SARS-CoV-2 detection using photoluminescent-polymer nanofibers with nucleic acids as luminescence quenchers

Abstract

Computed tomography and PCR techniques have become the gold standards for the diagnosis of COVID-19. However, these techniques are time-consuming and require specialists to carry them out. The LAMP technique offers similar or even better results to those obtained by PCR but in much less analysis time and with fewer requirements. In addition, the use of portable biosensors for rapid detection using antigen-antibody reactions has also been implemented. Although these types of devices are effective, they can produce a high number of false negatives because they detect the presence of the virus once the body has responded to its presence, which can take several days after contagion. It is necessary to use devices that can offer rapid detection with the reliability of a PCR technique. Biosensors are devices capable of identifying infectious agents according to the way they were functionalized and prepared. The use of polymeric fibers in creating devices for the sensing of contaminants has already been reported previously. The advantages these materials offer, such as their high surface-to-size ratio, make them excellent candidates for use in biosensors since they offer a large surface area to be used as a detection substrate. On the other hand, the use of lanthanide complexes in polymer matrixes has been demonstrated to be an effective way to give luminescent properties to the nanofibers for optical sensing approaches. In addition, it has been observed that the presence of Multiwalled carbon nanotubes in nanofibers can enhance the intensity of the luminescence coming from the fibers with lanthanide complexes. Moreover, the luminescence quenching of lanthanide complexes by DNA has also been addressed before. In this work, the methodology for polystyrene nanofibers obtention by the electrospinning technique is presented. The synthesis of a europium complex is described in addition to different routes for carbon nanotubes functionalization and their subsequent incorporation into the nanofibers along with the luminescent complex. Different characterization techniques analyzed all the obtained materials. Finally, and as a proof of concept, the ability of both the europium complex and the luminescent nanofibers to be used as sensing probes for pathogenic DNA is assessed. Homogenous fibers were obtained when a combination of carbon nanotubes and Eu complex was used compared to when only PS or PS/Eu complex was used. Furthermore, it was possible to show the responsiveness of the materials to many DNA copies from a LAMP reaction; a quenching in the overall luminescence was observed and taken as an indicator of the presence of the antigen. It is believed that these results will contribute to future sensing devices being more accurate and efficient than the currently available.