Nanocoatings of Bovine Serum Albumin on Glass: Effects of pH and Temperature

Protein adsorption is influenced by many factors such as temperature, pH, protein size and structure, or surface energy and roughness, among others. Self-assembled monolayers (SAMs) and the Langmuir-Blodgett (LB) technique are two of the techniques more used to produces ultrathin films of proteins on surfaces. In this work, we established protocols for the preparation of nanocoatings of bovine serum albumin (BSA) protein on glass surface using SAMs and LB. Furthermore, we determined how small changes in temperature and pH can affect the covering when SAMs are used. Using a combination of different analyses, such as relative roughness, dynamic contact angles, and atomic force microscopy (AFM), it was possible to establish conditions to obtain a uniform nanocoating using SAMs. The results of the analysis of the nanocoating performed using the LB technique were very similar to those obtained using SAMs. The Derjaguin–Landau–Verwey–Overbeek (DLVO) theory in conjunction with the AFM images showed that electrostatic interactions are very important in the self-assembly process, but a process dominated solely by attraction is not sufficient to achieve a good SAM nanocoating, since it does not allow proper orientation and packaging of BSA molecules on the glass surface.