Continuous monitoring of dsDNA fragments for biomanufacturing: Sensor development and feasibility study

Biomanufacturing processes based on cellular systems are difficult to set up and control due to variabilities in the bioreactor (upstream processing) and in the extraction and purification steps thereafter (downstream processing). For better understanding, monitoring, and control of these processes, sensors are needed that can measure biomolecular constituents such as small molecules, proteins, and nucleic acids. Here, we describe the development of a continuous sensor to monitor host cell DNA, which can function as a marker for cell death in upstream processing and as a marker for product impurity in downstream processing. We present a sensor for the measurement of double-stranded DNA fragments (dsDNA) using anti-dsDNA antibodies in a continuous biosensor based on particle motion with a competition format. Experimental results show that the sensor has reversible interactions with dsDNA fragments of different base pair lengths and gives responses in nano- and micromolar concentration ranges. Particles with varying motion behaviors are distinguished, and their dose-response characteristics are compared. Finally, fluctuating dsDNA concentrations are measured, and the next steps are defined for the development of sensors for the continuous monitoring of host cell DNA in biomanufacturing processes.