LNNano - Brazilian Nanotechnology National Laboratory

Monitoring the Surface Chemistry of Functionalized Nanomaterials with a Microfluidic Electronic Tongue

Flavio M. Shimizu,‡,∂ Anielli M. Pasqualeti,†,∂ Fagner R. Todão,†,∂ Jessica F. A. de Oliveira,†,§,€ Luis C. S. Vieira, Suely P. C. Gonçalves, Gabriela H. da Silva,†,|| Mateus B. Cardoso,†,§,€ Angelo L. Gobbi, Diego S. T. Martinez,†,|| Osvaldo N. Oliveira, Jr., and Renato S. Lima*,†,§

Laboratório Nacional de Nanotecnologia, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo 13083-970, Brasil

Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, São Paulo 13560-970, Brasil

§Instituto de Química, Universidade Estadual de Campinas, Campinas, São Paulo 13083-970, Brasil

Laboratório Nacional de Luz Síncrotron, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo 13083-970, Brasil

|| Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Piracicaba, São Paulo 13416-000, Brasil

These authors contributed equally to this work

ABSTRACT: Advances in nanomaterials have led to a tremendous progress in different areas with the development of high performance and multifunctional platforms. However, a relevant gap remains in providing the mass-production of these nanomaterials with reproducible surfaces. Accordingly, the monitoring of such materials across their entire life cycle becomes mandatory to both industry and academy. In this paper, we use a microfluidic electronic tongue (e-tongue) as a user-friendly and cost-effective method to classify nanomaterials according to their surface chemistry. The chip relies on a new single response e-tongue with association of capacitors in parallel, which consisted of stainless steel microwires coated with SiO2, NiO2, Al2O3, and Fe2O3 thin films. Utilizing impedance spectroscopy and a multidimensional projection technique, the chip was sufficiently sensitive to distinguish silica nanoparticles and multi-walled carbon nanotubes dispersed in water in spite of the very small surface modifications induced by distinct functionalization and oxidation extents, respectively. Flow analyses were made acquiring the analytical readouts in a label-free mode. The device also allowed for multiplex monitoring in an unprecedented way to speed up the tests. Our goal is not to replace the traditional techniques of surface analysis, but rather propose the use of libraries from e-tongue data as benchmark for routine screening of modified nanomaterials in industry and academy.

This article was published in ACS Sensors (ACS, DOI: 10.1021/acssensors.8b00056). This project has been conducted in Laboratório de Microfabricação (LMF, LNNano) in collaboration with Universidade de São Paulo.

Direct link: https://pubs.acs.org/doi/10.1021/acssensors.8b00056