Investigation on DAPC and DBPC liposome properties and their biomedicalapplications

Abstract

Nanotechnology is a promising developing field offering potential tools for the loading of curcumin in order to improve its various applications. Several types of nanoparticles have emerged one of which are liposomes vesicles. Formed by spontaneous self-assembly of lipids upon hydration, liposomes contribute a suitable alternative for curcumin delivery. Nevertheless, liposomes also suffered from low stability due to metabolic degradation which is why it was proposed to modify their surface by coating it with a polymeric layer such as chitosan oligosaccharide lactate.

In this thesis, we report in the first place the efficacy of curcumin as a fluorescence probe to determine the Tm, membrane permeability and partition coefficient of curcumin. These experiments were done for both DAPC and DBPC liposomes.

Actually, fluorescence intensity of curcumin – temperature profile was applied to determine the phase transition temperatures of these liposomes which were find to slightly affected with low curcumin’s concentration.

Moreover, the encapsulation of curcumin was elaborated into two kinds of liposomes forming four types of nanocapsules: DAPC-curcumin; DAPC-curcumin-chitosan; DBPC-curcumin; DBPC-curcumin-chitosan. The partition coefficient of curcumin into these systems was evaluated and found to be higher with the polymer layer and dependent on the physical state of the liposomes. Quenching studies with hydrophobic and hydrophilic quenchers were conducted to locate curcumin in the systems. We concluded that curcumin binds strongly to the liposomes’ membranes.

Furthermore, ionic liquids (ILs) are a type of green solvents that are recently being used for various applications. In that sense, the effect of 1-buytl-3-methyl imidazolium tetrafluoroborate (bmit) IL on the partition coefficient of curcumin was explored in this work by monitoring its interaction with DAPC and DBPC. The partition of curcumin was enhanced at low IL concentrations but depressed at higher concentrations while showing a dependence on the liposomes’ physical state.

Indeed, the successful encapsulation of curcumin into DAPC liposome was verified through UV-Visible, fluorescence emission spectra, XRD and SEM. Additionally, the effectiveness of chitosan as a protective layer was confirmed through zeta potential analysis and TGA study.

Moving on the application part, some biological applications for these nano-capsules were further investigated.

Mainly, DAPC based nanocapsules were used to study the anti-cancer activity of curcumin on MCF-7 breast cancer cells and Capan-1 pancreatic cancer cells along with evaluating the effect of the chitosan layer. It was observed that these nanoparticles inhibited up to 90% the proliferation of cancer cells after 72 hours.

On the other hand, DBPC based nanocapsules coated with chitosan layer (DBPC-CUR-Chi) played the role of potential, fast, easy, stable and selective nanosensors for the detection of RNA molecule. This was observed with the increase of the emission intensity of curcumin as the concentration of RNA was increased (0-20 and 30-500 μg/mL). The LOD attained were 36 ng/mL and 110 ng/mL. The recovery range was found to be 99.5 and 100.33%.