A highly sensitive electrochemical methodology for end-point detection of loop-mediated isothermal nucleic acid amplification reactions was developed. It is based on the oxidation process of phenol red (PR), commonly used as a visual indicator. The dependence of its redox process on pH, which changes during amplification, allows performing quantitative measurements. Thus, the change in the oxidation potential of PR during the amplification is used, for the first time, as the analytical signal that correlates with the number of initial DNA copies. As a proof-of-concept, the amplification of the pneumolysin gene from Streptococcus pneumoniae, one of the main pathogens causing community-acquired pneumonia, is performed. Combination of isothermal amplification with electrochemical detection, performed on small-size flexible electrodes, allows easy decentralization. Adaptation to the detection of other pathogens causing infectious diseases would be very useful in the prevention of future epidemics.

Quantitative polymerase chain reaction (qPCR) is considered the gold standard for pathogen detection. However, improvement is still required, especially regarding the possibilities of decentralization. Apart from other reasons, infectious diseases demand on‐site analysis to avoid pathogen spreading and increase treatment efficacy. In this paper, the detection of SARS‐CoV‐2 is carried out by reverse transcription loop‐mediated isothermal amplification, which has the advantage of requiring simple equipment, easily adaptable to decentralized analysis. It is proposed, for the first time, the use of palladium nanoclusters (PdNCs) as indicators of the amplification reaction at end point. The pH of the medium decreases during the reaction and, in turn, a variation in the catalytic activity of PdNCs on the oxygen reduction reaction (ORR) can be electrochemically observed. For the detection, flexible and small‐size screen‐printed electrodes can be premodified with PdNCs, which together with the use of a simple and small electrochemical equipment would greatly facilitates their integration in field‐deployable devices. This would allow a faster detection of SARS‐CoV‐2 as well as of other future microbial threats after an easy adaptation.

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