In Vitro and In Silico Studies of Functionalized Polyurethane Surfaces toward Understanding Biologically Relevant Interactions

Rationally Designed Binder with Polysulfide-Affinitive Moieties and Robust Network Structures for Improved Polysulfide Trapping and Structural Stability of Sulfur Cathode

Lithium-sulfur batteries (LSBs) have emerged as a promising next-generation energy storage application owing to their high specific capacity and energy density. However, inherent insulating property of sulfur, along with its significant volume expansion during cycling, and shuttling behavior of lithium-polysulfides (LiPSs), hinder their practical application. To overcome these issues, a crosslinked cationic waterborne polyurethane (CCWPU) is rationally designed as a binder for LSBs. The mechanical robustness of CCWPU enables it to withstand the high stress derived from volume expansion of sulfur, facilitating charge-transferring through conserved charge-transfer pathway and promoting interconversion of LiPSs. Additionally, polar urethane groups offer favorable interaction sites with LiPSs, mitigating shuttling behavior of LiPSs via polar-polar interaction. Density functional theory investigations further elucidate that the incorporation of cationic moieties enhances LiPSs immobilization by confining Sn x- (x = 1 or 2) in LiPSs, thereby improving sulfur utilization. Benefiting from these, the cell with CCWPU demonstrates reduced polarization, superior LiPSs conversion rates, and stable cycling performance. Moreover, water-processable nature of CCWPU aligns with environmental consciousness. These diverse functionalities of CCWPU provide valuable insights for the development of advanced binder for LSBs, ultimately improving the electrochemical performances of LSBs.

Improving Biocompatibility of Polyurethanes Apply in Medicine Using Oxygen Plasma and Its Negative Effect on Increased Bacterial Adhesion

Polyurethanes (PUs) are versatile polymers used in medical applications due to their high flexibility and fatigue resistance. PUs are widely used for synthetic blood vessels, wound dressings, cannulas, and urinary and cardiovascular catheters. Many scientific reports indicate that surface wettability is crucial for biocompatibility and bacterial adhesion. The use of oxygen plasma to modify PUs is advantageous because of its effectiveness in introducing oxygen-containing functional groups, thereby altering surface wettability. The purpose of this study was to investigate the effect of the modification of the oxygen plasma of polyurethane on its biocompatibility with lung tissue (A549 cell line) and the adhesion of Gram-positive bacteria (S. aureus and S. epidermidis). The results showed that the modification of polyurethane by oxygen plasma allowed the introduction of functional groups containing oxygen (-OH and -COOH), which significantly increased its hydrophilicity (change from 105° ± 2° to 9° ± 2°) of PUs. Surface analysis by atomic force microscopy (AFM) showed changes in PU topography (change in maximum height from ∼110.3 nm to ∼32.1 nm). Moreover, biocompatibility studies on A549 cells showed that on the PU-modified surface, the cells exhibited altered morphology (increases in cell surface area and length, and thus reduced circularity) without concomitant effects on cell viability. However, serial dilution and plate count and microscopic methods confirmed that plasma modification significantly increased the adhesion of S. aureus and S. epidermidis bacteria. This study indicate the important role of surface hydrophilicity in biocompatibility and bacterial adhesion, which is important in the design of new medical biomaterials.