Nanoconfinement and Sansetsukon-like Nanocrawling Govern Fibrinogen Dynamics and Self-Assembly on Nanostructured Polymeric Surfaces

Abstract

Surface nanostructures are increasingly more employed for controlled protein assembly on functional nanodevices, in nanobiotechnology, and in nanobiomaterials. However, the mechanism and dynamics of how nanostructures induce order in the adsorbed protein assemblies are still enigmatic. Here, we use single-molecule mapping by accumulated probe trajectories and complementary atomic force microscopy to shed light on the dynamic of in situ assembly of human plasma fibrinogen (HPF) adsorbed on nanostructured polybutene-1 (PB-1) and nanostructured polyethylene (PE) surfaces. We found a distinct lateral heterogeneity of HPF-polymer nanostructure interface (surface occupancy, residence time, and diffusion coefficient) that allow identifying the interplay between protein topographical nanoconfinement, protein diffusion mechanism, and ordered protein self-assembly. The protein diffusion analysis revealed high-diffusion polarization without correlation to the anisotropic friction characteristic of the polymer surfaces. This suggests that HPF molecules confined on the nanosized PB-1 needle crystals and PE shish-kebab crystals, respectively, undergo partial detachment and diffuse via a Sansetsukon-like nanocrawling mechanism. This mechanism is based on the intrinsic flexibility of HPF in the coiled-coil regions. We conclude that nanostructured surfaces that encourage this characteristic surface mobility are more likely to lead to the formation of ordered protein assemblies and may be useful for advanced nanobiomaterials.

Principles of Fibrinogen Fiber Assembly In Vitro

“…[ 18,83 ] This molecular orientation may originate from the intrinsic flexibility of fibrinogen, [ 61 ] which encourages surface mobility on nanostructured surfaces. [ 102 ] For the nonpolar, hydrophobic PE‐SC nanocrystals it was also assumed that fibrinogen adsorbs via its nonpolar D regions and the central E region, like it was suggested for varying smooth hydrophobic surfaces. Consequently, the polar αC‐regions may also be involved in fiber assembly on PE‐SC surfaces [ 83 ] and it may be concluded that the particular nanotopographies were responsible for the fiber formation rather than the hydrophobic polymer itself.…”

How Nanotopography-Induced Conformational Changes of Fibrinogen Affect Platelet Adhesion and Activation

“…Nanostructured high-density polyethylene (HDPE) (melt index of 2.2 g/10 min, Sigma-Aldrich, Germany) thin films were prepared in a similar manner to MD iPB-1 . 20 To obtain chemically similar yet topographically distinct iPB-1 nanostructured surfaces with lamellar crystals (LCs), iPB-1 solution (1 wt % in p-xylene) was spin-coated on a glass plate (1 cm in diameter) at 2000 rpm and fully dried in a vacuum oven at 50 °C for three days.…”

“…Statistical analysis for significant differences among groups was tested using one-way analysis of variance (ANOVA) with Holm-Sikad. 20 Figure 1a shows the AFM topography images of nanostructured polymeric surfaces with typical lamellar crystals (LCs), needle-like crystals (NLCs), and shish-kebab crystals (SKCs) for SC iPB-1, MD iPB-1, and MD HDPE, respectively. The crystals protrude ∼3 ± 2 nm out of the surface and are separated from each other by amorphous regions.…”

“…16,18,19 For instance, recent studies on HPF dynamics at single-molecule resolution revealed that such well-defined nanostructured surfaces can act as guiding platforms for protein assemblies. 20 Using the MAPT technique, 21 we identified a highly selective behavior of HPF on nanotopographically distinct polymeric surfaces in which HPF was found to preferably adsorb in a trinodular conformation to crystalline regions of the surfaces and to diffuse in a preferential direction.…”

“…To this end, approaches to control HPF adsorption through surface chemistry or surface micro- and nanostructuring have been explored previously. ,− In particular, it has been recognized that surfaces with topographical features comparable in size to the physical dimensions of HPF can provide a fine-tuning mechanism to manipulate its assembly behavior and conformation. , Among polymeric nanostructured surfaces, semicrystalline polybutene-1 (PB-1) and polyethylene (PE) thin films produced by melt-drawing (MD) and spin-coating (SC) techniques were proven to be versatile model surfaces to study the influence of nanoscale features on HPF adsorption. ,, For instance, recent studies on HPF dynamics at single-molecule resolution revealed that such well-defined nanostructured surfaces can act as guiding platforms for protein assemblies . Using the MAPT technique, we identified a highly selective behavior of HPF on nanotopographically distinct polymeric surfaces in which HPF was found to preferably adsorb in a trinodular conformation to crystalline regions of the surfaces and to diffuse in a preferential direction.…”