Self-Assembly of Maltoheptaose- block -Polystyrene into Micellar Nanoparticles and Encapsulation of Gold Nanoparticles

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Thermoresponsive Vesicular Morphologies Obtained by Self-Assemblies of Hybrid Oligosaccharide- block -poly( N -isopropylacrylamide) Copolymer Systems

International audienceThis work discusses the self-assembly properties of thermoresponsive hybrid oligosaccharide-block-poly(N-isopropylacrylamide) copolymer systems: maltoheptase-block-poly(N-isopropylacrylamide) (Mal(7)-b-PNIPAM(n)) copolymers. Those systems at different molar masses and volume fractions were synthesized Using Cu(I)-catalyzed 1,3-dipolar azide/alkyne cycloaddition, so-called "click" chemistry, between an alkynyl-functionalized maltoheptaose (I) and poly(N-isopropylacrylamide) having a terminal azido group (N(3)-PNIPAM(n)) prepared by atom transfer radical polymerization (ATRP). While the cloud point (T(cp)) of the N(3)-PNIPAM(n) ranged from 36.4 to 51.5 degrees C depending on the degree of polymerization, those obtained of the diblock copolymers ranged from 39.4 to 73.9 degrees C. The self-assembly of such systems is favored due to the hydrophobicity of the PNIPAM in water above the T(cp). While the N(3)-PNIPAM(n) present polydisperse globular shape with a mean diameter of 500 nm, well-defined vesicular morphologies with an approximate diameter of 300 nm are obtained in diblock copolymer systems. These results were obtained and confirmed using static and dynamic light scattering as well as imaging techniques such as transmission electron microscope experiments

Preparation of Polymeric Micelles of Poly(Ethylene Oxide-b-Lactic Acid) and their Encapsulation With Lavender Oil

Nanoparticles comprised of the poly(ethylene oxide)-b-poly (lactic acid) diblock copolymer (PEO-b-PLA) with and without the incorporation of lavender oil were prepared by nanoprecipitation. Diblock copolymers based on a fixed PEO block (5KDa) and two different PLA segments (4.5 or 10KDa) were used. The morphology, encapsulation efficiency, essential oil-polymer interaction and the release kinetics of the active agent in the nanoparticles, were evaluated. The hydrodynamic radius of the nanoparticles determined by light scattering was affected by the size of the poly(lactic acid) (PLA) block. The lavender essential oil encapsulation efficiency (at a concentration of 0.4 µL mL-1) determined by UV-VIS spectroscopy was in the range of 70-75%. The in vitro release suggests that the polymeric barrier is able to control the oil release

Stimuli-Responsive Poly(caprolactone) Vesicles for Dual Drug Delivery under the Gastrointestinal Tract

We report the first example of carboxylic functionalized poly(caprolactone) (PCL) block copolymer vesicles as a novel dual drug delivery pH responsive vehicle for oral administration under the gastrointestinal (GI) tract. A new carboxylic functionalized caprolactone monomer was custom designed through multistep organic reactions and polymerized under controlled ROP using polyethylene glycol (PEG-2000) to produce amphiphilic diblocks, PEG-b-CPCL x , with x = 25, 50, 75, and 100. These carboxylic PCL block copolymers were self-organized into 100–250 nm vesicular assemblies in water. The size and shape of the vesicular assemblies were confirmed by light scattering, zeta potential, and electron microscopes. These vesicles were capable of loading both hydrophilic molecules (Rhodamine B, Rh–B) and hydrophobic drugs such as ibuprofen (IBU) and camptothecin (CPT) in the core and layer, respectively. These pH-responsive PCL vesicles were stable in strong acidic conditions (pH < 2.0, stomach) and ruptured to release the loaded cargoes under neutral or basic pH (7.0 ≤ pH, similar to that of small intestine). The drug release kinetics under simulated GI tract revealed that the individual drug loaded vesicles followed the combination of diffusion and erosion pathway, whereas the dual drug loaded vesicles predominantly followed the diffusion controlled process. Thus, the custom designed PCL vesicles open up new area of pH stimuli responsive polymer vehicles for delivering multiple drugs in oral drug delivery which are yet to be explored for biomedical applications