This biosensor uses a novel aqueous-based nanoparticulate polyaniline (PANI), synthesised using dodecylbenzenesulphonic acid (DBSA) and aniline as starting material. These polymer nanoparticles have been electrodeposited on to the surface of carbon electrodes resulting in conductive nano-films, which were examined by electrochemistry, scanning electron microscopy (SEM), atomic force microscopy (AFM), profilometry and spectroelectrochemistry. Biomolecules were then electrostatically adsorbed onto this surface and physical techniques have shown that the nanofilm possesses properties which allow for uniform adsorption of protein to take place. This effective biosensor format has been characterised using a horseradish peroxidase (HRP) and H2O2 format. This sensor exhibits higher signal/noise (S/N) ratios and quicker response times than previous PANI biosensor formats developed by our group, due to its nanofilm characteristics