A real-time adaptive oxygen transfer rate estimator for metabolism tracking in Escherichia coli cultures.

Oxygen transfer rate (OTR) is the most significant signal for aerobic bioprocess control, since most microbic metabolic activity relies on oxygen consumption. However, accurate estimation of OTR is challenging due to the difficulty of determining uncertain oxygen transfer parameters and system dynamics. This paper presents an adaptive estimator, which incorporates exhaust gas, stir speed and dissolved oxygen measurements, to predict the real-time OTR.

A CMI (cell metabolic indicator)-based controller for achieving high growth rate Escherichia coli cultures.

A large fraction of biopharmaceuticals are produced in Escherichia coli, where each new product and strain currently requires a high degree of growth characterization in benchtop and industrial bioreactors to achieve economical production protocols. The capability to use a standard set of sensors to characterize a system quickly without the need to conduct numerous experiments to determine stable growth rate for the strain would significantly decrease development time. This paper presents a cell metabolic indicator (CMI) which provides better insight into the E.

A quantitative metric for pattern fidelity of bioprinted cocultures.

This article describes a quantitative metric for coculture pattern fidelity and its use in the assessment of bioprinting systems. Increasingly, bioprinting is used to create in vitro cell and tissue models for the purpose of studying cell behavior and cell-cell interaction. To create meaningful models, a bioprinting system must be able to place cells in biologically relevant patterns with sufficient fidelity.

Characterizing the effects of cell settling on bioprinter output.

The time variation in bioprinter output, i.e. the number of cells per printed drop, was studied over the length of a typical printing experiment.

Cell settling effects on a thermal inkjet bioprinter.

This paper seeks to quantify cell settling in the print media reservoir of a bioprinter in order to determine its effect on consistent cell delivery per printed drop. The bioprinter studied here is based on the thermal inkjet HP26A cartridge, but any system that dispenses controlled volumes of fluid may be affected similarly. A simple model based on Stokes' law suggests that the cell concentration in the bottom of the reservoir should increase linearly up to some maximum and that the cell concentration in the printed drops should follow this trend.

Post-bioprinting processing methods to improve cell viability and pattern fidelity in heterogeneous tissue test systems.

Bioprinted tissue test systems show promise as a powerful tool for studying cell-cell interaction in heterogeneous, tissue-like co-culture. Several challenges were encountered while attempting to consistently fabricate samples with high viability and pattern fidelity. This paper evaluates four methods for processing samples after bioprinting but prior to adding media for incubation.

Design and implementation of a two-dimensional inkjet bioprinter.

Tissue engineering has the potential to improve the current methods for replacing organs and tissues and for investigating cellular process within the scope of a tissue test system. Bioprinting technology can aid in the difficult task of arranging live mammalian cells and biomaterials in viable structures for tissue engineering purposes. This paper describes a system, based on HP26 series print cartridge technology, capable of precisely depositing multiple cell types in precise patterns.

EDTA enhances high-throughput two-dimensional bioprinting by inhibiting salt scaling and cell aggregation at the nozzle surface.

Tissue-engineering strategies may be employed in the development of in vitro breast tissue models for use in testing regimens of drug therapies and vaccines. The physical and chemical interactions that occur among cells and extracellular matrix components can also be elucidated with these models to gain an understanding of the progression of transformed epithelial cells into tumours and the ultimate metastases of tumour cells. The modified inkjet printer may be a useful tool for creating three-dimensional (3D) in vitro models, because it offers an inexpensive and high-throughput solution to microfabrication, and because the printer can be easily manipulated to produce varying tissue attributes.