Biomedical Platform Development of a Chlorophyll-Based Extract for Topic Photodynamic Therapy: Mechanical and Spectroscopic Properties

Abstract

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.

Interaction between mucoadhesive cellulose derivatives and Pluronic F127: Investigation on the micelle structure and mucoadhesive performance

“…Journal Pre-proof the polymeric platforms demonstrated a well organised morphology, which though heterogeneous, is well defined. Both polymeric combinations resulted in a sponge-like system, which is possible related to self-assembly of gel, as already described in the literature for other F127 blends [55,56]. Formulations containing F127 and HPMC (Fig.…”

“…The system composed of 20% (w/w) F127 and 3% (w/w) HPMC appeared relatively dense, representative of a highly cohesive system, as also observed by texture profile analysis previously [24]. Moreover, systems composed of 20% (w/w) F127 and 4% (w/w) HPMC demonstrated amorphous morphology when compared to the other formulations, since hydrophobic associations and hydrogen bonds may contribute to this cohesion [55,57].…”

“…This may be a consequence of the reduced volume fraction of trapped water, since the porous are result of the water sublimation during the lyophilisation process. The establishment of hydrogen bonds between PEO moieties of F127 and carboxylic segments of NaCMC may also have contributed to the formation of channels, as already observed for mixtures of F127 and poly(acrylic acid) derivatives [55,58,59]. It may be suggested that NaCMC exhibited greater potential for interaction with water compared to HPMC formulations, showing better space to trap hydrophilic drugs [24].…”

Mucoadhesive emulgel systems containing curcumin for oral squamous cell carcinoma treatment: From pre-formulation to cytotoxicity in tissue-engineering oral mucosa

“…3). Fragments and heterogeneous structures were observed in the micrographs of the emulgel, between a well-defined polymeric network without the presence of diverse channels commonly found in the micrographs of gels (Campanholi et al, 2018). Moreover, it was possible to observe some sparse holes were probably the oil phase would be located and rough surface in an oriented direction.…”

“…All samples were normalized to the carbon black-sample to eliminate the source emission intensity in each wavelength (Ames et al, 2017). The spectra of at least three porcine oral mucosa was investigated from the illuminated side of tissue to be measured and, subsequently, the tissue was upside down to illuminate the opposite side (Borghi-Pangoni et al, 2016;Campanholi et al, 2018).…”