Protein Adsorption at Nanorough Titanium Oxide Surfaces: The Importance of Surface Statistical Parameters beyond Surface Roughness

Abstract

The nanoscale surface topography of biomaterials can have strong effects on protein adsorption. While there are numerous surface statistical parameters for the characterization of nanorough surfaces, none of them alone provides a complete description of surface morphology. Herein, a selection of nanorough titanium oxide surfaces has been fabricated with root-mean-square roughness (Sq) values below 2.7 nm but very different surface morphologies. The adsorption of the proteins myoglobin (MGB), bovine serum albumin (BSA), and thyroglobulin (TGL) at these surfaces was investigated in situ by ellipsometry to assess the importance of six of the most common surface statistical parameters. For BSA adsorption, both protein film thickness and time constant of adsorption were found to scale linearly with Sq s. For TGL, however, the same adsorption characteristics depend linearly on the surface skewness (Ssk), which we attribute to the rather extreme size of this protein. Finally, a mixed behavior is observed for MGB adsorption, showing different linear correlations with Sq and Ssk. These results demonstrate the importance of a thorough morphological characterization of the surfaces employed in protein adsorption and possibly also cell adhesion studies.

Mechanism of Myoglobin Molecule Adsorption on Silica: QCM, OWLS and AFM Investigations

“…It should be mentioned that in contrast to ref. [ 29 ] the skewness and surface kurtosis of the substrate surfaces were not determined because of a rather large tip radius exceeding 10 nm.…”

“…In ref. [ 29 ], the adsorption of myoglobin, bovine serum albumin and thyroglobulin on titania layers sputtered on silica was studied at pH 7.4 by ellipsometry. Using AFM ambient air imaging, both the rms, the skewness and surface kurtosis of the substrate surfaces were determined and correlated with the adsorption kinetics and the protein film thickness.…”

Ion Beam Nanopatterning of Biomaterial Surfaces

“…Furthermore, in the case of polycrystalline films, the disorder between the different grains in the film may result in a loss of conformity already at low film thicknesses. In such a case, magnetron sputter deposition with an applied negative bias may be used to achieve dense and highly conformal films with no apparent surface texture other than the replicated nanopattern (see Figure 3a) [98,102]. If the nanopatterned substrate surface is crystalline, highly conformal films can also be grown epitaxially, if the lattice constants between film and substrate material are a match (see Figure 3b) [94].…”

Nanoscale Surface Topography Modulates hIAPP Aggregation Pathways at Solid–Liquid Interfaces

“…In contrast, the role of surface topography and, in particular, nanotopography in protein and peptide adsorption is still rather elusive. Even though the effects of different nanoscale surface topographies on the adsorption of various proteins have been investigated in numerous studies [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ], the underlying mechanisms are still not yet fully understood. This particularly concerns the question of how surface topography may affect also protein–protein interactions and protein aggregation during adsorption [ 14 , 21 , 22 , 23 , 24 ].…”

“…hIAPP is a 37-residue polypeptide hormone produced in the pancreas, whose aggregation is a key intermediate step in the development of type 2 diabetes mellitus [ 66 ] and is thus frequently studied in vitro, both in bulk solution [ 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 ] and in contact with solid surfaces [ 36 , 49 , 55 , 77 , 78 , 79 ]. Since random rough surfaces are difficult to describe and may exhibit very different morphologies despite identical roughness parameters [ 16 ], in the present work, we instead employed ion beam nanopatterning to produce silicon oxide surfaces with a well-defined and anisotropic nanoscale topography [ 80 ]. Using time-lapse atomic force microscopy (AFM) to characterize the evolution of hIAPP aggregate morphology quantitatively, we show that the presence of such nanopatterns modulates the hIAPP aggregation pathway.…”