Hybridization chain reaction-based DNA nanomaterials for biosensing,bioimaging and therapeutics

DNA nanomaterials hold great promise in biomedical fields due to its excellent sequence programmability,molecular recognition ability and biocompatibility.Hybridization chain reaction(HCR)is a simple and efficient isothermal enzyme-free amplification strategy of DNA,generating nicked double helices with repeated units.Through the design of HCR hairpins,multiple nanomaterials with desired functions are assembled by DNA,exhibiting great potential in biomedical applications.Herein,the recent progress of HCR-based DNA nanomaterials for biosensing,bioimaging and therapeutics are summarized.Representative works are exemplified to demonstrate how HCR-based DNA nanomaterials are designed and constructed.The challenges and prospects of the development of HCR-based DNA nanomaterials are discussed.We envision that rationally designing HCR-based DNA nanomaterials will facilitate the development of biomedical applications.

Physically modulated phytoplankton production and export at submesoscales in the oligotrophic South China Sea Basin

Oceanic submesoscales can significantly influence phytoplankton production and export owing to their similar timescales of days.Based on two-year Biogeochemical Argo(BGC-Argo) observations,this study investigated the development of submesoscale instabilities,particularly symmetric and mixed-layer baroclinic instabilities,and their impacts on biological production and export in the oligotrophic South China Sea basin.In the northern basin,near-surface winter blooms consistently cooccurred with seasonally deepened mixed layers.However,significantly stronger and weaker winter blooms were observed over two consecutive winters within the BGC-Argo observation period.During the first winter,symmetric-instability-induced upward nutrient entrainment played a crucial role in initiating the strong winter bloom in early December,when the mixed layer was approximately 20–30 m shallower than the nutricline.This bloom occurred approximately 20–30 days earlier than that anticipated owing to the contact between the seasonally deepened mixed layer and mesoscale-cyclone-induced uplifted nutricline.The symmetric instability also facilitated the export of fixed phytoplankton carbon from the surface to deeper layers.Conversely,during the second winter,remarkably intense mixed-layer baroclinic instability associated with an intense mesoscale anticyclone led to more significant shoaling of the mixed layer compared to the nutricline,thus increasing the vertical distance between the two layers.Under this condition,upward nutrient injection,phytoplankton bloom,and carbon export were suppressed.In contrast,the BGC-Argo float in the central basin revealed significantly inhibited seasonality of phytoplankton biomass and submesoscale instabilities compared to those in the northern basin,primarily owing to the significantly shallower winter mixed layer.

Lighted up by hydrogen-bonding: luminescence behavior and applications of AIEgen-doped interpenetrating network hydrogel

The interaction between the aggregation-induced emissive(AIE) luminogens(AIEgen) and the polymer is the key scientific question in the design of functional AIE hydrogels. In this study, we report the AIE behavior of a poly(acrylic acid)(PAAc) and poly(acrylamide)(PAAm) interpenetrating network(IPN) hydrogel doped with tetra-cationic tetraphenylethene(TCTPE). The cationic AIEgen can bind with PAAc through ionic interaction, while PAAc and PAAm chains can associate with each other through hydrogen-bonds(H-bonds). These two interactions can restrict the intramolecular rotation and thus activate the luminescence of the AIEgen. The PAAc-PAAm H-bonds can be broken by increasing temperature or p H, restoring the intramolecular rotation of the AIEgen and quenching the fluorescence of the hydrogel. Therefore, the TCTPE-doped IPN hydrogel is designed as temperature-and p H-sensitive displayers which can record information imprinted by photo-printing or iono-printing with good switchability and reversibility. Another application of this TCTPE-doped hydrogel is demonstrated as a luminescent soft actuator, which has fast shape deformation and editable fluorescence pattern. The above results reveal a pathway to tune the emission behavior through tuning polymer-polymer and polymer-AIEgen interactions, which may inspire new design strategies of aggregation-induced emissive polymers and broaden their applications.

A Review of Energy Supply for Biomachine Hybrid Robots

Biomachine hybrid robots have been proposed for important scenarios,such as wilderness rescue,ecological monitoring,and hazardous area surveying.The energy supply unit used to power the control backpack carried by these robots determines their future development and practical application.Current energy supply devices for control backpacks are mainly chemical batteries.To achieve self-powered devices,researchers have developed solar energy,bioenergy,biothermal energy,and biovibration energy harvesters.This review provides an overview of research in the development of chemical batteries and self-powered devices for biomachine hybrid robots.Various batteries for different biocarriers and the entry points for the design of self-powered devices are outlined in detail.Finally,an overview of the future challenges and possible directions for the development of energy supply devices used to biomachine hybrid robots is provided.