Effect of pH and Addition of Salt on the Adsorption Behavior of Lysozyme on Gold, Silica, and Titania Surfaces Observed by Quartz Crystal Microbalance with Dissipation Monitoring

Abstract

The adsorption behaviors of lysozyme on dentally related Au, SiO2, and TiO2 surfaces were investigated by a quartz crystal microbalance with dissipation monitoring (QCM-D) method. Frequency shifts indicated that while lysozyme (pI 11) was fairly adsorbed on the SiO2 (pI 1.9) surface at both pH 3 and 7, it was adsorbed on TiO2 (pI 6.3) surface only at pH 7. However, adsorption was disturbed by 50 mM NaCl. These results strongly suggested an electrostatic nature of the adsorption behavior. Though a large-scale adsorption of the lysozyme on Au sensor was pH-insensitive, softness of the adlayer as seen from the dissipation profile was pH-dependent, indicating an interaction of another type. With all the surfaces, the small dissipation change indicated a stiff lysozyme adlayer. Results of this study revealed that the controlled electrostatic interaction between the material surface and lysozyme might be a useful method for imparting antibacterial property to the dental materials.

Bridging interactions of proteins with silica nanoparticles: The influence of pH, ionic strength and protein concentration

“…1a) is surprising in view of earlier studies 4,6,8,9,42,43 which reported that increasing ionic strength is causing a decrease in adsorption of lysozyme on silica surfaces. Tentatively, we attribute the observed insensitivity of the binding characteristics against salt to a compensation of two opposing effects: (a) increasing silanol dissociation due to the added salt; 45,46,49 (b) counter-ions of the salt competing with the protein for the charged surface sites.…”

Action of the Hsp70 chaperone system observed with single proteins

“…The gold adsorption constant for lysozyme was calculated to be between 0.06 and 0.08 (ref. 44), implying that E100-125 ng of lysozyme are enough to cover the entire surface of the gold support (0.5 cm 2 ). This coverage of the surface leaves still enough protein in solution to control for chaperone activity (the effective concentration of lysozyme in solution would then be E18.5 mM).…”

“…The conditions tested were: 1, 5, 10 and 20 mM DnaJ without ATP; 10 mM DnaK in the presence of ATP; 10 mM DnaJ and 0.1 mM DnaK in the presence of ATP; 10 mM DnaJ and 5 mM DnaK in the presence of ATP; 10 mM DnaJ and 10 mM DnaK in the presence of ATP; 10 mM DnaK, 10 mM DnaJ and 20 mM GrpE in the presence of ATP. Refolding experiments at steady state were performed in the presence of 20 mM lysozyme to account for the specificity of the experiments conducted with chaperones and to control for unspecific substratesurface interactions as lysozyme readily adsorbs to gold 43,44 . The gold adsorption constant for lysozyme was calculated to be between 0.06 and 0.08 (ref.…”

Adsorption study of pellicle proteins to gold, silica and titanium by quartz crystal microbalance method

“…It is suggested that less adsorption of mucin to Ti and SiO2 sensors was mainly due to the electrostatic repulsion because mucin, Ti and SiO 2 were negatively charged. Some researches pointed out that difference of pH value contributed the adhesion of proteins to materials 10,31) . The influence of pH for the adhesion of pellicle proteins to dental materials should be further investigated.…”

“…When molecules bind to the oscillating quartz crystal, the oscillating frequency decreases in relation to the amount of protein bound to the crystal surface. The amount of protein adsorbed onto the biomaterial can be estimated by the Sauerbrey equation 9) There have been several reports on QCM monitoring for protein adsorption to titanium [10][11][12] . Photocatalytic decomposition of the pellicle on anatase surfaces was also investigated using the QCM method 13) ; however, most QCM studies of protein adsorption were carried out using 5 MHz AT-cut crystals.…”