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) aerogels containing amoxicillin 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.