Fluorescent Copolymer Research Articles

Detection of gaseous amines with a fluorescent film based on a perylene bisimide-functionalized copolymer

A fluorescent copolymer containing PBI units and hydroxyl-ethyl structures was developed for the fast and sensitive detection of gaseous amines

Fabrication of AIE-active fluorescent polymeric nanoparticles with red emission through a facile catalyst-free amino-yne click polymerization

Fluorescent polymeric nanoparticles (FPNs) as novel probes have attracted more and more attention for biomedical applications owing to their optical properties and multifunctional potential. However, most of FPNs based on conventional organic fluorogens encounter serious aggregation-caused quenching (ACQ) effect. In this work, to overcome these problems, amphiphilic fluorescent copolymers [Poly(PEGY-PhE)] containing aggregation-induced emission (AIE) fluorogens (AIEgens) have been prepared via a facile amino-yne click polymerization under rather mild experimental conditions (catalyst-free and room temperature). The Poly(PEGY-PhE) copolymers can self-assemble into FPNs and be well dispersed in aqueous solution. Fluorescence spectra demonstrate that Poly(PEGY-PhE) FPNs possess strong red fluorescence, excellent photostability and low critical micelle concentration. The biological assays confirm that these AIE-active Poly(PEGY-PhE) FPNs possess low cytotoxicity towards L929 cells and cell dyeing performance. More importantly, this amino-yne click polymerization provides a simple strategy to prepare robust biocompatible fluorescent nanoparticles for biological imaging because of their high efficiency, mild reaction conditions and simple experimental operation procedure.

Paclitaxel-loaded PLA/PEG/fluorescein anticancer agent prepared by Ugi reaction

ABSTRACTTwo different fluorescent block copolymers of poly(lactic acid) (PLA) and polyethylene glycol (PEG) containing fluorescein grafted to the polymer chain were synthesized by Ugi four-component condensation (UFCC). The structure of these PEG–PLA copolymers was confirmed by 1H-NMR and fluorescence spectroscopy. Paclitaxel-loaded fluorescent microspheres (PCT-FMS1 and PCT-FMS2) were prepared from them by the single-emulsion solvent evaporation method. A kinetic study of drug release in vitro using high-performance liquid chromatography showed a prolonged and controlled release of paclitaxel. Anticancer activity of release medium against colorectal cancer cell line (Caco-2) was determined using the cell viability assay. Paclitaxel-loaded microspheres were able to inhibit cancer cell growth and colony formation. The main contribution of this work is to propose a new application for UFCC in the preparation of biomasked fluorescent drug delivery systems able to improve cancer treatment.

Highly Fluorescent Conjugated Copolymers Constructed by Alternating Heterocyclic Diazoles and Alkoxy Benzene

Highly fluorescent copolymers Oxa‐Bz and Thia‐Bz consisting of alternating heterocyclic diazole derivative and alkoxy benzene were designed and regioselectively synthesized by the Suzuki–Miyaura reaction with a palladium catalyst. Density functional theory calculation of modeling the repetitive unit suggested the possibility of full conjugation along the polymer chain and the occurrence of intramolecular electron transfer in which the alkoxy benzene moiety was the electron donor and the diazole moiety was the electron acceptor. The extension of conjugation length from the corresponding monomers to the copolymer was confirmed by electrochemical analysis. The redox potentials of the resulting copolymers were significantly reduced in comparison with those of the monomers. The photophysical properties, including absorption and emission spectra, also showed that the energies of the frontier orbitals changed after the covalent bonding between the electron donor and acceptor groups. Moreover, the emission of these two copolymers showed solvent‐dependence, whereby the emission band shifted to longer wavelengths in higher polarity solvents. The fluorescence quantum yields of Oxa‐Bz reached 68% and that of Thia‐Bz 71%. This strong fluorescence might be guaranteed by the rigidity of these copolymers.

