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Browsing by Subject "macromolecule encapsulation"

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  • Kekki, Roosa (2024)
    Light-sensitive liposomes have gained attention for their ability to deliver cargo to tissues, offering spatiotemporal control over drug release. Red-light wavelengths have been utilized as an external trigger in light-sensitive reactive oxygen species (ROS)-mediated drug delivery, due to their favorable properties, such as the low light absorption by tissue chromophores. The ROS-sensitive drug delivery systems use photosensitizers (PS), which upon light exposure generate ROS in the presence of molecular oxygen. Palladium(II)phthalocyanine (Pd(II)PC), a new second-generation photosensitizer, can upon light irradiation generate relatively high singlet oxygen concentrations, enabling the efficient oxidation of the unsaturated lipids. The oxidation of the lipids leads to the disruption of the liposome bilayer and eventually, the release of the encapsulated cargo. To gain deeper insight on the phthalocyanine-labeled liposomes in drug delivery, a red light-triggered cationic liposome formulation encapsulating Pd(II)PC was formulated. The characteristics of the liposomes, the release mechanisms, and the release quantities of calcein (623 Da) and fluorescent-conjugated dextrans (4 000-70 000 Da) were studied following red-light exposer with 630 nm, 450 mW/cm2 laser while utilizing varying Pd(II)PC-loading quantities. Following oxygen removal and temperature-induced release studies, the mechanism of release of the liposomes was principally observed to be light-triggered reactive oxygen species-mediated. In the light-induced release studies an effective release of the calcein, and a relatively effective release of the Rhodamine B dextrans (10 kDa, 70 kDa) were observed from the liposomes via the Pd(II)PC-generated and reactive oxygen species-mediated oxidation of the unsaturated lipids. The release of the biomacromolecules from the liposomes was observed to require longer irradiation times than that of calcein. The longer irradiation times likely lead to deeper oxidation of the unsaturated phospholipids, resulting in a comprehensive eruption of the liposome bilayer. The comprehensive eruption of the liposome bilayer eventually enables the sufficient release of biomacromolecules from the liposomes.