Fluorescent Polymer Microspheres Research Articles

Synthesis and characterization of luminescent polymer microspheres based on terpyridine for detecting Fe(III)

The novel polymer fluorescent microspheres (PS-TPY) based on styrene and terpyridine units were successfully synthesized via radical precipitation polymerization using ethanol and water as mixing dispersion medium. The structures and properties of the polymer microspheres were systematically investigated by NMR, IR, UV–vis absorption and fluorescence emission spectra. The average diameter of 380–630 nm for the resulted polymer microspheres was verified by dynamic light scattering (DLS) and scanning electron microscopy (SEM), and could be regulated effectively through changing the ratio of the monomers and the composition of the dispersion medium. The introducing of the conjugated terpyridine unit into the microspheres resulted into a distinct blue emission at about 360–430 nm wavelength. Based on the interaction between the transition metal ions and the terpyridine structure, these fluorescent polymer microspheres displayed high selectivity and sensitivity for probing Fe3+.

Impact of Plasmonic and Dielectric Substrates on the Whispering-Gallery Modes in Self-Assembled Fluorescent Semiconductor Polymer Microspheres.

In this work, the impact of metallic and dielectric conducting substrates, gold and indium tin oxide (ITO)-coated glass, on the whispering gallery modes (WGMs) of semiconductor π-conjugated polymer microspheres is investigated. Hyperspectral mapping was performed to obtain the excitation-position-dependent emission spectra of the microspheres. Substrate-dependent quenching of WGMs sensitive to mode polarization was observed and explained. On a glass substrate, both transverse-electric (TE) and transverse-magnetic (TM) WGMs are quenched due to frustrated total internal reflection. On a gold substrate, however, only the TM WGMs are allowed in symmetry to leak into surface plasmons. An atomically flat gold substrate with subwavelength slits was used to experimentally verify the leakage of WGMs into the surface plasmon polaritons (SPPs). This work provides insight into the damping mechanisms of WGMs in microspheres on metallic and dielectric substrates.

Design, synthesis and performance of novel fluorescent polymer microspheres tracers based on aggregation induced emission

AbstractIn this study, blue fluorescent polymer microspheres tracers are prepared by dispersion polymerization using aggregation induced emission monomers, styrene and sodium vinyl benzene sulfonate as raw materials. The properties of the microspheres are investigated by field emission scanning electron microscopy, fluorescence microscopy and fluorescence spectrum. The results show that N‐(4‐(4‐(1,2,2‐triphenylvinyl)phenoxy)butyl)acrylamide exhibits typical AIE properties in a mixture of water and tetrahydrofuran. The fluorescent polymer microspheres are smooth and monodisperse. Concentration‐dependent experiments indicate that the fluorescence intensity of the fluorescent polymer microspheres increases with the increasing of concentration. In addition, we explore the effects of temperature, pH, and some metal ions on the fluorescent polymer microspheres, and find that the fluorescence intensity is still good under these influencing conditions. We also investigate the stability of the polymer, the fluorescence intensity of the polymer hardly changed during the 30‐day monitoring period, indicating its good stability. Therefore, the above research results indicate that the fluorescent polymer microspheres can be used as potential oilfield tracers.

Effect of short-term exposure to fluorescent red polymer microspheres on Artemia franciscana nauplii and juveniles

Microplastics (MPs) are ubiquitously present in the world’s seas with unknown potential toxic effects on aquatic ecosystems. The aim of this study was to evaluate biochemical responses caused by 1–5 μm diameter plastic fluorescent red polymer microspheres (FRM), under short-term exposure of nauplii and juveniles of Artemia franciscana, using a set of biomarkers involved in important physiological processes such as biotransformation, neuronal transmission and oxidative stress. Two FRM concentrations (0.4 and 1.6 mg mL−1) present in the water at ecologically relevant concentrations were used to study their toxicity. No significant differences were found in growth, survival and feeding behaviour of nauplii, after 2 days of exposure to both FRM concentrations. However, in juveniles, survival decreased after 5 days of exposure to FRM1.6; but no significant differences were found in either growth or feeding behaviour. It was observed that nauplii and juveniles, under short-term exposure, had the ability to ingest and egest FRM particles, although their accumulation was higher in nauplii than in juveniles, maybe related with the capacity of the latter to empty their gut content faster, in the presence of food. Regarding biomarkers responses in nauplii, all enzymatic activities increased significantly, after short-term exposure to the higher FRM concentration tested (FRM1.6), which could be related with detoxifying MPs-triggered oxidative stress. In juveniles, the inhibition of ChE and the decrease in the activity of antioxidant enzymes, after 5 days of exposure to FRM1.6, might indicate a neurotoxic effect and oxidative damage induced by FRM. This study provides further evidences that accumulation of MPs in the gut by nauplii and juveniles of A. franciscana can induce negative effects on important physiological processes with influence on their health, highlighting the general concern about the negative effects of MPs pollution on aquatic species, as well as the need to understand the mechanism of MPs toxicity and its possible impacts on environmental safety.Graphical abstract

