Blood Oxygenation Using Fluoropolymer-Based Artificial Lung Membranes

Abstract

Artificial lung (AL) membranes are used for blood oxygenation for patients undergoing open-heart surgery or acute lung failures. Current AL technology employs polypropylene and polymethylpentene membranes. Although effective, these membranes suffer from low biocompatibility, leading to undesired blood coagulation and hemolysis over a long term. In this work, we propose a new generation of AL membranes based on amphiphobic fluoropolymers. We employed poly­(vinylidene-co-hexafluoropropylene), or PVDF-co-HFP, to fabricate macrovoid-free membranes with an optimal pore size range of 30–50 nm. The phase inversion behavior of PVDF-co-HFP was investigated in detail for structural optimization. To improve the wetting stability of the membranes, the fabricated membranes were coated using Hyflon AD60X, a type of fluoropolymer with an extremely low surface energy. Hyflon-coated materials displayed very low protein adsorption and a high contact angle for both water and blood. In the hydrophobic spectrum, the data showed an inverse relationship between the surface free energy and protein adsorption, suggesting an appropriate direction with respect to biocompatibility for AL research. The blood oxygenation performance was assessed using animal sheep blood, and the fabricated fluoropolymer membranes showed competitive performance to that of commercial polyolefin membranes without any detectable hemolysis. The data also confirmed that the bottleneck in the blood oxygenation performance was not the membrane permeance but rather the rate of mass transfer in the blood phase, highlighting the importance of efficient module design.

The Roles of Membrane Technology in Artificial Organs: Current Challenges and Perspectives

“…However, it is technically difficult to process PTFE polymer into a thin, hollow fiber shape due to its high melt viscosity. Kim et al [50] have shown that other fluoropolymers with better processability, such as PVDF and P(VDF-co-HFP), can be processed into membranes with target pore size.…”

“…As the protein adsorption is the first step that initiates both the blood coagulation pathway and the inflammatory response [63], many works have focused on minimizing the protein adsorption onto blood-contacting devices [50,[64][65][66][67]. Generally, proteins bind to a surface via hydrophobic interaction, and hence the hydrophilic modification of a surface effectively lowers the protein adsorption, which in turn improves the hemocompati- As the protein adsorption is the first step that initiates both the blood coagulation pathway and the inflammatory response [63], many works have focused on minimizing the protein adsorption onto blood-contacting devices [50,[64][65][66][67]. Generally, proteins bind to a surface via hydrophobic interaction, and hence the hydrophilic modification of a surface effectively lowers the protein adsorption, which in turn improves the hemocompatibility [62].…”

“…The lowest surface energy reported is 9.3 mN/m using fluorinated polyhedral oligomeric silsesquioxanes (POSS) [93]. Protein adsorption can be further inhibited with super liquid-repellent surfaces, also known as superamphiphobic surfaces [50,[67][68][69][70]. The superarmphiphobic surface can only be realized with appropriate surface roughness modification and surface energy modification.…”

“…More recently, third generation artificial lung membranes have been proposed using fluoropolymers [ 50 ]. The characteristic low surface energy of fluoropolymers prevents unwanted protein adsorption onto the membrane surface, potentially improving the long-term hemocompatibility of artificial lung membranes.…”

“…Kim et al [ 50 ] have shown that other fluoropolymers with better processability, such as PVDF and P(VDF-co-HFP), can be processed into membranes with target pore size. Apart from these options, many possible possibilities exist in the realm of fluoropolymers, yet to be explored for artificial lung membranes.…”