The aim of the current study is to present a strategy to improve the efficiency of 5-fluorouracil (5-FU), which is widely used as antineoplastic agent against solid tumors-based on the use of gold nanocarriers to overcome the resistance of colorectal cancer cells. 5-FU was loaded on gold nanoparticles (AuNP) coated with anti-EGFR antibodies in order to target them towards colorectal cancer cells that overexpress epidermal growth factor receptors (EGFR). Physicochemical characterization has shown that AuNP size was approximately 20 nm and that AuNP functionalization led to spherical nanoparticles. Flow cytometry allowed observing that some compounds synthesized by our research group have induced apoptosis/necrosis and impaired the proliferation of colon cancer cell lines ‘HCT-116′ and ‘HT-29′. The antibody/drug combination in AuNP (AuNP 5FU EGFR) has improved the apoptosis rate and impaired cell proliferation in both cell lines, regardless of the exposure time. Overall, these results have shown that AuNP functionalization with monoclonal antibodies focused on delivering 5-FU to tumor cells is an exciting strategy against colorectal cancer.

Researchers worldwide have been studying alternatives to detect SARS-CoV-2 (COVID-19), and accurate and timely diagnosis is crucial for controlling the outbreaks of the disease. Surface plasmon resonance (SPR) is an effective strategy based on antibodies, and it can be used for simple and fast detection of antibodies due to COVID-19 infection. Accordingly, this paper reports on the highly sensitive and specific detection of antibody responses to SARS-CoV-2 spike (S) and nucleocapsid (N) proteins in COVID-19 patients. In this methodology, spike (S) and nucleocapsid (N) proteins belonging to the coronavirus genome were immobilized on the surface of a gold sensor using self-assembled monolayers. Previously, serum from COVID-19 patients was screened by immunochromatography-based COVID-19 IgG rapid test and/or ELISA in house to determine the presence of IgG titers. Serum from COVID-19-positive patients presenting with IgG were added on the surface and, at the time they bound to proteins, they caused refractive changes in the SPR angle. The antibody detection limit was determined through successive injections into the SPR apparatus – these injections ranged from pure (without dilution) to 1 : 200 μL. The system has shown good reproducibility between runs after coated surface regeneration with 0.1 M glycine-HCl solution (pH 3.0); all experiments were tested in triplicate. The antibodies targeted both S and N fragments and gave a high assay sensitivity by identifying 19 out of 20 COVID-19-positive patients. Most importantly, the assay time took less than 10 min. The results of this study indicate that the proposed simple strategy demonstrates high sensitivity and time-saving in the detection of SARS-CoV-2 response antibodies.