1,721,163 research outputs found
Membrane adsorbers as purification tools for monoclonal antibody purification
No full textDownstream purification processes for monoclonal antibody production typically involve multiple steps; some of them are conventionally performed by bead-based column chromatography. Affinity chromatography with Protein A is the most selective method for protein purification and is conventionally used for the initial capturing step to facilitate rapid volume reduction as well as separation of the antibody. However, conventional affinity chromatography has some limitations that are inherent with the method, it exhibits slow intraparticle diffusion and high pressure drop within the column. Membrane-based separation processes can be used in order to overcome these mass transfer limitations. The ligand is immobilized in the membrane pores and the convective flow brings the solute molecules very close to the ligand and hence minimizes the diffusional limitations associated with the beads. Nonetheless, the adoption of this technology has been slow because membrane chromatography has been limited by a lower binding capacity than that of conventional columns, even though the high flux advantages provided by membrane adsorbers would lead to higher productivity. This review considers the use of membrane adsorbers as an alternative technology for capture and polishing steps for the purification of monoclonal antibodies. Promising industrial applications as well as new trends in research will be addressed
Advances in Membrane Chromatography for the Capture Step of Monoclonal Antibodies
Full text linkBackground: 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
Removal of Antibiotics from Wastewaters by Membrane Operations
No full textThis is an excerpt from the content:
Antibiotics are persistent pollutants present in wastewaters originating from the pharmaceutical industry, but, due to their extensive human and veterinary use, they have also been found in municipal wastewaters. It has been observed that conventional activated sludge (CAS) wastewater treatment is not sufficient for the removal of antibiotics, and their presence in wastewater effluents is considered one of the causes of the emergence of antibiotic-resistant organisms. Several approaches have been proposed for the removal of antibiotics from wastewaters, the more promising being membrane bioreactors (MBRs), membrane filtration, and advanced oxidation processes or a combination of the above (Michael et al. 2013).
Conventional wastewater plants were not designed to treat pharmaceutical compounds and, in particular, antibiotics, due to their highly variable chemical structure and properties. As a consequence, the efficiency of antibiotic removal varies according to the different antibiotic ..
Antibiotic Production by Membrane Operations
No full textThere is no abstract, this is an excerpt from the content: Antibiotics are medicines produced by fermentation that fight bacterial infections; they can either kill other microorganisms or inhibit their growth.
The development of antibiotics started with the discovery of penicillin by Fleming in 1928 that gave rise to many other discoveries in the subsequent 40 years. The number of new antibiotics on the market had a steady increase until the 1980s, but the unrestrained use of antibiotics led to the emergence of antibiotic-resistant pathogens and the number of approved antibiotics decreased constantly in the last 30 years (Coates et al. 2011). The research for therapeutics endowed with a broaden antimicrobial range brought to the development of semisynthetic antibiotics which are produced by chemical or enzymatic transformation of penicillin and cephalosporins (Srirangan et al. 2013). Penicillin is still one of the antibiotics with the largest annual bulk production; it is part of the β-lactam antibiotic ..
Recovery of Antibiotics from Fermentation Broth Membrane Operations
No full textThis is an excerpt from the content:
The first step in the recovery of antibiotics from fermentation broths is the separation of the cells from the liquid growth media. However, the purification process is different whether or not the product is intracellular or extracellular. In antibiotic production, either options are possible even if the majority of antibiotics, including penicillins, cephalosporins, and streptomycin, are extracellular products. When the desired product is intracellular, after a coarse liquid removal step, the cells are lysed to release the product. The clarification of the antibiotic is then performed to remove the cell debris. In both cases, since the antibiotics are relatively small molecules, a concentrate containing the solid biomass and a permeate containing the antibiotic and other impurities are obtained (Brites Alves et al. 2002).
The important steps of the antibiotic production process are the separation of mycelial cells, the chemical extraction of the active molecule, and the purification a ..
Development and Characterization of Affinity Membranes for Immunoglobulin Purification
No full textThe purification of antibodies is conventionally performed using affinity
chromatography columns, with Protein A as ligand. The development of valid alternatives to Protein A is one of the challenges of the research in downstream processing, which becomes more important as the production capability of the biopharmaceutical industry increases. The objective of this work is the characterization of affinity membranes derivatized with two different synthetic ligands that show high specificity for immunoglobulins. The affinity membranes have been prepared and characterized, in view of their application in the capture purification step
Affinity membranes for the purification of autologous plasmin from serum
No full textPlasmin is protein of the fibrinolityc system, obtained by activation of plasminogen, which is of interest
for ophthalmology applications. It can be used as a treatment for diabetic rethinopaty, macular pukers,
but also as a facilitator for vitreoctomy since it has the properties to hydrolize a variety of glycoproteins
by degrading the links between these components of the vitreoretinal interface and the inner limiting
membrane. The purification of plasminogen from blood is conventionally performed with bead-based
affinity chromatography, by exploiting the affinity between plasminogen and L-lysine. However, due to
its low concentration, which is about 0.2 g/L in human blood, with a single step affinity purification
from serum or plasma it is not possible to obtain high levels of purity and a sufficient amount of protein.
In this work we describe several strategies that have been investigated in order to improve the affinity
chromatography step which is performed with lysine affinity membranes. The affinity membranes were
obtained by immobilization of L-lysine on regenerated cellulose membrane supports and characterized in
terms of ligand density, binding capacity and selectivity. The effect of operating parameters like flow rate,
type of blood source (serum, plasma or Cohn fractions) and elution conditions on the activity of plasmin
conversion have been investigated in detail. The comparison with a chromatography column packed with
a commercial lysine affinity beads demonstrated the superior performance of the affinity membranes and
the feasibility of the proposed process
Modelling and simulation of affinity membrane adsorption
No full textA mathematical model for the adsorption of biomolecules on affinity membranes is presented. The model considers convection, diffusion and adsorption kinetics on the membrane module as well as the influence of dead end volumes and lag times; an analysis of flow distribution on the whole system is also included. The parameters used in the simulations were obtained from equilibrium and dynamic experimental data measured for the adsorption of human IgG on A2P-Sartoepoxy affinity membranes. The identification of a bi-Langmuir kinetic mechanisms for the experimental system investigated was paramount for a correct process description and the simulated breakthrough curves were in good agreement with the experimental data. The proposed model provides a new insight into the phenomena involved in the adsorption on affinity membranes and it is a valuable tool to assess the use of membrane adsorbers in large scale processes
Dynamic characterization of affinity membranes for monoclonal antibodies purification
No full textDownstream processes for the purification of biological products are often the cost determining production steps. Affinity technology is widely used for the primary capture stage, based on chromatographic beads. In the last decades, significant attention has been devoted to affinity chromatography using microporous membranes as chromatographic supports. Membrane chromatography can overcome the limitation associated to conventional packed-bed columns, such as high pressure drops and slow mass transfer.
This work is focused on the purification of Immunoglobulin G (IgG) via affinity membranes. A new support, Sartoepoxy Protein A membranes (Sartorius, Göettingen, Germany) has been tested in detail in dynamic experiments, using pure solutions of polyclonal IgG as well as the supernatant of a fermentation broth containing monoclonal IgG. All the relevant parameters, namely the dynamic binding capacity, process yield and recovery have been evaluated. The influence of several operating parameters on the adsorption and elution performances has been studied to determine the optimal process conditions.
A mathematical model including convection, diffusion and multi-component adsorption is proposed to simulate the adsorption, washing and elution steps; the model also considers the possible effects of dead end volumes and flow distribution. Results of the simulation have been compared with the experimental data, giving a good description of the global process
- …
