<p>Bifunctional Therapeutic Application of Low-Frequency Ultrasound Associated with Zinc Phthalocyanine-Loaded Micelles</p>

Abstract

Purpose: Sonodynamic therapy (SDT) is a new therapeutic modality for the noninvasive cancer treatment based on the association of ultrasound and sonosensitizer drugs. Topical SDT requires the development of delivery systems to properly transport the sonosensitizer, such as zinc phthalocyanine (ZnPc), to the skin. In addition, the delivery system itself can participate in sonodynamic events and influence the therapeutic response. This study aimed to develop ZnPc-loaded micelle to evaluate its potential as a topical delivery system and as a cavitational agent for low-frequency ultrasound (LFU) application with the dual purpose of promoting ZnPc skin penetration and generating reactive oxygen species (ROS) for SDT. Methods: ZnPc-loaded micelles were developed by the thin-film hydration method and optimized using the Quality by Design approach. Micelles' influence on LFU-induced cavitation activity was measured by potassium iodide dosimeter and aluminum foil pits experiments. In vitro skin penetration of ZnPc was assessed after pretreatment of the skin with LFU and simultaneous LFU treatment using ZnPc-loaded micelles as coupling media followed by 6 h of passive permeation of ZnPc-loaded micelles. The singlet oxygen generation by LFU irradiation of the micelles was evaluated using two different hydrophilic probes. The lipid peroxidation of the skin was estimated using the malondialdehyde assay after skin treatment with simultaneous LFU using ZnPc-loaded micelles. The viability of the B16F10 melanoma cell line was evaluated using resazurin after treatment with different concentrations of ZnPc-loaded micelles irradiated or not with LFU. Results: The micelles increased the solubility of ZnPc and augmented the LFU-induced cavitation activity in two times compared to water. After 6 h ZnPc-loaded micelles skin permeation, simultaneous LFU treatment increased the amount of ZnPc in the dermis by more than 40 times, when compared to non-LFU-mediated treatment, and by almost 5 times, when compared to LFU pretreatment protocol. The LFU irradiation of micelles induced the generation of singlet oxygen, and the lipoperoxidation of the skin treated with the simultaneous LFU was enhanced in three times in comparison to the non-LFU-treated skin. A significant reduction in cell viability following treatment with ZnPc-loaded micelles and LFU was observed compared to blank micelles and non-LFU-treated control groups. Conclusion: LFU-irradiated mice can be a potential approach to skin cancer treatment by combining the functions of increasing drug penetration and ROS generation required for SDT.

The promise of low-intensity ultrasound: A review on sonosensitizers and sonocatalysts by ultrasonic activation for bacterial killing

“…Wu et al [24] found that Au@BTO NPs combining with ultrasound had an excellent antibacterial efficiency against both Gram-negative E. coli and Gram-positive S. aureus , they deduced that the sonodynamic ROS generation induced lipid peroxidation in cytomembrane, which enhanced the permeability of cell membrane and finally led to the intracellular protein leakage and irreversible damage to bacteria. Martins et al [101] got the same result in cancer cells, they studied the application of zinc phthalocyanine (ZnPc) as a sonosensitizer and discovered that the level of cellular lipid peroxidation increased three times after sonication.…”

Recent developments of sonodynamic therapy in antibacterial application

“…For example, Martins et al investigated the sonodynamic activity of ZnPc encapsulated in nanometric polymeric micelles of 1.2-distearoyl- sn -glyreco-3-phosphoethanolamine- N -[amino(polyethylene glycol)-2000] (DSPE-PEG). 95 Owing to the amphiphilic property of DSPE-PEG, the prepared micelles could dissolve insoluble drugs, greatly enhancing their solubility in aqueous media. This work also shown that DSPE-PEG micelles might improve ultrasonic cavitation activity, increasing the permeability of ZnPc to the skin and encouraging the generation of ROS.…”

Broad-Spectrum Theranostics and Biomedical Application of Functionalized Nanomaterials

“…Due to poor water solubility and decreased penetration, ZnPc molecules are encapsulated in DSPE–PEG micelles and subjected to skin cancer treatment. Data showed that the low-frequency ultrasound irradiation of ZnPc-loaded micelles generates reactive oxygen species and stimulates lipoperoxidation in the skin that would eventually lead to tumor cell death [ 21 ]. Similarly, Liu et al [ 22 ] reported that the encapsulation of meta -tetra(hydroxyphenyl)chlorine, a photosensitizer, in P23 micelles effectively increased blood circulation kinetics and ultimately enhanced selective photocytotoxicity on A431 cells.…”