Synthesis, characterization, catalytic activity and solar cell study of poly(aniline-co-thymolblue)/metal oxide nanocomposites

The fluorescent conducting copolymer/nanocomposite was prepared under different experimental conditions with variations in [thymolblue] (TB) and weight of metal oxide at 0–5°C under nitrogen atmosphere for 2h at constant aniline (ANI) concentration. The above synthesized copolymer nanocomposites were characterized by Fourier transform infrared (FTIR) spectroscopy, UV–vis spectroscopy, fluorescence emission spectroscopy, field emission scanning electron microscopy (FESEM), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and conductivity measurements. Due to the surface catalytic effect of metal oxide, the copolymer followed the 0.20 order of reaction. Further, the solar cell study was carried out to find out the conversion efficiency of the fluorescent copolymer nanocomposite system. Reduction of nitrophenol (NiP) into aminophenol was carried out in the presence of fluorescent copolymer/nanocomposite as a catalyst. The results were critically analyzed and compared with the literature values.

Fluorescent ROMP Monomers and Copolymers for Biomedical Applications.

The synthesis and characterization of a series of green, blue and red-fluorescent exo-oxanorbornene acid and imide monomers carrying nitrobenzofurazan, coumarin, and Rhodamin B, respectively, as fluorophores is presented. These monomers carry oxanorbornene as polymerizable unit, and were readily copolymerized with bioactive functional oxanorbornene monomers by ring-opening metathesis polymerization (ROMP), as demonstrated by gel permeation chromatography and NMR spectroscopy. Due to the ease of synthesis of these monomers, and their cost-effectiveness compared many to other fluorescent probes, they are useful for biomaterials applications.

Organoboron-Based Photochromic Copolymers for Erasable Writing and Patterning

We report herein the first examples of organoboron-based photochromic polymers. The synthesis of a series of blue fluorescent random copolymers bearing photochromic boron repeating units, poly[(6-B(ppy)Mes2)oxyhexyl methacrylate)m-r-(tert-butyl methacrylate)n], ppy = 2-phenylpyridyl and Mes = mesityl, via atom transfer free radical polymerization (ATRP) has been accomplished. These new polymers display thermally reversible photochromism, switching color from colorless to deep blue, and fluorescence from bright sky blue to deep blue. By controlling the monomer ratio, the photoisomerization quantum efficiencies of the polymers can be tuned effectively. In addition, the number of boron units in the polymer has been found to have a significant impact on fluorescence quenching efficiency. The new organoboron-based polymers can be used effectively as a switchable/erasable ink on glass or paper substrate or for creating switchable/erasable patterns as neat polymer films.

Synthesis of fluorescent diblock copolymer nanoparticle supported catalyst for the reduction of Cr(VI), p-nitrophenol and rhodamine 6G dye: a comparative study

A fluorescent diblock copolymer nanocomposite (DBCNC) was synthesized by ring opening polymerization (ROP) method using rhodamine 6G (R6G) dye as an initiator through bulk polymerization technique. ROP of caprolactone was carried out at $$160^{\circ } \hbox {C}$$ for 2 h under nitrogen atmosphere in the presence of stannous octoate (Sn(Oct) $$_{2}$$ ) as a catalyst followed by the ROP of tetrahydrofuran in the presence of phthalicanhydride as a co-monomer. Thus, synthesized fluorescent DBCNC was characterized by various analytical tools such as FTIR spectroscopy, UV–visible spectroscopy fluorescence emission spectroscopy, DSC, TGA and FESEM. The catalytic reduction of p-nitrophenol (NiP), Cr(VI) and R6G was carried out in the presence of DBCNC as a catalyst with the help of UV–visible spectrophotometer. The apparent rate constant ( $$k_{\mathrm{app}}$$ ) and induction time ( $$T_{\mathrm{i}}$$ ) were determined from the UV–visible spectral data. The nanosized $$\hbox {V}_{2} \hbox {O}_{5}$$ was prepared by a simple chemical reduction of bulk-sized $$\hbox {V}_{2}\hbox {O}_{5}$$ by using sodium borohydride ( $$\hbox {NaBH}_{4}$$ ) as a reducing agent. During the DBC formation, 0.01 g of nanosized $$\hbox {V}_{2}\hbox {O}_{5}$$ was added. This type of polymer supports the catalyst which is very much useful in the catalysis industry because of its easy separation and recyclable property.

