Physico-chemical properties and surface characterization of renewable hybrid nanofilms interacting with model proteins

Abstract

A comprehensive characterization of physical-chemical properties and biological interactions of ca. 200-nm-thick hybrid films based on silylated (inorganic part) castor oil (organic part) is proposed. A series of such nanofilms was fabricated and cross-linked by a sol-gel procedure, and their properties such as hydrophilicity, hardness and water vapour transmission rate were systematically studied as a function of the ratio of silylated agent to castor oil. It was found that the nanofilms have contact angles always below 90°, tunable Young modulus and hardness in the MPa range. Moreover, their water vapour transmission rates are increased by decreasing the silica ratio. The protein adsorption and cytocompatibility were evaluated using model proteins and cells. The adsorption of the proteins bovine serum albumin (BSA) and lysozyme was characterized using a quartz crystal microbalance in energy dissipation mode (QCM-D), and atomic force microscopy (AFM). The combination of the latter provided evidence for the different affinities of the proteins with the films. It was found that BSA and lysozyme form rigid layers on the surface with surface coverage close to 30 %, and that both protein layers decrease their thickness after their dehydration. Finally, cell culture experiments exhibited a good viability of the fibroblasts compared to ultra-low adhesion surfaces, which makes them potential candidates for biomedical applications.

Equilibrium Protein Adsorption on Nanometric Vegetable Oil Hybrid Film/Water Interface Using Neutron Reflectometry

“…Large-size cross-linked ICO films of thickness ~ 200 μm can be formed at the air-water interface 7 or by spin-coating. 10 In the SI (Fig. S2) the protein concentrations studied, allowing us to identify the optimum protein adsorption on these films.…”

“…Large-size cross-linked ICO films of thickness ∼200 μm can be formed at the air−water interface 7 or by spin-coating. 10 In the Supporting Information (Figure S2), the chemical structure of the castor oil and its functionalized form ICO is shown, and the macroscopic transparent solid film obtained after the cross-link reaction of 1 g of ICO deposited on a surface area of 50.3 cm 2 of water. Spatial characterization by wide angle X-ray scattering of the film, together with the virgin castor oil and the functionalized oil ICO, shows an amorphous structure with a strong peak at q = 1.4 Å −1 that decreases in intensity with functionalization and crosslinking, with no significant shift in the peak position.…”

“…Large-size cross-linked ICO films of thickness ~ 200 μm can be formed at the air-water interface 7 or by spin-coating. 10 In the SI (Fig. S2) the chemical structure of the castor oil and its functionalized form ICO are shown, and the macroscopic transparent solid film obtained after the cross-link reaction of 1g of ICO deposited on a surface area of 50.3 cm 2 of water.…”

“…7 Previously, we explored the formation of intermediate thickness (hundreds of nanometers) films, obtained by spin-coating and cross-linking functionalized castor oil (ICO), and investigated their tunability and protein adsorption from phosphate buffer saline of the model proteins, bovine serum albumin (BSA) and lysozyme. 10 In that study, atomic force microscopy (AFM) and quartz crystal micro- balance with dissipation (QCM-D) were used to follow adsorption/desorption kinetics. The surface coverage in aqueous medium was found to be close to 30 ± 8% for both proteins, showing that the major part of the substrates is occupied by the phosphate buffer.…”

“…For this reason, the understanding of interactions of biological materials on a nanoscale has been the topic of several studies. , We have recently studied the structure, mechanical properties, and cytotoxicity on thick (hundreds of microns) films . Previously, we explored the formation of intermediate thickness (hundreds of nanometers) films, obtained by spin-coating and cross-linking functionalized castor oil (ICO), and investigated their tunability and protein adsorption from phosphate buffer saline of the model proteins, bovine serum albumin (BSA) and lysozyme . In that study, atomic force microscopy (AFM) and quartz crystal microbalance with dissipation (QCM-D) were used to follow adsorption/desorption kinetics.…”