Development of novel chitosan / guar gum inks for extrusion-based 3D bioprinting: process, printability and properties

The major limitation of 3D bioprinting is the availability of inks. In order to develop new ink formulations, both their rheological behavior to obtain the best printability and the target bio-printed objects conformities must be studied. In this paper, for the first time in our knowledge, the preparation and the characterization of novel ink formulations based on two natural biocompatible polysaccharides, chitosan (CH) and guar gum (GG), are presented. Five ink formulations containing different proportions of CH and GG were prepared and characterized in terms of rheological properties and solvent evaporation. Their printability was assessed (by varying the nozzle diameter, pressure and speed) using an extrusion-based 3D bioprinting process performed directly in air at 37 °C. Results showed that the incorporation of GG improved both the printability of the pure chitosan ink by increasing the viscosity of the solution and the shape fidelity by accelerating the solvent evaporation. We showed that the ink containing 15% (w/w) of GG and 85% (w/w) of CH had the best printability. This formulation was therefore used for the preparation of membranes that were characterized by infrared spectroscopy (FTIR) and X-Ray Diffraction (XRD) before and after gelation as well as for their mechanical properties (Young modulus, strength and strain at break). The optimal process printing parameters were determined to be: 27 G micronozzle, extrusion pressure below 2 bars and robot head speed between 20 and 25 mm/s. This novel ink formulation is a guideline for developing 2D scaffolds (such as auto-supported membranes) or 3D scaffolds for biomedical applications.publishe

Nanoemulsions and topical creams for the safe and effective delivery of lipophilic antioxidant coenzyme Q10

International audienc

Influence of lecithin-lipid composition on physico-chemical properties of nanoliposomes loaded with a hydrophobic molecule

International audienceIn this work, we studied the effect of nanoliposome composition based on phospholipids of docosahexaenoic acid (PL-DHA), salmon and soya lecithin, on physico-chemical characterization of vector. Cinnamic acid was encapsulated as a hydrophobic molecule in nanoliposomes made of three different lipid sources. The aim was to evaluate the influence of membrane lipid structure and composition on entrapment efficiency and membrane permeability of cinnamic acid. These properties are important for active molecule delivery. In addition, size, electrophoretic mobility, phase transition temperature, elasticity and membrane fluidity were measured before and after encapsulation. The results showed a correlation between the size of the nanoliposome and the entrapment. The entrapment efficiency of cinnamic acid was found to be the highest in liposomes prepared from salmon lecithin. The nanoliposomes composed of salmon lecithin presented higher capabilities as a carrier for cinnamic acid encapsulation. These vesicles also showed a high stability which in turn increases the membrane rigidity of nanoliposome as evaluated by their elastic properties, membrane fluidity and phase transition temperature

Effects of Ar–H2–N2 microwave plasma on chitosan and its nanoliposomes blend thin films designed for tissue engineering applications

This work addresses the functionalization of chitosan thin films and its nanoliposomes blend films by a microwave-excited Ar/N2/H2 surface-wave plasma treatment which was found an effective tool to modify surface properties. Changes in the film properties (wettability, chemical composition, morphology) induced by the plasma treatment are studied using water contact angle measurements, X-ray photoelectron spectroscopy and scanning probe microscopy. The results suggest that hydrophilicity of the films is improved by plasma treatment in a plasma condition dependency manner. Water contact angle of chitosan films before and after plasma treatment are, respectively, 101° and 27°. Besides chemical changes on the surface, the nanoliposomes incorporation and plasma treatment also induce morphological modifications. Moreover, a correlation is found between the nanoliposomes composition and size, and the effects of plasma treatment. It is shown that the plasma treatment significantly improves the chitosan film functionalization. The effect of N2 content (88% and 100%) in the plasma gas mixture on the film etching is also pointed out. Lecithin; Doehlert experimental desig

Chitosan-coated liposomes encapsulating curcumin: study of lipid–polysaccharide interactions and nanovesicle behavior

International audienceDespite various spectacular therapeutic properties, curcumin has low bioavailability mainly due to its poor solubility in water. In this paper, we encapsulated curcumin by nanoliposomes prepared from salmon purified phospholipid and coated with chitosan. Various techniques were used in order to study the interactions among phospholipid, chitosan and curcumin. FTIR results showed both electrostatic and hydrophobic interactions as well as hydrogen bonding between chitosan and phospholipid, while hydrophobic forces and hydrogen bonding dominated the interactions between curcumin and phospholipid as well as between curcumin and chitosan. Shear viscosity measurements demonstrated a flow behavior change from Newtonian to shear thinning after liposome coating. The increase/decrease stress ramp showed that the addition of chitosan layer decreased significantly the hysteresis loop area (thixotropic behavior) and therefore increased significantly the liposomal dispersion stability. The viscoelastic properties investigated by small-amplitude oscillatory shear rheology demonstrated improvement of mechanical stability after chitosan addition. Small-angle X-ray scattering experiments revealed that the liposome membrane structure was not affected by the chitosan layer or the encapsulated curcumin

Breathable hydrogel dressings containing natural antioxidants for management of skin disorders

Traditional wound dressings are not effective enough to regulate the moisture content and remove excessive exudate from the environment. Wet wound dressings formed from hydrogels such as alginate are widely used in clinical practice for treatment of skin disorders. Here, we functionalize alginate dressings with natural antioxidants such as curcumin and t-resveratrol to render them both anti-inflammatory and antibacterial. The hydrogel maintains excellent mechanical properties and oxygen permeability over time. The release rate of the compounds from the hydrogels is assessed and their impact on bacterial and cellular growth is evaluated. The antioxidant compounds act as bactericidal agents and improve cell viability. The optimal concentration of active compounds in the engineered alginate-based dressings is determined