Polymeric scaffolds for enhanced stability of melanin incorporated in liposomes.
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.
Moraes
Marli L
ML
Universidade Federal de São Carlos, Campus Sorocaba, CP 3031, 18043-970 Sorocaba, São Paulo, Brazil. marli@ufscar.br
Gomes
Paulo J
PJ
Ribeiro
Paulo A
PA
Vieira
Pedro
P
Freitas
Adilson A
AA
Köhler
Ralf
R
Oliveira
Osvaldo N
ON
Raposo
Maria
M
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
D007097:Imines; D008081:Liposomes; D008543:Melanins; D010715:Phosphatidylglycerols; D011073:Polyamines; D011095:Polyethylenes; C505405:poly(ethylene imine); C063994:polyallylamine; C030345:1,2-dipalmitoylphosphatidylglycerol