV/vis irradiation and heat. This work may provide additional avenue for tuning fluorescent properties of multifunctional polymers.

On‐Chip Super‐Resolution Imaging with Fluorescent Polymer Films

AbstractWide field‐of‐view (FOV), label‐free, super‐resolution imaging is demonstrated using a specially designed waveguide chip that can illuminate a sample with multicolor evanescent waves travelling along different directions. The method is enabled by a polymer fluorescent film that emits over a broad wavelength range. Its polygonal geometry ensures coverage over all illumination directions, enabling high‐fidelity image reconstruction while minimizing distortion and image blurring. By frequency shifting and iterative stitching of different spatial frequencies in Fourier space, the reconstruction of 2D samples is achieved without distortion over wide FOVs. The fabrication process is facile and compatible with conventional semiconductor‐fabrication methods. The super‐resolution chip (SRC) can thus be produced with high yield, offering opportunities for potential conjunction of super‐resolution techniques integrated optical circuits or for the development of single‐use diagnostic kits.

Interfacial Synthesis of Conjugated Crystalline 2D Fluorescent Polymer Film Containing Aggregation-Induced Emission Unit.

A fully conjugated 2D fluorescent film containing a tetraphenylethene (TPE) unit is constructed by Glaser-Hay coupling reaction on the surface of copper foil. A large-area, freestanding fluorescent films with an average thickness 4.5 nm can be obtained through the strategy of solid-liquid interfacial synthesis. The film and the pore structure are characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS). High-resulution TEM and selected area electron diffraction (SAED) further confirm the dual pores structure with triangular- and hexagonal-shaped pores. The as-prepared 2D films exhibit excellent solid-state fluorescence emission arising from the confinement of TPE units.

Fabrication of composite optical fiber taper through “click” polymerization initiated by evanescent field for sensing

In this work, evanescent field initiated “click” polymerization on the surface of the waveguide is used to fabricate composite optical fiber taper probe for sensing. This improvement can effectively keep the polymerization within the scale of evanescent field on the surface of the fiber taper and prevent it in the precursor solution. Besides, for special sensing requirements, such as sensing target and sensitivity, this novel approach (photo-plating) is convenient to choose ingredients composed of the precursor solution in fabrication of a corresponding composite fiber taper probe. The photo-plating process usually completes within 30 s in specific precursor solution. As an example, a probe with a fluorescent polymer film composed of meso-tetrakis(4-allyloxyphenyl) porphyrin (TAOP) was made, which provides the binding sites for the nitro-based explosive molecules. The results indicate that the probe exhibits a good sensitivity and repeatability to trinitrotoluene (TNT), providing a fiber probe platform with miniaturization, real-time and remote monitoring for the detection of TNT vapor.