19 research outputs found
Photosensitizer Drug Delivery via an Optical Fiber
: An optical fiber has been developed with a maneuverable miniprobe tip that sparges O2 gas and photodetaches pheophorbide (sensitizer) molecules. Singlet oxygen is produced at the probe tip surface which reacts with an alkene spacer group releasing sensitizer upon fragmentation of a dioxetane intermediate. Optimal sensitizer photorelease occurred when the probe tip was loaded with 60 nmol sensitizer, where crowding of the pheophorbide molecules and self-quenching were kept to a minimum. The fiber optic tip delivered pheophorbide molecules and singlet oxygen to discrete locations. The 60 nmol sensitizer was delivered into petrolatum; however, sensitizer release was less efficient in toluene-d8 (3.6 nmol) where most had remained adsorbed on the probe tip, even after the covalent alkene spacer bond had been broken. The results open the door to a new area of fiber optic-guided sensitizer delivery for the potential photodynamic therapy of hypoxic structures requiring cytotoxic control
Singlet Oxygen Generation on Porous Superhydrophobic Surfaces: Effect of Gas Flow and Sensitizer Wetting on Trapping Efficiency
We describe physical-organic studies
of singlet oxygen generation
and transport into an aqueous solution supported on superhydrophobic
surfaces on which silicon–phthalocyanine (Pc) particles are
immobilized. Singlet oxygen (<sup>1</sup>O<sub>2</sub>) was trapped
by a water-soluble anthracene compound and monitored <i>in situ</i> using a UV–vis spectrometer. When oxygen flows through the
porous superhydrophobic surface, singlet oxygen generated in the plastron
(i.e., the gas layer beneath the liquid) is transported into the solution
within gas bubbles, thereby increasing the liquid–gas surface
area over which singlet oxygen can be trapped. Higher photooxidation
rates were achieved in flowing oxygen, as compared to when the gas
in the plastron was static. Superhydrophobic surfaces were also synthesized
so that the Pc particles were located in contact with, or isolated
from, the aqueous solution to evaluate the relative effectiveness
of singlet oxygen generated in solution and the gas phase, respectively;
singlet oxygen generated on particles wetted by the solution was trapped
more efficiently than singlet oxygen generated in the plastron, even
in the presence of flowing oxygen gas. A mechanism is proposed that
explains how Pc particle wetting, plastron gas composition and flow
rate as well as gas saturation of the aqueous solution affect singlet
oxygen trapping efficiency. These stable superhydrophobic surfaces,
which can physically isolate the photosensitizer particles from the
solution may be of practical importance for delivering singlet oxygen
for water purification and medical devices
Multifunctional core-shell nanoparticles as highly efficient imaging and photosensitizing agents
10.1021/la902235dLangmuir251710153-10158LANG