Dye Encapsulation

Jeremiah J. Gassensmith, Easwaran Arunkumar, and Bradley D. Smith Department of Chemistry and Biochemistry, 251 Nieuwland Science HaU, University of Notre Dame, Notre Dame, IN 46556, USA 

The most obvious way to alter dye performance is to synthetically modify the covalent structure. However, despite the continued advances in synthetic organic chemistry, the process of dye synthesis is still a tedious task that consumes materials and human resources. As a way of circumventing this problem, supramolecular chemists have started 

Molecular Encapsulation Organic Reactions in Constrained Systems Edited by Udo H. Brinker and Jean-Luc Mieusset 2010 John Wiley Sons, Ltd 

2 Reversible Dye Encapsulation Inside Organic Container Molecules 

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Dye doped silica nanoparticles are conventional biological dyes encapsulated in a ceramic matrix to protect them from oxygen, enhance chemical stability, and allows the surface of the nanoparticle to be modified to enhance the hydrophilic qualities and improve cell uptake [37],... 

The miniature fiber optic NO2 sensors based upon dye encapsulation in the silica sol-gel can produce linear and reproducible results87. The nitrogen dioxide sensor based on immobilization of ruthenium complex [Ru(bpy)3]Cl2 demonstrated sensitivity in the hundreds parts per million range with reversibility and rapid response time. 

Oxygen-sensitive dye Encapsulation medium Support Fabrication Technique Solvent Limitations/ improvements... 

Figure 9.5 Pyranene dye encapsulated in various sizes of vesicles made from an acid extract of the Murchison meteorite. (Adapted with permission from Dworkin, 2001)...

This chapter describes the synthesis, properties, and biomedical applications of cyanine and squaraine dyes encapsulated in CDs, CBs, Leigh-type tetralactam macrocycles, aptamers, and micro- or nano-particles. The optical and photochemical properties of supramolecular guest-host nanostructures that are based on intra-and intermolecular complexes of crown-containing styryl dyes with metal cations, and aggregates of carbocyanine dyes are discussed in a separate review [18]. 

The ionophores have been incorporated into the vesicle membranes and cation flux was assessed either by monitoring the fluorescence of pyranine dye encapsulated within vesicles for estimating the proton transport rate or by analyzing the line shape of Na nucleus by NMR spectroscopy to evaluate the flux rate of Na+ 106-110 Qf ionophores were expressed by percent activity relative... 

The combination of different fluorescent metal indicators with inert luminescent reference beads consisting of poly(acrylonitrile) containing Ru(dpp)3 leads to a sensor array in a microwell plate format, suited for ratiomet-ric time-resolved imaging [95]. The data can be acquired with the help of the f-DLR method (for details see Sect. 2.3). A cross-reactive sensor array was arranged for the determination of mixtures of calcium(II), copper(II), nickel(II), cadmium(II), and zinc(II) ions by nine different commercially available fluorescent indicators (Table 3). For a successful application, it is mandatory that all luminophores can be excited at the same wavelength range between 400 and 500 nm, and that the excitation and emission spectra of all indicators overlap with those of the reference dye encapsulated in the nanobeads. 

The leakage of small water-soluble dyes encapsulated in the aqueous interior of liposomes during their preparation is often used as a method to study their membrane integrity during incubation under various conditions (temperature, pH, presence of serum proteins, etc.). In the case of ARSL s, the release of CF or calcein has been used as a measure of the vesicle membrane integrity, during incubation of ARSL in buffer or in presence of serum proteins [80% FCS] at 37°C under mild agitation. Calcein (or CF) is encapsulated in the vesicles in a quenched concentration (100 mM), and, therefore, its release from the membrane can be calculated without separation of free and liposomal dye, as reported before (23). In brief, 20 pL of the incubated ARSL dispersion are drawn out from each incubation tube and diluted with 4 mL of PBS, pH 7.40. The fluorescence intensity of the samples is then measured (EM 490 nm, EX 520 nm, slit-slit 10-10), before and after the addition of Triton X-100 at a final... 

Fig. 5. Sandwich-hybridization assay (A) A biotinylated DNA oligonucleotide, which is complementary to one portion of the target sequence, is mixed with streptavidin and applied to form the capture zone 1.5 cm from the base of the membrane. An unmodified DNA oligonucleotide, which is complementary to the reporter probe sequence on the liposomes, is applied to form the control zone 2.5cm from the base of the membrane. (B) In the presence of target, a sandwich hybridization complex forms with dye-encapsulating liposomes resulting in a magenta-colored band at the capture zone. (C) In the absence of target, only the control band is visible as no sandwich complex has formed.

Edwards, K. A., and Baeumner, A. J. (2006) Optimization of DNA-tagged dye-encapsulating liposomes for lateral-flow assays based on sandwich hybridization. Anal Bioanal Chem. 386,1335-1343... 

The pharmacokinetic behavior of the liposomes was studied in vivo. Five rats were injected with dye encapsulated in liposomes, and blood samples were collected every... 

Figure 2 Pharmacokinetics of dye-encapsulated liposomes. The pharmacokinetics is illustrated by liposomes containing a fluorescent dye. The concentration in the blood is represented by the fluorescence of the sample. The upper curve represents the total concentration (encapsulated and free) in the blood, while the lower one is for the free, unencapsulated dye. Note the slow decay of the liposomes and the relatively small fraction of free dye in the blood. Source From Ref. 7, Figure 2.

A dual-analyte fiber optic biosensor for O2 and glucose was developed by Li and Walt [22] based on O2 quenching of a phosphorescent ruthenium dye. Excitation was at X = 480 nm, with fluorescent emission captured by a CCD camera. A relatively large (350 (U,m diameter) imaging fiber with 6000 elements was modified by attaching two separate drops of ruthenium dye encapsulated in poly(hydroxyethyl methacrylate) polymer (HEMA). The ruthenium dye allowed measurements of O2 in both encapsulated drops, which were approximately 50 ixm in diameter. A two-site Stern-Volmer quenching model (equation (4.32) with n — 2) was used to determine O2 concentration from measurements of fluorescence intensity. One of the drops had the enzyme glucose oxidase (EC... 

Related studies have shown that CB[7] binds fused tricyclic dyes such as Proflavine, Pyronine Y, and Thionine with higher association constants than the analogous CD, and that dye encapsulation increases the fluorescence quantum yield. In contrast to CB[7], the larger CB[8] encapsulates two dye molecules while the smaller CB[5] does not effectively encapsulate any tricyclic dye. In Figure II.I, the perceived colour of the dye... 

P. M.-Navajas, A. Corma, H. Garcia, Complexation and fluorescence of tricyclic basic dyes encapsulated in cucurbiturils, ChemPhysChem, 2008, 9, 713-720. 

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