Characterization of chlorophyll derivatives in micelles of polymeric surfactants aiming photodynamic applications.
The spectrophotometric properties of chlorophylls' derivatives (Chls) formulated in the Pluronics® F-127 and P-123 were evaluated and the results have shown that the Chls were efficiently solubilized in these drug delivery systems as monomers. The relative location of the Chls in the Pluronics® was estimated from the Stokes shift and micropolarity of the micellar environment. Chls with phytyl chain were located in the micellar core, where the micropolarity is similar to ethanol, while phorbides' derivatives (without phytyl chain) were located in the outer shell of the micelle, i.e., more polar environment. In addition, the thermal stability of the micellar formulations was evaluated through electronic absorption, fluorescence emission and resonance light scattering with lowering the temperature. The Chls promote the stability of the micelles at temperatures below the Critical Micellar Temperature (CMT) of these surfactants. For F-127 formulations, the water molecules drive through inside the nano-structure at temperatures below the CMT, which increased the polarity of this microenvironment and directly affected the spectrophotometric properties of the Chls with phytyl chain. The properties of the micellar microenvironment of P-123, with more hydrophobic core due to the small PEO/PPO fraction, were less affected by lowering the temperature than for F-127. These results enable us to better understand the Chls behavior in micellar copolymers and allowed us to design new drug delivery system that maintains the photosensitizer's properties for photodynamic applications.
Department of Chemistry, Universidade Estadual de Maringá, Av. Colombo 5.790, 87020-900 Maringá, PR, Brazil.
Adriana Passarella
AP
Gerola
Department of Chemistry, Universidade Estadual de Maringá, Av. Colombo 5.790, 87020-900 Maringá, PR, Brazil.
Flavia Amanda Pedroso
FAP
de Morais
Department of Chemistry, Universidade Estadual de Maringá, Av. Colombo 5.790, 87020-900 Maringá, PR, Brazil.
Paulo Fernando A
PFA
Costa
Department of Pharmacy, Universidade Estadual de Maringá, Av. Colombo 5.790, 87020-900 Maringá, PR, Brazil.
Elza
E
Kimura
Department of Chemistry, Universidade Estadual de Maringá, Av. Colombo 5.790, 87020-900 Maringá, PR, Brazil.
Wilker
W
Caetano
Department of Chemistry, Universidade Estadual de Maringá, Av. Colombo 5.790, 87020-900 Maringá, PR, Brazil. Electronic address: nhioka@uem.br.
Noboru
N
Hioka
D002734:Chlorophyll / Q000737:chemistry*; D016503:Drug Delivery Systems / Q000379:methods*; D004355:Drug Stability; D005453:Fluorescence; D057927:Hydrophobic and Hydrophilic Interactions; D008823:Micelles; D010778:Photochemotherapy / Q000379:methods; D011060:Poloxalene / Q000737:chemistry*; D020442:Poloxamer / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*; D013696:Temperature
D008823:Micelles; D013501:Surface-Active Agents; D020442:Poloxamer; D002734:Chlorophyll; C464484:pluronic block copolymer P123; D011060:Poloxalene
Chlorophylls; Drug delivery system; Formulation; Polymeric micelles