Plasma Deposited Polyoxazoline Thin Films for the Biofunctionalization of Electrochemical Sensors

Electrochemical immunosensors are an emerging technology for the fast, sensitive, and reliable diagnosis of diseases from bodily fluids. These sensors work by detecting a change in current upon analyte binding to an immuno-functionalized electrode. Current methods of electrode functionalization are lengthy processes involving self-assembled monolayer formation and wet chemistry biofunctionalization. Herein, thin films deposited from the plasma phase of oxazoline precursors are investigated and optimized as an alternative approach for electrode functionalization. The plasma-enabled method has the advantage of being substrate independent and allows the spontaneous binding of biomolecules in physiological buffer. Surface sensitive analysis techniques are employed to characterize the thickness, reactivity, and stability of the thin films before investigating their electrochemical properties on indium tin oxide and gold electrodes including the feasibility to reduce charge transfer resistance with gold nanoparticles. Last, these films are employed to develop an immunosensor for the detection of free epithelial cell adhesion molecule with a limit of detection of 8.7 ng mL⁻¹.