Sustainable air plasma regeneration of screen-printed gold electrodes with enhanced electroactive surface area and biosensing performance

Abstract

Miniaturized electroanalytical devices paired with screen-printed electrodes (SPE) are gaining popularity due to their compact design and minimal analyte requirements. However, their single-use nature and non-degradable polymer substrates with printed precious metals like gold limit their sustainability as biosensing interfaces. Disposing of each electrode after a single use is neither cost-effective nor sustainable. Herein, a green air plasma cleaning technique is introduced to regenerate multiple gold SPEs simultaneously within 10 minutes. Air plasma treatment resulted in surface hydrophilicity, significant reduction in surface nitrogen analyzed by X-ray photoelectron spectroscopy, and near-zero charge transfer resistance with a simplified equivalent circuit only limiting charge transfer processes by redox mass diffusion characterized by Warburg impedance. The regenerated electrode was reused to fabricate an electrochemical impedance spectroscopy-based biosensor using a thiol-modified thrombin-binding aptamer. A 1.24-fold increase in the electroactive surface area led to a 2-fold increase in thiol-modified ssDNA aptamer immobilization towards 50 nM thrombin with a 3-fold increase in the sensor signal. Air plasma cleaning is a sustainable and facile technique to regenerate contaminated gold SPEs for biosensor fabrication with enhanced capture probe loading and biosensing sensitivity.