title: Continuous pH monitoring in a perfused bioreactor system using an optical pH sensor.
abstract: Monitoring and regulating the pH of the solution in a bioprocess is one of the key steps in the success of bioreactor operation. An in-line optical pH sensor, based on the optical absorption properties of phenol red present in the medium, was developed and tested in this work for use in NASA space bioreactors based on a rotating wall-perfused vessel system supporting a baby hamster kidney (BHK-21) cell culture. The sensor was tested over three 30-day and one 124-day cell runs. The pH sensor initially was calibrated and then used during the entire cell culture interval. The pH reported by the sensor was compared to that measured by a fiber optically coupled Shimadzu spectrophotometer and a blood gas analyzer. The maximum standard error of prediction for all the four cell runs for development pH sensor against BGA was +/-0.06 pH unit and for the fiber optically coupled Shimadzu spectrophotometer against the blood gas analyzer was +/-0.05 pH unit. The pH sensor system performed well without need of recalibration for 124 days.
authors.affiliation: Wyle Laboratories, Life Sciences-Systems and Services, 1290 Hercules Drive, Suite 120, Mail Stop BT-37, Houston, Texas 77058, USA. ajeevara@ems.jsc.nasa.gov
authors.forename: Antony S
authors.initials: AS
authors.lastname: Jeevarajan
authors.forename: Sundeep
authors.initials: S
authors.lastname: Vani
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Taylor
authors.forename: Melody M
authors.initials: MM
authors.lastname: Anderson
mesh_terms: D000818:Animals; D018441:Biofilms / Q000254:growth & development; D019149:Bioreactors; D002460:Cell Line; D006224:Cricetinae; D003470:Culture Media; D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000379:methods; D005240:Feasibility Studies; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents / Q000032:analysis; D007668:Kidney / Q000737:chemistry / Q000166:cytology; D008562:Membrane Glycoproteins / Q000502:physiology; D055095:Optics and Photonics / Q000295:instrumentation*; D010477:Perfusion; D010637:Phenolsulfonphthalein / Q000032:analysis; D012680:Sensitivity and Specificity; D013053:Spectrophotometry / Q000295:instrumentation* / Q000379:methods*; D013997:Time Factors; D014159:Transducers; D014481:United States; D018557:United States National Aeronautics and Space Administration
chemical_list: D003470:Culture Media; D007202:Indicators and Reagents; D008562:Membrane Glycoproteins; C048022:substrate adhesion molecules; D010637:Phenolsulfonphthalein