Pillar[5]arene-Diketopyrrolopyrrole Fluorescent Copolymer: A Promising Recognition and Adsorption Material for Adiponitrile by Selective Formation of a Conjugated Polypseudorotaxane.

Conjugated pillar[5]arene-diketopyrrolopyrrole copolymer (P1) is synthesized by the copolymerization of a difunctionalized pillar[5]arene and a diketopyrrolopyrrole-based monomer, which shows large extinction coefficients (1.1 × 104 m-1 cm-1 ) at 519 nm and strong emission at 587 nm. P1 exhibits very strong host-guest binding affinity towards adiponitrile but low binding affinity towards 1,4-dihalobutane and 1,4-bis(imidazol-1-yl)butane. Such an enhanced selectivity is first found in the polypseudorotaxane between pillararene and neutral guests in organic solution and is successfully used for the recognition and adsorption of adiponitrile by the formation of a P1-adiponitrile polypseudorotaxane.

Performance of white light emitting diodes prepared by casting wavelength‐converting polymer on InGaN devices

ABSTRACTUV‐curable siloxane oligomers prepared by a hydrosilylation reaction were used as encapsulant. Two fluorescent copolymers with emission covering the range of green and red light were synthesized and blended with the UV‐curable siloxane oligomers and photoinitiator to make the wavelength‐converting polymer (WCP). WCP was casted on blue light emitting InGaN diodes and UV cured to fabricate white light emitting diodes (WLEDs). Effects of monomer compositions on the fluidity of uncured oligomer, together with the optical, thermal, and mechanical properties of the cured polysiloxane were studied. We also investigated the influence of red fluorescent polymer which was comprised of repeating units of dioctylfluorene, bisthienyl‐benzothiadiazole, and benzothiadiazole segments on the color rendering index, correlated color temperature, and luminous efficacy of WLED. Because of the good match between the absorption and emission features of the segments in the fluorescent copolymers, white LEDs can be produced by fluorescent copolymer blends which can support incomplete energy transfer. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45210.

Synthesis of amphiphilic fluorescent copolymers with smart pH sensitivity via RAFT polymerization and their application in cell imaging

In this paper, a fluorescein methacryloyl monomer (named Flu-MA) was firstly fabricated by the esterification reaction of fluorescein and methacryloyl chloride; subsequently, a novel amphiphilic fluorescent copolymer (Flu-PEG) with smart pH sensitivity was successfully prepared by RAFT copolymerizing of Flu-MA and poly(ethylene glycol) monomethacrylate (PEGMA). The result of 1H NMR and FTIR implied that both Flu-MA and PEGMA monomers were successfully incorporated into Flu-PEG copolymers, the molecular weight (M n) of which was about 39,800 with polydispersity index (PDI) as about 1.30. In aqueous solution, Flu-PEG copolymers could self-assemble into fluorescent organic nanoparticles (FONs) with about 200 nm diameters due to high water dispersibility and good fluorescence, respectively, endowed by PEGMA and Flu-MA, the fluorescence intensity of which was high sensitive to pH value of solution. More importantly, due to their high water dispersibility, excellent biocompatibility and good fluorescence, the as-prepared Flu-PEG FONs were high attractive for the application in cell imaging. A novel amphiphilic fluorescent copolymer (Flu-PEG) with smart pH-sensitivity was successfully fabricated by RAFT copolymerizing of Flu-MA and PEGMA, which showed high water dispersibility, uniform size and excellent biocompatibility, making them be highly potential for bioimaging application.

