Silicone glue-based graphite ink incorporate on cellulose nanomaterials as an accessible approach to construct stable electrochemical sensors

This study describes the use of electrochemical paper-based analytical devices (ePADs) manufactured using cellulose substrate, carbon-based paste combining silicone glue and graphite powder. The ePADs were manufactured using the screen-printed technique, which consisted of depositing the conductive ink on a screencast on the paper surface. In addition, an alternative electrical connector was designed and 3D-printed to make the detection method cheaper and more portable. The morphology, structural, and electrochemical properties of the conductive material developed were investigated through the techniques of scanning electron microscopy (SEM), Raman spectroscopy, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The ePADs combined with the alternative connector revealed high repeatability, reproducibility, and stable responses considering well-known redox probe ([Fe(CN)₆]^4-/3-). As proof of applicability, the ePADs were applied for ascorbic acid (AA) analysis in synthetic biofluids (blood plasma and saliva), vitamin C tablets, and food (gelatine and orange juice) samples. The calculated values of the limit of detection (LOD) and quantification (LOQ) were 2.5 and 8.5 µmol L^-1, respectively. The analytical parameters of the proposed method were compared with other reports in the literature and exhibited similar or even superior performance, highlighting the feasibility of the developed analytical system in the sensing field.