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Browsing by Subject "photodynamic therapy"

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  • Porfyriinivaloherkistäjät aminolevuliinihappo, metyyliaminolevulinaatti ja heksyyliaminolevulinaatti aktiinikeratoosien fotodynaamisessa hoidossa 
    Neittaanmäki, Eerika (2015)
    Actinic keratoses are premalignant skin lesions caused by sun UV-radiation. A small portion of these lesions progress into invasive squamous cell carcinoma over the years. Actinic keratoses are a growing problem in the healthcare around the world. P53 mutations are found in actinic keratosis and adjacent areas. Treatment options include surgical removal, cryotherapy, local treatment creams such as immunomodulators, and photodynamic therapy (PDT). Aminolevulenic acid (ALA) is an endogenous light-sensitizer used in PDT and methylaminolevulinate (MAL) and hexylaminolevulinate (HAL) are its esters. Either artificial light or daylight can be used as a light source in PDT. In PDT light activates the photosensitizer, which initiates a photochemical reaction and target cell destruction. The most common side effects of PDT are erythema and pain during treatment. The benefits of PDT are good cosmetic outcome and the possibility to treat large areas. In the present study 3 light-sensitizers (BF-200 ALA, MAL, HAL 0,2 % and 2 %) were tested on healthy volunteers to compare the skin irritation, pain and fluorescence caused by the treatment. Fluorescence intensity reflects PpIX production capacity. The second part of the present study was a clinical study comparing BF-200 ALA and MAL in treatment of actinic keratoses with daylight-PDT. Each patient received both light-sensitizers on opposite sides of the head and the results were evaluated 3 months after treatment. On healthy skin BF-200 ALA, MAL and HAL 2 % caused more irritation compared to HAL 0,2 %. HAL 2 % didn't differ from ALA and MAL-groups in severity of reactions, erythema or fluorescence photobleaching. In HAL-treated areas pain was smaller than in ALA- and MAL-groups. However, in lesional skin there might be differences in absorption, distribution and PpIX formation. Both BF-200 ALA and MAL were effective in daylight-PDT and there were no significant differences between the groups in either efficacy or pain caused by the treatment. Long-term follow up is still required to confirm if the results sustain.
  • Red light-triggered reactive oxygen species-mediated drug release from liposomes 
    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.

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