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, 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. Given the challenges associated with contamination and waste management in gold SPEs, it is essential to develop effective recycling strategies to reduce cost and environmental impact.Post-manufactured SPEs are markedly contaminated with