Sulfate limitation increases specific plasmid DNA yield and productivity in E. coli fed-batch processes.

Plasmid DNA (pDNA) is a key biotechnological product whose importance became apparent in the last years due to its role as a raw material in the messenger ribonucleic acid (mRNA) vaccine manufacturing process. In pharmaceutical production processes, cells need to grow in the defined medium in order to guarantee the highest standards of quality and repeatability. However, often these requirements result in low product titer, productivity, and yield.

High shear resistance of insect cells: the basis for substantial improvements in cell culture process design.

Multicellular organisms cultivated in continuous stirred tank reactors (CSTRs) are more sensitive to environmental conditions in the suspension culture than microbial cells. The hypothesis, that stirring induced shear stress is the main problem, persists, although it has been shown that these cells are not so sensitive to shear. As these results are largely based on Chinese Hamster Ovary (CHO) cell experiments the question remains if similar behavior is valid for insect cells with a higher specific oxygen demand.

A comprehensive antigen production and characterisation study for easy-to-implement, specific and quantitative SARS-CoV-2 serotests.

Background: Antibody tests are essential tools to investigate humoral immunity following SARS-CoV-2 infection or vaccination. While first-generation antibody tests have primarily provided qualitative results, accurate seroprevalence studies and tracking of antibody levels over time require highly specific, sensitive and quantitative test setups.

Methods: We have developed two quantitative, easy-to-implement SARS-CoV-2 antibody tests, based on the spike receptor binding domain and the nucleocapsid protein.

Accelerating HIV-1 VLP production using stable High Five insect cell pools.

Stable cell pools are receiving a renewed interest as a potential alternative system to clonal cell lines. The shorter development timelines and the capacity to achieve high product yields make them an interesting approach for recombinant protein production. In this study, stable High Five cell pools are assessed for the production of a simple protein, mCherry, and the more complex HIV-1 Gag-eGFP virus-like particles (VLPs).

PEI-Mediated Transient Transfection of High Five Cells at Bioreactor Scale for HIV-1 VLP Production.

High Five cells are an excellent host for the production of virus-like particles (VLPs) with the baculovirus expression vector system (BEVS). However, the concurrent production of high titers of baculovirus hinder the purification of these nanoparticles due to similarities in their physicochemical properties. In this study, first a transient gene expression (TGE) method based on the transfection reagent polyethylenimine (PEI) is optimized for the production of HIV-1 VLPs at shake flask level.

Evaluation of screening platforms for virus-like particle production with the baculovirus expression vector system in insect cells.

Recombinant protein and virus-like particle (VLP) production based on the baculovirus expression vector system is fast, flexible, and offers high yields. Independent from the product, a multitude of parameters are screened during process development/optimisation. Early development acceleration is a key requirement for economic efficiency, and µ-scale bioreactor systems represent an attractive solution for high-throughput (HTP) experimentation.

Exploring the Limits of Cell Adhesion under Shear Stress within Physiological Conditions and beyond on a Chip.

Cell adhesion processes are of ubiquitous importance for biomedical applications such as optimization of implant materials. Here, not only physiological conditions such as temperature or pH, but also topographical structures play crucial roles, as inflammatory reactions after surgery can diminish osseointegration. In this study, we systematically investigate cell adhesion under static, dynamic and physiologically relevant conditions employing a lab-on-a-chip system.

A microscale method of protein extraction from bacteria: Interaction of Escherichia coli with cationic microparticles.

We developed a simple, highly selective, efficient method for extracting recombinant proteins from Escherichia coli. Our recombinant protein yield was equivalent to those obtained with high pressure homogenization, and did not require exposure to harsh thermal, chemical, or other potentially denaturing factors. We first ground conventional resin, designed for the exchange of small anions, into microparticles about 1μm in size.

A surface acoustic wave-driven micropump for particle uptake investigation under physiological flow conditions in very small volumes.

Static conditions represent an important shortcoming of many in vitro experiments on the cellular uptake of nanoparticles. Here, we present a versatile microfluidic device based on acoustic streaming induced by surface acoustic waves (SAWs). The device offers a convenient method for introducing fluid motion in standard cell culture chambers and for mimicking capillary blood flow.

Intake of silica nanoparticles by giant lipid vesicles: influence of particle size and thermodynamic membrane state.

The uptake of nanoparticles into cells often involves their engulfment by the plasma membrane and a fission of the latter. Understanding the physical mechanisms underlying these uptake processes may be achieved by the investigation of simple model systems that can be compared to theoretical models. Here, we present experiments on a massive uptake of silica nanoparticles by giant unilamellar lipid vesicles (GUVs).

Implementation of proton transfer reaction-mass spectrometry (PTR-MS) for advanced bioprocess monitoring.

We report on the implementation of proton transfer reaction-mass spectrometry (PTR-MS) technology for on-line monitoring of volatile organic compounds (VOCs) in the off-gas of bioreactors. The main part of the work was focused on the development of an interface between the bioreactor and an analyzer suitable for continuous sampling of VOCs emanating from the bioprocess. The permanently heated sampling line with an inert surface avoids condensation and interaction of volatiles during transfer to the PTR-MS.