SARS-CoV-2 and SARS-CoV share a common human receptor ACE2. Protein-protein interaction structure modeling indicates that spike-RBD of the two viruses also has similar overall binding conformation and binding free energy to ACE2. In vitro assays using recombinant ACE2 proteins and ACE2 expressing cells confirmed the two coronaviruses' similar binding affinities to ACE2. The above studies provide experimental supporting evidences and possible explanation for the high transmissibility observed in the SARS-CoV-2 outbreak. Potent ACE2-blocking SARS-CoV neutralizing antibodies showed limited cross-binding and neutralizing activities to SARS-CoV-2. ACE2-non-blocking SARS-CoV RBD antibodies, though with weaker neutralizing activities against SARS-CoV, showed positive cross-neutralizing activities to SARS-CoV-2 with an unknown mechanism. These findings suggest a trade-off between the efficacy and spectrum for therapeutic antibodies to different coronaviruses, and hence highlight the possibilities and challenges in developing broadly protecting antibodies and vaccines against SARS-CoV-2 and its future mutants.

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To balance the requirements of transparency, mechanical strength, stable conductivity, and biocompatibility of traditional electronic conductive hydrogels in intelligent devices is still a formidable challenge. The increase of ionic conductive gels has provided decent transparency, stretchability, and wearability in artificial skins but the dilemma still exists between stability and functionality. This article reports a facile strategy to develop a visual thermosensitive physically and chemically dual cross-linked ion-based conductive hydrogel through in situ free-radical copolymerization, achieving robust mechanical properties, an obvious response, and a multiple sensing process. As an archetypical template, the ion-based conductive hydrogel offers an evaluation and monitoring of electrocardiogram (ECG), which is comparable to commercial electrodes. Intriguingly, such kinds of conductive gels exhibit tunable upper critical solution temperature (UCST) behaviors. Taking advantage of their high temperature responsive accuracy, the visualized qualitative observation for smart response and digitized measurement and calibration for thermal stimulus can be simultaneously achieved. We therefore believe that this work will inspire the design of skinlike sensing materials, promote the preparation of biocompatible and multiple sensing abilities and the synthesis of intelligent hydrogels, and realize their applications in biosensors, wearable devices, and biomedicine.

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