Browsing by Author "Othmane, Ali"
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- Dual-aptasensor array: optimization of the aptamers immobilizationPublication . Ezziddine, Maha; Meirinho, Sofia G.; Veloso, Ana C.A.; Dias, L.G.; Rodrigues, Lígia R.; Othmane, Ali; Peres, António M.In the present work it is intended to establish the optimal experimental conditions that allow enhancing the performance of an electrochemical dual-aptasensor array for the detection of osteopontin, which has been reported as a cancer biomarker. The aptamer concentration, time and temperature of immobilization onto dual-screen printed gold electrodes (Dual-SPGE), as well as the aptamer-protein interaction time were evaluated using a 2k factorial experimental design. The preliminary results allowed identifying the optimal experimental conditions, namely: (i) aptamer concentration of 0.5 μM for both DNA and RNA aptamers; (ii) incubation temperature of 4ºC; (iii) time for aptamer immobilization onto the Dual-SPGE at 4ºC of 20 min; and, (iv) aptamer-protein interaction time of 30 min. The evaluation of the best experimental conditions was carried out by cyclic and square wave voltammetry using a ferro/ferricyanide solution ([Fe(CN)6]3−/4−) as a redox probe. Aptamers were immobilized onto the Dual-SPGE via streptavidin-biotin interaction. With the preliminary optimal experimental conditions herein obtained, we will further assess the sensitivity of the Dual-SPGE using synthetic plasma.
- Dual-aptasensor array: optimization of the aptamers immobilizationPublication . Ezziddine, Maha; Merinho, Sofia G.; Veloso, Ana C.A.; Dias, L.G.; Rodrigues, Lígia R.; Othmane, Ali; Peres, António M.Cancer diseases are associated with the presence of several protein biomarkers. Aptasensor arrays allow early multiple-detection of these biomarkers which can hold significant improvements in the cancer patients lives. Clinical studies suggest that osteopontin, a protein that is over expressed in tumor cells, may be potentially used as a diagnostic and prognostic biomarker for several cancers.
- Optimization of the aptamers’ immobilization conditions for maximizing the response of a dualaptasensor for cancer biomarker detectionPublication . Meirinho, Sofia G.; Ezziddine, Maha; Veloso, Ana C.A.; Dias, L.G.; Rodrigues, Lígia R.; Othmane, Ali; Peres, António M.Osteopontin (OPN) is a protein that is present in several body fluids and has been reported as a possible cancer biomarker, being its overexpression associated with tumour progression and metastasis [1,2]. A simple and sensitive method that allows the simultaneous detection of single or multiple cancer biomarkers is envisaged and may be an important tool in cancer diagnosis. In this work, two bioreceptors specific for OPN, a RNA aptamer (OPN-R3) previously described by Mi and co-workers [3] and a DNA aptamer (C10K2) developed by our research group, were biotinylated and immobilized on a dual-screen printed gold electrode through streptavidin-biotin interaction. The voltammetric signals generated by the dual-aptasensor array, after the formation of the aptamers-protein complex, were monitored using cyclic voltammetry (CV) and square- wave voltammetry (SWV), using [Fe(CN)6]−3/−4 as a redox probe. The optimal immobilization conditions for the dual-aptasensor array were established by response surface methodology. The maximum voltammetric response was obtained for a 0.5 μM aptamer concentration after 20 min of aptamers’ immobilization and 30 min of aptamer- OPN interaction time at an incubation temperature of 4ºC. The satisfactory preliminary results obtained, although needing further confirmation for synthetic or real human samples, point out that the proposed electrochemical dual-aptasensor array could be a simple and sensitive tool for the detection of OPN, as well as for other potential cancer biomarkers and therefore, may be applied in the future for cancer disease monitoring.
- Optimization of the aptamers’ immobilization conditions for maximizing the response of a dualaptasensor for cancer biomarker detectionPublication . Meirinho, Sofia G.; Ezziddine, Maha; Veloso, Ana C.A.; Dias, L.G.; Rodrigues, Lígia R.; Othmane, Ali; Peres, António M.A simple and sensitive method that allows the simultaneous detection of single or multiple cancer biomarkers is envisaged and may be an important tool in cancer diagnosis. Osteopontin (OPN) is a protein that is present in several body fluids and has been reported as a possible cancer biomarker. The voltammetric signals generated by the dual-aptasensor array, after the formation of the aptamers-protein complex, were monitored using cyclic voltammetry (CV) and square-wave voltammetry (SWV), using [Fe(CN)6] 3/ 4 as a redox probe. The aim of this work is to optimize the experimental conditions to development a label-free voltammetric dual-aptasensor array for the detection of human osteopontin using a 2k factorial experimental design.