Synthesis, characterization, bioactivity and biocompatibility of nanostructured materials based on the wollastonite-poly(ethylmethacrylate-co-vinylpyrrolidone) system
Composite materials are very promising biomaterials
for hard tissue augmentation. The approach assayed
in this work involves the manufacturing of a composite
made of a bioactive ceramic, natural wollastonite (W) and a
nanostructured copolymer of ethylmethacrylate (EMA) and
vinylpyrrolidone (VP) to yield a bioresorbable and biocompatible
VP–EMA copolymer. A bulk polymerization was
induced thermally at 508C, using 1 wt % azobis(isobutyronitrile)
(AIBN) as free-radical initiator. Structural characterization,
compressive strength, flexural strength (FS), degradation,
bioactivity, and biocompatibility were evaluated in
specimens with a 60/40 VP/EMA ratio and ceramic content
in the range 0–60%. A good integration between phases
was achieved. Greater compression and FS, in comparison
with the pure copolymer specimens was obtained only
when the ceramic load got up to 60% of the total weight.
The soaking in NaCl solution resulted in the initial swelling
of the specimens tested. The maximum swelling was
reached after 2–3 h of immersion and it was significantly
greater for lower ceramic loads. This result makes the polymer
component the main responsible for the interactions
with the media. After soaking in SBF, microdomains segregation
can be observed in the polymer component that can
be related with a dramatic difference in the reactivity of
both monomers in free radical polymerization, whereas the
formation of an apatite-like layer on the W surfaces can be
observed. Biocompatibility in vitro studies showed the absence
of cytotoxicity of all formulations. The cells were able
to adhere on the polystyrene negative control and on specimens
containing 60 wt % wollastonite forming a monolayer
and showing a normal morphology. However, a low cellular
growth was observed. 2008 Wiley Periodicals, Inc.
J Biomed Mater Res 88A: 53–64, 2009Peer reviewe
