In the present study, oligonucleotides were adsorbed onto the surface of cationic liposomes and nanoparticles at different ratios. As a result, the surface charges of the colloidal carriers were decreased with increasing oligonucleotide concentration. At a certain oligonucleotide concentration, complete charge neutralization led to the aggregation of the carrier systems. Further increasing oligonucleotide concentrations reversed the surface charge of liposomes and nanoparticles to a negative one. Ultrasonication was investigated as a possible means for the homogenization of the formed aggregates. However, the use of ultrasonication led to a time-dependent damage of oligonucleotides adsorbed onto AH-Chol liposomes and MMAEMC-nanoparticles, as well as of unbound oligonucleotides. Nearly 60% of the oligonucleotides adsorbed to MMAEMC-nanoparticles and 65% of ODNs adsorbed to the liposomes were degraded by the effect of cavitation produced by ultrasonication within 10 min. In contrast, the oligonucleotides were protected from degradation when DEAE-stabilized PHCA-nanoparticles were employed as ODN carriers. More than 80% of the oligonucleotides entangled in the surface matrix of these nanoparticles remained intact.

Cyanoacrylates↗

PubMedDate not supplied

Studies on the transport pathway of PBCA nanoparticles in ocular tissues.

The transport pathway of PBCA nanoparticles through the rabbit cornea and conjunctiva was studied using fluorescence microscopy. Nanoparticles were produced by an emulsion-polymerization process, purified by a GPC procedure, and labelled with rhodamine 6G or propidium iodide as fluorescent laser dyes. The stability of the dye label, particle diameter, and zeta potential of the nanoparticles were determined. Freshly excised rabbit cornea and conjunctiva were incubated with a suspension of labelled nanoparticles for about 30 min in standard perfusion cells. After incubation the particles were visualized, due to their fluorescent character, using laser scanning confocal microscopy. The results show a fluorescence signal inside the cells. In particular conjunctival cells showed an uptake of nanoparticles. Fluorescent particles were visually observed inside the cells, in what appeared to be vesicles or granules. Thus, either endocytosis of the nanoparticles by conjunctival tissue or lysis of the cell wall by nanoparticle metabolic degradation products, are possible explanations of the data. A fluorescence signal was also observed within corneal cells. Only a transcellular pathway was observed. A possible penetration through tight junctions was not noticed; moreover, penetration was observed only into the first two cell layers and no full tissue penetration occurred.

Animals↗