Synthesis and Characterization of Calcium Silicate Nanoparticles Stabilized with Amino Acids

Abstract

This work presents the development of a method for the synthesis of calcium silicate nanoparticles stabilized with essential amino acids. CaSiO3 nanoparticles were obtained through chemical precipitation. In the first stage, the optimal calcium-containing precursor was determined. The samples were examined using scanning electron microscopy. It was found that Ca(CH3COO)2 was the optimal calcium-containing precursor. Then, the phase composition of calcium silicate was studied using X-ray phase analysis. The results showed the presence of high-intensity bands in the diffractogram, which characterized the phase of the nanosized CaSiO3—wollastonite. In the next stage, the influence of the type of amino acid on the microstructure of calcium silicate was studied. The amnio acids studied were valine, L-leucine, L-isoleucine, L-methionine, L-threonine, L-lysine, L-phenylalanine, and L-tryptophan. The analysis of the SEM micrographs showed that the addition of amino acids did not significantly affect the morphology of the CaSiO3 samples. The surface of the CaSiO3 samples, both without a stabilizer and with amino acids, was represented by irregularly shaped aggregates consisting of nanoparticles with a diameter of 50–400 nm. Further, in order to determine the optimal amino acid to use to stabilize nanoparticles, computerized quantum chemical modeling was carried out. Analysis of the data obtained showed that the most energetically favorable interaction was the CaSiO3–L-methionine configuration, where the interaction occurs through the amino group of the amino acid; the energy value of which was −2058.497 kcal/mol. To confirm the simulation results, the samples were examined using IR spectroscopy. An analysis of the results showed that the interaction of calcium silicate with L-methionine occurs via the formation of a bond through the NH3+ group of the amino acid.

Composite Powders Synthesized from the Water Solutions of Sodium Silicate and Different Calcium Salts (Nitrate, Chloride, and Acetate)

“…According to the SEM images presented in Figure 4, all synthesized powders consisted of nanosized particles with morphology close to isometric form and with dimensions of 10-50 nm in all synthesized powders Ca_N, Ca_Cl, and Ca_Ac. These data on the microstructure of powders and particle dimensions differ slightly from the data on powders, in particular, those synthesized from calcium nitrate presented in the article [40]. As it was noticed before, the quantity of the same by-product captured by the synthesized powder can give some base for the estimation of the specified surface area and the dimension of particles [33].…”

“…The quantity of captured by-product in the Ca_Ac powder was relatively lower for this reason. differ slightly from the data on powders, in particular, those synthesized from calcium nitrate presented in the article [40]. As it was noticed before, the quantity of the same byproduct captured by the synthesized powder can give some base for the estimation of the specified surface area and the dimension of particles [33].…”

“…The powders of hydrated calcium silicate consisting of fine particles were synthesized via precipitation from aqua solutions of sodium silicate Na 2 SiO 3 and different calcium salts including nitrate Ca(NO 3 ) 2 , chloride CaCl 2 , and acetate Ca(CH 3 COO) 2 [40]. Synthesis from solutions of sodium silicate Na 2 SiO 3 and acetate Ca(CH 3 COO) 2 was also made in the presence of amino acids [40]. From the listed examples, one can see that CaO, CaCO 3 , Ca(NO 3 ) 2 , CaCl 2 , and Ca(CH 3 COO) 2 can be used as a precursors of Ca 2+ in the syntheses of hydrated calcium silicates.…”