Biotechnology is one of the future core technologies in our society. The entire branch is growing rapidly. It involves separation science in various facets and different fields. Separation scientists are often challenged by the increasing demands and needs. To account for the growing importance and impact of separation science in this technology field, Journal of Separation Science has decided to publish this special issue.
Actually, biotech is not a single sector but more a summary of various technologies. Commonly it is divided in “red biotechnology” (related to agricultural processes), “green biotechnology” (related to medical processes), and “white biotechnology” (tantamount to industrial biotechnology, which is biotechnology applied to industrial processes). The latter field is the primary focus of this special issue. Industrial biotechnology uses enzymes and micro-organisms to make bio-based products by a process which transforms biomass into targeted chemicals. It has changed pharmaceutical research and has led to the growing popularity of biologics as therapeutic and diagnostic concepts. Amongst them monoclonal antibodies and other therapeutic proteins, DNA, vaccines, plasmids, and viruses are the most relevant biologics. They hold great promise as future pharmaceuticals.
Their production by biotechnological processes has vastly developed in the last decades, in many instances due to advances in bioreactor technology, media and strain selection, and last but not least genetic engineering of utilized microorganisms and other biotechnological innovations. These developments in “upstream processing” have led to elevated titers of the biological products in the fermentation broths and cell supernatants, respectively. Around 60 years ago, fermentation broths from penicillin production had titers of ca. 0.5 g/L. Nowadays titers contain more than 50 g/L. Such extraordinary yields are not yet achievable for monoclonal antibody, recombinant protein or plasmid production, yet constantly increase. This puts high demands on downstream processing and purification methods.
Unlike in production of low molecular drugs, chromatographic separations are integral part of the production process of biopharmaceuticals and are critical for the entire process of biologics, which are dedicated for pharmaceutical application. In order to achieve pharmaceutical quality, purification from fermentation broths or cell supernatants, known as “downstream processing”, involves besides other bioseparations usually a three step chromatographic separation comprised of capture, purification, and polishing, which must be capable of removing host cell proteins and nucleic acids, endotoxins, and viruses. High demands are nowadays posed on utilized chromatographic media such as high loading capacity, stability, conservation of product structure and its activity, as well as good kinetic properties. A significant number of papers in this issue are dealing with properties of biochromatography media, their chemistry and physical properties, methods of their testing, as well as application for biopharmaceuticals and protein biomarker purification. However, non-chromatographic bioseparation methods are also included in this issue.
Likewise, analytical methods are challenged in biotechnology. In the course of bioprocess optimization, metabolomics approaches are sometimes used and in this context cellular components must be analyzed in extremely complex samples. Still, reliability of the resultant assay is the ultimate demand. Sample preparation is the most critical step and rigorous application of validation methodologies such as uncertainty concepts may be useful in method optimization. One paper in this issue is dealing with this concept.
Analytical separations are having also a great deal of applicability in process control that comprises all production steps both in upstream and downstream processing at each individual step. Simple, reliable, and robust methods which can be automated and have a high throughput capacity are needed. HPLC methods are often preferred for this purpose but electrophoretic platforms in chip format may develop favorably in the future to fulfill these requirements.
The analysis of the quality of the final product on the other hand may also be more demanding than with conventional drugs. There are stringent demands on product purity and target contents >99% with absence of aggregates, host cell proteins, host cell DNA, viruses, endotoxins, prions and ligand leakages in the product must be verified. In general microheterogeneity and impurities are allowed but must be consistent between batches and this must be documented by adequate analytical methods. Adequate potency of the biopharmaceutical must be assured by correct posttranslational modifications and correct folding. Thus, the strict quality requirements set by regulatory authorities for biopharmaceuticals in terms of purity and quality have to be secured by applying adequate quality control analysis methods. All these quality criteria are challenging from analytical point of view. To move the field forward several papers concentrate on analytical methods that are suitable for this purpose. Thereby, speed of separations, robustness and good recovery are main method requirements. Modern methods with sub-2 μm column, core-shell particles, monoliths, and high-temperature LC are discussed. The high resolving power of capillary electrophoresis for charge variants is well known. A group of researchers document herein the robustness of such methods by an interlaboratory study showing that they are fit for application in quality control laboratories.
Overall, the present special issue should illustrate the remarkable capabilities and impact of separation science in industrial biotechnology. It should document the important role separations play in this field.
Herewith, I would like to thank all authors for their excellent contributions and the reviewers for their valuable cooperation. I hope that the readers will find this special issue useful, stimulating, and informative.
Michael Lämmerhofer (Tuebingen)