Fluorescent microcapsules

Chinnayelka S. Microcapsule biosensors based on competitive binding and fluorescence resonance energy transfer assays. Louisiana Tech University, 2005. 

Fig. 6 Adsorption of microcapsules onto the (PLL/HA)24/PLL films, (a-c) Confocal fluorescent microscopy images of the capsules exposed to the near-IR light irradiation, (d) CLSM image of the film surface (the film is prepared with PLL-FITC black lines are scratches made by a needle for easier film imaging), (e) Cross-sectional profile of the capsules after step-by-step laser exposure (the sections from top to bottom correspond to the images a-c, respectively), (f) Optical microscopy images of the capsules after light irradiation. Scale bars (a-c, f) 4 pm, (d) 25 pm. Reproduced from [100]...

Fig. 11.2. Polymeric microcapsules imprinted with Listeria monocytogenes. The image was obtained using laser confocal microscopy. Photograph shows an optical cross-section through capsules. Listeria cells were labelled with a fluorescent dye and therefore appear as bright dots .

Fig. 11.4. Laser confocal and SEM of the materials prepared according to the process depicted in Fig. 11.3. Photographs show individual stages in the cell-mediated lithography of polymer surfaces using Listeria monocytogenes (left column a, c, e, g) and Staphylococcus aureus (right column b, d, f, h) as templates. Imprinted microcapsules (a, b) and solid polymer beads before (c, d) and after (e, f) the removal of template cells, (g, h) Show the imprint sites after reacting the beads with fluorescent-labelled Concanavalin A.

Poly(amino acid)s (PAAs) have also been used in drug delivery PEO-(l-aspartic acid) block copolymer nano-associates , formed by dialysis from a dimethyl acetamide solution against water, could be loaded with vasopressin. PLA-(L-lysine) block copolymer microcapsules loaded with fluorescently labelled (FITC) dextran showed release profiles dependent on amino acid content. In a nice study, poly(glutamate(OMe)-sarcosine) block copolymer particles were surface-grafted with poly(A-isopropyl acrylamide) (PNIPAAm) to produce a thermally responsive delivery system FITC-dextran release was faster below the lower critical solution temperature (LCST) than above it. PAAs are prepared by ring-opening polymerisation of A-carboxyanhydride amino acid derivatives, as shown in Scheme 1. 

The authors also reported on the supramolecular self-assembly from rod—coil—rod triblock copolymers prepared by copolymerization of 5-acetyl-2-aminob-ezophenone with diacetyl functionalized polystyrene with low polydispersity (Scheme 12).110 In contrast to the rod—coil diblock copolymers which exhibit multiple morphologies, the triblock copolymers were found to spontaneously form only microcapsules or spherical vesicles in solution as evidenced by optical polarized, fluorescence optical, and scanning electron microscopies (Figure 33). 

Several studies have utilized CLSM techniques to study the distribution and release of biomolecules incorporated in microcapsules and microspheres and to measure the encapsulation efficiency (9,10). Lipophilic fluorophores have been utilized to locate oil-rich regions within mixed-phase microspheres and to examine the distribution of polymeric components with microcapsules. Encapsulated oil could be differentiated from other components, and other fluorescent markers allowed visualization of polymer distribution in the capsule wall (11). The technique has also been used to explore the... 

Various preparations of 8-endotoxin (CrylA(c), CrylC, or Cry3A) are also marketed. The toxins are produced by engineered Pseudomonas fluorescence and are formulated as microcapsules or as granular formulations. They are used against Lepidoptera, armyworms, Colorado beetles, and corn borers. 

Rapid and facile generation of capsules from tandem assembly in aqueous media is amenable to encapsulation of water-soluble compounds. Encapsulation of ICG dye within PAH/H2PO4 aggregates was shown by Yu et al. Enzyme encapsulation and the feasibility of capsules to serve as reaction vessels was demonstrated by Rana et al. In their study, they encapsulated acid phosphatase enzyme in PLL-citrate-silica sols and suspended the spheres in a solution containing fluorescein diphosphate. Fluorescence increased in intensity within the shell walls as fluorescein was formed by enzymatic cleavage of phosphate groups. This study showed that microcapsules could serve as reaction vessels that allow enzymatic action to take place in a protective environment and allow for reactants and/or products to diffuse through permeable shell walls. 

Aim of this worit was to demonstrate a particular example of a sensor system, which combines catalytic activity for urea and at the same time, enabling monitoring enzymatic reaction by optical recording. The proposed sensor system is based on multilayer polyelectrolyte microcapsules containing urease and a pH-sensitive fluorescent dye, which translates the enzymatic reaction into a fluorescendy registered signal. 

Confocal fluorescent microscopy Confocal laser scanning microscopy Layer-by-Layer (LbL) technique Microcapsules... 

In another study, thiol-funaionalized HA was used for the preparation of disulfide aoss-linked nanogels with physically entrapped green fluorescence protein siRNA by an inverse w/o emulsion approach. The same group prepared disulfide-cross-linked HA miaogds and prepared shell cross-linked HA/polylysine layer-by-layer polyelectrolyte microcapsules through layer-by-layer approach followed by the removal of the reducible HA miaogd cores with dithiothreitol (DTT). ... 

Figure 14 (a) Fluorescence micrograph of solid microcapsules dried from a copolymer 43 (with n= 50, m= 500) dispersion (excitation wavelength 540 nm). (b) Scanning electron microscopy image of microcapsules from a copolymer 43 (with n=50, m=250) solution dried at 25°C and coated with a 10 nm gold layer. Reprinted with permission from Chen, X. L. Jenekhe, S. A. Macromolecules 33.4610-4612, Copyright 2000 American Chemical Society. ... 

It was shown that polyelectrolyte microcapsules containing metallic nanoparticles in their walls could be remotely activated inside living cells to release encapsulated material inside them (Figure 3.4.). These metal nanoparticles served as absorption centers for the energy supplied by a laser beam. These absorption centers caused local heating that disrupted the polyelecrolyte shell and allowed the encapsulated material to leave the interior of the capsule. Fluorescently labeled polymers were used as a model system of encapsulated material. 

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