Leaf-Based Electrochemical Sensors for Dopamine and Paracetamol Detection

A group of Brazilian researchers led by professors Bruno Janegitz of the Federal University of São Carlos and Thiago Paixão of the University of São Paulo (USP), who heads the Electronic Tongues and Chemical Sensors Lab (L2ESQ), have now presented a very inventive solution that involves printing electrochemical sensors on fallen tree leaves. The research was published in the journal ACS Sustainable Chemistry & Engineering.

3D printing offers speed, design flexibility, and the ability to use waste as a substrate for the fabrication of sensors. A variety of results have been acquired in a circular economy mode, where waste materials are repurposed as low-cost resources.

The research was funded by FAPESP.

We used a CO₂ [carbon dioxide] laser to print the design of interest on a leaf by means of pyrolysis and carbonization. We thereby obtained an electrochemical sensor for use in determining levels of dopamine and paracetamol. It is very easy to operate. A drop of the solution containing one of these compounds is placed on the sensor, and the potentiostat to which it is coupled displays the concentration. 

Bruno Janegitz, Professor, Laboratory of Sensors, Nanomedicine and Nanostructured Materials, Federal University of São Carlos

Simply put, the leaf is burned by the laser beam, converting its cellulose to graphite through a pyrolytic process. The graphite body is then printed in the leaf's structure in a form suitable for use as a sensor.

To attain the best results, the CO₂ laser's parameters, such as laser power, pyrolysis scan rate, and scan gap, are methodically changed during the production process.

The sensors were characterized by morphological and physicochemical methods, permitting exhaustive exploration of the novel carbonized surface generated on the leaves. Furthermore, the applicability of the sensors was confirmed by tests involving the detection of dopamine and paracetamol in biological and pharmaceutical samples. For dopamine, the system proved efficient in a linear range of 10–1,200 micromoles per liter, with a detection limit of 1.1 micromole per liter. For paracetamol, the system worked well in a linear range of 5-100 micromoles per liter, with a detection limit of 0.76.

Bruno Janegitz, Professor, Laboratory of Sensors, Nanomedicine and Nanostructured Materials, Federal University of São Carlos

The electrochemical sensors made from fallen tree leaves demonstrated a commendable level of repeatability and reasonable analytical performance in the dopamine and paracetamol proof-of-concept tests. These results underscore the potential of these sensors as a viable substitute for traditional substrates.

Substituting fallen tree leaves for conventional materials yields significant gains in terms of cost-cutting and, above all, environmental sustainability.

The leaves would have been incinerated or, at best, composted. Instead, they were used as a substrate for high-value-added devices in a major advancement for the fabrication of next-generation electrochemical sensors.

Bruno Janegitz, Professor, Laboratory of Sensors, Nanomedicine and Nanostructured Materials, Federal University of São Carlos

Journal Reference:

‌Blasques, V, R., et al. (2024) Green Fabrication and Analytical Application of Disposable Carbon Electrodes Made from Fallen Tree Leaves Using a CO₂ Laser. ACS Sustainable Chemistry & Engineering. doi.org/10.1021/acssuschemeng.3c06526.