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

Effects of nanoliposomes based on soya, rapeseed and fish lecithins on chitosan thin films designed for tissue engineering

International audienceThis work addresses the preparation of chitosan thin films functionalized in volume by nanoliposomes based on plant and marine lecithins, and then characterizes their properties by various physicochemical techniques. Firstly, the main fatty acid compositions of lecithins was analyzed by gas chromatography, secondly the stability of nanoliposomes and nanoliposomes/chitosan blends was determined by zetasizer, tensiometer, Transmission Electron Microscopy and rheometer. Finally, different properties of chitosan and the nanoliposomes/chitosan blend thin films were characterized by water contact angle, Fourier Transform Infrared Spectroscopy, Dynamic-Mechanical Thermal Analysis, Wide-Angle X-ray Scattering and Scanning Probe Microscopy in HarmoniX™ mode. From these experiments, the influences of nanoliposomes on thin films wettability, morphology, viscosity, mechanical properties and structural alteration were determined. The addition of nanoliposomes to chitosan and resulting nanoliposomes/chitosan blend thin films provides greater possibility of producing new materials for potential tissue engineering application

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

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

International audienc

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

Role of active nanoliposomes in the surface and bulk mechanical properties of hybrid hydrogels

Nanoliposomes are widely used as delivery vehicles for active compounds. Nanoliposomes from rapeseed phospholipids were incorporated into interpenetrating polymer network hydrogels of gelatin methacryloyl and alginate. The multiscale physicochemical properties of the hydrogels are studied both on the surface and through the thickness of the 3D network. The obtained composite hydrogels exhibited strong mechanical properties and a highly porous surface. The blend ratio, as well as the concentration of nanoliposomes, affects the properties of the hydrogels. Nanofunctionalized hydrogels induced keratinocyte growth. These advantageous characteristics may open up many applications of the developed hydrogels in drug delivery and tissue engineerin

Native phosphocaseinate powder during storage: Lipids released onto the surface

Native phosphocaseinate (NPC) is an innovative dairy based ingredient. However, its storage induced lipids released onto the surface, which has repercussions on powder functional properties. In this study we have investigated the effect of storage on surface composition, water sorption properties and powder microstructure. The combination of these analytical methods has been used to enhance the understanding of powder lipids released during storage. First, lipids were found to accumulate preferentially at the surface of the particle even when they were stored at 20 °C. Powder microstructure after storage showed the presence of pores, indicating a possible way of lipids released. Sorption studies revealed that the monolayer moisture capacity (Xm) decreased during storage is mainly due to the formation of a lipid barrier on the powder surface. Finally, we have confirmed observations made by other researchers on the localization of milk components during spray drying and we have added new knowledge during storage

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