Low cost paper electrodes and the role of oxygen functionalities and edge-plane sites towards trolox sensing

The development of electrochemical sensors as miniaturized and low-cost platforms for rapid and sensitive detection of biomolecules demands for disposable economically viable and easy manufacturable electrodes. Moreover affordable, sensitive, specific, user-friendly, and robust electrodes for sensing (ASSURES) applications through simple do it yourself (DIY) strategy is the need of the hour. This could be achievable only if substrate for electrodes are inexpensive, easily manufacturable and should be from reusable sources. Paper offers unique advantages such as, easily printable, impregnable and its innate cellulose structures make them biomolecules friendly. In addition, porous structure acts as good filter, and facilitates lateral flow. Considering aforementioned properties, herein paper has been explored as substrate for fabrication of electrochemical paper analytical device (e-PAD) with paper electrodes (PPE). Using simple photolithography and stamping technique, we could achieve hydrophobic and hydrophilic regions and 3-in-1 electrode patterns consists of working, counter and reference electrodes. The as-designed and developed PPE was further characterized by surface morphological and electrochemical studies. As a proof of concept, sensing utility of PPE for trolox (analogue of Vitamin E, an antioxidant) is also demonstrated by exploring the interplay between edge plane sites and oxygen functionalities. The calibration plot showed a linear range from 5 mu M to 400 mu M for trolox with detection limit of (S/N = 3) of 1.17 mu M. The present findings demonstrated simple fabrication of PPE is possible unlike the widely used screen printing, inkjet printing, and laser scribing of electrodes onto different substrates, which requires sophisticated instrumentation and skilled personal.