Self-Assembly of Elastin-like Polypeptide Brushes on Silica Surfaces and Nanoparticles

Abstract

Control over the placement and activity of biomolecules on solid surfaces is a key challenge in bionanotechnology. While covalent approaches excel in performance, physical attachment approaches excel in ease of processing, which is equally important in many applications. We show how the precision of recombinant protein engineering can be harnessed to design and produce protein-based diblock polymers with a silica-binding and highly hydrophilic elastin-like domain that self-assembles on silica surfaces and nanoparticles to form stable polypeptide brushes that can be used as a scaffold for later biofunctionalization. From atomic force microscopy-based single-molecule force spectroscopy, we find that individual silica-binding peptides have high unbinding rates. Nevertheless, from quartz crystal microbalance measurements, we find that the self-assembled polypeptide brushes cannot easily be rinsed off. From atomic force microscopy imaging and bulk dynamic light scattering, we find that the binding to silica induces fibrillar self-assembly of the peptides. Hence, we conclude that the unexpected stability of these self-assembled polypeptide brushes is at least in part due to peptide–peptide interactions of the silica-binding blocks at the silica surface.

Design of Polypeptides Self-Assembling into Antifouling Coatings: Exploiting Multivalency

“…As we have shown for B - E diblocks, this method allows for a straightforward determination of both the concentration of protein required for a stable adsorbed polypeptide brush and the brush height via dynamic light scattering (DLS). 28 The results are shown in Figure 6 a. The results show that a protein concentration of ∼1 μM is required for the formation of a stable brush.…”

“…A trimer of the M block has a height of 5 nm and a diameter of 7 nm. The hydrodynamic diameter of a single E block 28 is 9 nm. Hence, the observed assemblies with a hydrodynamic diameter D H ≈ 22 nm could very well correspond to the B - M - E trimers, but this cannot be established with certainty from the DLS measurements alone.…”

“…We showed that these polymers assemble into stable hydrophilic brushes on silica surfaces and nanoparticles. 28 While the coatings were relatively stable against prolonged rinsing with phosphate-buffered saline (PBS), solutions with higher ionic strengths (>0.5 M NaCl) were still able to displace the adsorbed polymers.…”

“…Previously, we have reported the design of a protein-based diblock polymer B - E comprised of a silica-binding SBP, B , and a hydrophilic elastin-like domain E (Figure c, left). We showed that these polymers assemble into stable hydrophilic brushes on silica surfaces and nanoparticles . While the coatings were relatively stable against prolonged rinsing with phosphate-buffered saline (PBS), solutions with higher ionic strengths (>0.5 M NaCl) were still able to displace the adsorbed polymers.…”

Broadening Approaches in Nanoparticle Synthesis Through Elastin-Like Polypeptides

“…Instead, best examples of organic-inorganic hybrid materials based on elastin-like polypeptides found in the fabrication of biomedical devices are minded for applications as tissue engineering, hydrogels actuators, cardiovascular implants or antimicrobial materials between others (Anh et al, 2013;Wang et al, 2013;Mbundi et al, 2021). The main approach to build hybrid NP-based biomedical devices is to perform a conjugation of the ELP to the surface of the nanoparticle but also ligand exchange, hydrophobic interactions or physical immobilization have been used in a post-synthetic route (Ta et al, 2017;Zhang et al, 2018;Alvisi et al, 2021) (2021). Another example of ELPs opportunities in synthetic procedures is the incorporation of specific protein domains other than targeting moieties able to trigger the biomineralization of the assemblies.…”