PRODAN Photophysics as a Tool to Determine the Bilayer Properties of Different Unilamellar Vesicles Composed of Phospholipids

Abstract

Vesicles formed by phospholipids are promising candidates for drug delivery. It is known that the lipid composition affects properties such as the rigidity−fluidity of the membrane and that it influences the bilayer permeability, but sometimes sophisticated techniques are selected to monitor them. In this work, we study the bilayer of different unilamellar vesicles composed of different lipids (1,2-dioleoyl-sn-glycero-3-phosphocholine, DOPC, and lecithin) and diverse techniques such as extruder and electrospun templates and using 6-propionyl-2-(N,N-dimethyl) aminonaphthalene (PRODAN) and its photophysics. Moreover, we were able to monitor the influence of cholesterol on the bilayers. We demonstrate that the bilayer properties can be evaluated using the emission feature of the molecular probe PRODAN. This fluorescent probe gives relevant information on the polarity and fluidity of the microenvironment for unilamellar vesicles formed by two different methods. The PRODAN emission at 434 nm suggests that the bilayer properties significantly change if DOPC or lecithin is used in the vesicle preparation especially in their fluidity. Moreover, cholesterol induces alterations in the bilayer's structural and microenvironmental properties to a greater or lesser degree in both vesicles. Thus, we propose an easy and elegant way to evaluate physicochemical properties, which is fundamental for manufacturing vesicles as a drug delivery system, simply by monitoring the molecular probe emission band centered at 434 nm, which corresponds to the PRODAN species deep inside the bilayer.

Electrochemical Characterization of the Encapsulation and Release of 5-Fluorouracil in Nanocarriers Formed from Soy Lecithin Vesicles

“…Next, the appropriate volume of phosphate buffer pH 7 was added, and the solution was stirred using a shaker to form multilamellar lecithin vesicles. The resulting suspension was then passed through extrusion equipment 10–12 times to obtain unilamellar vesicles. , …”

“…This extruder featured metal filters, along with 25 mm polycarbonate membrane filters with 0.2 μm pore size from GVS North America and 25 mm polycarbonate membrane filters with 0.1 μm pore size from Thomas Scientific. The extrusion process was conducted at 25 °C. , …”

“…The interactions of small molecules with the vesicle bilayer are studied by analyzing the different spectroscopic responses that probe molecules in the presence or absence of vesicles, but several drugs do not have accessible optical bands. Furthermore, the vesicular aggregates are influenced by the scattering of the solution, which may impede their respective analysis by these techniques.…”

“…Now, it is possible to obtain vesicles from natural sources, which further increases the biocompatibility of these systems, making them even more interesting for their pharmaceutical application. This is the case of soy lecithin (SL), which is a mixture of phospholipids with an amphiphilic nature, which, in the presence of water, can form vesicles. , …”

“…Studies have shown that soy lecithin vesicles (SLVs) have antioxidant properties, defined and uniform sizes, high encapsulation capacity, and excellent physical stability against the digestive process. Furthermore, it has also been determined that the encapsulation of analytes does not affect the polydispersity or the size of these vesicles. ,− …”