Soft robots possess many attributes that are difficult, if not impossible, to achieve with conventional robots composed of rigid materials 1,2. Yet, despite recent advances, soft robots must still be tethered to hard robotic control systems and power sources 3-10. New strategies for creating completely soft robots, including soft analogues of these crucial components, are needed to realize their full potential. Here we report the untethered operation of a robot composed solely of soft materials. The robot is controlled with microfluidic logic 11 that autonomously regulates fluid flow and, hence, catalytic decomposition of an on-board monopropellant fuel supply. Gas generated from the fuel decomposition inflates fluidic networks downstream of the reaction sites, resulting in actuation 12. The body and microfluidic logic of the robot are fabricated using moulding and soft lithography, respectively, and the pneumatic actuator networks, on-board fuel reservoirs and catalytic reaction chambers needed for movement are patterned within the body via a multi-material, embedded 3D printing technique 13,14. The fluidic and elastomeric architectures required for function span several orders of magnitude from the microscale to the macroscale. Our integrated design and rapid fabrication approach enables the programmable assembly of multiple materials within this architecture, laying the foundation for completely soft, autonomous robots. Soft robotics is a nascent field that aims to provide safer, more robust robots that interact with humans and adapt to natural environments better than do their rigid counterparts. Unlike conventional robots composed of rigid materials, soft robots based on hydrogels 15,16 , electroactive polymers 17 , granular media 18 and elastomers 5,19 exhibit elastic moduli ranging from 10 kPa to 1 GPa (ref. 1), are physically resiliant 7,20 and have the ability to passively adapt to their environment 1,2,19. Moulded and laminated elastomers with embedded pneumatic networks are widely used materials in soft robotics 1,21,22. Actuation of these elastomeric composites occurs when interconnected channels that make up the pneumatic network are inflated with incompressible fluids or gases supplied via tethered pressure sources 1. Robotic end effectors with bioinspired 10 and rapid 6 actuation, deployable crawlers 3,7 and swimmers 8 with complex body motions, and robust jumpers 9,23 have been developed on the basis of this design strategy. However, in each case, these robots are either tethered to or carry rigid systems for power and control, yielding hybrid soft-rigid systems 4,7-9. Creating a new class of fully soft, autonomous robots 24 is a grand challenge, because it requires soft analogues of the control and power hardware currently used. Recently, monopropellant fuels have been suggested as a promising fuel source for pneumatically actuated soft robots 4,12. Their rapid decomposition into gas upon exposure to a catalyst offers a strategy for powering soft robotic systems that obviates the need for batteri...

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COVID-19, caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), represents a global crisis. Key to SARS-CoV-2 therapeutic development is unraveling the mechanisms driving high infectivity, broad tissue tropism and severe pathology. Our 2.85 Å cryo-EM structure of SARS-CoV-2 spike (S) glycoprotein reveals that the receptor binding domains (RBDs) tightly bind the essential free fatty acid (FFA) linoleic acid (LA) in three composite binding pockets. The pocket also appears to be present in the highly pathogenic coronaviruses SARS-CoV and MERS-CoV. LA binding stabilizes a locked S conformation giving rise to reduced ACE2 interaction in vitro. In human cells, LA supplementation synergizes with the COVID-19 drug remdesivir, suppressing SARS-CoV-2 replication. Our structure directly links LA and S, setting the stage for intervention strategies targeting LA binding by SARS-CoV-2.

The discovery of large multiprotein complexes in cells has increased the demand for improved heterologous protein production techniques to study their molecular structure and function. Here we describe MultiBac, a simple and versatile system for generating recombinant baculovirus DNA to express protein complexes comprising many subunits. Our method uses transfer vectors containing a multiplication module that can be nested to facilitate assembly of polycistronic expression cassettes, thereby minimizing requirements for unique restriction sites. The transfer vectors access a modified baculovirus DNA through Cre-loxP site-specific recombination or Tn7 transposition. This baculovirus has improved protein expression characteristics because specific viral genes have been eliminated. Gene insertion reactions are carried out in Escherichia coli either sequentially or concurrently in a rapid, one-step procedure. Our system is useful for both recombinant multiprotein production and multigene transfer applications.