Highly Crosslinked and Clickable Poly(divinylbenzene) Microspheres by Type II Photoinitiated Precipitation Polymerization

Front Cover: In article number 2100022 by Tugrul Cem Bicak, a new method, namely “Type-II photoinitiated precipitation polymerisation”, is described for the synthesis and functionalisation of highly crosslinked microspheres in one step. Using this method, click functionality is introduced to the particles at room temperature by UV irradiation. A pyrene group is then attached onto the particles by CuAAC click reaction to confirm the presence and accessibility of the alkyne moiety, paving the way for fluorescent polymer microspheres.

FLOW DYNAMICS OF BEVELED-TIP AND FLAT-TIP VITREOUS CUTTERS.

To compare the flow dynamics of beveled-tip to that of flat-tip vitreous cutters. The aspiration rates of balanced salt solution and swine vitreous were measured for 25-gauge and 27-gauge beveled-tip and flat-tip vitreous cutters. Fluorescent polymer microspheres were mixed with balanced salt solution to make the flow visible. The flow dynamics at maximal cutting rates and reflux of balanced salt solution were measured with video images of a high-speed camera. The aspiration rates of balanced salt solution of the 25-gauge and 27-gauge beveled-tip cutters were significantly higher than that of the flat-tip cutters at 7,500 cut/min (P = 0.0001, P = 0.038, respectively). The aspiration rate of swine vitreous by the 25-gauge beveled-tip cutter was significantly higher than that of the flat-tip cutters (P = 0.006). The mean aspiration flow in front of the cutter was significantly faster for both beveled-tip than flat-tip cutters (P = 0.003, P = 0.023). The angle of the mean aspiration flow of both beveled-tip cutters was turned to the proximal side (P = 0.004, P = 0.003). The mean reflux flow of both beveled-tip cutters was significantly faster than that of the flat-tip cutters (P = 0.006, P = 0.006). The beveled-tip cutters have a greater velocity of aspirating frontal and proximal flow resulting in higher aspiration rates and greater reflux flow velocity.

Influence mechanism of fluorescent monomer on the performance of polymer microspheres

Abstract In order to quantitatively study the migration and retention of polymer microspheres in oil reservoirs, three kinds of fluorescent polymer microspheres P(AM-BA-AMCO), P(AM-BA-Ac-Flu) and P(AM-BA-RhB) were synthesized. Effects of fluorescent monomer on the performance of polymer microspheres were researched systematically. The results showed that addition of low concentration fluorescent monomers had no significant effect on initial particle size and swelling property of polymer microspheres. When the fluorescent monomers were added to microspheres, red shift of the luminescence spectrums occurred and the red shift distance of coumarin monomer was the shortest. The fluorescence intensity of microspheres was greater than that of fluorescent monomer itself, and the fluorescence intensity of the microsphere containing rhodamine monomer increased to a greater extent. The addition of fluorescent monomer could destroy the structure of hydrophilic polymer microsphere bulk gel to a certain extent and affect the creep performance of polymer microsphere bulk gel.

Fluorescein ether-ester dyes for labeling of fluorinated methacrylate nanoparticles

Fluorescent core-shell particles are used as versatile fluorophores in confocal microscopy based image analysis and as a colloidal model system to study short and long-range interactions. Bright and stable microspherical probes are proposed as promising materials, especially in bioimaging applications. The release of dyes from fluorescent polymer microspheres is undesirable. Covalent linking of dyes within polymeric spheres during the polymerization process can solve the problem of dye leaching. This requires, e.g. the introduction of reactive groups into the dyes. Its more lipophilic ester-ether derivatives considerably reduced fluorescence. The fluorescent quantum yield of prepared nanoparticles was determined to be below 10%. As-prepared nanoparticles exhibited a low refractive index (1.293–1.349), hence their use is recommended. Scanning electron microscope (SEM) images and the fluorescence correlation spectroscopy (FCS) measurements confirmed high polydispersity of synthesized particles (40–230 nm), and are in agreement with the dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA) results (hydrodynamic diameters 203 ± 9, 548 ± 50, 146 ± 2 nm). The zeta potential of fluorescent 1H,1H-heptafluoro-n-butyl methacrylate (HFBMA) shell nanoparticles (NPs) with propargyl ether-esters, 2-methyl allyl ether-esters and allyl ether-esters of fluorescein was -44.5,-14, -44.7 mV, respectively. The values are different despite the slight difference in the structure of ester-ether derivatives.

