SARS-CoV-2 papain-like protease activates nociceptors to drive sneeze and pain.

SARS-CoV-2, the virus responsible for COVID-19, triggers symptoms such as sneezing, aches and pain.1 These symptoms are mediated by a subset of sensory neurons, known as nociceptors, that detect noxious stimuli, densely innervate the airway epithelium, and interact with airway resident epithelial and immune cells.2-6 However, the mechanisms by which viral infection activates these neurons to trigger pain and airway reflexes are unknown. Here, we show that the coronavirus papain-like protease (PLpro) directly activates airway-innervating trigeminal and vagal nociceptors in mice and human iPSC-derived nociceptors. PLpro elicits sneezing and acute pain in mice and triggers the release of neuropeptide calcitonin gene-related peptide (CGRP) from airway afferents. We find that PLpro-induced sneeze and pain requires the host TRPA1 ion channel that has been previously demonstrated to mediate pain, cough, and airway inflammation.7-9 Our findings are the first demonstration of a viral product that directly activates sensory neurons to trigger pain and airway reflexes and highlight a new role for PLpro and nociceptors in COVID-19.

Charge Dispersion Strategy for High-Performance and Rain-Proof Triboelectric Nanogenerator.

Triboelectric nanogenerator (TENG) is becoming a sustainable and renewable way of energy harvesting and self-powered sensing because of low cost, simple structure, and high efficiency. However, the output current of existing TENGs is still low. It is proposed that the output current of TENGs can be dramatically improved if the triboelectric charges can distribute inside the triboelectric layers. Herein, a novel single-electrode conductive network-based TENG (CN-TENG) is developed by introducing a conductive network of multiwalled carbon nanotubes in dielectric triboelectric layer of thermoplastic polyurethane (TPU). In this CN-TENG, the contact electrification-induced charges distribute on both the surface and interior of the dielectric TPU layer. Thus, the short-circuit current of CN-TENG improves for 100-fold, compared with that of traditional dielectric TENG. In addition, this CN-TENG, even without packing, can work stably in high-humidity environments and even in the rain, which is another main challenge for conventional TENGs due to charge leakage. Further, this CN-TENG is applied for the first time, to successfully distinguish conductive and dielectric materials. This work provides a new and effective strategy to fabricate TENGs with high output current and humidity-resistivity, greatly expanding their practical applications in energy harvesting, movement sensing, human-machine interaction, and so on.

Selectively Adsorbed p-Aminothiophenol Molecules Improve the Electrocatalytic and Photo-Electrocatalytic Hydrogen Evolution on Au/TiO2.

Electrocatalytic hydrogen evolution reaction (HER) is receiving increasing attention as an effective process to produce clean energy. The commonly used precious metal catalysts can be hybridized with semiconductors to form heterostructures for the improvement of catalytic efficiency and reduction of cost. It will be promising to further improve the efficiency of heterostructure-based nanocatalysts in electrocatalytic and photocatalytic HER using a simple and effective method. Herein, we improve the efficiency of Au/TiO2 in electrocatalytic and photo-electrocatalytic HER by selectively adsorbing p-aminothiophenol (PATP) molecules. The PATP molecules are adsorbed on the gold surface by using a simple solution-based method and favor the charge separation at the Au-TiO2 interface. We also compare the PATP molecules with other thiophenol molecules in the enhancement of electrocatalytic HER. The PATP-induced enhancement in electrocatalysis is then further investigated by density functional theory (DFT) calculations, and this enhancement is attributed to a reduction in Gibbs energy of adsorbed hydrogen after surface adsorption of PATP molecules. This work provides a simple, cost-effective, and highly efficient approach to improve the electrocatalytic and photo-electrocatalytic efficiency of Au/TiO2, and this approach could be easily extended to other heterostructure-based nanocatalysts for performance enhancement and may be used in many other catalytic reactions.

Density-of-States Matching-Induced Ultrahigh Current Density and High-Humidity Resistance in a Simply Structured Triboelectric Nanogenerator.

Triboelectric nanogenerators (TENGs) can covert mechanical energy into electricity in a clean and sustainable manner. However, traditional TENGs are mainly limited by the low output current, and thus their practical applications are still limited. Herein, a new type of TENG is developed by using conductive materials as the triboelectric layers and electrodes simultaneously. Because of the matched density of states between the two triboelectric layers, this simply structured device reaches an open-circuit voltage of 1400 V and an ultrahigh current density of 1333 mA m-2 when poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) film and copper (Cu) or aluminum (Al) foil are used as the triboelectric pair. The current density increases by nearly three orders of magnitude compared with traditional TENGs. More importantly, this device can work stably in high-humidity environments, which is always a big challenge for traditional TENGs. Surprisingly, this TENG can even perform well in the presence of water droplets. This work provides a new and effective strategy for constructing high-performance TENGs, which can be used in many practical applications in the near future.

