Quantitative Single Molecule Measurements on the Interaction Forces of Poly(l-glutamic acid) with Calcite Crystals

Abstract

The interaction between poly(L-glutamic acid) (PLE) and calcite crystals was studied with AFM-based single molecule force spectroscopy. Block copolymers of poly(ethylene oxide) (PEO) and PLE were synthesized and covalently attached to the tip of an AFM cantilever. In desorption measurements the molecules were allowed to adsorb on the calcite crystal faces and afterward successively desorbed. The corresponding desorption forces were detected with high precision, showing for example a force transition between the two blocks. Because of its importance in the crystallization process in biominerals, the PLE-calcite interaction was investigated as a function of the pH as well as the calcium concentration of the aqueous solution. The sensitivity of the technique was underlined by resolving different interaction forces for calcite (104) and calcite (100).

Formation of shaped barium sulfate-dye hybrids: waste dye utilization for eco-friendly treatment of wastewater

“…Unlike the other inorganic skeletons (Yang et al 2006;Yu and Yoshimura 2000), e.g., calcium carbonate Sonnenberg et al 2007;Kulak et al 2007), barium sulfate was rarely selected in mineralization reactions (Nagaraja et al 2009;Yu et al 2003). However, it is more suitable for use in wastewater treatment owing to its water insoluble and acid-resistant.…”

Supramolecular Chemistry and Mechanochemistry of Macromolecules: Recent Advances by Single-Molecule Force Spectroscopy

“…However, it could be seen that the middle part of the force curve in water at 35 C was even lower than that in organic solvents, which could be explained by two factors. First, water was a poor solvent for PNIPAM at 35 C, and the amount of bound water around the PNIPAM chain was considerably reduced in this condition compared to the case at RT [85][86][87]. Thus, compared to the case in water at RT, the energy needed for the water rearrangement upon stretching PNIPAM chain was greatly reduced in water at 35 C. This factor may roughly correspond to the energy difference between water at RT and organic solvents.…”

“…That is, the entropies of the final state are the same (S % 0) in the two conditions. However, it is known that the conformation of PNIPAM in water at 35 C is much more compact than that in water at RT, i.e., the initial entropy of PNIPAM at 35 C is much less than that at RT. Thus, the energy cost of a compact conformation would be less than that of a coil conformation.…”

“…The other strategy to form a macromolecular bridge between the tip and the substrate is to bind the molecule to the surfaces covalently. The terminal groups of the target molecule and the tip (and/or the substrate) are modified with chemically reactive groups, which can form a bond (covalent, coordination, or other intermolecular interactions with similar strength) upon contact at room temperature [33][34][35]. For both strategies, the interaction between the tip and the target molecule should be stronger than the non-covalent interactions to be measured.…”

“…Thus, the deviation between the force curves obtained at T > 35 and 35 C was mainly contributed by the intrachain H-bonds of PNIPAM. This change of single-chain mechanics from 35 C to 40 C can be used to realize the thermalmechanical energy conversion at the single-molecule level. That is, the single PNIPAM chain can convert the thermal energy to mechanical work in the range of [35][36][37][38][39][40] C (see Fig.…”