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Biomaterial surface modification through the introduction of defined and repeated patterns of topography helps study cell behavior in response to defined geometrical cues. The lithographic molding technique is widely used for conferring biomaterial surface microscale cues and enhancing the performance of biomedical devices. In this work, different master molds made by UV mask lithography were used to prepare poly (D,L-lactide-co-glycolide) - PLGA micropatterned membranes to present different features of topography at the cellular interface: channels, circular pillars, rectangular pillars, and pits. The effects of geometrical cues were investigated on different cell sources, such as neuronal cells, myoblasts, and stem cells. Morphological evaluation revealed a peculiar cell arrangement in response to a specific topographical stimulus sensed over the membrane surface. Cells seeded on linear-grooved membranes showed that this cue promoted elongated cell morphology. Rectangular and circular pillars act instead as discontinuous cues at the cell-membrane interface, inducing cell growth in multiple directions. The array of pits over the surface also highlighted the precise spatiotemporal organization of the cell; they grew between the interconnected membrane space within the pits, avoiding the microscale hole. The overall approach allowed the evaluation of the responses of different cell types adhered to various surface patterns, build-up on the same polymeric membrane, and disclosing the effect of specific topographical features. We explored how various microtopographic signals play distinct roles in different cells, thus affecting cell adhesion, migration, differentiation, cell-cell interactions, and other metabolic activities.

In Figures 1 and 2a and b of our original article (https://pubs.acs.org/doi/full/10.1021/acssuschemeng.1c00785), the abscissa tick labels were shifted to the left, taking most of them out of alignment with the tick marks on the axes. Two labels were also truncated. All other data in the figures are correct as originally published. (Figure Presented).

Layer-by-layer (LBL) assembly is a versatile technology with the ability to produce charged thin film active layers by absorbing oppositely charged polyelectrolytes or nanomaterials through various interactions, which has been proven to be a promising method for preparing separation membranes with desired properties. Recently, nanocomposite membranes fabricated by incorporating various kinds of nanomaterials through the LBL technique have gained increasing interest due to their excellent membrane performances in terms of improved permeability, selectivity, anti-fouling, chlorine resistance, and long-term stability. This review aims to provide a comprehensive investigation of the state-of-the-art achievements of the nanocomposite membranes prepared by LBL assembly. Different LBL assembly methods such as dip coating, spray coating, spin coating, inkjet printing, electric field, and high gravity technologies are introduced. The detailed membrane fabrication processes and their applications in different separation areas including nanofiltration, reverse osmosis, ultrafiltration, microfiltration, pressure retarded osmosis, forward osmosis, pervaporation and organic solvent nanofiltration are summarised and discussed. The advantages and challenges of the LBL nanocomposite membranes are also addressed. Overall, this review provides some fundamental clues for the exploration of LBL assembly techniques for the preparation of separation membranes with preferable performances and applications.

Novel layer-by-layer (LBL) organic solvent nanofiltration (OSN) membrane was developed via inkjet printing of polyethyleneimine (PEI) and single walled carbon nanotube (SWCNT) on a polyketone (PK) membrane surface, followed by post-treatment using three different cross-linking agents: glutaraldehyde (GA), (±)-epichlorohydrin (ECH) and trimesoyl chloride (TMC). The effects of PEI and SWCNT concentrations, bilayer numbers, and cross-linking conditions in the formation of the selective layers were evaluated in terms of membrane OSN performances. PEI concentration of 10.0 g/L and SWCNT concentration of 1.0 g/L with eight cycles of printing bilayers were chosen as optimal conditions. GA cross-linking was found to give the best membrane performance, and thus GA was considered as the best cross-linking agent for inkjet-printed LBL membrane modification among the three kinds of cross-linkers. The (PEI/SWCNT)8-GA exhibited Rose Bengal (RB) rejection over 99% with high organic solvent permeances. Compared to the cross-linking time, cross-linking agent concentration was found to have a greater effect on the membrane modification in terms of rejection performance. Moreover, the inkjet-printed LBL membrane showed negligible changes in membrane weight and OSN performance after immersion in different organic solvents over a period of three weeks, indicating its high mechanical and chemical stability. Finally, the possible applications of our printed LBL membranes in the pharmaceutical and hemp industries were evaluated. Overall, our work could further develop inkjet printing method for LBL OSN membrane fabrications.

This study investigates the inkjet printing technique as an efficient way to fabricate polyelectrolyte multilayer membranes (PEM) for organic solvent nanofiltrtaion (OSN). Polyethyleneimine (PEI) and poly(sodium 4-styrene sulfonate) (PSS) were used as polycation and polyanion, respectively. Single walled carbon nanotube (SWCNT) was incorporated into membranes to enhance the membrane physical and chemical stability. The polyketone (PK) membrane served as substrate for OSN because of its organic solvent resistance property in nature. The effects of numbers of bilayer, polyelectrolyte concentration, and the cross-linking condition on the membrane OSN performances were evaluated. The best OSN performance was achieved with 10 bilayers of polyelectrolytes printing, noted as (PEI/PSS-CNT)10. The (PEI/PSS-CNT)10 membrane exhibited ethanol, methanol, IPA and acetone permeances of 2.52, 4.21, 1.21 and 4.75 L m−2 h−1 bar−1, respectively, along with good dye rejection rate (Rose Bengal (RB) rejection >98%). Moreover, the inkjet printed OSN membrane was found to be stable after soaking in different organic solvents for two weeks. The membrane weights and the performances exhibited negligible changes. The 12 h continuous filtration tests also confirmed the membrane stability property. Our work broadened the use of inkjet printing technology for membrane fabrication and validated the technology as a promising method for producing multilayer OSN membranes, which may open a new avenue for OSN membrane preparations.

Recently, there is an increasing interest on organic solvent nanofiltration (OSN) for the separation and recovery of organic solvents due to the high energy consumption and the high cost involved in conventional organic solvent recovery processes. Conventional organic solvent recovery processes often involve, thermal phase separation processes such as distillation and deactivation which utilizes varying boiling points of organic solvents. Owing to such issues, pressure driven, membrane-based OSN process attracted significant attention as a low energy and low-cost alternative approach for the recovery of the organic solvents which utilizes the molecular size sieving effect via varying membrane pore sizes. However, the low solvent permeate flux, low stabilities of polymeric membranes under organic solvents and controlling the membrane properties suited for separation of various organic solvents/solutes has risen as significant challenges in implementing OSN membranes/process in practical applications. To overcome such challenges, chemically stable nanomaterials have been used as an additive material in nanocomposite membrane fabrication for OSN applications. This paper comprehensively review the nanomaterial-based OSN nanocomposite membranes based on different types of nanofillers used and the different fabrication approaches. Besides, this paper also discusses the major issues involved in different nanocomposite membrane fabrication and possible solutions for the issues involved. Moreover, the challenges and future prospective are also provided to present the current research gaps and to further develop nanomaterial-based OSN membranes for practical application.

The urgent need for environmental sustainability has increasingly prompted policy makers to emphasize resource recovery from desalination brine streams. Recent research on resource recovery from waste streams has shown rising momentum with near term viability for several new technologies. In this perspective, we focus on new opportunities for metal resource recovery from seawater desalination brine, while outlining associated sustainability challenges and opportunities. The potential of metals recovery is discussed.