Figure 2 . Water contact angles of cellulose acetate nanofiber
(CA) (a) and cellulose acetate nanofiber impregnated with annatto
extract (CA@A) (b).
As Figure 2 shows, both nanofiber types were hydrophilic, with contact
angles below 90°. The contact angle for the CA nanofiber was
approximately 77±3°, while adding annatto to the CA decreased the
contact angle to 50±3. This effect can be attributed to the hydrophilic
nature of annatto molecules such as norbixin. A more hydrophilic
nanofiber surface is ideal for supporting cell attachment. According to
Menzies et al. [37], the hydrophilicity of a material directly
corresponds to its capacity for cell adhesion. Improved wettability
(evidenced by low contact angle values in water tests) results in
improved biocompatibility for the analyzed material.