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1.  Development of a Sensor System for the Determination of Sanitary Quality of Grapes 
Sensors (Basel, Switzerland)  2013;13(4):4571-4580.
An instrument for the automatic quantification of glycerol in grapes has been developed. We verify here that this analyte can be used as a benchmark of a serious disease affecting the grapevines, namely Botrytis cinerea. The core of the instrument is an amperometric biosensor consisting of a disposable screen printed electrode, generating the analytical signal thanks to a bi-enzymatic process involving glycerol dehydrogenase and diaphorase. The full automation of the analysis is realised by three micropumps and a microprocessor under control of a personal computer. The pumps allow the correct and constant dilution of the grape juice with a buffer solution also containing [Fe(CN)6]3− redox mediator and the injection of NAD+ cofactor when the baseline signal reaches a steady state; the instrument leads to automated reading of the analytical signal and the consequent data treatment. Although the analytical method is based on an amperometric technique that, owing to heavy matrix effects, usually requires an internal calibration, the analyses indicate that a unique external calibration is suitable for giving accurate responses for any grapes, both white and black ones.
doi:10.3390/s130404571
PMCID: PMC3673100  PMID: 23567525
amperometric sensor; glycerol; glycerol dehydrogenase; diaphorase; Botrytis cinerea; screen printed electrodes; micropumps; microprocessor; grapes
2.  Peptide nucleic acids tagged with four lysine residues for amperometric genosensors 
Artificial DNA, PNA & XNA  2012;3(2):80-87.
A homothymine PNA decamer bearing four lysine residues has been synthesized as a probe for the development of amperometric sensors. On one hand, the four amino groups introduced make this derivative nine times more soluble than the corresponding homothymine PNA decamer and, on the other hand, allow the stable anchoring of this molecule on Au nanostructured surface through the terminal -NH2 moieties. In particular, XPS and electrochemical investigations performed with hexylamine, as a model molecule, indicate that the stable deposition of primary amine derivatives on such a nanostructured surface is possible and involves the free electron doublet on the nitrogen atom. This finding indicates that this PNA derivative is suitable to act as the probe molecule for the development of amperometric sensors.
 
Thanks to the molecular probe chosen and to the use of a nanostructured surface as the substrate for the sensor assembly, the device proposed makes possible the selective recognition of the target oligonucleotide sequence with very high sensitivity.
doi:10.4161/adna.20777
PMCID: PMC3429534  PMID: 22772036
DNA recognition; PNA; amperometric genosensors; nanostructured surfaces; amine deposition

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