SARS-COV-2 viral RNA detection through oligonucleotide-capped nanoporous anodic alumina supports.

We describe herein a sensor containing nanoporous anodic alumina (NAA) as sensing platform to identify SARS-COV-2 RNA using a gating mechanism. The system is based on NAA that contains a fluorescent dye (Rhodamine B; RhB) and is capped with an oligonucleotide sequence that hybridize specifically a region of SARS-CoV-2 genome. In the presence of RNA from SARS-COV-2 virus, the oligonucleotide of the surface is displaced, uncapping the pores, and producing a delivery of RhB. The detection of the virus is achieved measuring the fluorescence of the fluorophore. The nanosensor demonstrates to be highly sensitive and selective in aqueous buffers and in biological media, having a limit of detection (LOD) of 50 ± 30 copies mL-1 of SARS-CoV-2 RNA extracted from patients. Moreover, preliminary results using 18 real nasopharyngeal swab samples indicate the potential of the system to differentiate between infected and non-infected patients. Compared to the conventional RT-PCR method, in our system there is no need for sample pretreatment or RNA isolation, providing diagnostic outcomes within 60 mins while maintaining a high level of reliability.