Abstract
In this study, we investigate how a surface structure underneath a surface-attached polymer coating affects the bioactivity of the resulting material. To that end, structured surfaces were fabricated using colloidal lithography (lateral dimensions: 200 nm to 1 µm, height ~15 to 50 nm). The surface structures were further functionalized either with antimicrobial, cell-adhesive polycations or with protein-repellent polyzwitterions. The materials thus obtained were compared to non-functionalized structured surfaces and unstructured polymer monolayers. Their physical properties were studied by contact-angle measurements and atomic force microscopy (AFM). Protein adhesion was studied by surface plasmon resonance spectroscopy, and the antimicrobial activity against Escherichia coli bacteria was tested. The growth of human mucosal gingiva keratinocytes on the materials was analyzed using the Alamar blue assay, optical microscopy, and live-dead staining. The data shows that the underlying surface structure itself reduced protein adhesion and also bacterial adhesion, as evidenced by increased antimicrobial activity. It also enhanced cell adhesion to the surfaces. Particularly in combination with the adhesive polycations, the surfaces increased the cell growth compared to the unstructured reference materials. Thus, functionalizing structured surfaces with adhesive polymer could be a valuable tool for improved tissue integration.
Highlights
Chemical and physical surface properties, such as surface chemistry, interfacial energy, roughness or structuring determine to a large extent how organisms interact with materials [1,2,3,4,5]
The aim of this paper was to find out how an underlying surface pattern with lateral dimensions between 200 nm and 1 μm and a height between ~15–50 nm affects the bioactivity of polymer-functionalized surfaces
The bioactivity of unstructured polymer monolayers made from either the antimicrobial, polycationic synthetic mimics of antimicrobial peptides’ (SMAMPs) (SMAMP monolayer, Figure 2a), or the protein-repellent, polyzwitterionic PSB (PSB monolayer, Figure 2a) was compared to structured monolayers made from the same materials (SMAMP@Au_SMAMP@Si or PSB@Au_PSB@Si, respectively, Figure 2b)
Summary
Chemical and physical surface properties, such as surface chemistry, interfacial energy, roughness or structuring determine to a large extent how organisms interact with materials [1,2,3,4,5]. By deliberately designing surface properties, the interaction of matter with life can be directed. This has implications for all technical products that come into contact with mammalian cells, bacteria, yeasts or even plant cells like algae—for example medical devices, ship hulls, water transportation and purification systems, and building parts. Through customized surface properties, desired interactions can be enhanced (e.g., when tailor-made implant surfaces lead to successful tissue integration), and undesired interactions can be suppressed (e.g., when protein-repellent coatings suppress algae attachment on a ship hull). In the context of biomedical devices, one of the most pressing problems is undesired biofilm formation
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