Suchergebnisse

In this work, we combined electrochemical techniques with SPR (eSPR) for the label-free detection of cancer biomarker miRNA-145. Detection was performed in a simple two-step assay. In the first step, the gold sensor surface, previously functionalized with a self-assembled monolayer (SAM) of thiolated RNA probes is incubated with the sample containing the target RNA biomarker. In this step, hybridization of RNA fragments with complementary immobilized probes was monitored in real-time by SPR. In the second step, eSPR measurements were performed to improve the sensitivity of the hybridization assay. Potential-induced deposition of a redox probe at the sensor surface resulted in enhanced SPR response promoted by the electrochemical process, thereby allowing the detection of miRNA-145 at femtomolar level (LOD = 0.56 fM), without sample derivatization or post-hybridization treatment for signal amplification. Good linearity was achieved (R2 = 0.984) over the concentration range from 1.0 fM and 10 nM. Furthermore, the developed eSPR biosensor showed high selectivity towards single-base and two-base mismatch sequences and detection of target miRNA-145 in synthetic human serum was successful achieved. ; This research had the financial support of FCT (Fundação para a Ciência e Tecnologia) and co-financed by the European Union (FEDER funds) under the Partnership Agreement PT2020, Research Grants UIDB/00081/2020 (CIQUP), NORTE-2020 under the project RamSERS (grant NORTE-01-0247-FEDER-017834). J.A. Ribeiro (ref. SFRH/BPD/105395/2014) acknowledges FCT under the QREN – POPH – Advanced Training, subsidized by European Union and national MEC funds. ; info:eu-repo/semantics/publishedVersion

This work reports the development of a simple and rapid electrochemical immunosensor for the determination of breast cancer biomarker Cancer Antigen 153 (CA153). Disposable and cost-effective chips, consisting of gold screen-printed electrodes (AuSPEs), were used to develop the portable electrochemical devices for monitoring the biomarker in point-of-care (PoC), under clinical context. The biosensor preparation consisted of two simple steps. First, a self-assembled monolayer (SAM) of mercaptosuccinic acid (MSA) was formed at the AuSPE surface. Then, the CA153 antibody was covalently bound to the carboxylic groups standing at the electrode surface using EDC/NHS chemistry. The performance of the developed immunosensor was evaluated by assessing the sensor sensitivity, linear response interval, selectivity and detection limit (LOD). The developed immunosensor provided a wide linear concentration range (from 1.0 to 1000UmL1) and low detection levels were achieved (LOD of 0.95UmL1), enabling the sensitive detection of the cancer biomarker at clinically relevant levels, using square wave voltammetry (SWV) as electroanalytical technique. Moreover, selectivity studies performed against other cancer biomarkers (CA 125 and CA 199) revealed that the antibody has high selectivity for CA15-3 antigen. The immunosensor was applied to the quantification of CA15-3 in artificial serum samples with satisfactory results. ; This research had the financial support of FCT (Fundação para a Ciência e Tecnologia) and co-financed by the European Union (FEDER funds) under the Partnership Agreement PT2020, Research Grants Pest-C/QUI/UIDB/00081/2020 (CIQUP) and NORTE-01-0247-FEDER-017834 (project RamSERS). J.A. Ribeiro (ref. SFRH/BPD/105395/2014) and C.M. Pereira (ref. SFRH/BSAB/150320/2019) acknowledge FCT under the QREN – POPH – Advanced Training, subsidized by European Union and national MEC funds. ...