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    Aumento De Sensibilidade De Sensor De Ressonância Plasmônica De Superfície Para Detecção De Proteínas
    (Universidade Federal de São Paulo (UNIFESP), 2017-02-10) Macedo, Erenildo Ferreira De [UNIFESP]; Tada, Dayane Batista [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    This study describes the development of a method to increase the sensitivity of a Surface Plasmon Resonance Biosensor (SPR) to detect proteins at low concentrations. The method used gold nanoparticles (AuNPs) in two different approaches. In the first one, the protein to be detected was covalently linked to the AuNPs and then analyzed on the SPR sensor. In the second approach AuNPs were functionalized with specific antibody to capture protein of interest free in solution. The chosen proteins were lectins Arachis hypogaea (PNA) and Canavalia ensiformis (conA), and the biomarker of ovarian cancer, mesothelin. The second approach was more efficient in amplifying the signal, providing a better resolution response and reduced detection limit. The sensor response was compared to the detection of free protein in solution and the detection of protein covalently linked to AuNPs. In this order, the limit of detection for the approach of using the AuNPs to capture proteins was 98% and 89% lower in PNA detection and 79% and 77% lower in conA detection. It is possible that the higher efficiency was due to the role of AuNPs in enhancing the concentration of protein at NPs surface, as well as in providing the plasmonic coupling between the AuNPs and the gold surface of the SPR sensor. This result motivated the use of capture AuNPs in the detection of the protein mesothelin, an important biomarker used in the diagnosis of ovarian cancer and mesothelioma. The test was performed based on the cutoff point used to diagnose ovarian cancer (415pM). The result showed a detection limit of 35pM, which was of great relevance, demonstrating the efficiency of detection of mesothelin at low concentrations, demonstrating the potential use of this method for future studies in the area of cancer diagnosis.