Functional Properties of PEG-b-PLys/C-60/ZnTPPS Micelle
Chai, ZH (Chai, Zhi-hua)[ 1 ] ; Li, A (Li, Ang)[ 1 ] ; An, YL (An, Ying-li)[ 1 ] ; Shi, LQ (Shi, Lin-qi)[ 1 ]
ACTA
POLYMERICA SINICA, 2017, 2: 393-398
DOI: 10.11777/j.issn1000-3304.2017.16306
WOS:000397858300024
Abstract
Block copolymer micelles of poly(ethylene
glycol)-block-poly(L-lysine) (PEG-b-PLys) was used to load fullerene (C-60) and
zinc tetrakis (4-sulfonatophenyl) porphyrin (ZnTPPS) in water. The diblock
copolymer of PEG-b-PLys was firstly synthesized via ring-opening
polymerization. Then the PEG-b-PLys/C-60 micelles were prepared by association
between PEG-b-PLys and C-60 in aqueous solution. ZnTPPS was added to the
PEG-b-PLys/C-60 micelle solution and PEG-b-PLys/C-60/ZnTPPS complex micelles
were finally obtained by electrostatic interaction between ZnTPPS and PLys. The
structure and photochemical properties of the PEG-b-PLys/C-60/ZnTPPS complex
micelles were characterized by dynamic light scattering, transmission electron
microscopy, UV-Visible spectroscopy and fluorescence spectroscopy. The results
showed that the PEG-b-PLys/C-60/ZnTPPS complex micelles were reasonably
monodisperse with an average hydrodynamic diameter of 80 nm. The complex
micelles showed the typical UV-Vis spectra of ZnTPPS and C-60. The Soret-band
peak of ZnTPPS in the complex micelles was red-shifted from 421 to 430 nm,
which was possibly caused by electron transfer from the ZnTPPS to the
fullerene. In addition, the fluorescence emission spectra of ZnTPPS was
obviously quenched in the complex micelles. These results suggested that ZnTPPS
was assembled successfully into PEG-b-PLys/C-60 micelles. In order to
investigate the role of C-60 in the photoprotection of ZnTPPS, the illumination
of ZnTPPS encapsulated in different micelles was carried out under identical
conditions using a 360 nm cut-off filter. Compared with ZnTPPS in the
PEG-b-PLys/ZnTPPS electrostatic micelles, the ZnTPPS loaded in the complex
micelles possessed higher photostability because of the reduced generation of
singlet oxygen. The photoreduction of methyl viologen hydrate (MV2+) was chosen
as the model reaction to evaluate the electron-transfer efficiency of the
complex micelles. The amount of MV+. produced by the complex micelles was
higher than that by both free ZnTPPS and PEG-b-PLys/ZnTPPS electrostatic
micelles. Thus the complex micelles showed better electron transfer ability and
higher photoactivity because of the electron transfer from the porphyrin to the
fullerene in the complex micelles.