Aqueous synthesis of amphiphilic graphene quantum dots and their application as surfactants for preparing of fluorescent polymer microspheres

Amphiphilic carbon-based nanoparticles have recently attracted much attention in stabilizing Pickering emulsions owing to their low cytotoxicity, cost-effectiveness and biocompatibility. In this work, a facile and aqueous synthesis method was developed for the preparation of amphiphilic graphene quantum dots by modifying hydrophilic GQDs (GQDs-COOH) with hydrophobic hexylamine. Distinctive from pristine GQDs-COOH, amphiphilic GQDs show interesting surface-active properties and can stabilize water-in-cyclohexane Pickering emulsions. As efficient particle surfactants, amphiphilic GQDs could be applied in a mini-emulsion polymerization system to synthesize submicron-sized polystyrene particles. Particularly, the as-prepared PS particles were highly luminescent as produced by the highly fluorescent amphiphilic GQDs.

Preparation of a fluorescent polymer microsphere and stability evaluation of its profile control system by a fluorescence stability index

A quantitative stability evaluation method of a profile control system based on fluorescence intensity of fluorescent polymer microsphere was constructed due to the inaccurate measurement of conventional method. One kind of fluorescent polymer microspheres were prepared in this research, and microstructure of them was characterized by FT-IR spectra, laser particle size analyzer, inverse fluorescence microscope and ESEM. The swelling behavior of polymer microspheres was evaluated by weighing method. The fluorescent intensity of polymer microspheres was measured by fluorescence spectrometer. The stability influence factors and the stability mechanism of florescent polymer microsphere profile control system(FPMPCS)were studied using Fluorescent Stability Index (FSI) which was proposed in this research. The results show that higher polymer or surfactant concentration can promote the stability of the system. There is great influence of temperature on the system stability during the high temperature range, and every kind of polymer microsphere has an optimum salinity from the aspect of stability. There is a limit to improve the system stability by reducing the average size of fluorescent polymer microspheres. To improve the stability of this kind of system, bulk viscosity, the space barrier and electrostatic repulsion among the particles should be considered.

Preparation and Properties of Magnetic-fluorescent Microporous Polymer Microspheres

Microporous microspheres can be used as functional nanomaterial carriers for their microporous structure and higher specific surface area. In this study, magnetic fluorescent polymer microspheres were prepared by incorporating Fe3O4 nanoparticles and CdSe/ZnS quantum dots(QDs) into hyper-crosslinked microporous polymer microspheres(HCMPs) via the in situ coprecipitation method and swelling-diffusion. The HCMPs predominantly have micropores, and their specific surface area is as high as 703.4 m2/g. The magnetic-fluorescent microspheres maintain the superparamagnetic behavior of Fe3O4, and the saturation magnetization reaches 38.6 A·m2/kg. Moreover, the composite microspheres exhibit an intense emission peak at 530 nm and achieve good fluorescence.

Synthesis and plugging behavior of fluorescent polymer microspheres as a kind of conformance control agent in reservoirs.

The fluorescent polymer microsphere is a newly developed chemical agent for conformance control in reservoirs. In this paper, one kind of fluorescent polymer microspheres P(AM-BA-RhB) was synthesized via the inverse suspension polymerization method with Rhodamine B as a fluorescence functional monomer. Laboratory experiments were performed to characterize the morphology, fluorescent property, swelling property and plugging behavior of fluorescent polymer microspheres. The experimental results showed that the polymer microspheres P(AM-BA-RhB) displayed stable fluorescence performance in solutions containing metal ions at pH values between 3.0 and 10.0. The swelling property was not dramatically affected by the Rhodamine B embedded in the polymer microspheres by grafting. Both a visual micromodel test and sand-pack tubes experiment demonstrated that the fluorescent polymer microspheres could pass directly or by deformation through porous media and get into the in-depth formation. The injection pressure showed the phenomenon of “Wave-type Variation”. Three plugging behaviors such as piston plugging, protruding plugging and fingering plugging were put forward. The introduction of fluorescent polymer microspheres could provide one method to research the conformance control and EOR mechanism of polymer microspheres in the reservoirs.

