Enhancing the Hemocompatibility of 3D-Printable Silicone Elastomers for Artificial Lung Applications

Clinical hollow-fiber artificial lungs are prone to clotting, necessitating the use of systemic anticoagulation and thus increasing the risk of bleeding events. This study seeks to address these limitations by creating hemocompatible and biomimetic 3D-printed artificial lungs. This study investigates the nonthrombogenic effects of imbuing a polydimethylsiloxane (PDMS or silicone elastomer)-based 3D-printable resin with hydrophilic molecules with the goal of reducing the body's natural coagulation response to foreign materials, increasing device lifetime, and reducing systemic anticoagulation, thereby coming closer to mimicking the native in vivo blood interface. First, contact angle (hydrophilicity) tests were done to narrow down the number of candidate modifications for the development of a high-resolution PDMS resin for vat photopolymerization (VPP). Then, dynamic blood flow-through testing was performed using a high-resolution PDMS base resin modified by (1) adding 1% 2-methacryloyloxyethyl phosphorylcholine (MPC) to the base resin; (2) adding 1.8% poly(ethylene glycol) methacrylate (PEGMA) to the base resin; or (3) infusing the neat PDMS devices with 2% dimethylsiloxane-[60-70% ethylene oxide] (PEO-PDMS) in ethanol post printing. Biomimetic microfluidic capillary devices designed in SOLIDWORKS were 3D-printed via VPP, cleared of uncured resin, and tested for coagulation with freshly drawn ovine whole blood. Devices (n ≥ 12 per group) were exposed to blood for 10 min at 0.8 mL/min and evaluated for clotting via fluorescent confocal microscopy, percent clotting area analyses, pressure data, and flow cytometry. The 1% MPC, 1.8% PEGMA, and 2% PEO-PDMS infusion resin groups demonstrated a significant decrease in clotting area and fluorescence intensity when compared to the unmodified base resin and a commercially available resin (FTD Nano Clear). The top-performing modification (PEO-PDMS infusion) decreased the clotting area by 57.5 and 65.2% and fluorescence intensity by 84.6 and 88.3% relative to the unmodified base resin and FTD Nano Clear resin, respectively.