PULM3: The Effects of a Two-step Coating Process and Flow on Artificial Lung Fiber Fouling.

Abstract

The densely packed fiber bundle design of the artificial lung increases the gas exchange efficiency of the device by dramatically increasing its surface area to volume ratio. However, the close arrangement of the lung’s fibers is a significant source for blood coagulation, and therefore the effectiveness of their in-situ coating for effective protein antifouling activity requires a process that uniformly applies the coating across the bundle thickness. In this study, polydopamine/polysulfobetaine methacrylate (pDOPA/pSBMA) was grafted onto the artificial lung circuit using a two-step surface modification process consisting of an ultraviolet-oxygen plasma surface activation followed by surface grating in pDOPA/pSBMA dissolved in tris(hydroxymethyl)aminomethane (TRIS, pH 8.5) buffer. The antifouling activities of coating on fiber mats at the surface or buried in the bundle, on fiber bundle exposed to 24hr phosphate buffered saline (pH 7.34, temp. ~37C) flow (1.22L/min), and uncoated controls were analyzed. Fibrinogen (Fg) and platelet (plt) fouling on fibers were used as metrics of antifouling activity. Ultimately, the utility of fully priming the lung circuit with pDOPA/pSBMA coating solution with a side-to-side positioning of the primed device every 10 minutes for 2 hrs was evaluated for coating uniformity across bundle thickness. Fg and plt fouling on uncoated controls, coated bundle surface fibers, coated bundle buried fibers, coated bundle surface fibers after 24hr flow, and coated bundle buried fibers after 24hr flow were respectively (0.83±0.01, 0.20±0.003) (0.36±0.01 pval=0.026, 0.36±0.01 pval=8.740E-11), (0.38±0.004 pval=0.026, 0.01±0.02 pval=8.740E-11), (2.64±0.53 pval=0.077, 0.02±0.003 pval=0.218), and (2.70±0.72 pval= 0.077, 0.03±0.01 pval=0.218). The data indicated that while the pDOPA/pSBMA coating significantly reduced fouling, not only did its appearance vary across the bundle thickness but so did its antifouling activity. This warrants the optimization of the coating process.