The effect of the buffer solution on the adsorption and stability of horse heart myoglobin on commercial mesoporous titanium dioxide: a matter of the right choice

Abstract

Despite the numerous studies on the adsorption of different proteins onto mesoporous titanium dioxide and indications on the important role of buffer solutions in bioactivity, a systematic study on the impact of the buffer on the protein incorporation into porous substrates is still lacking. We here studied the interaction between a commercial mesoporous TiO and three of the most used buffers for protein incorporation, i.e. HEPES, Tris and phosphate buffer. In addition, this paper analyzes the adsorption of horse heart myoglobin (hhMb) onto commercial mesoporous TiO as a model system to test the influence of buffers on the protein incorporation behavior in mesoporous TiO. N sorption analysis, FT-IR and TGA/DTG measurements were used to evaluate the interaction between the buffers and the TiO surface, and the effect of such an interaction on hhMb adsorption. Cyclic voltammetry (CV) and electron paramagnetic resonance (EPR) were used to detect changes in the microenvironment surrounding the heme. The three buffers show a completely different interaction with the TiO surface, which drastically affects the adsorption of myoglobin as well as its structure and electrochemical activity. Therefore, special attention is required while choosing the buffer medium to avoid misguided evaluation of protein adsorption on mesoporous TiO.

On the stability of microwave-fabricated SERS substrates – chemical and morphological considerations

“…These media frequently contain a complex mixture of different compounds and also have different pH values. The choice of a suitable media is of utmost importance for many biological investigations as it can alter the structure of biomolecules (e.g., proteins) [ 33 ]. We tested five commonly used buffer systems which include phosphate-buffered saline (PBS), HEPES-buffered glucose solution (HBG), tris-borate-EDTA (TBE), an acetate buffer, and a carbonate buffer.…”

Buffer Influence on the Amino Acid Silica Interaction

“…TRIS has two protonation states with net charge +1e (TRIS positive ) and 0 (TRIS neutral ), while the protonation state of MOPS have net charge 0 (MOPS neutral ) and −1e (MOPS negative ). It has been previously reported that the buffer interacts with different oxide surfaces of titanium . Due to their charge the buffer species will also interact with silica and the AA, leading to competing interactions .…”

“…It has been previously reported that the buffer interacts with different oxide surfaces of titanium. [11] Due to their charge the buffer species will also interact with silica and the AA, leading to competing interactions. [11,49] Therefore, we evaluated the free energy of adsorption of the different buffer species to silica and also quantified the interaction between the buffer species and AAs.…”

“…[11] Due to their charge the buffer species will also interact with silica and the AA, leading to competing interactions. [11,49] Therefore, we evaluated the free energy of adsorption of the different buffer species to silica and also quantified the interaction between the buffer species and AAs. The binding affinity of the buffer species and the two strongly binding AAs (R and K) are shown in Figure 2b below.…”

“…[8] The latter comprises not only the peptide and the surface but also the solvent, which often contains a buffer to stabilize the pH of the system. The fact that buffer ions can compete with the peptide/ protein in binding to the surface is well known and investigated, [9][10][11][12][13][14][15][16][17][18][19][20] but to the best of our knowledge this has never been done for single amino acids especially for silica. A rational understanding of peptide or protein interactions with surfaces would benefit greatly from data on the interactions of individual amino acids.…”