Influence of Model Globular Proteins with Different Isoelectric Points on the Precipitation of Calcium Carbonate

Abstract

Several mechanisms have been proposed to explain the interactions between proteins and mineral surfaces formed during biomineralization. To investigate the effect of the surface charge of proteins on calcium carbonate precipitation, a group of globular proteins with similar sizes and molecular weights but with different isoelectric points (iep) has been selected to be added to a CaCl2 solution in free-drift calcium carbonate precipitation experiments. These proteins are lysozyme (Lyz; theoretical iep 9.32), ribonuclease-A (Rib-A; theoretical iep 8.64), myoglobin (Myo; theoretical iep 7.36), and α-lactalbumin (α-La; theoretical iep 4.83). Depending on their isoelectric point and their concentration in the solution, these proteins affected the nucleation, growth, polymorphism and growth morphology of calcium carbonate in different manners, evidencing different types of protein−surface interactions. For the protein with an acidic isoelectric point (α-La), electrostatic interactions were predominant. For proteins with isoelectric points around neutrality or slightly higher (Myo and Rib-A), the foremost interactions were hydrophobic with a certain electrostatic contribution. For the protein with a basic isoelectric point (Lyz), there was not any notable effect on most of the analyzed precipitation properties, evidencing a weaker protein−surface interaction.

Reversed Crystal Growth of Calcite in Naturally Occurring Travertine Crust

“…During the preparation process, these structure directing agents may play the role of a template and a surfactant. A careful selection of the structure directing agent is necessary as their ability to selectively adsorb onto a preferred surface allows many factors such as the polymorphic phase, the nucleation, alignment of crystallites, and also the morphology to be stringently controlled [31][32][33]. Similar hierarchical microstructures have been described for biogenic calcite, where organic macromolecules and inorganic mineral form a hybrid structure over many length scales [34,35].…”

PMA‐b‐PAA‐controlled synthesis of one‐dimensional CaCO3 superstructures

“…Over the past decade, the general morphological control of CaCO 3 crystals using numerous organic additives has become a focus of recent interest, such as surfactants [7], polymers [8,9] and biomolecules [10,11]. Particularly, the double-hydrophilic block copolymers (DHBCs) as functional polymers have been selected to mediate CaCO 3 morphologies through specific interactions between the growing crystals and the copolymers [12].…”

Evolving application of biomimetic nanostructured hydroxyapatite

“…146,147 The interaction between proteins and hydroxyapatite surfaces plays an important role in many applications, namely medicine, pharmacy, nanodevices, biosensors, and bioengineering. 148 In particular, in the biomaterials field, its study is fundamental to learn more about the biomineralization process in vivo, 149 to test the material performance in biological environment, 150 or to check its ability as inorganic carrier for biomolecules. 151,152 Although protein adsorption on solid surfaces has been widely studied for decades, its mechanisms are still far from being fully understood.…”