Tuning the pore structure of supercritical CO2 foamed PCL scaffolds by a novel mould micro-patterning approach

LEONARDI, AGUSTINA.A,*; SALERNO, AURELIOB ; DI MAIO, ERNESTOC ; PEDRAM, PARISAB,C; FANOVICH, ALEJANDRAA ; NETTI, PAOLO ANTONIOB,

Campinhas

Congreso; Iberoamerican Conference of Supercritical Fluids; 2019

PROSCIBA

In the area of tissue engineering, the fabrication of an optimized polymeric scaffold is affected by different factors as nature of polymer, solvent used, temperature, etc. Many strategies have been reported for producing ?ideal? scaffolds, however, some challenges persist when the support is evaluated in in vivo and in vitro assays. A common problem encountered when using synthetic scaffolds is the rapid formation of tissue on the outer edge, which leads to the development of a necrotic core due to the limitations of cell penetration and nutrient exchange. To address this issue, one of the most useful approachis the fabrication of open porous scaffolds with a pre-defined network of aligned channels.In this work, a new method of addressing this issue is proposed, that consist on the combination of supercritical CO2 foaming and mould micro-patterning approaches. In particular, we fabricated specifically designed polytetrafluoroethylene moulds, characterized by ordered arrays of vertical pillars with different diameter and spatial distribution by micromilling technique and these moulds were used as templating platform for foamed polycaprolactone (PCL) scaffolds. A mould without pillars was usedas reference. The moulds were filled with 250 µL of solution of 25% w/v of PCL in dimethyl carbonate. After that, it was left overnight at 80ºC to evaporate solvent, leaving a polymeric film on the bottom of the vessel. Then, the foaming process was carried out in a high pressure vessel by varying the saturation temperature, in the 32-40ºC range and saturation pressure, equal to 10 and 15 MPa. Foaming was induced by quenching the pressure to the ambient pressure by selecting different times, namely 1, 4 and 500s.Scaffolds were characterized to assess their morphology, porosity, mechanical properties and biocompatibility by means of Scanning Electronic Microscopy, Micro-Computed Tomography, displacement method and in vitro cell culture tests. The obtained scaffolds presented an average porosity of 87%, while the the Young modulus increased from 2 to 4.93MPa for the micro-patterned scaffolds. The in vitro tests evidenced that scaffolds were biocompatible and allowed cells adhesion and proliferation.