An in-line flow injection optical biosensor for real-time bioprocess monitoring

The development of a flow injection analysis (FIA) module for use in conjunction with an optical biosensor to permit its use for on-line bioprocess measurement is described. The system allows automated delivery of a sample from the process to the biosensor. Automation of sampling and sample analysis by the use of an FIA system allows a frequency of measurement sufficient that the data can be used for the purposes of real-time monitoring and control. The system also removes the possibility of human error at both the sampling and measurement stages. A modification of the biosensor is described to allow its use for simultaneous monitoring using two independently addressable channels/sensor surfaces enabling direct comparison to be made between the ligands immobilized in each channel. Referencing of the signals arising from each channel allows production of data representative of the specific interaction of product with one ligand, while eliminating those interactions which are not of interest by selection of a second ligand. This enables use of the system to determine product concentrations by use of the second channel as a reference where non-specific binding to the sensor surface can be a problem. More sophisticated assays, which could determine both inactive and active product forms may also be developed. The interaction of D1.3 anti-Hen Egg Lysozyme Fv antibody fragments with Hen Egg Lysozyme have been studied in order to demonstrate the potential of the monitoring system for real-time data with potential for process control.