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Abstract Purpose  Intravitreal injection of nonviral gene complexes may be promising in the treatment of retinal diseases. This study investigates the permeation of lipoplexes and polystyrene nanospheres through the neural retina and their uptake by the retinal pigment epithelium (RPE) either with or without ultrasound application. Materials and Methods  Anterior parts and vitreous of bovine eyes were removed. The neural retina was left intact or peeled away from the RPE. (Non)pegylated lipoplexes and pegylated nanospheres were applied. After 2 h incubation, the RPE cells were detached and analyzed for particle uptake by flow cytometry and confocal microscopy. Results  The neural retina is a significant transport barrier for pegylated nanospheres and (non)pegylated lipoplexes. Applying ultrasound improved the permeation of the nanoparticles up to 130 nm. Conclusions  Delivery of liposomal DNA complexes to the RPE cells is strongly limited by the neural retina. Ultrasound energy may be a useful tool to improve the neural retina permeability, given the nucleic acid carriers are small enough. Our results underline the importance to design and develop very small carriers for the delivery of nucleic acids to the neural retina and the RPE after intravitreal injection. [ABSTRACT FROM AUTHOR]

Abstract??The fluorescent dye Nile red was used as a probe for the sensitive detection of large, denatured aggregates of the model protein ?-galactosidase (E. coli) in solution. Aggregates were formed by irreversible heat denaturation of ?-galactosidase below and above the protein?s unfolding temperature of 57.4?C, and the presence of aggregates in heated solutions was confirmed by static light scattering. Interaction of Nile red with ?-galactosidase aggregates led to a shift of the emission maximum (?max) from 660 to 611?nm, and to an increase of fluorescence intensity. Time-resolved fluorescence and fluorescence correlation spectroscopy (FCS) measurements showed that Nile red detected large aggregates with hydrodynamic radii around 130?nm. By steady-state fluorescence measurements, it was possible to detect 1?nM of denatured and aggregated ?-galactosidase in solution. The comparison with size exclusion chromatography (SEC) showed that native ?-galactosidase and small aggregates thereof had no substantial effect on the fluorescence of Nile red. Large aggregates were not detected by SEC, because they were excluded from the column. The results with ?-galactosidase demonstrate the potential of Nile red for developing complementary analytical methods that overcome the size limitations of SEC, and can detect the formation of large protein aggregates at early stages. [ABSTRACT FROM AUTHOR]