An Amperometric Enzyme Biosensor Fabricated from Polyaniline Nanoparticles

Abstract

The biosensor described here uses a novel aqueous-based nanoparticulate polyaniline (PANI), doped with dodecylbenzenesulfonic acid (DBSA). The nanoparticles were applied to a glassy carbon electrode surface by electrodeposition techniques, and horseradish peroxidase (HRP) was subsequently electrostatically adsorbed to the nanoparticle-modified surface. This biosensor format was demonstrated for H 2 O 2 sensing. Electrodeposited polymer nanoparticles resulted in highly ordered conductive nanostructured films, which were examined by scanning electron microscopy (SEM), atomic force microscopy (AFM), profilometry and spectroelectrochemistry. The surface of the films were characterized by a uniform array of nanoparticulate PANI (nanoPANI/DBSA) nodules and were shown to have a thickness of 350 nm. Physical techniques have shown that the nanofilms possess properties which allow for uniform electrostatic adsorption of protein to take place. This effective biosensor format, exhibits higher signal-tobackground ratios and shorter response times than previous PANI biosensor configurations.

Electrochemical Sensors

“…136 The electrodeposition of the polyaniline nanoparticles instead of polyaniline itself on the electrode lead to a smoother, highly ordered conductive nanostructured film. HRP immobilized on the nanoPANI film through electrostatical interaction showed improved deposition characteristics and better signal to noise ratios compared to the direct PANI depositing approach.…”

Novel biosensor fabrication methodology based on processable conducting polyaniline nanoparticles

“…However, even at these volumes, the electron transfer rates of these PANI films in HCl (1 mol dm À3 ) was still not ideal. Drop-coating may not result in a continuous polymer chain as the nanoparticles may not aggregate on the electrode surface in an ordered fashion, as occurs for the electrodeposition method [19], which may reduce the quality of the charge propagation throughout the film and hence the electrochemistry. It was not possible to deposit films using lower volumes than 5 ll, as these volumes did not cover the surface of the 3 mm diameter electrode adequately due to the low surface energy of the carbon paste electrode.…”

“…Recently, our group used this methodology to characterise a similar biosensor platform where a more complex, electrodeposition technique was used for the immobilisation of nanoPANI/DBSA films on carbon electrodes [19]. The average catalytic signal from the cast films was comparable to these electrodeposited nanoPANI/DBSA on glassy carbon, where the HRP was electrostatically immobilised (42 ± 11 lA) [19]. However, the S/B of the cast film was only about half that of the electrosynthesised biosensor (61 ± 3 lA).…”

“…A recent paper has reported, the application of these nanoparticles in a biosensing application where the nanoparticles were electrodeposited on the surface of glassy carbon electrodes to form nanofilms [19]. HRP was subsequently electrostatically attached to these films.…”

“…This was shown to be an effective biosensor format. The signal-to-background (S/B) was comparable to the biosensor developed using electrodeposited nanoparticles [19] but has the added advantage of ease of fabrication; a method that would lend itself to techniques such as ink-jet printing [20,21] for mass production of biosensors.…”