Influence of Biomacromolecules on Calcium Phosphate Formation on TiO2 Nanomaterials

Abstract

Calcium phosphates (CaP) composites with biomacromolecules and/or nanomaterials have recently emerged as a potential solution to improve the poor mechanical properties and biological response of CaP. Among the methods available for preparation of such composites, precipitation at low temperatures attracts special interest as it allows preservation of the activity of biomacromolecules. However, precipitation of CaP in the presence of two additives is a complex process that needs to be studied in detail to rationalize composite preparation. This study aimed to investigate co-precipitation of CaP on different TiO2 nanomaterials (TiNMs), including nanoparticles (TiNPs), nanoplates (TiNPls), nanotubes (TiNTs), and nanowires (TiNWs), in the presence of bovine serum albumin (BSA) and chitosan (Chi). The obtained results have shown that both BSA and Chi inhibited transformation of amorphous to crystalline CaP, even in the presence of TiNMs at concentrations that promoted transformation. Chi proved to be a stronger inhibitor due to its more flexible structure. The presence of BSA and Chi did not influence the composition of the CaP formed as calcium-deficient hydroxyapatite (CaDHA) was formed in all the systems. However, both macromolecules influenced the morphology of the formed CaDHA in different ways depending on the type of TiNM used. BSA and Chi adsorbed on all the TiNMs, as confirmed by zeta potential measurements, but this adsorption reduced the amount of CaP formed on TiNMs only in the case of TiNWs. The obtained results contribute to the understanding of the influence of BSA and Chi on CaP precipitation in the presence of nanomaterials and thus to the rational design of CaP-based multi-composite materials.

Comparison of bovine serum albumin and chitosan effects on calcium phosphate formation in the presence of silver nanoparticles

“…5 and SI 10 †). This change in morphology is consistent with previous studies showing the inuence of BSA 21,75 and Chi 21,76,77 on the morphology of different CaP phases.…”

“…This is consistent with the previously observed effect of polyelectrolytes and proteins on ACP transformation. 39,53 As has been shown before, 21 Chi acted as a stronger inhibitor compared to BSA, as its inhibitory effect was observed at much lower concentrations (Table 2).…”

“…To the best of our knowledge, the only literature data on the inuence of BSA and Chi on the rate of ACP transformation come from our previous study, 21 in which similar trends were observed. It is worth noting that in this study we used precipitation systems with the same calcium and phosphate ion concentrations as previously, but in 10 fold larger reaction volume.…”

“…Precipitation systems were prepared by rapidly mixing 200 cm 3 of anionic and cationic reactant solutions, resulting in initial reactant concentrations c(CaCl 2 ) = c(Na 2 HPO 4 ) = 4 × 10 −3 mol dm −3 , and g (AgNPs) = 10 mg dm −3 , g (BSA) = 25-100 mg dm −3 , g (Chi) = 5-25 mg dm −3 , at pH = 7.4. The concentrations of the biomacromolecules were chosen based on our previous research, 21 which showed that inhibition of CaPs formation occurs at higher concentrations. Precipitation experiments were performed in a double-walled vessel at 25 ± 0.1 °C without additional stirring.…”

“…77 In our previous work, no change in the precipitate composition, which consisted only of CaDHA, was observed in the presence of either biomacromolecules. 21 Different effects were observed in the PXRD patterns when AgNPs were added to the precipitation system. In the presence of AOT-AgNPs and PVP-AgNPs, a decreased intensity of the most prominent OCP peaks was observed.…”