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.