Development of polypyrrole (nano)structures decorated with gold nanoparticles toward immunosensing for COVID-19 serological diagnosis.

The rapid and reliable detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroconversion in humans is crucial for suitable infection control. In this sense, many studies have focused on increasing the sensibility, lowering the detection limits and minimizing false negative/positive results. Thus, biosensors based on nanoarchitectures of conducting polymers are promising alternatives to more traditional materials since they can hold improved surface area, higher electrical conductivity and electrochemical activity. In this work, we reported the analytical comparison of two different conducting polymers morphologies for the development of an impedimetric biosensor to monitor SARS-CoV-2 seroconversion in humans. Biosensors based on polypyrrole (PPy), synthesized in both globular and nanotubular (NT) morphology, and gold nanoparticles are reported, using a self-assembly monolayer of 3-mercaptopropionic acid and covalently linked SARS-CoV-2 Nucleocapsid protein. First, the novel hybrid materials were characterized by electron microscopy and electrochemical measurements, and the biosensor step-by-step construction was characterized by electrochemical and spectroscopic techniques. As a proof of concept, the biosensor was used for the impedimetric detection of anti-SARS-CoV-2 Nucleocapsid protein monoclonal antibodies. The results showed a linear response for different antibody concentrations, good sensibility and possibility to quantify 7.442 and 0.4 ng/mL of monoclonal antibody for PPy in the globular and NT morphology, respectively. The PPy-NTs biosensor was able to discriminate serum obtained from COVID-19 positive versus negative clinical samples and is a promising tool for COVID-19 immunodiagnostic, which can contribute to further studies concerning rapid, efficient, and reliable detections.

Green does not always mean go: A sulfated galactan from Codium isthmocladum green seaweed reduces melanoma metastasis through direct regulation of malignancy features.

Melanoma is the most lethal form of skin cancer, with a worldwide increase in incidence. Despite the increased overall survival of metastatic melanoma patients given recent advances in targeted and immunotherapy, it still has a poor prognosis and available treatment options carry diverse severe side effects. Polysaccharides from seaweed have been shown to exert antitumor activities. Here we show in vitro and in vivo antitumor activities of a sulfated homogalactan (named 3G4S) from Codium isthmocladum seaweed in the B16-F10 murine melanoma cell line. 3G4S did not induce cytotoxicity or proliferation changes; however, it was able to reduce solid tumor growth and metastasis, while not inducing side effects in mice. B16-F10 cells traits related to the metastatic cascade were also impaired by 3G4S, reducing cell invasion, colony-forming capacity and membrane glycoconjugates. Therefore, 3G4S shows promising antitumor activities without the commonly associated drawbacks of cancer treatments and can be further explored.