Plasma Deposited Polyoxazoline Thin Films for the Biofunctionalization of Electrochemical Sensors

Abstract

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.

Electrochemical behavior of oxazoline‐based plasma polymers for biosensing applications

“…MePOx was introduced to the reactor to the required working pressure, and the plasma was ignited and deposited for 30 s, as described previously. [ 12 ] A ball valve was used to rapidly stop the monomer flow when the required plasma deposition time had elapsed. Three distinct coatings were tested, each prepared with different deposition parameters (plasma ignition power monomer working pressure), as presented in Table 1.…”

“…Due to the nature of the plasma‐polymerization process, different ignition powers and monomer flow rates produce films with different chemistries and thicknesses. [ 12 ] These differences may affect their electrochemical responses. In this study, we prepared three plasma‐polymer coatings that were deposited in different conditions using the 2‐methyl‐2‐oxazoline monomer (MePOx).…”

“…[11] More recently, we have reported the use of POx thin films to functionalize electrodes in electrochemical biosensors. [12] Other groups have also shown that plasma-polymer films can be used as part of a nanocomposite to functionalize electrodes and develop biosensors with a low limit of detection and good sensitivity and selectivity. [13,14] These examples used plasma-polymerized thin films of polyacrylic acid [13] or polyaniline [14] as part of nanocomposite surface functionalization.…”

Functional Nanomaterials from Waste and Low‐Value Natural Products: A Technological Approach Level

“…Among currently available technological approaches that could be implemented in biowaste valorization, two groups that feature distinct physical and chemical processes stand out: thermochemical techniques [48,52] and plasma-based techniques. [53][54][55] While thermochemical techniques utilize high temperatures as the main process driver, the plasma technology utilizes electricity-driven processes. [56][57][58] Taking these two features into account, it appears natural to consider in detail the examples of the traditional thermal (thermochemical) and the plasma-based approaches.…”

“…Among currently available technological approaches that could be implemented in biowaste valorization, two groups that feature distinct physical and chemical processes stand out: thermochemical techniques [ 48,52 ] and plasma‐based techniques. [ 53–55 ] While thermochemical techniques utilize high temperatures as the main process driver, the plasma technology utilizes electricity‐driven processes. [ 56–58 ]…”