The impact of nanostructuring on the hemocompatibility of polysulfobetaine (PSB) coated hydrogel surfaces

A series of nanostructured polysulfobetaine (PSB) hydrogel-coated surfaces were fabricated and tested for hemocompatibility in contact with human blood. PSB films were grafted onto SiO₂-coated silicon wafers or Au/quartz via photochemically induced polymerization of a sulfobetaine-based monomer (SBMA, [2-(methacryloylamino)propyl]dimethyl(3-sulfopropyl)ammonium hydroxide). An anodized aluminum oxide (AAO) membrane and latex beads (LB) were used as sacrificial template structures to synthesize polysulfobetaine nanowires (PSB_AAO) and hyperporous (PSB_LB) networks, respectively. Two soft sacrificial templates, a liquid crystalline medium (LC) and amide-based non-ionic deep eutectic solvent (ni-DESs) providing one-dimensional ordered arrays and flickering clusters, respectively, were utilized to grow nanofibrous (PSB_LC) and mesoporous (PSB_DES) polysulfobetaine film. Selective dissolution of the sacrificial templates affords the transposed pattern of the template with long-range periodicity from nano to micro scale (20 to 400 nm). Electron micrograph studies revealed nanostructured materials in the form of wires (198 ± 5 nm), cavities (300 nm) and fibers (20 ± 2 nm) when AAO, LB and LC-medium were used as templates, while the polymer films prepared from ni-DESs (PSB_DES), water (PSB_WAT) and methanol (PSB_MeOH) were devoid of any noticeable topographical features. PSB-coated surfaces (except for PSB_LB) inhibited non-specific adhesion of protein and biomolecules when presented with purified human proteins, i.e., albumin, fibrinogen, hemoglobin, or human plasma, down to 20-125 ng cm^-2 as shown by the QCM studies. Interestingly, the hierarchical nanostructures in polymer films (PSB_AAO and PSB_LC) resisted the adsorption of albumin and hemoglobin (<20 ng cm^-2), even at 50 mg mL^-1 concentration. The hemocompatibility of the PSB nanostructures, analyzed after contact with human whole blood for one hour on the PSB_AAO and PSB_LC, revealed reduced complement activation, quantified as the generation of C3bc fragments and terminal complement sC5b-9 complex formation, in comparison to acrylate glass. The nanowires of PSB_AAO showed significantly lower MPO release than the PSB_WAT-onto surface, whereas no difference in platelet activation was seen between the surfaces. Compactly organized nanowires and fibers increase the water of hydration layers to strengthen the antifouling and hemocompatibility features, demonstrating the bio-inert nature of the PSB nanostructures. The inherent gelation (hydrophilicity) afforded by the PSB has substantial implications in designing bio-inert surfaces for hemocompatible devices.