How Surface Properties of Silica Nanoparticles Influence Structural, Microstructural and Biological Properties of Polymer Nanocomposites

Abstract

The aim of this work was to study effect of the type of silica nanoparticles on the properties of nanocomposites for application in the guided bone regeneration (GBR). Two types of nanometric silica particles with different size, morphology and specific surface area (SSA) i.e., high specific surface silica (hss-SiO2) and low specific surface silica (lss-SiO2), were used as nano-fillers for a resorbable polymer matrix: poly(L-lactide-co-D,L-lactide), called PLDLA. It was shown that higher surface specific area and morphology (including pore size distribution) recorded for hss-SiO2 influences chemical activity of the nanoparticle; in addition, hydroxyl groups appeared on the surface. The nanoparticle with 10 times lower specific surface area (lss-SiO2) characterized lower chemical action. In addition, a lack of hydroxyl groups on the surface obstructed apatite nucleation (reduced zeta potential in comparison to hss-SiO2), where an apatite layer appeared already after 48 h of incubation in the simulated body fluid (SBF), and no significant changes in crystallinity of PLDLA/lss-SiO2 nanocomposite material in comparison to neat PLDLA foil were observed. The presence and type of inorganic particles in the PLDLA matrix influenced various physicochemical properties such as the wettability, and the roughness parameter note for PLDLA/lss-SiO2 increased. The results of biological investigation show that the bioactive nanocomposites with hss-SiO2 may stimulate osteoblast and fibroblast cells’proliferation and secretion of collagen type I. Additionally, both nanocomposites with the nanometric silica inducted differentiation of mesenchymal cells into osteoblasts at a proliferation stage in in vitro conditions. A higher concentration of alkaline phosphatase (ALP) was observed on the material modified with hss-SiO2 silica.

Silica Replicas Derived from Mammalian Cells as an Innovative Approach to Physically Direct Cell Lineage Decisions of Mesenchymal Stem Cells

“…The observed higher gene upregulation when the silica replicas were used to induce the osteogenic differentiation as compared to the chondrogenic differentiation of MSCs, can be attributed to both the mechanical and osteoinductive properties of silica which can further influence cell differentiation to an osteogenic lineage. 39 A very slight, although statistically significant, upregulation of the RUNX2 marker was observed for the silica-based substrates (i.e., smooth SiO 2 , SiO 2 -MSs, and HCs@SiO 2 replicas) as compared to the glass coverslips when the growth medium was used. However, since there were no marked differences among the different silica-containing substrates, we attribute these osteogenic properties to the material and not to the topography of the substrates.…”

“…Enhanced upregulation for the SOX9, COL2A1, and ACAN was observed only when the HCs@SiO 2 -based substrates were used in combination with chondrogenic media. The observed higher gene upregulation when the silica replicas were used to induce the osteogenic differentiation as compared to the chondrogenic differentiation of MSCs, can be attributed to both the mechanical and osteoinductive properties of silica which can further influence cell differentiation to an osteogenic lineage . A very slight, although statistically significant, upregulation of the RUNX2 marker was observed for the silica-based substrates (i.e., smooth SiO 2 , SiO 2 -MSs, and HCs@SiO 2 replicas) as compared to the glass coverslips when the growth medium was used.…”

“…Hence, we hypothesize that these silica replicas may find applications for in vitro cell culture vessels to reduce the use of growth factors, thus minimizing the costs and risks of side effects. Furthermore, due to the mechanical properties and osteoinductive properties of silica, the as-prepared replicas could be embedded within scaffolds for bone tissue engineering applications …”

Silicate Clay-Hydrogel Nanoscale Composites for Sustained Delivery of Small Molecules

“…We investigated three nanosilicate clays, namely LAP, MMT, and HNT, which had different shape, size, and crystallographic structure (Figure ). Those were chosen because they have previously been shown to be noncytotoxic − and because the nanoclay shape and structure were expected to affect small molecule adsorption/desorption and subsequent release from nanocomposite hydrogels . The nanoclays used here were purchased directly from suppliers to ensure minimal impurities, which could otherwise affect small molecule adsorption and release kinetics.…”

Low-cost pathways to synthesize silica-smectite clay-based composites

“…They are of great interest as their fabrication can be easily designed according to specific applications. Their electrical, optical, thermal, conductive, medical, dielectric, mechanical or surface properties can be then targeted [3][4][5][6][7][8][9][10] Nowadays, composites based on smectite clays are subjected to more attention due to their very large specific surface that is highly reactive.…”