Micro-porous PLGA/β-TCP/TPU scaffolds prepared by solvent-based 3D printing for bone tissue engineering purposes

The 3D printing process of fused deposition modelling is an attractive fabrication approach to create tissue-engineered bone substitutes to regenerate large mandibular bone defects,but often lacks desired surface porosity for enhanced protein adsorption and cell adhesion.Solvent-based printing leads to the spontaneous formation of micropores on the scaffold’s surface upon solvent removal,without the need for further post processing.Our aim is to create and characterize porous scaffolds using a new formulation composed of mechanically stable poly(lactic-co-glycol acid)and osteoconductiveβ-tricalcium phosphate with and without the addition of elastic thermoplastic polyurethane prepared by solvent-based 3D-printing technique.Large-scale regenerative scaffolds can be 3D-printed with adequate fidelity and show porosity at multiple levels analysed via micro-computer tomography,scanning electron microscopy and N_(2) sorption.Superior mechanical properties compared to a commercially available calcium phosphate ink are demonstrated in compression and screw pull out tests.Biological assessments including cell activity assay and live-dead staining prove the scaffold’s cytocompatibility.Osteoconductive properties are demonstrated by performing an osteogenic differentiation assay with primary human bone marrow mesenchymal stromal cells.We propose a versatile fabrication process to create porous 3D-printed scaffolds with adequate mechanical stability and osteoconductivity,both important characteristics for segmental mandibular bone reconstruction.

Eco-friendly regeneration of end-of-life PVDF membrane with triethyl phosphate:Efficiency and mechanism

Membrane will inevitably reach the end of its lifespan due to the irrecoverable fouling accumulation in membrane bioreactors(MBRs)during long-term operation.Herein,we developed an eco-friendly membrane regeneration strategy with triethyl phosphate(TEP),which successfully prolonged the lifespan of end-of-life(EOL)polyvinylidene fluoride(PVDF)membranes in a large-scale MBR.The regenerated(Rg)membrane exhibited a water permeance of 534.8±45.7 L m^(-2)h^(-1)bar-1,along with stable rejection rate,which was comparable with that of the new membrane.Furthermore,compared to the membrane subjected solely to preliminary cleaning,the Rg membrane presented a more hydrophilic surface due to the combination of preliminary cleaning and solvent-based processing.Besides,the Rg membrane presented less fouling propensity with the critical flux of 15.2 L m^(-2)h^(-1),significantly higher than that of the EOL membrane(4.0 L m^(-2)h^(-1)).Importantly,the membrane regeneration strategy was capable of guaranteeing the effluent quality in MBR systems for treating real municipal wastewater.This study provides an eco-friendly membrane regeneration strategy for effectively removing the irrecoverable foulants,thereby promoting the advancement of sustainable membrane-based wastewater treatment technology.