Photodynamic hydrogel based on Carbomer-TMPyP complex: in vitro release and Pseudomonas aeruginosa photoinactivation

Córdoba

Congreso; Ricifa 2020+1; 2021

RICIFA

Photodynamic antimicrobial chemotherapy is a proposed alternative for localized infections in the era of antibiotic resistance. Although topical administration of a photosensitizer followed by irradiation is a viable application due to the accessibility of the target site, the design of effective and safe delivery systems for the photosensitizer is necessary. Previously, we designed hydrogels based on ionic complexes between Carbomer-974P and TMPyP, a commercially available cationic porphyrin. These hydrogels exhibited slight delay in the photoinactivation of P.aeruginosa compared to TMPyP solution. Here we study the in vitro release kinetics from an hydrogel using Franz-type cells, as well as the interaction/association kinetics of TMPyP with P.aeruginosa by fluorescence microscopy.Release profiles better fit zero-order kinetics (R2=0.993). The release rate from the hydrogel was 6.5 times slower than TMPyP solution. Hydrogel-treated cultures exhibited delayed appearance of fluorescent bacteria. Then, the hydrogel behaves as a reservoir of TMPyP from which it is slowly released by the dissociation of ionic pairs. Controlled release of TMPyP would modify its bacterial internalization/association kinetics, requiring prolongation of contact and irradiation period to achieve P.aeruginosa eradication. These results together with known bioadhesive and rheological properties of carbomer hydrogels allow us to consider them as a promising platform for designing topical TMPyP delivery systems.