Fabrication, Characterization, Modification, and Application of Carbons Electrodes Derived from Paper

C. D. GARCIA; T. E. BENAVIDEZ ; G. DURAN; A. RIOS; J. GIULIANI ; F. COMBA; E. EVANS

San Diego, California

Simposio; 229th The Electrochemical Society Meeting. Carbon Nanostructures and Devices; 2016

The Electrochemical Society

Since the first report in 1962, the field of biosensors has made astounding progress. Among those, electrochemical biosensors have now moved beyond the classic examples involving glucose oxidase and have been adapted to quantify a wide range of analytes, feature adequate sensitivity for clinical applications, offer independence from optical interferences, require minimal sample and power consumption, and are highly compatible with modern microfabrication techniques. While recent advances in nanotechnology have allowed the development of improved sensors based on modified metallic surfaces, the vast majority of the community has opted for carbon-based materials. These materials share a common structure composed of sp2-bonded atoms that supports electrical conductivity, the capacity to form charge-transfer complexes, unique optical properties, chemical reactivity, and the possibility to interact with a variety of biorecognition elements. While most of these materials have the potential to enable operational electrochemical sensors, most of them offer limited surface area and their application for the development of electrochemical biosensors is restricted by the resistivity of the material, which results in quasi-reversible or irreversible electrochemical behavior. Addressing these deficiencies, this presentation will describe the possibility of preparing electrodes by pyrolysis of paper. The resulting electrodes, which can be fabricated from a variety of substrates, feature low resistivity, large surface area, and uniform thickness. More importantly, the electrodes can be used for the development of biosensors by simply immersing them in a solution containing a selected enzyme. Herein we present results related to the selection of the substrate, the characterization performed (microscopy and electrochemical) as well as their potential for the development of an electrochemical biosensor. To increase the electrochemical activity of the sensors, the presentation will also discuss results related to a one-step method for the synthesis of paper-based carbon electrodes modified with CuNPs. The methodology is based on the pyrolysis (under reductive conditions) of paper strips pretreated with a CuSO4 solution. This process, one of the simplest reported to date, yields abundant CuNPs distributed on the surface of the carbonized cellulose fibers. The resulting electrodes were characterized by scanning electron microscopy, EDX, Raman spectroscopy, and electrical/electrochemical techniques. Their potential application as working electrodes for non-enzymatic determination of glucose in alkaline media was also demonstrated. Electrodes were also integrated to paper-based microfluidic devices and applied for the analysis of clinically-relevant analytes with limits of detection relevant to biomedical applications.