The unique chemical and physical properties of nanoparticles make them extremely suitable for designing new and improved sensing devices, especially electrochemical sensors and biosensors. Many kinds of nanoparticles, such as metal, oxide and semiconductor nanoparticles have been used for constructing electrochemical sensors and biosensors, and these nanoparticles play different roles in different sensing systems. The important functions provided by nanoparticles include the immobilization of biomolecules, the catalysis of electrochemical reactions, the enhancement of electron transfer between electrode surfaces and proteins, labeling of biomolecules and even acting as reactant. This minireview addresses recent advances in nanoparticle-based electrochemical sensors and biosensors, and summarizes the main functions of nanoparticles in these sensor systems.

Advanced printing and deposition methodologies are revolutionising the way biological molecules are deposited and leading to changes in the mass production of biosensors and biodevices. This revolution is being delivered principally through adaptations of printing technologies to device fabrication, increasing throughputs, decreasing feature sizes and driving production costs downwards. This review looks at several of the most relevant deposition and patterning methodologies that are emerging, either for their high production yield, their ability to reach micro- and nano-dimensions, or both. We look at inkjet, screen, microcontact, gravure and flexographic printing as well as lithographies such as scanning probe, photo- and e-beam lithographies and laser printing. We also take a look at the emerging technique of plasma modification and assess the usefulness of these for the deposition of biomolecules and other materials associated with biodevice fabrication.

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Aqueous polyaniline (PANI) nanodispersions doped with dodecylbenzenesulfonic acid (DBSA) were synthesized and successfully inkjet-printed using a piezoelectric desktop printer. This paper examines the optimization and characterization of the nanoparticulate formulation for optimal film electrochemistry and stability. PANI nanoparticle synthesis was optimized in terms of the ratio of monomer (aniline) to oxidant (ammonium persulphate, APS) and dopant (DBSA). Particle size, UV-vis spectroscopy, electrochemical, and conductivity analyses were performed on all materials. Optimal synthesis conditions were found to be at a molar ratio of 1.0:0.5:1.2 aniline/APS/DBSA. This resulting nanodispersion showed a uniform particle size distribution of approximately 82 nm, and UV-vis analysis indicated a high doping level. These synthetic conditions resulted in the highest conductivity, and the electrochemistry of the resulting films was well-defined and stable. Surface tension analysis and rheological studies demonstrated that the aqueous nanodispersions were suitable for inkjet printing. Successful inkjet printing of these polyaniline nanoparticulate formulations is demonstrated.

This review summarizes recent advances in the development of electrochemical sensors and biosensors based on nanomaterial doped conducting polymers.

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.

Screen-printing technology is widely used for the mass-production of disposable electrochemical sensors. The practical utility of carbon screen-printed electrodes has been exploited, despite the fact that little is known about the nature of the electrode reactions. (Wang, J.; Pedrero, M.; Sakslumd, H.; Hammerich, O.; Pingarron, J. Electrochemical activation of screenprinted carbon strips. The Analyst 1996, 121 (3), [345][346][347][348][349][350]. Given the complexity of carbon electrodes in general, and differences in the composition of commercial carbon inks, the question arises as to how such differences and complexity affect their electrochemical reactivity. The aim of this

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