Supercritical CO2 assisted formation of Poly (vinylidenefluoride) aerogels containing Amoxicillin, used as controlled release device

In this work, a supercritical CO2 (SC-CO2) drying process for the formation of poly(vinylidenefluoride) (PVDF) aerogelscontainingamoxicillin has been tested. Experiments at pressures ranging between 150 and 250 bar and at temperatures ranging between 35 and 55 °C have been performed; then, the PVDF – isopropyl alcohol – N-methylpirrolidone solution at 10% (w/w) polymer has been selected for the addition of amoxicillin at concentrations between 10 and 30% (w/w) with respect to PVDF. Since amoxicillin is soluble in isopropyl alcohol, a quaternary solution has been obtained that produced PVDF aerogels characterized by drug coated nanometric fibers. A two step formation mechanism has been hypothesized that puts in evidence the non-interference of amoxicillin on PVDF gelation process and the heterogeneous amoxicillin precipitation on PVDF nanofibers. The coverage of nanofibers by amoxicillin turned the structure from hydrophobic to quasi-hydrophilic. A homogeneous drug distribution was obtained; a quasi-constant release rate and no burst effect were observed.