posted on 2021-04-01, 10:23authored byXiaoning Sun, Fang Cheng, Wei He
Herein, the applicability of an unconventional, non-vinylic type
of amine-epoxide microgels (MGs) to promote silica deposition from
tetraethyl orthosilicate (TEOS) was investigated. Simply mixing MGs
with TEOS in water at 25 °C resulted in the formation of hybrid
silica-MG particles (sMGs) as a function of silicification time. The
sMGs were cationic with thermal-sensitive swelling capability. Extending
silicification time to 24 h was shown to increase silica content to
43%. Besides, the sMGs became structurally more rigid to resist drying-induced
deformation and exhibited a rugged surface texture. Mechanistically,
the aminated nature of the MGs was proved beneficial for the success
of their silicification, fulfilling dual functions of the catalyst
for TEOS hydrolysis and template for silica deposition. Through electrostatic
adsorption, the sMGs provided a facile yet robust option for surface
modifications toward bone-related applications. Surface-induced mineralization
in simulated biological fluids was observed with sMG-immobilized surfaces,
where the presence of hydroxyapatite was characterized in the deposited
apatite. In vitro MC3T3-E1 pre-osteoblast cell studies showed that
cell adhesion, morphology, and proliferation could be influenced by
both sMG types and their adsorption density. Of particular interest
is the finding of cells exhibiting elongated and greatly polarized
morphology on the surface with high adsorption density of sMGs of
43% silica. It was postulated that the rugged appearance of such sMGs
could have presented a hierarchically structured surface toward cells,
an interesting aspect to be further exploited for the engineering
of cell–surface interactions.