Al. Oliveira et al., Surface modification tailors the characteristics of biomimetic coatings nucleated on starch-based polymers, J MAT S-M M, 10(12), 1999, pp. 827-835
Citations number
24
Categorie Soggetti
Multidisciplinary
Journal title
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE
This work describes the influence of surface pretreatments over the nucleat
ion and growth of an apatite layer, formed by a biomimetic process, on whic
h a bioactive glass is used as a precursor of the calcium-phosphate (Ca-P)
formation on the materials surface. SEVA-C, a corn starch-based biodegradab
le blend, was used as substrate. The surfaces were pretreated during variou
s periods by: (i) physical methods, namely ultraviolet radiation (u.v.), an
d over exposure to ethylene oxide sterilization (EtO); and (ii) chemical me
thods, namely potassium hydroxide (KOH) and acetic anhydride (CH3CO)(2) etc
hings. The surface modifications, performed before the production of the bi
omimetic coatings, resulted in a faster formation of Ca-P nuclei during the
first stages of SBF immersion, particularly in the case of the KOH etching
. In this case, it was possible to observe a decrease in the average surfac
e roughness, as measured by laser profilometry, and an increase of the hydr
ophilicity of the material, which was evident from a clear increment in the
water-uptake ability and quantified by contact angle measurements. With th
is treatment it was possible not only to reduce the induction period for th
e formation of a well defined and dense apatite-like layer, as observed by
scanning electron microscopy (SEM), but also to improve the adhesion of the
Ca-P layer to the substrate, as confirmed by the adhesion strength tests.
For all the studied pre-treatments, the composition of the films, analyzed
by energy dispersive spectroscopy (EDS) and identified by thin-film X-ray d
iffraction (TF-XRD), seems to be very similar to that of human bone apatite
s. (C) 1999 Kluwer Academic Publishers.