Electrospun ZnO/poly(vinylidene fluoride-trifluoroethylene) scaffolds for lung tissue engineering

Due to the morbidity and lethality of pulmonary diseases, new biomaterials and scaffolds are needed to support the regeneration of lung tissues, while ideally providing protective effects against inflammation and microbial aggression. In this study, we investigated the potential of nanocomposites of poly(vinylidene fluoride-co-trifluoroethylene) [P(VDF-TrFE)] incorporating zinc oxide (ZnO), in the form of electrospun fiber meshes for lung tissue engineering. We focused on their anti-inflammatory, antimicrobial and mechano-electrical character according to different fiber mesh textures (i.e., collected at 500 rpm and 4000 rpm) and compositions: (0/100) and (20/80) w/w% ZnO/P(VDF-TrFE), plain and composite, respectively. The scaffolds were characterized in terms of morphological, physico-chemical, mechanical and piezoelectric properties, as well as biological response of A549 alveolar epithelial cells in presence of lung infecting bacteria. By virtue of ZnO, the composite scaffolds showed a strong anti-inflammatory response in A549 cells, as demonstrated by a significant decrease of interleukin (IL) IL-1α, IL-6 and IL-8 expression in 6 h. In all the scaffold types, but remarkedly in the aligned composite ones, transforming growth factor β (TGF-β) and the antimicrobial peptide human β defensin 2 (HBD-2) were significantly increased. The ZnO/P(VDF-TrFE) electrospun fiber meshes hindered the biofilm formation by S. aureus and P. aeruginosa and the cell/scaffold constructs were able to impede S. aureus adhesion and S. aureus and P. aeruginosa invasiveness, independently of the scaffold type. The data obtained suggested that the composite scaffolds showed potential for tunable mechanical properties, in the range of alveolar walls and fibers. Finally, we also showed good piezoelectricity, which is a feature found in elastic and collagen fibers, the main extracellular matrix molecules in lungs. The combination of all these properties make ZnO/P(VDF-TrFE) fiber meshes promising for lung repair and regeneration

Adsorption of emerging contaminants by graphene related materials and their alginate composite hydrogels

Graphene nanosheets and nanoplatelets -alginate composite hydrogels were prepared by ionic gelation and the resulting gel beads were exploited for the removal of a mixture of eight selected emerging contaminants (ECs) in tap water, including bisphenol A, ofloxacin and diclofenac. The role of graphene related materials (GRM) on the gel bead structure, adsorption selectivity, kinetic, mechanism, and efficiency was investigated. Combined Scanning Electron Microscopy (SEM) and confocal Raman microscopy mapping showed a porous structure with pore size in the range of 100–200 \ub5m and a homogeneous distribution of graphene nanosheets or nanoplatelets at the pores surface. The adsorption kinetic of GRM was much faster than that of granular activated carbon (GAC), the industrial sorbent benchmark, with removal capacity of ofloxacin from 2.9 to 4.3 times higher. A maximum adsorption capacity of 178 mg/g for rhodamine B was estimated by adsorption isotherm studies for reduced graphene oxide-based beads (a value comparable to that of powered activated carbon). Regeneration test performed on saturated beads by washing with EtOH, and subsequent reiterated reuses, showed no loss of adsorption performance up to the fourth reuse cycle