Pristine paper-based device for non-enzymatic electrochemical detection of creatinine: sensitization via electrode and paper modification strategies.

Herein, we report a non-enzymatic paper-based device for selective electrochemical detection of creatinine. This work demonstrates three modification strategies adopted for the paper-based electrochemical sensing device (PESD) for the detection of creatinine. Copper, a non-enzymatic metal electrode, was fabricated on the Whatman paper without sophisticated instrumentation. The fabricated pristine non-enzymatic PESD could detect creatinine in the linear range 10 µM to 90 µM with a detection limit of 6.6 µM. Further, the electrode and Whatman paper were modified with silver to improve the sensitivity of PESD towards creatinine. Firstly, the working electrodes were modified by the Scotch tape strategy via galvanic displacement of Ag on Cu. The Ag-modified Cu electrodes were stuck on the Whatman paper, which sensitized the creatinine in the linear range 10 nM to 240 nM with a detection limit of 0.089 nM. Secondly, the Whatman paper was modified by mussel-inspired soak, polymerize, and then reduction of silver on the paper. The modified paper works similarly to the modified electrode with Ag in the linear range 10 nM to 90 nM with a detection limit of 2.5 nM. Further, the fabricated pristine PESD was tested for Jaffe's inspired indirect electrochemical detection of creatinine in the linear range 10 µM to 100 µM with a detection limit of 6.4 µM. The sensitivity of the fabricated pristine PESD was improved from µM to nM by adopting modification strategies. The reported PESD with the least interference from the co-existing biomolecules has the potential applicability of monitoring creatinine in urine sample analysis.