Process-based LCA of ultrafiltration for drinking water production.

Researchers and industrials need decision-making tools to make informed decisions on environmental mitigation strategies and proceed with the overall ecodesign of processes. In this study, a tool that couples membrane filtration process modelling and life cycle analysis has been developed, for which material and energy flows are calculated for variable operating conditions and are the basis for environmental impact assessment. The resulting generic model has been applied to dead-end ultrafiltration of ground and surface waters for drinking water production with cellulose triacetate hollow fibers. Operating strategies have been investigated to mitigate environmental impacts of the two major hotspots (electricity and backwash cleaning chemical consumptions). Adjusting filtration cycle duration and filtration flux has shown to be a promising lever. The developed model is sufficiently flexible and modular for its adaptation to other membrane materials, filtration configurations (i.e. cross-flow) as well as to other applications.

Modeling equations and dataset of model parameters for ultrafiltration membrane fabrication.

In the related research article, entitled "A generic process modeling ‒ LCA approach for UF membrane fabrication: Application to cellulose acetate membranes" [1], a generic model is described and used to obtain the list of material and energy flows as a function of operating conditions for ultrafiltration (UF) hollow fibers preparation by non-solvent induced phase separation. In this data article, equations of the model, a dataset of model parameters and modelled data are detailed. modeling equations are developed from material and energy balances for each unit operation (i.e. from polymer solution mixing to module conditioning) based on an industrial membrane fabrication process of UF cellulose acetate modules. These equations may be reused as such or adapted to other membrane materials and industrial practices. The dataset of model parameters relates to industrial on-site measurements and scientific literature for the existing cellulose-based module. The modelled data corresponds to a reference situation for which hollow fibers (inner and outer diameters equal to 0.93 mm and 1.67 mm, respectively) are fabricated from a polymer solution composition of 20 wt.% of cellulose triacetate, 78 wt.% N-methyl-2-pyrrolidone and 2 wt.% lithium chloride.

Development of double porous poly (ε - caprolactone)/chitosan polymer as tissue engineering scaffold.

Polymer blend made from poly(ε - caprolactone)/chitosan (PCL/CHT) offers interesting opportunities for biological applications. The paper presents a new way to fabricate PCL/CHT double-porosity (macrovoids with interconnected microporosity) membrane materials from a chemical optimization of the solvent and non-solvent phases and from a modified phase inversion technique. By varying the PCL/CHT proportion, it is shown that it is possible to improve the chemical and physical properties of the CHT carbohydrate polymer. The PCL/CHT membranes are fully characterized in term of physico-chemical properties (ATR-FTIR, XRD and DSC) to understand the miscibility of the two-polymer blend. Morphological characterization by SEM shows that by increasing CHT wt% in the blend, the size of the macrovoids was increasing. Rapid enzymatic degradation of PCL from all the blend was found by using lipase (from P. cepacia). The mechanisms at the origin of the morphological structuration of the material is also discussed. To test the ability to operate these materials as small diameter vascular scaffolds, cell culture with human umbilical vein endothelial cells (HUVECs) were carried out on the membrane and the results analyzed with laser scanning confocal microscopy (LSCM). Data suggest that the blend membrane with higher concentration of CHT polymer wt% have suitable properties that promote high number of cells on the surface by maintaining cellular cytoskeleton integrity within 3 days. The blend membrane with a double porous morphology could be potentially applicable in future for small diameter vascular graft application. The surface macrovoids (20-90 µm) could be useful for three-dimensional cellular adhesion and proliferation and interconnected microporous spongy network (7-20 µm) is expected to transfer essential nutrients, oxygen, growth factor between the macrovoids and the supernatant.

Double porous poly (Ɛ-caprolactone)/chitosan membrane scaffolds as niches for human mesenchymal stem cells.

