Electrochemical biosensors for sensitive molecular diagnostics

Biosensors are self-contained analytical devices in which a bioreceptor is integrated with a transducer. The interaction between the bioreceptor and a target analyte generates a signal suitable for analytical purposes. In electrochemical biosensors, a change in the redox state of the biorecognition/analyte system generates a change in an electrochemical quantity which can be monitored by electroanalytical techniques. Electrochemical sensors can also be miniaturized using ultramicroelectrodes and nanoelectrodes and their arrays as transducers. These devices are characterized by high specificity and sensitivity and improved detection limits. Within the frame of the TRANS2CARE project, the Laboratory of Electrochemical Sensors (http://lsegroup.wix.com/website-lse-group) of the University Ca’ Foscari of Venice is collaborating with some of the project partners in order to develop bioelectrochemical sensors/nanosensors for clinical/molecular diagnostics

Molecular diagnostics with electrochemical biosensors and arrays

Biosensors are self-contained analytical devices in which a bioreceptor is integrated with a transducer. The interaction between the bioreceptor and a target analyte generates a signal suitable for analytical purposes. In electrochemical biosensors, a change in the redox state of the biorecognition/analyte system generates a change in an electrochemical quantity which can be monitored by electroanalytical techniques. Electrochemical sensors can be miniaturized using ultramicroelectrodes and nanoelectrodes and their arrays as transducers. These devices are characterized by high specificity and sensitivity and improved detection limits. Biosensors can be used by non-specialist operators at the point of care. For the above reasons, within the frame of the Trans2care project, the Laboratory of Electrochemical Sensors of the University Ca’ Foscari of Venice will collaborate with the project partners to develop electrochemical sensors suitable for specific clinical needs

Ensembles of nanoelectrodes modified with gold nanoparticles: characterization and application to DNA-hybridization detection

A new method to increase the active area (A (act)) of nanoelectrode ensembles (NEEs) is described. To this aim, gold nanoparticles (AuNPs) are immobilized onto the surface of NEEs using cysteamine as a cross-linker able to bind the AuNPs to the heads of the nanoelectrodes to obtain the so-called AuNPs-NEEs. The analysis of the cyclic voltammograms recorded in pure supporting electrolyte showed that the presence of the nanoparticles reflects in an, approximately, ten-times increase in the electrochemically active area of the ensemble. The measurement of the amount of electroactive polyoxometalates, which can be adsorbed on the gold surface of NEEs vs. AuNPs-NEEs, confirmed a significant increase of active area for the latter. These evidences indicate that there is a good electronic connection between the AuNPs and the underlying nanoelectrodes. The possibility to exploit AuNPs-NEEs for biosensing application was tested for the case of DNA-hybridization detection. After immobilization on the gold surface of AuNPs-NEEs of a thiolated single-stranded DNA, the hybridization with complementary sequences labeled with glucose oxidase (GOx) was performed. The detection of the hybridization was achieved by adding to the electrolyte solution the GOx substrate (i.e., glucose) and a suitable redox mediator, namely the (ferrocenylmethyl) trimethylammonium (FA(+)) cation; when the hybridization occurs, an electrocatalytic increase of the oxidation current of FA(+) is recorded. Comparison of electrocatalytic current recorded at DNA modified NEEs and AuNPs-NEEs indicate, for the latter, a significant increase in sensitivity in the detection of the DNA-hybridization event

Experimental thermal performance comparison of pure and metal foam-loaded PCMs

The thermal performance of latent heat thermal energy storage (LHTES) systems considerably depends on thermal conductivity of adopted phase change materials (PCMs). To increase the low thermal conductivity of these materials, pure PCMs can be loaded with metal foams. In this study, the melting process of pure and metal-foam loaded phase change materials placed in a rectangular shape case is experimentally investigated by imposing a constant heat flux at the top. Two different paraffin waxes with melting point of about 35°C are tested. The results obtained with pure PCM are compared with those achieved from the use of PCM combined with two different porous metals: a 10 PPI aluminum foam with 96% porosity and a 20 PPI copper foam with 95% porosity. The results demonstrate how metal foams lead to a significant improvement of conduction heat transfer reducing significantly the melting time and the temperature difference between the heater and PCM

Supplementary data for the article: Habtamu, H. B.; Sentic, M.; Silvestrini, M.; De Leo, L.; Not, T.; Arbault, S.; Manojlovic, D.; Sojic, N.; Ugo, P. A Sensitive Electrochemiluminescence Immunosensor for Celiac Disease Diagnosis Based on Nanoelectrode Ensembles. Analytical Chemistry 2015, 87 (24), 12080–12087. https://doi.org/10.1021/acs.analchem.5b02801

Supporting information for: [https://doi.org/10.1021/acs.analchem.5b02801]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2014

