Acoustic Biosensors Coated With Phosphorylcholine Groups for Label-Free Detection of Human C-Reactive Protein in Serum

Mass-sensitive biosensor devices based on surface acoustic waves (SAWs) were coated with commercially available 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer for label-free detection of the inflammatory marker C-reactive protein (CRP) in human serum. Owing to the phosphorylcholine groups, the MPC polymer coating enables both binding of CRP and reduction of nonspecific adsorption of other proteins. Hence, MPC offers a simple and economic method to prepare CRP-specific biosensing layers without the use of additional capture molecules. Direct detection and a binding inhibition assay test format were used, where the latter was applied to minimize effects from the serum sample matrix. MPC polymer coated SAW biosensors could be used with both test formats to differentiate CRP serum concentrations in the normal range (i.e., 10 mg/L and below) from significantly increased serum concentrations which would indicate bacterial infection, tissue injury, and inflammation.