Electroactive polymer coating on hydrogel filaments for vascular-mimicking structures

Sammanfattning

Cardiovascular diseases remain a leading cause of mortality globally, driving acritical clinical demand for advanced artificial blood vessels capable of replicating the dynamic nature of natural vasculature. Traditional synthetic graftslack the physiological ability to undergo vasodilation and vasoconstriction. Thisstudy aims to adress these limitations by developing and optimizing electroactive polymer-coated hydrogel filaments to serve as dynamic, vascular-mimickingstructures. Soft filaments were fabricated using extrusion-based 3D bioprintingof a modified hyaluronan (HA-BCN) precursor ink into an alginate support bath.To introduce biomimetic actuation, the filaments were subsequently coated withthe conducting polypyrrole (PPy) via chemical polymerization. The influence of key polymerization parameters- including monomer soak time,polymerization duration, reaction temperature and the concentration of the surfactant dopant sodium dodecylbenzenesulfonate (NaDBS)- was systematicallyevaluated regarding coating uniformity, electrochemical properties and actuation. Furthermore, a comparative analysis was conducted between two oxidizingagents, Ammonium Persulfate (APS) and Iron(III)Chloride (FeCl3). The experimental results demonstrate that FeCl3 is superior to APS for achieving high-performance, structurally homogeneous conductive networks. WhileAPS confined polymerization primarily to a superficial surface layer resultingin early saturation and lower conductivity, FeCl3 produced dense PPy layerswith a strong time-dependent capacitive performance. Under cyclic voltammetry and chronoamperometry, FeCl3-polymerized filaments demonstrated significantly larger, electrochemcially driven diameter oscillations compared to the APScounterparts. Incorporating NaDBS as a dopant revealed an optimization threshold at 0.05 M, yielding a maximal charge storage capacity for both the APS andthe FeCl3. Finally, biocompatibility assessments indicated an absence of acute cytotoxicity for all APS configurations. Conversely, undoped FeCl3 coatings exhibitedsevere cytotoxic effects, which were successfully mitigated by the introductionof NaDBS, establishing a favorable environment for cell adhesion, spreading andproliferation.