Fluorescence imaging and spectroscopy for real-time, in-situ characterization of interactions of free radicals with oil-in-water emulsions

Physical and chemical modifications of lipid structures to inhibit permeation of free radicals in a supported lipid membrane model

“…The results show no significant change in BODIPY emission as a function of time (see ESI †) in the absence of the free radical generator AAPH. This expectation is also supported by the results of our previous studies 12,25,26 in which we have demonstrated that the peroxidation sensor molecules are uniformly distributed in the oil phase of the emulsion without any preferential accumulation at the interface. Because the molecular geometry of the probe is similar to other rod-shaped lipid probes such as diphenylhexatriene (DPH), the anticipated average position of BODIPY is in-between the two bilayer leaflets, at a distance of approximately 2 nm below the hydrophobichydrophilic interface.…”

The role of the PCM in reducing oxidative stress induced by radical initiated photoencapsulation of chondrocytes in poly(ethylene glycol) hydrogels

“…23,24 Once the diacetate is hydrolyzed, carboxy-H 2 DFF can react with ROS (e.g., hydroxyl radicals, peroxyl radicals, superoxide anions, and hydrogen peroxide) to produce a stable fluorescent product. 23,24 In the absence of cells, the diacetate group was hydrolyzed with 200 mM KOH for 1 h. 25 The hydrolyzed dye was added at a final concentration of 20 mM to chondrocyte medium containing 0, 1, 2, 4.5 or 11 mM photoinitiator. Wells were either left untreated or exposed to 365 nm light (w4 mW/cm 2 ) for 10 min and fluorescence immediately assayed on a FLUOstar Optima plate reader (BMG Labtech, Cary, NC) with 488 nm excitation and 525 nm emission.…”

Effect of physical state (solid vs. liquid) of lipid core on the rate of transport of oxygen and free radicals in solid lipid nanoparticles and emulsion

“…This approach is similar to our previous study, in which we measured the interactions of hydroxyl radicals using a free radical sensitive dye encapsulated in emulsion. 25 In this experiment, AAPH was used to generate peroxyl radicals in the aqueous phase. Using AAPH, the rate of radical generation could be precisely controlled and maintained constant over an extended period of time (approximately 175 h, the half life of AAPH).…”

“…In the liquid state, the emulsion droplets showed distribution of dye characteristic of liquid emulsions such as canola oil. 25 However, in the solid state, two prominent differences were observed as compared to the liquid state emulsion. The first prominent difference was the decrease in fluorescence intensity of individual solid particles as compared to emulsion droplets under the same set of imaging conditions (exposure time and intensity of excitation light).…”

“…These methods were developed in our previous studies and are based on measurement of change in the fluorescence of either oxygen or free radical sensitive dyes dispersed in the oil phase of emulsion upon interaction with atmospheric oxygen or free radicals generated in the aqueous phase. 25,26 Materials and methods Chemicals Eicosane, bile salts, sodium azide and 2,2 0 -azobis-2-methylpropanimidamide dihydrochloride (AAPH) were obtained from Sigma Aldrich chemicals (Sigma-Aldrich, St Louis, MO). High melting lecithin (HML) (PhospholiponÒ 80 H) was a gift from American Lecithin Inc. (Oxford, CT).…”