Preparation and performance of fluorescent polyacrylamide microspheres as a profile control and tracer agent

Polyacrylamide microspheres have been successfully used to reduce water production in reservoirs, but it is impossible to distinguish polyacrylamide microspheres from polyacrylamide that is used to enhance oil recovery and is already present in production fluids. In order to detect polyacrylamide microspheres in the reservoir produced fluid, fluorescent polyacrylamide microspheres P(AM-BA-AMCO), which fluoresce under ultraviolet irradiation, were synthesized via an inverse suspension polymerization. In order to keep the particle size distribution in a narrow range, the synthesis conditions of the polymerization were studied, including the stirring speed and the concentrations of initiator, Na2CO3, and dispersant. The bonding characteristics of microspheres were determined by Fourier transform infrared spectroscopy. The surface morphology of these microspheres was observed under ultraviolet irradiation with an inverse fluorescence microscope. A laboratory evaluation test showed that the fluorescent polymer microspheres had good water swelling capability, thus they had the ability to plug and migrate in a sand pack. The plugging rate was 99.8 % and the residual resistance coefficient was 800 after microsphere treatment in the sand pack. Furthermore, the fluorescent microspheres and their fragments were accurately detected under ultraviolet irradiation in the produced fluid, even though they had experienced extrusion and deformation in the sand pack.

Transport of colloids in unsaturated packed columns: Role of ionic strength and sand grain size

The main objective of this study was to better understand the combined effects of ionic strength, and sand grain size on colloid fate and transport in unsaturated porous media. Spherical fluorescent polymer microspheres with three different sizes (0.075, 0.30 and 2.1μm), and laboratory columns packed with two size fractions of clean quartz sand (0.513 and 0.181mm) were used. The saturation level of the packed columns was set to 83–95% with solutions having a wide range of ionic strength (0.1–1000mM). The electrophoretic mobility of colloids and sand grains were evaluated for various ionic strength conditions. The single collector removal and collision efficiencies were quantified using the classical colloid filtration theory. Furthermore, theoretical collision efficiencies were estimated with appropriate DLVO energies using a Maxwell model. The experimental results suggested that the retention of the bigger colloids (2.1μm) was slightly higher compared to the conservative tracer and smaller colloids (0.3 and 0.075μm) in deionized-distilled-water, indicating attachment at air–water interfaces or straining. Moreover, relatively smaller attachment was observed onto fine than medium quartz sand. The mass recovery of the 0.3μm microspheres in NaCl solution was shown to significantly decrease with increasing ionic strength. Both the experimental and theoretical collision efficiencies based on colloid interactions with solid–water interfaces, were increased with increasing ionic strength.

Responsive Micromolds for Sequential Patterning of Hydrogel Microstructures

Microscale hydrogels have been shown to be beneficial for various applications such as tissue engineering and drug delivery. A key aspect in these applications is the spatial organization of biological entities or chemical compounds within hydrogel microstructures. For this purpose, sequentially patterned microgels can be used to spatially organize either living materials to mimic biological complexity or multiple chemicals to design functional microparticles for drug delivery. Photolithographic methods are the most common way to pattern microscale hydrogels but are limited to photocrosslinkable polymers. So far, conventional micromolding approaches use static molds to fabricate structures, limiting the resulting shapes that can be generated. Herein, we describe a dynamic micromolding technique to fabricate sequentially patterned hydrogel microstructures by exploiting the thermoresponsiveness of poly(N-isopropylacrylamide)-based micromolds. These responsive micromolds exhibited shape changes under temperature variations, facilitating the sequential molding of microgels at two different temperatures. We fabricated multicompartmental striped, cylindrical, and cubic microgels that encapsulated fluorescent polymer microspheres or different cell types. These responsive micromolds can be used to immobilize living materials or chemicals into sequentially patterned hydrogel microstructures which may potentially be useful for a range of applications at the interface of chemistry, materials science and engineering, and biology.

Analysis of Circular PDMS Microballoons With Ultralarge Deflection for MEMS Design

This paper presents the simplified analytical and numerical analyses of the ultralarge deflection of circular polydimethylsiloxane (PDMS) microballoons (MBs) under pressure for microelectromechanical systems design. The analytical model assuming spherical symmetry on the deformed shape of MB yields a simplified solution on the pressure-normalized maximum deflection and two in-plane principal strains of the ultralargely deflected MB. The accuracy of the theoretical model is evaluated by comparing against the experimental results. Furthermore, by using a computational analysis that incorporates a Mooney-Rivlin model for a PDMS micromembrane, the properties of the PDMS fabricated at a mixing ratio of 10:1 base to catalyst, a curing temperature of 20°C, and a curing time of 48 h are determined for noncircular PDMS micromembrane analysis. In the experimental study, eight types of PDMS MBs, each of which has a membrane radius of 143, 202, 452, or 904 μm and a membrane thickness of 10 or 20 μm, are characterized in air and in cell culture media. A new strain-measuring method using fluorescent polymer microspheres for the PDMS MB is also introduced. The characterization of the PDMS MBs in air validates our theoretical model and shows an increase in elastic modulus as the membrane thickness decreases. The effect of cell culture media on the membrane rigidity of PDMS is also examined for biological applications of PDMS.

