Current Organic Chemistry - Volume 21, Issue 17, 2017

Objective: This paper describes examples of membrane engineering for water that take inspiration from biology. Next generation, high permeability, desalination membranes incorporating natural Aquaporin water channels are described. A potential consequence of raised flux is boundary layer mass transfer limitation which can be alleviated by unsteady shear stress, such as vibrations, adopted by some aquatic species to improve respiration. In many applications, biofilms on membranes cause detrimental biofouling. Method: Various triggers, or agents, in the biofilm development cycle are being used to control the fouling by ‘biomimicry’. Conclusion: Beneficial biofilms can also exist on membranes, as exemplified by the gravity-driven biostabilized UF process for water treatment being evaluated as a low energy pretreatment for seawater RO.

Background: The development of bio-inspired materials is of high interest to produce advanced materials able to improve the quality of life through sustainable industrial production. Membranes associated/functionalized with biomolecules, are very suitable to develop biohybrid and biomimetic systems, because they simulate the biological membrane compartmentalization. This system integration, could be divided into membrane bioreactor (MBR) or biocatalytic membrane reactor (BMR) on the basis of biomolecule state (immobilized on the membrane or not) and on membrane role. Potentially, these systems could be used in various fields including food, pharmaceutical etc. Nevertheless, the technology funds industrial application just in water treatment, where it is recognized as the technology of choice. Objective: Although some examples of industrial applications in food and pharmaceutical field already exist, the technology in the mentioned sectors is at an emerging development state. In this review, recent progress of MBR/BMR technology in food, pharmaceutical and biofuel production was reported. Special emphasis is given to patent analysis and systems developed by industries, in the mentioned application fields, with the aim to demonstrate the potentiality of MBRs in non-conventional application fields and inspire the future research activity.

Background: The development of fuel cells device, which used bioelements as catalyst, converts the chemical energy from a fuel into electricity through an electrochemical reaction with oxygen oxidizing agent, and demonstrates the potential of electrochemical techniques for energy generation. The development of sustainable energy production prompted the researcher community to propose and investigate the use of biocatalysts. Aim: This article review presents the development of bio catalyst in biofuel cell devices. Two kinds of biotcatalyst are used to produce electricity: enzyme and microorganisms. Enzymatic biofuel cell and microbial fuel cell are presented after an historical review for each device. Effects of material electrode and design of the electrode are discussed to improve the electrical connection of biocatalyst (enzyme or microorganism) and thus to enhance the energy production. Conclusion: Application of biofuel cell in desalination process is shown and the results demonstrated the capacity of coupling between biofuel cell and electrodialysis process to remove salt from sea water. This work opens new perspectives to enhance the power production simultaneously with water treatment.

Objective: This paper discusses the performance of two, potentially important membrane processes of the next future, namely the biocatalytic membrane reactor (BMR) and membrane aerated biofilm reactor (MABR). It discusses what kinds of methods are applying for enzyme immobilization, which membrane materials can be used for immobilization and what biochemical reactions can be realized by the biocatalytic membrane reactor. Methodology: A one-dimensional, diffusion-convection-reaction model equation is recommended for modeling of the reactant(s) transport through a biocatalytic membrane reactor by means of the Michaelis-Menten kinetics and in order to predict the reactor performance, in presence of the boundary layer mass transfer resistance, as well. Membrane aerated biofilm reactor is also a promising future process primarily for wastewater treatment, nitrification/denitrification processes, COD elimination, which can more effectively be carried out than the conventional one providing higher oxygen supply rate and/or higher oxygen concentration level. The mathematical model of the substrate transport given for homogeneous and heterogeneous biofilm structure has briefly been discussed applying dual-substrate transport limitation.

Background: Proteins are important players in most membrane bioprocesses due to their high propensity to interact with solid surfaces. Their structural behavior when adsorbing to surfaces is not only dependent on protein structural stability, but also it is influenced by the chemical and topographical characteristics of the surfaces. The intensity of protein-surface interactions has a determinant role in the transport of proteins through porous media, thus influencing the performance of membrane and chromatographic separation processes. Also, protein structural dynamics is intimately related to its molecular recognition ability, i.e. their capacity to bind their specific substrates when used as an immobilized ligand or catalyst, to promote cell anchorage to tissue scaffolds while mediators of cell-surface interactions in tissue engineering applications or to be bound/recognized by specific ligands when they are the target solutes. Objective: All these aspects motivated the development of several approaches envisaging a good control of protein-surface interactions and the optimization of membrane processes. The design of functional surfaces capable of an non-invasive modulation of the protein structural dynamics at surfaces and their binding ability has been regarded as a key issue for the optimization of protein purification processes and for development of biomedical devices, e.g. tissue scaffolds or implants, with improved biocompatibility and able to induce the desirable cell responses.

Background: Whey is a valuable by-product obtained from cheese manufacture and employed as a source of proteins that present remarkable potential in food or pharmaceutical industries. Although chromatography is the common method to isolate whey proteins at preparative scale, it reports some disadvantages like its high operational cost. Objective: Membrane processes can play an important role in protein separation, as a consequence of the relatively lower energy consumption, good yields and easy scalability. Important effort has been done on the development of membrane chromatography as an innovative technique to obtain and isolate the different whey proteins. Pressure-driven membrane processes have become standard unit operations in different applications performed in the dairy industry. In this sense, membrane filtration can be applied for protein separation and isolation under adequate conditions. Conclusion: The application of an electrical field or the use of charged membranes combined with pressuredriven membrane processes, provide good results and decrease undesirable phenomena such as concentration polarization when compared to conventional membrane separations. This manuscript provides an overview of the main membrane methods employed in the literature to carry out the separation and isolation of whey proteins.

Background: Monoclonal antibodies are nowadays by far the most important of all biotherapeutics. Unfortunately, they are complex proteins, so that their production is complicated and expensive, which eventually leads to an elevated average cost per treatment per patient. An important research effort is dedicated to the development of a process that may allow a reduction of antibodies production costs. Objective: In particular, the main target is to replace the capture step based on the very expensive use of protein A beads, which is, and has been, the standard for the last 20 years. Among the possible alternatives the use of membrane chromatography for antibody capture will be considered in this work. Despite the development of new convective stationary phases with improved binding capacity, the use of membrane adsorbers for capture chromatography is still limited to niche applications. Conventional packed bead columns are still preferred due to their higher binding capacity even if they suffer from several limitations such as high pressure drop, slow mass transfer through the diffusive pores and strong dependence of the binding capacity on flow rate. An overview of the recent work performed in the field and a critical review of how technology advances could make a breakthrough will be presented here.

Background: In tissue engineering applications, advanced membrane systems provide useful and adaptable biomimetic microenvironment able to sustain cell viability and functions, enabling the delivery and diffusion of biochemical factors, cell nutrients, and products, and mimicking the natural biological extracellular matrix. Proper cell-material interactions favour cell adhesion and trigger cell growth, migration, proliferation, differentiation and functional activation. The wide availability of biocompatible polymers offers the possibility to develop membranes with tuned morphological, physico-chemical, mechanical and transport properties for targeted tissues. Objective: In this review, an in-depth examination of how the membrane properties are able to influence and direct the cellular morpho-functional behaviour of specific engineered tissues is discussed. Furthermore, an overview of the advanced membrane systems, in different configuration and composition, for the biofabrication of tissues and organs is reported.