Bioreactors biocompatibility

Biocompatible nanosized polyamidoamine (PAMAM) dendrimer films provided a suitable microenvironment for heme proteins to transfer electron directly with underlying pyrolytic graphite electrodes. The Mb-PAMAM film can catalytically reduced oxygen, hydrogen peroxide, and nitrite, indicating that the potential applicability of the film can be used to fabricate a new type of biosensor or bioreactor based on the direct electron transfer of Mb [234],... 

Membrane-based separation, lactic acid production and, 14 120 Membrane biocompatibility, in hemodialysis, 26 823—824 Membrane bioreactors, 16 26 Membrane-bound enzymes, 10 338 Membrane cell process, 9 620 Membrane cells... 

In this type of bioreactor, there is a compartment where cells remain attached to a surface or immobilized on or inside a biocompatible bed. Culture medium has to be pumped through this compartment for cells to have access to nutrients and dissolved oxygen. The main disadvantages of these bioreactors, developed for the cultivation of adherent cells that require a surface for proliferation, are the impossibility of obtaining homogeneous samples of the cell population and the limitations of scale-up. 

As a basic in B LMs for the wastewater treatment the author presents two-phase partitioning bioreactors. He presents the main criteria which must be considered in the selection of the LM solvent biocompatibility (toxicity of the solvent to the microorganism), bioavailabihty (resistance of the solvent to biodegradation by the microorganism used), immiscibility in the aqueous phase, high solubility of pollutant in the solvent, favorable mass-transfer characteristics, etc. Biodegradation mechanisms and kinetics are discussed. Apphcations of bioreactors in wastewater treatment in laboratory, phot, and industrial scale are reviewed. Potential applications are considered also. 

In recent years, liposomes and supported membranes composed of fluid lipids have seen increased use as biolabeling and targeting agents, coatings for sensor transducers and biocompatible materials, nanoscale bioreactors, and separations media. Due to their enhanced stability, functionalized poly(lipid) materials have also been created and characterized for these applications. 

Cell adhesion to artificial surfaces plays a key role in a wide variety of demanding products and technologies such as medical implants or bioreactor systems. Adhesion of eukaryotic and bacterial cells to a biomaterial surface can be a major factor mediating its biocompatibility. For a proper integration of an implant into tissue, cell adhesion may be desired, whereas bacterial cell adhesion to medical devices must be prevented in order to minimize the risk of infections and toxicity. 

This chapter deals primarily with monolayers of surfactants at fluid interfaces, but some attention is also given to (nano) coatings such as Langmuir-Blodgett (LB) and Langmuir-Schaefer (LS) films, self-assembled monolayers (SAMs), and layers obtained by alternating polyelectrolyte deposition. Such coatings may be applied for the functionalization of surfaces, for instance, to achieve biocompatibility of biomaterials, improve specificity and selectivity of biosensors and membranes, and control immobilization of enzymes or cells in bioreactors. 

When reviewing the diverse range of bioreactors currently available, it is worth revisiting the notion of biocompatibility, which is an essential prerequisite for all bioreactor components that come in contact with the cells and culture medium. Analogous to biomaterials used for clinical applications, the materials used for bioreactor chambers, gas and medium exchange and contact instruments need to be as inert and neutral as possible, so that the cells and molecular factors in culture medium are not affected. In addition, however, components of bioreactors that deliver biophysical cues must also be able to retain their biocompatibility, as much as possible, as they perform their various tasks (e.g., platens used to provide compressive forces or electrodes, which impart electrical stimuli, must not corrode during cultivation). 

Hemoperfusion circulates blood directly over sorbents, such as charcoal or anion exchange resins, or other more complex biochemical reactors, including immobilized enzymatic bioreactors, which allows the chemical processing of specific biologic products. This technique is limited by the loss of other useful substances and can cause complications, such as bleeding when there is an excessive removal of coagulation factors and platelets. To minimize these losses and improve biocompatibility, sorbents can be coated with cellulose to avoid direct contact with blood or plasma, although this in turn reduces the effectiveness of the sorbents. 

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