Hybrid nanocomposites of a fluorescent block copolymer and quantum dots: An efficient way for energy transfer

Förster resonance energy transfer (FRET) phenomenon has great potential in several applications, whose efficiency is dependent on the energy transfer between a suitable pair of fluorophores. In this work, a new block copolymer, PS-b-PS(co-pyren-1-yl), with fluorescent properties, was synthetized and used as donor component in the fluorophores pair copolymer/cadmium telluride quantum dots (CdTe QDs). Thus, water-soluble CdTe QDs, previously transferred into organic phase, by replacing the stabilizer ligands, thioglycolic acid by 1-dodecanethiol (1-DDT), were used to prepare a new hybrid nanocomposite. FRET studies between the fluorescent copolymer and CdTe-DDT QDs revealed that this fluorophores pair can experience FRET with an efficiency of 48%, being an efficient antenna system for light harvesting applications.

A new AIE multi-block polyurethane copolymer material for subcellular microfilament imaging in living cells.

A multi-block fluorescent amphiphilic polyurethane copolymer (TPE-PU), self-assembling into hairy, water-soluble micelles, is used as a subcellular microfilament probe in living cells.

Drug Release by Direct Jump from Poly(ethylene-glycol-b-ε-caprolactone) Nano-Vector to Cell Membrane.

Drug delivery by nanovectors involves numerous processes, one of the most important being its release from the carrier. This point still remains unclear. The current work focuses on this point using poly(ethyleneglycol-b-ε-caprolactone) micelles containing either pheophorbide-a (Pheo-a) as a fluorescent probe and a phototoxic agent or fluorescent copolymers. This study showed that the cellular uptake and the phototoxicity of loaded Pheo-a are ten times higher than those of the free drug and revealed a very low cellular penetration of the fluorescence-labeled micelles. Neither loaded nor free Pheo-a displayed the same cellular localization as the labeled micelles. These results imply that the drug entered the cells without its carrier and probably without a disruption, as suggested by their stability in cell culture medium. These data allowed us to propose that Pheo-a directly migrates from the micelle to the cell without disruption of the vector. This mechanism will be discussed.

Digitization of Endocytic pH by Hybrid Ultra-pH-Sensitive Nanoprobes at Single-Organelle Resolution.

A multispectral hybrid nanotransistor consisting of modular fluorescent block copolymers with discrete and sharp pH transitions in one nanoparticluate system is presented. This nanotransistor probe allows digitized reporting of dynamic maturation at single-organelle resolution over time. This nanotechnology platform offers a powerful tool in fundamental studies of organelle biology, cell signaling in diseases characterized by pH dysregulation in the endosomes or lysosomes.

Complex Structured Fluorescent Polythiophene Graft Copolymer as a Versatile Tool for Imaging, Targeted Delivery of Paclitaxel, and Radiotherapy.

Advances in polymer chemistry resulted in substantial interest to utilize their diverse intrinsic advantages for biomedical research. Especially, studies on drug delivery for tumors have increased to a great extent. In this study, a novel fluorescent graft copolymer has been modified by a drug and targeting moiety and the resulting structure has been characterized by alterations in fluorescent intensity. The polythiophene based hybrid graft copolymer was synthesized by successive organic reactions and combination of in situ N-carboxy anhydride (NCA) ring opening and Suzuki coupling polymerization processes. Initially, targeted delivery of the graft copolymer was investigated by introducing a tumor specific ligand, anti-HER2/neu antibody, on the structure. The functionalized polymer was able to differentially indicate HER2-expressing A549 human lung carcinoma cells, whereas no signal was obtained for Vero, monkey kidney epithelial cells, and HeLa, human cervix adenocarcinoma cells. After integrating paclitaxel into the structure, cell viability, cell cycle progression, and radiosensitivity studies demonstrate HER2/neu targeting polymers were most effective to inhibit cell proliferation. Importantly, the graft copolymer used had no cytotoxic effects to cells, as evidenced by cell viability and cell cycle analysis. This work clearly confirms that a specially designed and fabricated graft copolymer with a highly complex structure is a promising theranostic agent capable of targeting tumor cells for diagnostic and therapeutic purposes.

