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This paper describes the optimal implementation of three newly conceived sensors for both health and environmental applications, utilizing a wide range of detection methods and complex nanocomposites. The first one is inorganic and based on matrices of calcium oxide, the second is based on protein arrays and a third one is based on Langmuir-Blodgett laccase multi-layers. Special attention was paid to detecting substances significant to the environment (such as carbon dioxide) and medicine (drug administration, cancer diagnosis and prognosis) by means of amperometric, quartz crystal microbalance with frequency (QCM_F) and quartz crystal microbalance with dissipation monitoring (QCM_D) technologies. The resulting three implemented nanosensors are described here along with proofs of principle and their corresponding applications.

Homogeneous matrices of calcium oxide (CaO) were prepared by mixing this material with polyethylene glycol (PEG) acting as malleable inert support in order to obtain processable composites. Preliminary tests were carried out to assess the best concentration of CaO in the composite, individuated in the CaO/PEG weight ratio of 1/4. Experimental data highlighted that the composite was able to selectively detect carbon dioxide (CO2) via a nanogravimetric method by performing the experiments inside an atmosphere-controlled chamber filled with CO2. Furthermore, the composite material showed a linear absorption of CO2 as a function of the gas concentration inside the atmosphere-controlled chamber, thus paving the way for the possible use of these matrices for applications in the field of sensor devices for long-term evaluation of accumulated environmental CO2.

Matrices and sensors resulting from inorganic, organic and biological nanocomposites are presented in this overview. The term nanocomposite designates a solid combination of a matrix and of nanodimensional phases differing in properties from the matrix due to dissimilarities in structure and chemistry. The nanoocomposites chosen for a wide variety of health and environment sensors consist of Anodic Porous Allumina and P450scc, Carbon nanotubes and Conductive Polymers, Langmuir Blodgett Films of Lipases, Laccases, Cytochromes and Rhodopsins, Three-dimensional Nanoporous Materials and Nucleic Acid Programmable Protein Arrays.

A new nanostructured composite film based on thiol gold nanoparticles dispersed in polycarbonate and prepared by evaporating a solution of 1-dodecanthiol gold nanoparticles and polycarbonate was developed for applications as optical lenses. Lenses with superior mechanical properties, coloring and UV ray absorption and with the same transparency as the matrix were obtained. The supporting highly transparent polycarbonate matrix and the chloroform solution of thiol gold nanoparticles, 3 nm mean size, was mixed according to a doping protocol employing different concentrations of thiol gold nanoparticles vs. polycarbonate. The presence of nanoparticles in the polymer films was confirmed by the spectrophotometric detection of the characteristic absorbance marker peak at 540–580 nm. The nanostructured films obtained show a better coverage in the UV-vis range (250–450 nm) even at very low doping ratios, of the order of 1:1,000. These results offer a very promising approach towards the development of efficient nanostructured materials for applications to optical lenses.

In the present work the layer-by-layer nano-assembly technique was used for the development of complex catalytic microparticles on the basis of firefly luciferase (FL). FL films containing 1, 2, or 3 monolayers were assembled on silver electrode QCM-resonators and on 520-nm diameter sulfonated polystyrene latex by alternate adsorption of FL and polycations using electrostatic interactions for the interlayer interaction. The assembly process was studied with quartz crystal microbalance, UV-vis spectroscopy, and microelectrophoresis (surface potential). Structural studies of the resulting multilayers confirmed stepwise deposition of FL and cationic poly(dimethyldiallyl ammonium chloride) with a bilayer thickness of 14 nm; a systematic shift of the surface potential from +28 mV for poly(dimethyldiallyl ammonium chloride) to –14 mV for luciferase outermost layer was established. The functionality and stability of the biocolloids were demonstrated by monitoring the intensity of the light emission. Factors influencing the light emitted upon catalytic activity of FL such as the number of luciferase layers in the film and polyion layer at the outermost layer were studied. © 2003 Wiley Periodicals. Biotechnol Bioeng 84: 286–291, 2003. [ABSTRACT FROM AUTHOR]

The recombinant catalytic subunit of human protein kinase CK2 bas been mutagenised at the C-terminal region in an attempt to induce this tail to fold. We suppose in fact that this unstructured C-terminus just might be responsible for the high degradability of the human enzyme. On the basis of theoretical calculations we choose to substitute two distal prolines with alanines (PA 382-384). The mutant bas been purified to the electrophoretic homogeneity by means of three chromatographic steps. By circular dichroism Spectroscopy we verified if the double amino acids substitution reflected on the secondary structure of the recombinant &agr; subunit. According to our theoretical predictions, we observed that the &agr;-helix content of the protein increased when the two distal prolines were substituted by alanines. Moreover the mutant catalytic subunit shows a reduced ability to bind a classical inhibitor such as heparin. [ABSTRACT FROM AUTHOR]