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The aim of this work was to create human liver microtissue spheroids metabolically active by using a hollow fiber membrane bioreactor whose design and structural features ensure a uniform microenvironment and adequate oxygenation. Human hepatocyte spheroids with uniform size and shape were formed through self-assembling and cultured into the bioreactor. Adjacent spheroids fused, giving rise to larger microstructures around the fibers forming liver-like tissue, which retained functional features in terms of urea synthesis, albumin production, and diazepam biotransformation up to 25days. The overall data strongly corroborates that within the bioreactor a proper oxygenation and supply of nutrients were provided to the cells ensuring a physiological amount even in the spheroids core. The oxygen uptake rate and the mathematical modelling of the mass transfer directly elucidated that liver microtissue spheroids are not exposed to any oxygen mass transfer limitation. The minimum oxygen concentration reached at the center of multiple spheroids with diameter of 200μm is significantly higher than the one of the perivenous zone in vivo, while for larger microtissues (400μm diameter) the oxygen concentration drops to values that are equal to the maximum concentration found in the liver periportal zone. Both experimental and modelling investigations led to the achievement of significant results in terms of liver cell performance. Indeed, the creation of a permissive microenvironment inside the bioreactor supported the formation and long-term maintenance of functional human liver microtissues., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Biomolecules immobilization is a key factor for many biotechnological applications. For this purpose, the covalent immobilization of bovine serum albumin (BSA), lipase from Candida rugosa and protein G on differently functionalized regenerated cellulose membranes was investigated. Dynamic light scattering and electrophoresis measurements carried out on biomolecules in solution indicated the presence of monomers, dimers and trimers for both BSA and protein G, while large aggregates were observed for lipase. The immobilization rate and the surface coverage on functionalized regenerated cellulose membranes were studied as a function of biomolecule concentration. Results indicated that the saturation coverage of BSA and protein G was concentration independent (immobilized protein amount of 2.40±0.03mg/g and 2.65±0.07mg/g, respectively). Otherwise, a different immobilization kinetics trend was obtained for lipase, for which the immobilized amount increases as a function of time without reaching a saturation value. Atomic force microscopy (AFM) micrographs showed the formation of monolayers for both BSA and protein G on the membrane surface, while a multilayer structure is found for lipase, in agreement with the trends observed in the related immobilization kinetics. As a result, the morphology of the proteins layer on the membrane surface seems to be strictly dependent on the proteins behavior in solution. Besides, the surface coverage has been described for BSA and protein G by the pseudo second order models, the results indicating the surface reaction as the controlling step of immobilization kinetics. Finally, enzyme activity and binding capacity studies indicated the preservation of the biomolecule functional properties., (Copyright © 2016 Elsevier B.V. All rights reserved.)

This study aims to evaluate the potential of an integrated membrane system in the treatment of olive mill wastewaters (OMWs) to produce a purified fraction enriched in low molecular weight polyphenols, a concentrated fraction of organic substances and a water stream which can be reused in the extractive process of olive oil. In particular, a sequence of two ultrafiltration (UF) processes followed by a final nanofiltration (NF) step was investigated on laboratory scale operating in selected process parameters. The produced fractions were analyzed for their total content of polyphenols, total antioxidant activity (TAA), free low molecular weight polyphenols and total organic carbon (TOC). The performance of selected membranes in terms of productivity, fouling index and selectivity toward compounds of interest was also evaluated and discussed. An integrated membrane process was proposed to achieve high levels of purification of OMWs and a water fraction which can be discharged in aquatic systems or to be reused in the olive oil extraction process., (Copyright © 2013 Elsevier B.V. All rights reserved.)