| The objective of this research is to develop a supramolecular system with photochemically induced permeability by incorporating a photochromic molecule into the lipid bilayer of a liposome. Two spirooxazines were synthesized with substituents similar to those on lipids, 6',7',10',11'-tetra- n-dodecyloxy-1,3-dihydro-1,3,3-trimethyl-spiro[2H-indole-2,3'-[3 H]phenanthro[9,10b][1,4]oxazine] (1), and N -(12-triethylammoniododecyl)-3,3-dimethylspiro[2H-indoline-2,3'-[3 H]phenanthro[9,10b][1,4]oxazine (3), to improve their incorporation into the lipid bilayer. The spectral properties of a third spirooxazine, the precursor to 3 N-(12-bromodocecyl)-3,3-dimethylspiro[2 H-indole-2,3'-[3H]phenanthro[9,10b][1,4]oxazine (2) were also studied.;The inclusion of 1 and 3 in the lipid bilayer of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) liposomes was observed with absorption spectroscopy and differential scanning calorimetry (DSC). Absorption spectroscopy was used to study the k-1 of 1 and 3 in large unimolecular vesicles (LUVs) to observe the potential of these spirooxazines to form a photoresponsive system. The relative location of 1 and 3 within the lipid bilayer was also determined by comparing the lambdaMC for 1 and 3 in various solvents, with the lambda MC in LUVs. In addition, DSC of multilamellar vesicles (MLVs) incorporating 1 and 3 was studied to support the relative locations of 1 and 3 in the lipid bilayer established with absorption spectroscopy.;The photochemically induced permeability of LUVs incorporating 1 and 3 was studied using fluorescence and absorption spectroscopy. LUV permeability was observed by encapsulating in the LUVs the fluorescent probe, 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS), which has a fluorescence intensity that is dependent on concentration. As a result, any changes in LUV permeability were correlated to the changes in HPTS fluorescence. LUVs incorporating 1 had relatively little to no photochemically induced permeability, whereas LUVs incorporating 3 did have a small amount of photochemically induced permeability. These results suggest that the different substituents on 1 and 3 affect differing amounts of photochemically induced permeability.;The solvatochromism and isomerization of spirooxazines 1-3 were studied using ultraviolet and visible (UV-Vis) absorption spectroscopy. The wavelength of maximum absorption for the MC isomer (lambdaMC) was observed to be solvatochromic, and was used to determine the location of the spiro moiety on 1 and 3 in the lipid bilayer. The photochemical isomerization of 1-3 was observed and the rate constant of thermal isomerization (k-1) was studied for 1-3 after irradiation with light centered at 350 nm (WA). The k-1 for 1-3 were affected by solvent polarity, and for 1 and 2 there was a competing factor of solvent viscosity. |
