Fast and powerful: A polyelectrolyte multilayer film was used to fabricate a humidity‐responsive actuator that can drive a walking device carrying a load 120 times heavier than the actuator to walk steadily on a ratchet substrate under periodic alternation of the relative humidity (RH) between 11 and 40 % (see picture). NOA 63: Norland Optical Adhesive 63, PAA: poly(acrylic acid), PAH: poly(allylamine hydrochloride).

Neutrophil extracellular traps (NETs), composed primarily of DNA and proteases, are released from activated neutrophils and contribute to the innate immune response by capturing pathogens. Plasmodium falciparum, the causative agent of severe malaria, thrives in its host by counteracting immune elimination. Here, we report the discovery of a novel virulence factor of P. falciparum, a TatD-like DNase (PfTatD) that is expressed primarily in the asexual blood stage and is likely utilized by the parasite to counteract NETs. PfTatD exhibits typical deoxyribonuclease activity, and its expression is higher in virulent parasites than in avirulent parasites. A P. berghei TatD-knockout parasite displays reduced pathogenicity in mice. Mice immunized with recombinant TatD exhibit increased immunity against lethal challenge. Our results suggest that the TatD-like DNase is an essential factor for the survival of malarial parasites in the host and is a potential malaria vaccine candidate.

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Fabrication of light-driven actuators that can prolong their deformation without constant irradiation poses a challenge. This study shows the preparation of polymeric actuators that are capable of reversible bending/unbending movements and prolonging their bending deformation without UV irradiation by releasing thermally cross-linked azobenzene-containing polyelectrolyte films with a limited free volume from substrates. Layer-by-layer assembly of poly{1-4[4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2-ethanediyl sodium salt} (PAZO)-poly(acrylic acid) (PAA) complexes (noted as PAZO-PAA) with poly(allylamine hydrochloride) (PAH) produces azobenzene-containing PAZO-PAA/PAH films. UV irradiation induces trans-cis isomerization of azobenzenes and allows large-scale bending deformation of the actuators. The actuators prolong the bending deformation even under visible light irradiation because the cis-trans back isomerization of azobenzenes is inhibited by the limited free volume in the actuators. Unbending of actuators is attained by exposing the actuators to a humid environment at room temperature. Film expansion in a humid environment produces a mechanical force that is sufficiently strong to enable the cis-trans back isomerization of azobenzenes and restore the bent actuators to their original configuration. The capability of the force produced by film expansion for cis-trans azobenzene isomerization can be helpful for designing novel polymeric actuators.

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