Dexamethasone delivery of porous PEG-PCL-PEG scaffolds with supercritical carbon dioxide gas foaming

Abstract

Triblock copolymers of PEG-PCL-PEG (PEGCL) were fabricated using ring opening polymerization (ROP) of ϵ-caprolactone. 1H NMR and FTIR spectra of the PEGCL triblock were used to confirm the structure and determine the molecular weight. The peaks from –OCH3 and –CH2CH2O- in PEG blocks and –(CH2)3–, –COCH2-, and –CH2OCO- within PCL blocks were determined. PEGCL powder was mixed with dexamethasone (DXMT) and then compressed applying a hydraulic pressure of 9 × 10 −2 MPa, which resulted in the formation of disc-like tablets. Following that, the scaffolds with tablet shape were placed into the scCO2 gas foaming apparatus. Central composite design (CCD) was used to obtain the maximum porosity % with the scCO2 variables of soaking time (ts), pressure (P), temperature (T), and time required to depressurize (td). At the maximum porosity % (79.18%), P, T, Ts, and Td were 234 bar, 49 °C, 2.0 h, and 5 min, respectively. Cumulative in-vitro drug release assay revealed that at post-scCO2 treatment, the scaffolds delivered an almost complete release (79.18 ± 1.39%) while at pre-scCO2 treatment, release percentage was 41.07 ± 1.72% after 30 days. This confirmed suitable release time and properties for controlled delivery of the dexamethasone loaded in PEG-PCL-PEG (PEGCL) triblock copolymer-based scaffolds. So, using the scCO2 gas foaming method provides the possibility to construct morphologically and structurally adjustable porous PEG-PCL-PEG scaffolds.