In this paper, we developed membrane scaffolds to mimic the biochemical and biophysical properties of human mesenchymal stem cell (hMSC) niches to help direct self-renewal and proliferation providing to cells all necessary chemical, mechanical and topographical cues. The strategy was to create three-dimensional membrane scaffolds with double porosity, able to promote the mass transfer of nutrients and to entrap cells. We developed poly (Ɛ-caprolactone) (PCL)/chitosan (CHT) blend membranes consisting of double porous morphology: (i) surface macrovoids (big pores) which could be easily accessible for hMSCs invasion and proliferation; (ii) interconnected microporous network to transfer essential nutrients, oxygen, growth factors between the macrovoids and throughout the scaffolds. We varied the mean macrovoid size, effective surface area and surface morphology by varying the PCL/CHT blend composition (100/0, 90/10, 80/20, 70/30). Membranes exhibited macrovoids connected with each other through a microporous network; macrovoids size increased by increasing the CHT wt%. Cells adhered on the surfaces of PCL/CHT 100/0 and PCL/CHT 90/10 membranes, that are characterized by a high effective surface area and small macrovoids while PCL/CHT 80/20 and PCL/CHT 70/30 membranes with large macrovoids and low effective surface area entrapped cells inside macrovoids. The scaffolds were able to create a permissive environment for hMSC adhesion and invasion promoting viability and metabolism, which are important for the maintenance of cell integrity. We found a relationship between hMSCs proliferation and oxygen uptake rate with surface mean macrovoid size and effective surface area. The macrovoids enabled the cell invasion into the membrane and the microporosity ensured an adequate diffusive mass transfer of nutrients and metabolites, which are essential for the long-term maintenance of cell viability and functions.

Tunable Microstructured Membranes in Organs-on-Chips to Monitor Transendothelial Hydraulic Resistance.

Tissue engineering is an interdisciplinary field, wherein scientists from different backgrounds collaborate to address the challenge of replacing damaged tissues and organs through the in vitro fabrication of functional and transplantable biological structures. Because the development and optimization of tissue engineering strategies rely on the complex interaction of cells, materials, and the physical-chemical tissue microenvironment, there is a need for experimental models that allow controlled studies of these aspects. Organs-on-chips (OOCs) have recently emerged as in vitro models that capture the complexity of human tissues in a controlled manner, while including functional readouts related to human organ physiology. OOCs consist of multiple microfluidic cell culture compartments, which are interfaced by porous membranes or hydrogels in which human cells can be cultured, thereby providing a controlled culture environment that resembles the microenvironment of a certain organ, including mechanical, biochemical, and geometrical aspects. Because OOCs provide both a well-controlled microenvironment and functional readouts, they provide a unique opportunity to incorporate, evaluate, and optimize materials for tissue engineering. In this study, we introduce a polymeric blend membrane with a three-dimensional double-porous morphology prepared from a poly(ɛ-caprolactone)-chitosan blends (PCL-CHT) by a modified liquid-induced phase inversion technique. The membranes have different physicochemical, microstructural, and morphological properties depending on different PCL-CHT ratios. Big surface pores (macrovoids) provide a suitable microenvironment for the incorporation of cells or growth factors, whereas an interconnected small porous (macroporous) network allows transfer of essential nutrients, diffusion of oxygen, and removal of waste. Human umbilical vein endothelial cells were seeded on the blend membranes embedded inside an OOC device. The cellular hydraulic resistance was evaluated by perfusing culture medium at a realistic transendothelial pressure of 20 cmH2O or 2 kPa at 37°C after 1 and 3 days postseeding. By introducing and increasing CHT weight percentage, the resistance of the cellular barrier after 3 days was significantly improved. The high tuneability over the membrane physicochemical and architectural characteristics might potentially allow studies of cell-matrix interaction, cell transportation, and barrier function for optimization of vascular scaffolds using OOCs. Impact Statement Organs-on-chips (OOCs) offer interesting potential for progress in the treatment of diseases and injury in the growing field of tissue engineering and regenerative medicine. The article presents a new way to develop polymer membrane with a tunable microstructured morphology and to implement this biomaterial inside an OOC device. The reader should find measurements of the transendothelial hydraulic resistance in real time during endothelial cells culture: a simple and controlled way of mimicking human physiological condition for vascular tissue regeneration. This combination of novel biomaterial inside an OOC will explore innovative ideas in tissue engineering field.