Chitosan‐g‐Polyester Microspheres: Effect of Length and Composition of Grafted Chains

Abstract

Hydrophobic segments made of oligo(l,l‐ or d,l‐lactides) or poly(l,l‐lactide) are grafted onto chitosan backbone in order to use their amphiphilic behavior to prepare degradable microcarriers intended to be used for tissue engineering. Hydrophilic–lipophilic balance of these copolymers is adjusted playing on the respective length of their hydrophilic and hydrophobic moieties. Thanks to their self‐emulsifying properties, these graft copolymers are processed into microspheres in the absence of hydrophilic emulsifier commonly added in the aqueous phase of the oil/water emulsion. The copolymers containing amorphous oligolactide segments of medium length are demonstrated to be the most effective ones for microparticle fabrication. The microparticles are characterized using SEM, EDX, and FTIR. The reactivity of amine group is demonstrated using fluorescein isothiocyanate staining. The resulting microspheres disclose a porous core and a shell enriched by the hydrophilic polysaccharide moieties. Stabilization of the oil/water interface during the microsphere fabrication, total yield, size distribution, and microparticle surface morphology are mainly affected by the macromolecular features of the copolymers.

Biodegradable Cell Microcarriers Based on Chitosan/Polyester Graft-Copolymers

“…The presence and accessibility of amino groups onto microparticle surface has been also verified using staining with FITC reagent as reported earlier using a Leica DFC-450 C (Leica Microsystems, Germany) fluorescent microscope [22].…”

“…Although slightly lower than observed for control poly(D,L-lactide) microparticles stabilized with polyvinyl alcohol (PVA), this material recovery is significantly higher than one observed for chitosan-g-poly(L,L-lactide) copolymers, i.e., 10 wt. % [22]. The majority of the copolymer microparticles have a size bigger than 200 µm, while the mean diameter of control microparticles is lower than 125 µm.…”

“…Microspheres were prepared by oil/water emulsion solvent evaporation technique as described previously [22]. The oil phase-8 wt.…”

“…Recently, chitosan-g-oligo/polylactide copolymers were also adopted to prepare self-stabilized microspheres via the oil/water solvent evaporation technique. As a function of graft chain polymerization degree, the nature of polyester fragments, and chitosan characteristics, a set of microparticles with complex morphology was developed [21,22]. This former study evidenced that, above critical molecular weights of the hydrophilic chitosan backbone or of the hydrophobic polylactide moieties, the migration and self-assembly of these amphiphilic macromolecules at the oil/water interface was thwarted, resulting in a poor microparticle production yield.…”

Solid-State Synthesis of Water-Soluble Chitosan-g-Hydroxyethyl Cellulose Copolymers

“…Such a type of advanced carrier contains a bioactive component within a polymeric core, and a surface layer supporting the adhesion and growth of anchorage-depended cells [40]. Since biodegradable particles are promising materials either in the form of nano/micro-particles as a drug/cell carrier, or as a starting material for the fabrication of 3D structures, developing new types of microparticles is of great importance [41,42].…”