An ultra-sensitive electrochemical biosensor using the Spike protein for capturing antibodies against SARS-CoV-2 in point-of-care.

This work presents an innovative ultra-sensitive biosensor having the Spike protein on carbon-based screen-printed electrodes (SPEs), for monitoring in point-of-care antibodies against SARS-CoV-2, a very important tool for epidemiological monitoring of COVID-19 infection and establishing vaccination schemes. In an innovative and simple approach, a highly conductive support is combined with the direct adsorption of Spike protein to enable an extensive antibody capture. The high conductivity was ensured by using carboxylated carbon nanotubes on the carbon electrode, by means of a simple and quick approach, which also increased the surface area. These were then modified with EDC/NHS chemistry to produce an amine layer and undergo Spike protein adsorption, to generate a stable layer capable of capturing the antibodies against SARS-CoV-2 in serum with great sensitivity. Electrochemical impedance spectroscopy was used to evaluate the analytical performance of this biosensor in serum. It displayed a linear response between 1.0 â€‹pg/mL and 10 â€‹ng/mL, with a detection limit of ∼0.7 â€‹pg/mL. The analysis of human positive sera containing antibody in a wide range of concentrations yielded accurate data, correlating well with the reference method. It also offered the unique ability of discriminating antibody concentrations in sera below 2.3 â€‹µg/mL, the lowest value detected by the commercial method. In addition, a proof-of-concept study was performed by labelling anti-IgG antibodies with quantum dots to explore a new electrochemical readout based on the signal generated upon binding to the anti-S protein antibodies recognised on the surface of the biosensor. Overall, the alternative serologic assay presented is a promising tool for assessing protective immunity to SARS-CoV-2 and a potential guide for revaccination.

Land-Use Effect on Olive Groves Pest Prays oleae and on Its Potential Biocontrol Agent Chrysoperla carnea.

Olive growing has been intensified through the simplification of agricultural landscapes. In order to rethink the environmental drawbacks of these practices, conservation biological control techniques have been examined. In this work, Prays oleae and its natural enemy Chrysoperla carnea were monitored to account for the effects of the amount and diversity of different land-uses. We found that C. carnea showed an attraction to areas with high abundances of P. oleae but this predator did not display any affection by the different land-uses. Inversely, P. oleae abundance was lower in diverse landscapes and higher in simplified ones. Importantly, higher abundances of C. carnea were related to lower infestation levels of P. oleae in the late part of the season. These results corroborate the attraction of C. carnea to the olive moth, highlighting the potential of C. carnea as a biological control agent of this pest, assert that the promotion of land-use diversity can reduce P. oleae and confirm that landscapes dominated by olive groves can promote this pest. The present study aims at contributing to the discussion about the management of agricultural ecosystems by providing farmers with sustainable alternatives that do not have harmful effects on the environment and public health.