Supplementary data for the article: Habtamu, H. B.; Sentic, M.; Silvestrini, M.; De Leo, L.; Not, T.; Arbault, S.; Manojlovic, D.; Sojic, N.; Ugo, P. A Sensitive Electrochemiluminescence Immunosensor for Celiac Disease Diagnosis Based on Nanoelectrode Ensembles. Analytical Chemistry 2015, 87 (24), 12080–12087. https://doi.org/10.1021/acs.analchem.5b02801

Supporting information for: [https://doi.org/10.1021/acs.analchem.5b02801]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2014

Functionalized ensembles of nanoelectrodes as affinity biosensors for DNA hybridization detection

A novel electrochemical biosensor for DNA hybridization detection based on nanoelectrode ensembles (NEEs) is presented. NEEs are prepared by electroless deposition of gold into the pores of a templating track-etched polycarbonate (PC) membrane. The wide surface of the templating membrane surrounding the nanoelectrodes is exploited to bind the capture DNA probes via amide coupling with the carboxylic groups present on the PC surface. The probes are then hybridized with the complementary target labelled with glucose oxidase (GO). The occurrence of the hybridization event is detected by adding, to the supporting electrolyte, excess glucose as the substrate and the (ferrocenylmethyl) trimethylammonium cation (FA) as suitable redox mediator. In the case of positive hybridization, an electrocatalytic current is detected. In the proposed sensor, the biorecognition event and signal transduction occur in different but neighbouring sites, i.e., the PC surface and the nanoelectrodes, respectively; these sites are separated albeit in close proximity on a nanometer scale. Finally, the possibility to activate the PC surface by treatment with permanganate is demonstrated and the analytical performances of biosensors prepared with KMnO4-treated NEEs and native NEEs are compared and critically evaluated. The proposed biosensor displays high selectivity and sensitivity, with the capability to detect few picomoles of target DNA

Detection of DNA hybridization by methylene blue electrochemistry at activated nanoelectrode ensembles

Nanoelectrode ensembles (NEEs) obtained by electroless gold deposition in track-etched polycarbonate (PC) membranes are functionalized and applied for DNA hybridization detection, using methylene blue (MB) as electroactive probe. To this aim, an amine terminated ss DNA probe is immobilized on the PC surface of the NEE by reaction via carbodiimide and N -hydroxysulfosuccinimide. In order to increase the number of carboxylic groups present on PC and suitable for the functionalization, the surface of NEEs is oxidized with potassium permanganate. The presence of carboxylic functionalities is verified by spectrochemical titration with thionin acetate (THA) and the effect of the activation treatment on the electrode performances is evaluated by cyclic voltammetry (CV). After activation and functionalization with the probes, the NEE-based sensor is hybridized with complementary target sequences. The effect of the functionalization of the NEEs both with the ss DNA probe alone and after hybridization with the target, is studied by measuring the changes in the MB reduction signal by square wave voltammetry (SWV), after incubation in a suitable MB solution, rinsing and transfer to the measurement cell. It was observed that this peak signal decreases significantly after hybridization of the probe with the complementary target. Experimental evidences suggest that the interaction between MB and the guanines of ss DNA and ds DNA is at the basis of the development of the here observed analytical signal. The proposed approach allows the easy preparation and testing of NEE-based sensors for the electrochemical DNA hybridization detection

Diet, lifestyle and quality of life in breast cancer patients

Despite much research investigating the role of diet and lifestyle in breast cancer, the evidence for many dietary factors remains uncertain. The main focus of this thesis concerns the role of dietary patterns and fat in breast cancer risk and also recurrence and survival in breast cancer patients. Meta-analyses conducted in this thesis have suggested that a prudent dietary pattern may reduce the risk of breast cancer, whilst a drinker dietary pattern may increase risk. High saturated fat intake was also found to be associated with breast cancer mortality. Data obtained from participants of the DietCompLyf study, a prospective cohort of breast cancer patients in the UK, was used in this thesis to investigate dietary patterns and fat intake in relation to breast cancer recurrence and quality of life. The physical activity questionnaire used in the DietCompLyf study was also retrospectively validated in this thesis to determine how best to use the physical activity information as a confounder in the" diet and breast cancer recurrence and quality of life analyses in this thesis. In participants of the DietCompLyf study, adherence to a Traditional dietary pattern was associated with an increased risk of breast cancer recurrence. A prudent dietary pattern was associated with a better quality of life, whilst Western dietary patterns associated with a poorer quality of life in unadjusted analyses. The complicated nature of the diet and quality of life relationship was highlighted when adjustment for potential confounders modified and attenuated the observed associations. Results observed in this thesis suggest possible roles for diet in both risk of breast cancer and breast cancer mortality. Further analyses of data obtained from the DietCompLyf cohort should be conducted in the future to clarify theses observations.EThOS - Electronic Theses Online ServiceGBUnited Kingdo