# Exploring the Feasibility of Paper-Based Substrates for User-Friendly Electrochemiluminescent Sensors

## TL;DR

This paper explores using paper-based materials for electrochemiluminescent sensors, aiming to simplify and improve their usability and storage.

## Contribution

The study introduces a novel integration of electrochemiluminescence with paper substrates, enabling reagent storage and simplified user operation.

## Key findings

- Office paper showed better sensor performance due to lower porosity.
- Filter paper caused signal loss and reduced analytical performance.
- Paper-based substrates offer sustainable and cost-effective ECL sensing.

## Abstract

Electrochemiluminescence
(ECL) is a light-emitting process
in which
electrochemically generated excited states relax to the ground state
and emit photons; in many systems, this excitation is produced through
reactions involving a coreactant. ECL has been successfully employed
in devising analytical methodologies requiring exceptional sensitivity
and ultralow background, critical for precise measurements. Its seamless
integration with paper-based platforms further enhances easiness of
use, portability and cost-efficiency, expanding its applicability
across biomedical, environmental, and point-of-care fields. This novel
study aims at integrating the sensitivity offered by ECL and the experimental
convenience of paper-based substrates, thus bridging a gap in the
science of measurements and providing a new analytical tool with relevant
features. Office paper and filter paper were evaluated and compared
to conventional and widely used polyester-based screen-printed electrodes.
The main goal was to assess their electrochemical behavior, analytical
performance and reliability for long-term reagent storage. In fact,
the use of paper might lead to a key innovation in the field: tripropylamine,
the sacrificial coreactant successfully employed in combination with
the luminophore tris­(2,2′-bipiridine)­ruthenium­(II), namely
Ru­(bpy)3
2+, in a model ECL system, was dried
by taking advantage of the paper’s porosity. This allowed eliminating
manual reagent addition/mixing during analysis, with the result of
simplifying the experimental procedure at the end-user and enhancing
storage stability. As promising results, the electrochemical characterization
revealed that office paper exhibited superior sensor’s performance
due to its lower porosity, while the highly porous filter paper caused
signal loss and reduced analytical performance. Features such as sensitivity,
stability, repeatability and storage ability were assessed. Overall,
this study demonstrates the potential of paper-based substrates, especially
commercial office paper, as sustainable and cost-effective platforms
for ECL sensing.