Institute of Chemistry , State University of Campinas , Campinas , São Paulo 13083-872 , Brazil.
Langmuir. 2018 Jul 17;34(28):8230-8244. doi: 10.1021/acs.langmuir.8b00658. Epub 2018 Jul 6.
Photodynamic therapy (PDT) is a therapeutic modality that has shown effectiveness in the inactivation of cancer cell lines and microorganisms. Treatment consists of activating the photosensitizer (PS) upon light irradiation of adequate wavelength. After reaching the excited state, the PS can handle the intersystem conversion through energy transfer to the molecular oxygen, generating reactive oxygen species. This especially applies to singlet oxygen (O), which is responsible for the selective destruction of the sick tissue. Photosensitizing compounds (chlorophylls and derivatives) existing in the spinach extract have applicability for PDT. This study aimed to develop and characterize the thermoresponsive bioadhesive system composed of Pluronic F127 20.0%- and Carbopol 934P 0.2% (w/w) (FC)-containing chlorophyll-based extract 0.5% (w/w) (FC-Chl). Mechanical and rheological properties, in vitro release, sol-gel transition temperature, and ex vivo permeability of the spinach extract PS components (through pig ear skin) were investigated. Furthermore, photodynamic activity of the system was accessed through uric acid and time-solved measurements. The sol-gel transition temperature obtained for the FC-Chl system was 28.8 ± 0.3 °C. Rheological and texture properties of the platform were suitable for use as a dermatological system, exhibiting easy application and good characteristics of retention in the place of administration. In vitro release studies showed the presence of two distinct mechanisms that reasonably obey the zero-order and first-order kinetics models. PS components presented skin permeability and reached a permeation depth of 830 μm (between the epidermis and dermis). The photodynamic evaluation of the FC-Chl system was effective in the degradation of uric acid. The quantum yield (ΦO) and life time (τO) of singlet oxygen showed similar values for the spinach extract and the isolated chlorophyll a species in ethanol. These results allowed for the classification of the FC-Chl platform as potentially useful for the delivery of the chlorophyll-based extract in the topic PDT, suggesting that it is worthy for in vivo evaluation.
光动力疗法（PDT）是一种已被证明能有效灭活癌细胞系和微生物的治疗方法。该疗法的治疗过程包括在适当波长的光照射下激活光敏剂（PS）。PS 到达激发态后，可以通过能量转移到分子氧，发生系间窜跃，从而产生活性氧物种。这尤其适用于单线态氧（O），它负责选择性地破坏患病组织。菠菜提取物中的光敏化合物（叶绿素及其衍生物）可用于 PDT。本研究旨在开发并表征由 Pluronic F127 20.0%-和 Carbopol 934P 0.2%（w/w）（FC）组成的温敏型生物粘附系统，该系统含有 0.5%（w/w）（FC-Chl）的基于叶绿素的提取物。研究了菠菜提取物 PS 成分（通过猪耳皮肤）的机械和流变性能、体外释放、溶胶-凝胶转变温度和体外渗透性。此外，还通过尿酸和时间分辨测量来评估该系统的光动力活性。FC-Chl 系统的溶胶-凝胶转变温度为 28.8±0.3°C。该平台的流变学和质构特性适合用作皮肤病学系统，具有易于应用和在给药部位良好保留的特性。体外释放研究表明存在两种不同的机制，它们可以合理地遵循零级和一级动力学模型。PS 成分具有皮肤渗透性，达到 830μm 的渗透深度（在表皮和真皮之间）。FC-Chl 系统的光动力评估有效地降解了尿酸。FC-Chl 系统中，叶绿素 a 类物质的量子产率（ΦO）和寿命（τO）与菠菜提取物相似。这些结果表明，FC-Chl 平台可作为将基于叶绿素的提取物递送至局部 PDT 的潜在有用载体，表明其值得进行体内评价。
