title: Polymeric scaffolds for enhanced stability of melanin incorporated in liposomes.
abstract: The use of melanin in bioinspired applications is mostly limited by its poor stability in solid films. This problem has been addressed here by incorporating melanin into dipalmitoyl phosphatidyl glycerol (DPPG) liposomes, which were then immobilized onto a solid substrate as an LbL film. Results from steady-state and time-resolved fluorescence indicated an increased stability for melanin incorporated into DPPG liposomes. If not protected by liposomes, melanin looses completely its fluorescence properties in LbL films. The thickness of the liposome-melanin layer obtained from neutron reflectivity data was 4.1+/-0.2 nm, consistent with the value estimated for the phospholipid bilayer of the liposomes, an evidence of the collapse of most liposomes. On the other hand, the final roughness indicated that some of the liposomes had their structure preserved. In summary, liposomes were proven excellent for encapsulation, thus providing a suitable environment, closer to the physiological conditions without using organic solvents or high pHs.
authors.affiliation: Universidade Federal de São Carlos, Campus Sorocaba, CP 3031, 18043-970 Sorocaba, São Paulo, Brazil. marli@ufscar.br
authors.forename: Marli L
authors.initials: ML
authors.lastname: Moraes
authors.forename: Paulo J
authors.initials: PJ
authors.lastname: Gomes
authors.forename: Paulo A
authors.initials: PA
authors.lastname: Ribeiro
authors.forename: Pedro
authors.initials: P
authors.lastname: Vieira
authors.forename: Adilson A
authors.initials: AA
authors.lastname: Freitas
authors.forename: Ralf
authors.initials: R
authors.lastname: Köhler
authors.forename: Osvaldo N
authors.initials: ON
authors.lastname: Oliveira
authors.forename: Maria
authors.initials: M
authors.lastname: Raposo
mesh_terms: D004355:Drug Stability; D007097:Imines / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry*; D008543:Melanins / Q000494:pharmacology*; D010715:Phosphatidylglycerols / Q000737:chemistry*; D011073:Polyamines / Q000737:chemistry; D011095:Polyethylenes / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties
chemical_list: D007097:Imines; D008081:Liposomes; D008543:Melanins; D010715:Phosphatidylglycerols; D011073:Polyamines; D011095:Polyethylenes; C505405:poly(ethylene imine); C063994:polyallylamine; C030345:1,2-dipalmitoylphosphatidylglycerol