Disposable paper-based electrochemical sensor using thiol-terminated poly(2-methacryloyloxyethyl phosphorylcholine) for the label-free detection of C-reactive protein

A paper-based electrochemical sensor is described that is based on the use of thiol-terminated poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC-SH) that was self-assembled on a gold nanoparticle-modified screen-printed electrode (SPE). The SPE sensor was used for label-free detection of C-reactive protein (CRP). Gold nanoparticles (AuNPs) were first electrodeposited on the SPCE, followed by the self-assembly of PMPC-SH on gold. The electrochemical response of the modified SPE to CRP was measured by differential pulse voltammetry (DPV). If the CRP on the paper device is contacted with Ca (II) ions, the current (measured by using hexacyanoferrate as the electrochemical probe) decreases. The signal drops in the 5 to 5000 ng·mL−1 CRP concentration range, and the lower detection limit (at 3 SD/slope) is 1.6 ng·mL−1. The use of a PMPC-modified surface also reduces the nonspecific adsorption of proteins. The sensor is not interfered by bilirubin, myoglobin and albumin. It was successfully applied to CRP detection in certified human serum. This sensor is applicable as an attractive protocol for an inexpensive, highly sensitive, and disposable material for electrochemical detection of CRP.