Bile in the esophagus-model for a bile acid biosensor.

Acid and bile acids form important constituents of the refluxed substances in patients who suffer from gastroesophageal reflux disease. Whilst 24h ambulatory pH monitoring using antimony or glass pH electrodes measures acid levels 5 cm above the gastroesophageal junction, there are no reliable methods of measuring other constituents of duodenal juices such as bile acids. Past studies in detection of bile acids have included esophageal aspiration studies with detection of bile acids with HPLC or indirect methods using fiber-optic bile sensor "Bilitec" to detect bilirubin in the bile. These methods have either been impracticable or unreliable for routine and accurate measurement of bile acid. More recently, impedance technology has been used to define "weakly" acid or alkaline reflux. There are many potential applications of biosensors of various types, and it is envisaged that a biosensor specific for bile acid would be a more practical tool for routine measurement. This paper looks at a model for development of a biosensor for bile acid based on molecular imprinted polymers.