Synthesis of hollow fluorescent polymeric microspheres with movable magnetic cores

AbstractLow‐dispersity hollow poly[(ethyleneglycol dimethacrylate)‐co‐(N‐vinylcarbazole)] (P(EGDMA‐co‐NVCz)) fluorescent microspheres with movable magnetic cores were prepared by quantitative removal of the silica component in hydrofluoric acid aqueous solution from the corresponding magnetite/silica/P(EGDMA‐co‐NVCz) tri‐layer hybrid microspheres. The tri‐layer microspheres with magnetic cores and fluorescent polymer shells were synthesized by distillation precipitation copolymerization of ethyleneglycol dimethacrylate crosslinker and N‐vinylcarbazole fluorescent monomer in acetonitrile in the presence of 3‐(methacryloxy)propyltrimethoxysilane‐modified magnetite/silica particles as seeds, which were afforded by a modified Stöber sol–gel process, to coat the magnetite cores. The corresponding hollow fluorescent polymer microspheres with movable magnetic cores were studied using transmission electron microscopy, Fourier transform infrared spectroscopy, vibrating sample magnetometry, UV‐visible spectroscopy and fluorescence spectroscopy. Copyright © 2010 Society of Chemical Industry

Buoyancy-Driven Continuous SPLITT Fractionation: A New Technique for Separation of Microspheres

A new method of Continuous Fractionation using a SPLITT cell is conceived, developed, and tested, and is demonstrated to be useful for separation of collections of particles with different sizes and densities. With this previously uninvestigated mode of operation, this is accomplished for particles by buoyancy-driven separation. Some of the capabilities of this system are illustrated by successful separations of different-sized fluorescent polymer microspheres, with different carrier densities. The resulting experimentally-measured fraction recovery variations are then in good agreement with theoretical calculation from buoyancy-driven SPLITT theory.

Integrin Response To Altered Actin-Myosin Mechanochemistry In Cardiac Myocytes

Altered contractility in cardiac myocytes associated with motor protein mutations has been implicated in several pathologies such as familial hypertrophic (FHC) and dilated (DCM) cardiomyopathies. The mechanism(s) by which these altered contractile forces result in cell phenotype changes are poorly understood. However, they are generally believed to involve mechanotransduction of force by cell adhesion molecules such as the integrin class of proteins. Here we investigate the use of blebbistatin and other small molecule effectors of actin-myosin mechanochemistry as a chemical model for the reduced contractile force associated with the pathogenesis of DCM. In order to establish intercalated-disk cell associations in vitro that are representative of in vivo conditions, we employ micropatterned cardiac myocyte cell culture, where the extracellular matrix proteins collagen and laminin are printed onto the culture vessel surface in 10μm wide lines. Fluorescent polymer microspheres (0.25μm dia.) are embedded in the collagen layer. As the beads move from myocyte contraction, the movement amplitude is measured by nanometer-resolution position analysis, both in the presence of blebbistatin and in the rescue state where blebbistatin is removed. Relative force generation is calculated from the position analysis data and matrix modulus. Cells are then fixed and prepared with fluorescent antibodies for observation of connexin-43 and β1 integrin expression and localization by confocal microscopy. By employing micropatterned cardiac myocyte cell culture, optical contractile force measurement, and subsequent observation of the expression and localization of connexin-43 and β1 integrin, we assess the changes in integrin activity due to blebbistatin-induced reduction in contractile force.

Labelling of silica microspheres with fluorescent lanthanide-dopedLaF3 nanocrystals

Fluorescent microspheres have been demonstrated to be useful in a variety of biologicalapplications. Fluorescent silica or polymer microspheres have been produced byincorporation of chromophores into the microspheres, which usually produces microsphereswith nonuniform sizes and reduced fluorescence. Here we present a simple andstraightforward method to produce silica microspheres with fluorescent lanthanide-dopedLaF3 nanocrystals grownon the surface. LaF3 nanocrystals are in situ grown on silica microspheres of different sizes to forma raspberry-like structure. The microspheres exhibit strong fluorescenceand the colour could be altered by changing the lanthanide ions doped inLaF3 nanocrystals.