Biomedical Engineering Reference
In-Depth Information
Fig. 7
Release profiles for CBC samples loaded with quercetin (
N
) and thymol (
)at20MPa
and 323 K for 3 h and soaked into an ethanolic solution at 2 mg/mL for 3 h (
M
)
The release profiles of CBC membranes, simultaneously impregnated with
quercetin and thymol, at 20 MPa/313 K is shown in Fig.
7
. The results show a
more sustained release profile for quercetin that the authors justified due to its
higher molecular volume, lower solubility in water and also, and most important,
due to specific interactions between the -OH groups of the molecule with -
NH(CH
2
)
4
COOH groups from CBC and still some unmodified -NH
2
groups (from
chitosan) and -NHCOCH
3
groups (from chitin) [
45
,
87
,
99
,
100
]. The lower
molecular volume of thymol together with its higher aqueous solubility justifies
its faster release. Fig.
7
also presents the release profile for a CBC sample soaked
into an ethanolic solution of quercetin at 2 mg/mL (maximum solubility at room
temperature) for 3 h. It is clear that the SSI process significantly enhances the
amount of quercetin that can be loaded into the polymeric matrix (almost duplicates
its value) also avoiding the ethanol evaporation step. This improvement in quercetin
loading, releasing and consequently on its bioavailability is most probably due to
quercetin particle sizes reduction during SSI processing what was confirmed by
SEM analysis [
45
].
Finally, the antioxidant capacity of the CBC membrane loaded with quercetin
and thymol at 20 MPa/323 K was tested using a method based on the coupled
oxidation of
“
-carotene/linolenic acid system [
101
] optimized by Braga et al. [
102
].
This colorimetric based method consists in evaluating the capacity of a potential
