Supercritical CO2-assisted impregnation of cellulose microparticles with R-carvone: Effect of process variables on impregnation yield

In this work, the supercritical CO2-assisted impregnation of microcrystalline cellulose (MCC) particles with R-(-)-carvone, an antimicrobial monoterpene, was investigated. The effect of CO2 density (278-600 kg m(-3)), temperature (40-60 degrees C), carvone:MCC mass ratio (0.5-1.0), and depressurization mode (cold-hot), on the impregnation yield was studied. Carvone loadings were obtained in the range of 0.6-3.6 wt%, and the addition of ethanol (2 wt%) as cosolvent enhanced the impregnation yield up to 10 wt%. The high crystallinity of cellulose (81-84%) remained unchanged after the supercritical process, although SEM analysis showed a partial separation of fiber agglomerates. Carvone release in simulated saliva solution from particles impregnated using cosolvent was slightly slower than from the pure CO2-impregnated particles. The observed release profile could be useful for pharmaceutical and biomedical applications, such as the prevention of oral cavity infections or their treatment at early stages.