In vitro degradation and biocompatibility evaluation of fully biobased thermoplastic elastomers consisting of poly(beta-myrcene) and poly(L-lactide) as stent coating

Currently coronary stent coating materials focus on biodegradable polymers requiring excellent performances, including biodegradability, cytocompatibility and hemocompatibility as well as ductility. To endow poly(L-lactide) (PLLA) with good ductility as stent coating, two kinds of high branched PLLA grafted copolymers with introduction of biobased poly(beta-myrcene) rubber segments were developed towards sent coating. The impacts of topological architectures (including linear comb and star comb) on physical properties, hydrolytic and enzymatic degradation behaviors, cytocompatibility, hemocompatibility and coating morphology were investigated. It was found that the nonbiodegradable poly(beta-myrcene) rubber segments delayed the degradation rate, and further decreased with more complex architectures. Proteinase K accelerated enzymatic degradation compared with hydrolytic degradation. Biocompatibility testing showed that the fully biobased thermoplastic elastomers possessed good cytocompatibility and hemocompatibility. Morphological characterization of stent coatings indicated that the linear comb and star comb PLLA grafted copolymers improved the surface smooth of pure PLLA coating. Thus, these highly branched fully biobased thermoplastic elastomers are promising to as potential coating materials in drug eluting stent. (C) 2020 Elsevier Ltd. All rights reserved.