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- Breast cancer biomarker (HER2-ECD) detection using a molecularly imprinted electrochemical sensorPublication . Pacheco, João; Rebelo, Patrícia; Freitas, Maria; Nouws, Henri; Delerue-Matos, CristinaThe extracellular domain of the human epidermal growth factor receptor 2 (HER2-ECD) is a protein breast cancer biomarker. Its quantification in peripheral blood could provide an important contribution to diagnostics and patient follow-up. In this work an electrochemical molecularly imprinted polymer (MIP) sensor for the quantification of HER2-ECD was developed. The MIP was electropolymerized by cyclic voltammetry using a solution containing phenol and HER2-ECD on a screen-printed gold electrode (AuSPE). The sensor was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The analysis of HER2-ECD was performed by differential pulse voltammetry using ([Fe(CN)6]3−/4−as redox probe. The linear range was established in the concentration interval from 10 to 70 ng/mL HER2-ECD, with a limit of detection of 1.6 ng/L and a limit of quantification of 5.2 ng/mL. Through the analysis of other protein biomarkers, the MIP sensor was found to be selective. Furthermore, these proteins did not interfere in the analysis of the selected biomarker. The developed sensor was used for the analysis of spiked human serum samples, providing adequate recovery values and precise results. The outcomes of this study indicate that the developed MIP sensor could be useful in the non-invasive analysis of HER2-ECD in breast cancer patients.
- Molecularly imprinted electrochemical sensor prepared on a screen printed carbon electrode for naloxone detectionPublication . Lopes, Frederico; Pacheco, João; Rebelo, Patrícia; Delerue-Matos, CristinaNaloxone (NLX) is a pharmaceutical used as opioid antagonist. A molecular imprinted polymer electrochemical sensor for simple and rapid detection of NLX was prepared through the modification of commercial available screen printed carbon electrode (SPCE). The SPCE was modified with multi-walled carbon nanotubes (MWCNT) by drop coating to increase the signal response and improve the sensitivity. The MIP preparation was carried out via in situ electropolymerization using 4-aminobenzoic acid (4-ABA) as functional monomer. The morphology of the obtained sensor was characterized by scanning electron microscopy (SEM). Several parameters controlling the preparation and performance of the MIP sensor were studied and optimized. The electrochemical behavior of NLX at MIP and control non-imprinted (NIP) sensor was evaluated by differential pulse voltammetry (DPV), demonstrating a better MIP response and the success of the imprinting. The proposed MIP/MWCNT/SPCE sensor showed a linear relationship between peak current intensity and NLX concentration in the range between 0.25 and 10.0 μM, with limits of detection (LOD) and quantification (LOQ) of 0.20 μM and 0.67 μM respectively. The repeatability and reproducibility were also tested with relative standard deviations (RSD) of 4.6 and 9.6% respectively. Moreover, the applicability of the method was successfully confirmed with detection of NLX in biological samples (urine and human serum). The sensor is promising to be used for screening NLX in point-of-care people with opioid overdose.
- Molecularly imprinted electrochemical sensor for the point-of-care detection of a breast cancer biomarker (CA 15-3)Publication . Pacheco, João; Silva, Marta S.V.; Freitas, Maria; Nouws, Henri; Delerue-Matos, CristinaThe incidence of breast cancer has been increasing over the years. To control and monitor this disease several tumor biomarkers have been proposed for early diagnosis, patient follow-up and/or treatment guidance. The only serum breast cancer biomarker in current use is the cancer antigen 15-3 (CA 15-3). In this work a molecularly imprinted polymer (MIP)-based electrochemical (voltammetric) sensor to monitor breast cancer was developed, based on direct surface imprinting of CA 15-3 on a screen-printed gold electrode (Au-SPE). The imprinting was performed in two steps: (1) adsorption of CA 15-3 on the surface of the Au-SPE and (2) electropolymerization of 2-aminophenol around the adsorbed protein. After extraction of the imprinted protein voltammetric analysis was conducted using hexacyanoferrate(II/III) as redox probe, measuring the signals before and after protein binding. The sensor was characterized by voltammetric techniques and electrochemical impedance spectroscopy, and the analytical responses of imprinted and non-imprinted polymer sensors were studied. A linear relationship between the peak current intensity of the redox probe and the logarithm of CA 15-3 concentration was established between 5 and 50 U mL−1, achieving a limit of detection of 1.5 U mL−1. The prepared MIP-sensor provides fast (15 min) analysis and is cheap, easy to prepare, disposable and could easily be integrated in small portable point-of care devices.