Sabato D’Auria

A surface acoustic wave bio-electronic nose for detection of volatile odorant molecules.

In this work, a bio-electronic nose for vapour phase detection of odorant molecules based on surface acoustic wave (SAW) resonators is presented. The biosensor system is composed of an array of five SAW resonators coated with three types of odorant-binding proteins (OBPs): the wild-type OBP from bovine (wtbOBP), a double-mutant of the OBP from bovine (dmbOBP), and the wild-type OBP from pig (wtpOBP). High resolution deposition of OBPs onto the active area of SAW resonators was implemented through laser-induced forward transfer (LIFT). The resonant frequency shifts of the SAW resonators after the deposition of the biomolecules confirmed the immobilisation of the proteins onto the Al/Au inter-digital transducers (IDTs). In addition, a low increase of insertion losses with a limited degradation of Q-factors is reported. The bio-electronic nose fabricated by LIFT is tested in nitrogen upon exposure to separated concentrations of R-(-)-1-octen-3-ol (octenol) and R-(-)-carvone (carvone) vapours. The bio-electronic nose showed low detection limits for the tested compounds (i.e. 0.48 ppm for the detection of octenol, and 0.74 ppm for the detection of carvone). In addition, the bio-sensing system was able to discriminate the octenol molecules from the carvone molecules, making it pertinent for the assessment of food contamination by moulds, or for the evaluation of indoor air quality in buildings.

A near-infrared fluorescence assay method to detect patulin in food.

Patulin (PAT) is a toxic secondary metabolite (mycotoxin) of different fungal species belonging to the genera Penicillium, Aspergillus, and Byssochlamys. They can grow on a large variety of food, including fruits, grains, and cheese. The amount of PAT in apple derivative products is a crucial issue because it is the measure of the quality of both the used raw products and the performed production process. Actually, all current methodologies used for the quantification of PAT are time-consuming and require skilled personnel beyond the sample pretreatment methods (e.g., high-performance liquid chromatography, mass spectrometry, and electrophoresis techniques). In this work, we present a novel fluorescence polarization approach based on the use of emergent near-infrared (NIR) fluorescence probes. The use of these fluorophores coupled to anti-PAT antibodies makes possible the detection of PAT directly in apple juice without any sample pretreatment. This methodology is based on the increase of fluorescence polarization emission of a fluorescence-labeled PAT derivative on binding to specific antibodies. A competition between PAT and the fluorescence-labeled PAT derivative allowed detecting PAT. The limit of detection of the method is 0.06 μg/L, a value that is lower than maximum residue limit of PAT fixed at 50 μg/L from European Union regulation.

Binding of mycotoxins to proteins involved in neuronal plasticity: a combined in silico/wet investigation

We have applied a combined computational procedure based on inverse and direct docking in order to identify putative protein targets of a panel of mycotoxins and xenobiotic compounds that can contaminate food and that are known to have several detrimental effects on human health. This procedure allowed us to identify a panel of human proteins as possible targets for aflatoxins, gliotoxin, ochratoxin A and deoxynivalenol. Steady-state fluorescence and microscale thermophoresis experiments allowed us to confirm the binding of some ofxa0these mycotoxins to acetylcholinesterase and X-linked neuroligin 4, two proteins involved in synapse activity and, particularly for the second protein, neuronal plasticity and development. Considering the possible involvement of X-linked neuroligin 4 in the etiopathogenesis of autism spectrum syndrome, this finding opens up a new avenue to explore the hypothetical role of these xenobiotic compounds in the onset of this pathology.

The fluorescent monomeric protein Kusabira Orange. Pressure effect on its structure and stability

The structure and stability of the fluorescent protein monomeric Kusabira Orange (mKO), a GFP-like protein, was studied under different pressure levels and in different chemical environments. At different pH values (between pH 7.4 and pH 4.0) and under a pressure up to 600 MPa (at 25 °C), mKO did not show significant fluorescence spectral changes, indicating a structural stability of the protein. In more extreme chemical conditions (at pH 4.0 in the presence of 0.8 M guanidine hydrochloride), a marked reduction of mKO fluorescence intensity emission was observed at pressures above 300 MPa. This fluorescence emission quenching may be due to the loss of the intermolecular bonds and, consequently, to the destructuration of the mKO chromophore structure. Since the electrostatic and hydrophobic interactions as well as the salt bridges present in proteins are usually perturbed under high pressure, the reduction of mKO fluorescence intensity emission is associated to the perturbation of the protein salt bridges network.

Analysis of the binding of mycotoxins to proteins involved in ASD with a combined computational/experimental approach.

Reference EPFL-CONF-214088doi:10.1002/pro.2823View record in Web of Science Record created on 2015-12-02, modified on 2017-05-12

Surface Acoustic Wave Biosensor Based on a Recombinant Bovine Odorant-Binding Protein

In this work we present a Surface Acoustic Wave (SAW) biosensor system based on a recombinant bovine odorant-binding protein (bOBP) suitable to detect boletus odorant.

Fluorescence Biosensors for Continuously Monitoring the Blood Glucose Level of Diabetic Patients

Diabetes mellitus is increasing rapidly and will double in the next 15 years.1,2 In addition, diabetic patients have a mortality excess for cardiovascular disease up to 2.5-4 times more than non diabetic population.3,4 In the last years became evident a cluster of cardiovascular risk factors like hypertension, central obesity, dyslipidemia with low HDL-cholesterol and high triglycerides, impaired fibrinolysis, hypercoagulation and endothelial dysfunction that has been called metabolic syndrome.5 The underlying defect that shares all these alterations is insulin resistance with compensatory hyperinsulinemia that is associated with increased cardiovascular events and mortality.6,7 Patients with diabetes and/or metabolic syndrome must be treated aggressively about every risk factors to minimize the cardiovascular events. Hyperglycemia is clearly related to microvascular complication of diabetes: retinopathy, nephropathy and neuropathy, while for macrovascular complication other coexisting risk factors are important. Many studies have demonstrated that an intensive treatment of diabetes reduces the macro and microvascular complications and the best results are obtained when every risk factor is aggressively treated.8–10