RESUMEN
Hydrogels offer a promising potential for the encapsulation and regulated release of drugs due to their biocompatibility and their tunable properties as materials. Only a limited number of systems and procedures enable the encapsulation of sensitive proteins. N-terminally fmoc-protected phenylalanine has been shown to self-assemble into a transparent, stable hydrogel It can be considered a supergelator due to the low amount of monomers necessary for hydrogelation (0.1% w/v), making it a good candidate for the encapsulation and stabilization of sensitive proteins. However, application options for this hydrogel are rather limited to those of many other fibril-based materials due to its intrinsic lack of mechanical strength and high susceptibility to changes in environmental conditions. Here, we demonstrate that the stability of a fibrillary system and the resulting release of the protein-photosensitizer Azulitox can be increased by combining the hydrogel with a tightly cross-linked BSA hydrogel. Azulitox is known to display cell-penetrating properties, anti-proliferative activity and has a distinctive fluorescence. Confocal microscopy and fluorescence measurements verified the maintenance of all essential functions of the encapsulated protein. In contrast, the combination of fibrillary and protein hydrogel resulted in a significant stabilization of the matrix and an adjustable release pattern for encapsulated protein.
Asunto(s)
Hidrogeles , Fenilalanina , Preparaciones de Acción Retardada , Fármacos Fotosensibilizantes , Medicina de PrecisiónRESUMEN
Azulitox as a new fusion polypeptide with cancer cell specificity and phototoxicity was generated and is composed of a photosensitizer domain and the cell-penetrating peptide P28. The photosensitizer domain (EcFbFP) was derived from a bacterial blue-light receptor, which belongs to the family of light-oxygen-voltage proteins and produces reactive oxygen species (ROS) upon excitation. P28 is derived from the cupredoxin protein azurin that is known to specifically penetrate cancer cells and bind to the tumor suppressor protein p53. We show that the P28 domain specifically directs and translocates the fused photosensitizer into cancer cells. Under blue-light illumination, Azulitox significantly induced cytotoxicity. Compared to the extracellular application of EcFbFP, Azulitox caused death to about 90% of cells, as monitored by flow cytometry, which also directly correlated with the amount of ROS produced in the cells. Azulitox may open new avenues toward targeted polypeptide-photosensitizer-based photodynamic therapies with reduced systemic toxicity compared to conventional photosensitizers.