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Application of nanoparticulate conducting polyaniline in novel biosensor fabricationprocesses

Principal Researcher: Dr. Aoife Morrin

Collaborator: Prof. Gordon Wallace, Institute of Intelligent Polymer Research, University of Wollongong, NSW, Australia

The considerable flexibility of conducting polymers in their chemical structures and their reversible redox characteristics make them attractive materials for sensing, in particular biosensing. They can act as excellent materials for immobilisation of biomolecules and have rapid electron transfer properties for the fabrication of efficient biosensors. Modification of carbon paste electrodes with conducting polymer is generally straightforward, and most commonly done by electrochemical synthesis from monomer. Today, the sensing field demands further development of this platform for fabrication of cheap electrodes as disposable, reproducible sensors, that have the ability to obviate the need for regeneration.

Polyaniline (PANI) has been widely studied due to its excellent characteristics as a conducting polymer. However, like all materials, it possesses some characteristics that are non-ideal. The use of nanoscale particles help to overcome processability issues associated with polyaniline. Such nanoparticles are readily dispersed in aqueous media. Nanodimensional conducting polymers have also been shown to exhibit greater conductivity and more rapid electrochemical switching speeds. These nanoscale materials offer bulk solution handling characteristics with nanoscale material control and can be combined with biomolecular species at this point, or subsequent to their fabrication on a sensor surface. This work is investigating nanoparticles of PANI, (synthesised using dodecylbenzenesulphonic acid (DBSA) as a dopant) as a novel, highly processable, non-diffusional mediating species in enzyme biosensing applications. These nanoparticles are readily dispersed in aqueous media, helping overcome some of the processability issues with polyaniline. The emphasis of the project is to develop low cost, disposable biosensor platforms using these types of conducting nanomaterials.

Modification of screen-printed electrodes can be  readily done with these aqueous nanoparticle dispersions, where the nanoparticles are simply cast by a drop-coating method. After suitable pH adjustment, it was shown that horseradish peroxidase (HRP) enzyme could be added to the dispersion, and cast simultaneously with the conducting polyaniline. This effective fabrication method involves no electrochemical steps, and as such is easily amenable to mass production. The feasibility of casting enzyme with PANI nanoparticles is demonstrated. More accurate deposition of protein-containing inks onto electrode surfaces is currently being examined. Work is currently underway to transfer the drop-coating protocol from manual deposition to large-scale production by mechanical methods such as ink-jet printing.                                   

 

Polyaniline exiting tip of a MicroFab CT-M3-01 JetDrive piezoelectric ink-jet printing device

 

relevant publications

  • Luo X.L., Killard A.J., Smyth, M.R. (2007). Nanocomposite and nanoporous polyaniline conducting polymers exhibit enhanced catalysis of nitrite reduction. Chem. Eur. J. 13 (7) 2138-2143.
  • Ambrosi, A., Morrin, A., Killard A.J., Smyth, M.R. (2007). Characterization of immunological interactions at an immunoelectrode by scanning electron microscopy. Electroanalysis 19(2-3) 244-252.
  • Luo X.L., Killard A.J., Morrin, A., Smyth, M.R. (2006). In situ electropolymerised silica-polyaniline core-shell structures: Electrode modification and enzyme biosensor enhancement. Electrochim. Acta 52(5) 1865-1870.
  • Luo X.L., Killard A.J., Morrin, A., Smyth, M.R. (2006). Enhancement of a conducting polymer-based biosensor using carbon nanotube-doped polyaniline. Anal. Chim. Acta 575 (1): 39-44.
  • Luo X.L., Morrin A., Killard A.J., Smyth, M.R. (2006). Application of nanoparticles in electrochemical sensors and biosensors. Electroanal. 18 (4) 319-326.
  • Lori J.A., Morrin A., Killard A.J., Smyth, M.R. (2006). Development and characterization of nickel-NTA-polyaniline modified electrodes. Electroanal. 18 (1): 77-81.
  • Ngamna O., Morrin A., Moulton S.E., Killard A.J., Smyth M.R., Wallace G.G. (2005). An HRP based biosensor using sulphonated polyaniline. Synth. Met.  Part 2 Sp. Iss. SI 153 (1-3) 185-188.
  • Morrin, A., Wilbeer, F., Ngamna, O., Killard, A.J., Moulton, S., Smyth, M.R., Wallace, G.G. (2005). Novel biosensor fabrication methodology based on processable conducting polyaniline nanoparticles. Electrochem. Comm., 3:317-322.
  • Iwuoha, E.I., Williams-Dottin, A.R., Hall, L.A, Morrin, A., Mathebe, G.N., Smyth, M.R. and Killard, A. J. (2004). Electrochemistry and application of a novel monosubstituted squarate electron transfer mediator in a glucose oxidase-doped poly(phenol) sensor. Pure App. Chem., 76:789-799.
  • Morrin, A., Moutloali, R.M., Killard, A.J., Smyth, M.R., Darkwa, J. and Iwuoha, E.I. (2004). Electro-catalytic sensor devices: (I) cyclopentadienylnickel(II) thiolato schiff base monolayer self-assembled on gold. Talanta, 64:30-38.
  • Morrin, A., Moutloali, R.M., Killard, A.J., Smyth, M.R., Darkwa, J. and Iwuoha, E.I. (2004). Organic phase cyclopentadienylnickel thiolate sensor system for electrochemical determination of sulfur dioxide. Electroanal., 16:1944-1948.
  • Morrin, A., Ngamna, O., Killard, A.J., Moulton, S., Smyth, M.R., Wallace, G.G. (2004). An amperometric biosensor fabricated from polyaniline nanoparticles. Electroanal., 17:423-430.
  • Morrin, A., Killard, A.J., Smyth, M.R. (2003). Electrochemical characterisation of commercial and home-made screen-printed carbon electrodes. Anal. Lett., 36:2021-2039.
  • Morrin, A., Guzman, A., Killard, A.J., Pingarron, J.M., Smyth, M.R. (2003) Characterisation of horseradish peroxidase immobilised on an electrochemical biosensor by colorimetric and amperometric techniques. Biosens. Bioelectron., 18:715-720.