Rapid SARS-CoV-2 sensing through oxygen reduction reaction catalysed by Au@Pt/Au core@shell nanoparticles.

The development of rapid, accurate, sensitive, and low-cost diagnostic methods for COVID-19 detection in real-time is the unique way to control infection sources and monitor illness progression. In this work, we propose an electrochemical biosensor for the rapid and accuracy diagnosis of COVID-19, through the determination of ORF1ab specific sequence. The biosensor is based on the immobilization of a thiolated sequence partially complementary (domain 1) to ORF1ab on gold screen-printed electrodes and the use of bifunctional Au@Pt/Au core@shell nanoparticles modified with a second thiolated sequence partially complementary to ORF1ab (domain 2) as electrochemical indicator of the hybridization of DNA sequences. The synthesized Au@Pt/Au nanoparticles consist of an Au core, a shell of Pt (Au@Pt NPs), that provides an excellent electrocatalytic activity toward the oxygen reduction reaction (ORR) even after formation of hybrid biomaterials by modification, through the Au protuberances growth on the NPs surface, with an oligonucleotide with recognition ability. The ORR electrochemical activity, enhanced by the label element (Au@Pt/Au NPs), has been employed, for the first time, as indicator of the hybridization event. Based on this strategy, target sequences of the SARS-CoV-2 virus have been detected with a detection limit of 32 pM. The selectivity of the biosensor was confirmed by analysing ORF1ab sequence in the presence of DNA sequences from other viruses. The biosensor has been successfully applied to the direct detection of the virus in non-amplified samples of nasopharyngeal swabs from infected and non-infected patients. Results compare well with those obtained through RT-qPCR but our method is more rapid since does not need any amplification process.

Unfolded p53 as a Marker of Oxidative Stress in Mild Cognitive Impairment, Alzheimer's and Parkinson's Disease.

AIMS: There are several candidate biomarkers for AD and PD which differ in sensitivity, specificity, cost-effectiveness, invasiveness, logistical and technical demands. This study is aimed to test whether plasma concentration of unfolded p53 may help to discriminate among the neurodegenerative processes occurring in Mild Cognitive Impairment, Alzheimer's disease and Parkinson's disease. METHODS: An electrochemical immunosensor was used to measure unfolded p53 in plasma samples of 20 Mild Cognitive Impairment (13 males/7 females; mean age 74.95±5.31), 20 Alzheimer's (11 males/9 females; mean age: 77.25±7.79), 15 Parkinson's disease patients (12 males/3 females; mean age: 68.60 ± 7.36) and its respective age/sex/studies-matched controls. RESULTS: We observed a significantly higher concentration of unfolded p53 in the plasma of patients of each of the three pathologies with respect to their control groups (p=0.000). Furthermore, the plasma concentration of unfolded p53 was significantly higher in Alzheimer's disease patients in comparison with Mild Cognitive Impairment patients (p=0.000) and Parkinson's disease patients (p=0.006). No significant difference between Mild Cognitive Impairment and Parkinson's disease patients was observed (p=0.524). CONCLUSION: Our results suggest that unfolded p53 concentration in the plasma may be a useful biomarker for an undergoing neuropathological process that may be common, albeit with different intensity, to different diseases.