Supercritical carbon dioxide assisted impregnation of eugenol into polyamide fibers for application as a dental floss

Abstract

Supercritical CO2-assisted impregnation was applied to incorporate eugenol into polyamide fibers in order to develop a solvent-free material with antimicrobial properties to be potentially applied as dental floss. Impregnation runs were carried out in a high-pressure cell at 60 °C during 2 h, and the effect of pressure (8-12 MPa) and depressurization rate (0.5 and 5 MPa min-1) on impregnation loading was evaluated. Loading values of 8-15% (w/w) were obtained, achieving higher values at low depressurization rate. Mechanical properties were investigated, observing a decrease of Young modulus as well as an enhancement of tensile strength as a consequence of high-pressure treatment. Eugenol release kinetics from impregnated floss to the air and in artificial saliva was experimentally studied under atmospheric conditions. Two empirical equations (one-site and two-site desorption model) and a diffusion model based in the second Fick's law were applied to correlate the release profiles, with a good agreement. Fiber morphology was investigated by optical and scanning electron microscopy (SEM). Finally, the antimicrobial activity of impregnated floss samples against Escherichia coli and Staphylococcus aureus using a dynamic contact conditions test was investigated, achieving an inhibition higher than 99.99% and a log-reduction of 4.04-4.14.