Fluorescent Poly Methyl Methacrylate Research Articles

Polarized Stimulated Emission of 2D Ensembles of Plasmonic Nanolasers

Plasmonic nanolasers produce coherent light with wavelengths on a scale similar to their own or larger. In the past decade they have attracted intense interest, particularly from the emerging areas of integrated photonic circuits and biomedicine. Despite these capabilities, plasmonic nanolasers are still not completely understood, and this lack of understanding leads to confusing them with spasers and random lasers. Herein, the operation of pure spaser‐based plasmonic nanolaser arrays is presented. For this, a monolayer of silver nanoparticles (NPs) affixed to a dielectric surface and covered with a fluorescent polymethyl methacrylate (PMMA)–coumarin solid composite is investigated. The input–output characteristic measured for the composites on a bare substrate (without Ag NPs) reveals that the emission at pump pulse energies above 2.4 mJ (at 355 nm excitation wavelength) stops growing, and instead is inhibited by saturation. In contrast, in such structures with Ag NPs an additional emission band pops up over a fluorescence background. It has a spectral width order of units of nanometers and its intensity grows faster than at lower pump pulse energies, revealing a nonlinear dependence of the input–output characteristic. The spaser‐based lasing observed is completely linearly polarized and clearly directed as 45° from the substrate.

Spontaneous immobilization of both a fluorescent dye and a functional sugar during the fabrication of submicron-sized PMMA particles in an aqueous solution

Fluorescent particles with sugar chains immobilized on the particle surface are expected to be widely used as a fluorescent probe for biomaterial imaging and a fluorescent label for cell imaging as well as a highly accurate detection tool for toxic proteins and pathogenic viruses. Based on the expectation, a facile and environmentally friendly method for the one-pot incorporation of a fluorescent dye and alkylated functional sugar molecules during the fabrication of submicron-sized polymethyl methacrylate (PMMA) particles was established in the present work. This method used coumarin 7 as a hydrophobic fluorescent dye and octyl-β-d-glucopyranoside (octyl-glc), in which an octyl group is glycoside bound to a glucose skeleton, as a functional sugar. During PMMA particle formation by soap-free emulsion polymerization, coumarin 7 was spontaneously incorporated into the PMMA particles. At the same time, due to its hydrophobicity, the octyl group entered the PMMA particles, and due to its hydrophilicity, the glucose was in contact with the water medium. The immobilization of octyl-glc on the particle surfaces was evaluated using concanavalin A (ConA) as a lectin, which has a selective affinity for glucose. It was found that the characteristics of fluorescence and ConA adsorption were maintained, even after immersing the sugar-immobilized fluorescent PMMA particles in water for one and a half years, indicating that coumarin 7 was retained inside the PMMA particles, and octyl-glc was stably immobilized for a long time on the surface layer of the PMMA particle by using an octyl group as an anchor. Furthermore, as shown by the confocal laser scanning microscopy images of the water-dispersed particles, coumarin 7 was incorporated into almost all the particles, which were dispersed without aggregation in water, indicating that the sugar-immobilized fluorescent PMMA particles enable high-accuracy fluorescence analysis and imaging.

Feeding and digestion of the marine isopod Idotea emarginata challenged by poor food quality and microplastics

Ingestion of microplastics can impair nutrition of marine invertebrates. In a laboratory study, we tested whether microplastics affect ingestion rates and gastrointestinal enzyme activities in the marine isopod Idotea emarginata. Isopods were fed for eight days with one out of four different food formulations: natural food (the brown alga Fucus vesiculosus) or synthetic diet consisting of freeze-dried algal powder embedded in agarose, both, with or without microplastic particles (fluorescent polymethyl methacrylate, 10–100 μm) at a concentration of 40 items per mg of food. The isopods accepted both types of food but consumed significantly more (average 3.1-fold) of the agar based synthetic food. I. emarginata responded to the reduced content of digestible organic matter in the synthetic food by a compensatory adjustment of the ingestion rates. Addition of microplastics had no effect on ingestion rates in natural food whereas the feeding rates for synthetic food varied in response to microplastics. Similarly, activity patterns of digestive enzymes, particularly those of esterases, changed significantly in the treatment with synthetic food. Isopods fed with synthetic food alone showed elevated esterase activities in the gut while those isopods fed with synthetic food and microplastics showed elevated esterase activities in the midgut gland but not in the gut. Apparently, not the exposure to microplastic alone, but the combined effects of reduced nutrient availability and microplastic ingestion caused considerable biochemical reactions in the digestive organs of the isopods.

Thin-Film LSCs Based on PMMA Nanohybrid Coatings: Device Optimization and Outdoor Performance

This study concerns the design optimization of thin-film luminescent solar concentrators (TLSCs) based on polymethylmethacrylate (PMMA)/silica nanohybrid films doped with coumarin dyestuffs specialized in coloring plastics. Two designs of TLSCs had been prepared and characterized. The first consists of a transparent nanohybrid layer coated on a fluorescent PMMA substrate. The second design is the ordinary configuration in which fluorescent nanohybrid layer is coated on a transparent PMMA substrate. The investigation of the spectral properties and efficiency parameters recommended the best solar energy conversion efficiency for the second design. The outdoor performance of optimized TLSC was also evaluated under clear sky conditions of Riyadh city, and the hourly values of the optical efficiency,ηopt, were calculated for one year. The best performance was achieved in summer since the short circuit current for PV cell was doubled after being attached to TLSC and the value ofηoptreached 40% which is higher than other values recorded before due to the abundant solar energy potential in the Arabian Peninsula.

Multilayered optical bit memory with a high signal-to-noise ratio in fluorescent polymethylmethacrylate

We report on the three-dimensional optical memory utilizing a photoluminescence (PL) change in polymethylmethacrylate. Irradiation with a femtosecond pulsed laser (800 nm, 1 kHz, 100 fs) induced a strong PL spectrum in the visible range, which may result from the photogeneration of emissive radicals. Multilayered patterns were recorded inside the bulk sample by tightly focusing a pulsed laser beam. The pattern images were read out by a reflection-type fluorescent confocal microscope which detected the blue-green emission at 410–510 nm. The stored bits were retrieved with a high signal-to-noise ratio in the absence of any cross-talk.

Preparation of Monodisperse, Fluorescent PMMA–Latex Colloids by Dispersion Polymerization

We report a single step procedure to prepare monodisperse colloidal poly(methyl)methacrylate (PMMA) particles where fluorescent dyes are incorporated into the polymer network. The particles are sterically stabilized against flocculation by poly(12-hydroxystearic acid). The fluorescent dyes are RITC (rhodamine isothiocyanate)-aminostyrene (RAS) and 4-methylaminoethylmethacrylate-7-nitrobenzo-2-oxa-1,3-diazol (NBD-MAEM), which are prepared from (commercially available) RITC and 4-chloro-7-nitrobenzo-2-oxa-1,3-diazol (NBD-Cl), respectively, as starting materials. The particles can be grown larger with nonfluorescent PMMA. Examples of the usefulness of these model particles in colloid science are given.