Fluorescent amphiphilic copolymer-based tumor theranostics for facile DOX-loading and tumor microenvironment-triggered release

Novel reduction/pH dual-stimuli responsive fluorescent amphiphilic copolymer PEG-Cys-P(DEAEMA-co-Rh6GEAm) with detachable poly(ethylene glycol) (PEG) corona through bio-reducible disulfide linkage and pendent cationic groups was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization for tumor theranostic application. The doxorubicin (DOX)-loaded micelles could be easily fabricated via facile micellization in the presence of DOX in water, with a high drug-loading capacity (DLC) of 39.2%. They exhibited fast release ratio with the synergetic effect of reductive agent and pH in the simulated tumor micro-environment, while the leakage can be efficiently avoided in the physiological media. Furthermore, the fluorescence intensity of the copolymer possessed a reversibly transformation in different pH media, indicating the potential application for intracellular fluorescence imaging of tumors.

PH-Mediated Fluorescent Polymer Particles and Gel from Hyperbranched Polyethylenimine and the Mechanism of Intrinsic Fluorescence.

We report that fluorescence properties and morphology of hyperbranched polyethylenimine (hPEI) cross-linked with formaldehyde are highly dependent on the pH values of the cross-linking reaction. Under acidic and neutral conditions, water-soluble fluorescent copolymer particles (CPs) were produced. However, under basic conditions, white gels with weak fluorescence emission would be obtained. The water-soluble hPEI-formaldehyde (hPEI-F) CPs show strong intrinsic fluorescence without the conjugation to any classical fluorescent agents. By the combination of spectroscopy and microscopy techniques, the mechanism of fluorescence emission was discussed. We propose that the intrinsic fluorescence originates from the formation of a Schiff base in the cross-linking process between hPEI and formaldehyde. Schiff base bonds are the fluorescence-emitting moieties, and the compact structure of hPEI-F CPs plays an important role in their strong fluorescence emission. The exploration on fluorescence mechanism may provide a new strategy to prepare fluorescent polymer particles. In addition, the investigation shows that the hPEI-F CPs hold potential as a fluorescent probe for the detection of copper ions in aqueous media.

Polymeric Gene Carriers Bearing Pendant β-Cyclodextrin: The Relevance of Glycoside Permethylation on the "In Vitro" Cell Response.

The incorporation of cyclodextrins (CDs) to nonviral cationic polymer vectors is very attractive due to recent studies that report a clear improvement of their cytocompatibility and transfection efficiency. However, a systematic study on the influence of the CD derivatization is still lacking. In this work, the relevance of β-CD permethylation has been addressed by preparing and evaluating two series of copolymers of the cationic N-ethyl pyrrolidine methacrylamide (EPA) and styrenic units bearing pendant hydroxylated and permethylated β-CDs (HCDSt and MeCDSt, respectively). For both cell lines, CDs permethylation shows a strong influence on plasmid DNA complexation, "in vitro" cytocompatibility and transfection efficiency of the resulting copolymers over two murine cell lines. While the incorporation of the hydroxylated CD moiety increased the cytotoxicity of the copolymers in comparison with their homopolycationic counterpart, the permethylated copolymers have shown full cytocompatibility as well as superior transfection efficiency than the controls. This behavior has been related to the different chemical nature of both units and tentatively to a different distribution of units along the polymeric chains. Cellular internalization analysis with fluorescent copo-lymers supports this behavior.

Optically induced mode splitting in self-assembled, high quality-factor conjugated polymer microcavities.

We investigate the whispering gallery modes (WGMs) of self-assembled single microspheres. They consist of a recently developed highly fluorescent π-conjugated copolymer and exhibit excellent optical properties with Q-factors up to 104. Under continuous laser irradiation, we observe a splitting of the highly degenerate spherical WGMs into a multiplet of lines. Comparison with the calculated spectral response of a weakly distorted sphere shows that the optical excitation induces a change of the optical path length in the microcavity so that it resembles a prolate spheroid. The separation of the lines is given by the ellipticity and the azimuthal mode number. Measurements in various gaseous environments suggest that the distortion is caused by light induced oxidation of the polymer. Our findings show that photooxidation can be a beneficial mechanism for in-situ tuning of optically active polymer structures.