Adsorbed p-Aminothiophenol Molecules on Platinum Nanoparticles Improve Electrocatalytic Hydrogen Evolution.

Electrocatalytic hydrogen evolution is an important approach to produce clean energy, and many electrocatalysts (e.g., platinum) are developed for hydrogen production. However, the electrocatalytic efficiency of commonly used metal catalysts needs to be improved to compensate their high cost. Herein, the electrocatalytic efficiency of platinum nanoparticles (PtNPs) in hydrogen evolution is largely improved via simple surface adsorption of sub-monolayer p-aminothiophenol (PATP) molecules. The overpotential goes down to 86.1 mV, which is 50.2 mV lower than that on naked PtNPs. This catalytic activity is even better than that of 20 wt.% Pt/C, despite the much smaller active surface area of PATP-adsorbed PtNPs than Pt/C. It is theoretically and experimentally confirmed that the improved electrocatalytic activity in hydrogen evolution can be attributed to the change in electronic structure of PtNPs induced by surface adsorption of PATP molecules. More importantly, this strategy can also be used to improve the electrocatalytic activity of palladium, gold, and silver nanoparticles. Therefore, this work provides a simple, convenient, and versatile method for improving the electrocatalytic activity of metal nanocatalysts. This surface adsorption strategy may also be used for improving the efficiency of many other nanocatalysts in many reactions.

High-Performance Organic Electrochemical Transistor Based on Photo-annealed Plasmonic Gold Nanoparticle-Doped PEDOT:PSS.

Organic electrochemical transistors (OECTs), particularly the ones based on PEDOT:PSS, are excellent candidates for chemical and biological sensing because of their unique advantages. Improving the sensitivity and stability of OECTs is crucially important for practical applications. Herein, the transconductance of OECT is improved by 8-fold to 14.9 mS by doping the PEDOT:PSS channel with plasmonic gold nanoparticles (AuNPs) using a solution-based process followed by photo annealing. In addition, the OECT also possesses high flexibility and cyclic stability. It is revealed that the doping of AuNPs increases the conductivity of PEDOT:PSS and the photo annealing improves the crystallinity of the PEDOT:PSS channel and the interaction between AuNPs and PEDOT:PSS. These changes lead to the increase in transconductance and cyclic stability. The prepared OECTs are also demonstrated to be effective in sensitive detection of glucose within a wide concentration range of 10 nM-1 mM. Our OECTs based on photo-annealed plasmonic AuNP-doped PEDOT:PSS may find great applications in chemical and biological sensing, and this strategy may be extended to prepare many other high-performance OECT-based devices.

Non-canonical odor coding in the mosquito.

Aedes aegypti mosquitoes are a persistent human foe, transmitting arboviruses including dengue when they feed on human blood. Mosquitoes are intensely attracted to body odor and carbon dioxide, which they detect using ionotropic chemosensory receptors encoded by three large multi-gene families. Genetic mutations that disrupt the olfactory system have modest effects on human attraction, suggesting redundancy in odor coding. The canonical view is that olfactory sensory neurons each express a single chemosensory receptor that defines its ligand selectivity. We discovered that Ae. aegypti uses a different organizational principle, with many neurons co-expressing multiple chemosensory receptor genes. In vivo electrophysiology demonstrates that the broad ligand-sensitivity of mosquito olfactory neurons depends on this non-canonical co-expression. The redundancy afforded by an olfactory system in which neurons co-express multiple chemosensory receptors may increase the robustness of the mosquito olfactory system and explain our long-standing inability to disrupt the detection of humans by mosquitoes.

Sensory Discrimination of Blood and Floral Nectar by Aedes aegypti Mosquitoes.

Blood-feeding mosquitoes survive by feeding on nectar for metabolic energy but require a blood meal to develop eggs. Aedes aegypti females must accurately discriminate blood and nectar because each meal promotes mutually exclusive feeding programs with distinct sensory appendages, meal sizes, digestive tract targets, and metabolic fates. We investigated the syringe-like blood-feeding appendage, the stylet, and discovered that sexually dimorphic stylet neurons taste blood. Using pan-neuronal calcium imaging, we found that blood is detected by four functionally distinct stylet neuron classes, each tuned to specific blood components associated with diverse taste qualities. Stylet neurons are insensitive to nectar-specific sugars and respond to glucose only in the presence of additional blood components. The distinction between blood and nectar is therefore encoded in specialized neurons at the very first level of sensory detection in mosquitoes. This innate ability to recognize blood is the basis of vector-borne disease transmission to millions of people worldwide.