Surface modification of carbon felt by cold remote plasma for glucose oxidase enzyme immobilization

Despite their chemical inertness and poor hydrophilicity, carbon-based materials are widely used in electro-chemical applications due to their robustness, good electrical conductivity and corrosion resistance. The purpose of the work carried was to increase the wettability of nonwoven carbon fiber felts for improved efficiency in bio/electrochemical applications. Virgin Carbon Felt (VCF) was first treated with cold remote plasma (CRP) using a mixture of nitrogen and oxygen (1 or 2%) as plasma gas. Bio-functionalization of the carbon felts with glucose oxidase (GOx) enzyme was then carried using physical adsorption method. FTIR and XPS analysis showed an integration of new oxygenated functional groups (C-O and C=O) as well as amines and amides on the surface of VCF treated by the CRP treatment, which improved the wettability of the samples. Capillary uptake increased from around 0% (for VCF) to nearly 750% with 2% oxygen in plasma gas. GOx enzyme showed higher activity after immobilization at pH 5.5 on the CRP treated samples, maintaining up to 50% of its initial enzymatic activity after six cycles while with the VCF, no enzymatic activity was observed after the fourth cycle. These obtained felts can be used as electrodes in sustainable bioprocesses.