Polylactide, Processed by a Foaming Method Using Compressed Freon R134a, for Tissue Engineering

Fabricating polymeric scaffolds using cost-effective manufacturing processes is still challenging. Gas foaming techniques using supercritical carbon dioxide (scCO2) have attracted attention for producing synthetic polymer matrices; however, the high-pressure requirements are often a technological barrier for its widespread use. Compressed 1,1,1,2-tetrafluoroethane, known as Freon R134a, offers advantages over CO2 in manufacturing processes in terms of lower pressure and temperature conditions and the use of low-cost equipment. Here, we report for the first time the use of Freon R134a for generating porous polymer matrices, specifically polylactide (PLA). PLA scaffolds processed with Freon R134a exhibited larger pore sizes, and total porosity, and appropriate mechanical properties compared with those achieved by scCO2 processing. PLGA scaffolds processed with Freon R134a were highly porous and showed a relatively fragile structure. Human mesenchymal stem cells (MSCs) attached to PLA scaffolds processed with Freon R134a, and their metabolic activity increased during culturing. In addition, MSCs displayed spread morphology on the PLA scaffolds processed with Freon R134a, with a well-organized actin cytoskeleton and a dense matrix of fibronectin fibrils. Functionalization of Freon R134a-processed PLA scaffolds with protein nanoparticles, used as bioactive factors, enhanced the scaffolds’ cytocompatibility. These findings indicate that gas foaming using compressed Freon R134a could represent a cost-effective and environmentally friendly fabrication technology to produce polymeric scaffolds for tissue engineering approaches.

Chondroitin Sulphate and Gas Foaming Concurrently Improve Articular Cartilage Regeneration in Electrospun Poly(L-lactide-co-ε-caprolactone)/Silk Fibroin Based Scaffolds

Degenerated cartilage tissues remain a burgeoning issue to be tackled, while bioactive engineering products available for optimal cartilage regeneration are scarce. In the present study, two-dimensional (2DS) poly(L-lactide-co-ε-caprolactone)/silk fibroin (PLCL/SF)-based scaffolds were fabricated by conjugate electrospinning method, and then cross-linked with chondroitin sulfate (CS) to further enhance their mechanical and biological performance. Afterwards, three-dimensional PLCL/SF scaffolds (3DS) and CS-crosslinked three-dimensional scaffolds (3DCSS) with tailored size were successfully fabricated by in situ gas foaming in a confined mold and subsequently freeze-dried. Gas-foamed scaffolds exhibited high porosity, rapid water absorption, and stable mechanical properties. While all of the scaffolds exhibited excellent cytocompatibility in vitro; 3DCSS showed better cell seeding efficiency and chondro-protective effect as compared to the other scaffolds. Histological analysis of chondrocytes-seeded constructs after cultivation for up to 6 weeks in vitro also confirmed that 3DCSS scaffolds supported the formation of cartilage-like tissues along with the more secretion of cartilage-specific extracellular matrix than that of the other groups. The reparative potential of 3DCSS was further evaluated in an articular cartilage defect model in rabbits, which exhibited a well-integrated boundary and attenuated inflammation demonstrating less expression of pro-inflammatory cytokines, such as interleukin (IL)-1β and tumor necrosis factor (TNF)-α. Taken together, the engineered biomimetic 3DCSS may provide a well-suited therapeutic option for cartilage tissue regeneration applications.

Design of Monolithic Closed-Cell Polymer Foams via Controlled Gas-Foaming for High-Performance Solar-Driven Interfacial Evaporation

Solar-driven interfacial evaporation has emerged as an innovative and sustainable technology for clean water production. Rational fabrication of monolithic three-dimensional (3D) steam generators has accordingly become a topic of growing...

Isolated single iron atoms anchored on a N, S-codoped hierarchically ordered porous carbon framework for highly efficient oxygen reduction

An in situ gas-foaming strategy was presented to prepare atomic Fe anchored on N, S-codoped hierarchically ordered porous carbon (HOPC) framework. The HOPC and FeN4S2 catalytic centers make it exhibit superb ORR and Zn–air battery properties.