Inspired by the densely covered capillary structure inside a dog's nose, we report an artificial nanostructure, i. e., poly(sodium p-styrenesulfonate)-functionalized reduced graphene oxide nanoscrolls (PGNS), with high structural perfection and efficient gas sensing applications. A facile supramolecular assembly is introduced to functionalize graphene with the functional polymer, combined with the lyophilization technique to massively transform the planar graphene-based nanosheets to nanoscrolls. Detailed characterizations reveal that the bioinspired nanoscrolls exhibit a wide-open tubular morphology with uniform dimensions that is structurally distinct from the previously reported ones. The detailed morphologies of the graphene-based nanosheets in each scrolling stage during lyophilization are monitored by cryo-SEM. This unravels an asymmetric polymer-induced graphene scrolling mechanism including the corresponding scrolling process, which is directly presented by molecular dynamics simulations. The fabricated PGNS sensors exhibit superior gas sensing performance with reliable repeatability, excellent linear sensibility, and, especially, an ultrahigh response ( R/ R = 5.39, 10 ppm) toward NO. The supramolecular assembly combined with the lyophilization technique to fabricate PGNS provides a strategy to design biomimetic materials for gas sensors and chemical trace detectors.

Heterostructure rough spindle‐knot microfibers (HRSFs) are fabricated via a flexible parallel‐nozzle microfluidic method. In this method, the bioinspired HRSF with a roughness gradient between spindle‐knots and joints, can be manufactured in large‐scale, and with which the size of the spindle‐knots and joints can be precisely adjusted by regulating flow rates. The HRSFs, fabricated with chitosan and calcium alginate, have strong mechanical properties and corrosion resistance in acid environment (pH = 5) and alkaline environment (pH = 9), respectively. More attractively, under controlled treatment conditions, the morphology of the spindle‐knots on the HRSFs can be effectively managed by changing the composite content of calcium chloride in the fluid. During the water collection process, tiny droplets of moisture can be captured on the surface of the HRSFs, subsequently, the droplets can coalesce and be transported from joint to spindle‐knot sections. It is demonstrated that the surface morphology of spindle‐knots directly influences the water collection efficiency, where a higher roughness gradient generates higher water collection efficiency. This parallel‐nozzle microfluidic technology provides a low‐cost and flexible method to manufacture high biocompatibility bioinspired rough spindle‐knot microfibers, which has many potential applications in large‐scale water collection, sustained drug release, and directional water collection.

In this work, we report the formation of a supramolecular assembly of graphene with a donor-π-acceptor (D-π-A) molecule to detect low concentration NO. 5-Aminonaphthalene-1-sulfonic acid (ANS) was used herein to π-π stack with reduced graphene oxide (rGO), the resulting π-conjugated bridge being linked by a donor unit (-NH) and an acceptor unit (-SOH). The prepared ANS-rGO shows the highest response (R/R = 13.2 to 10 ppm NO) so far among the reported organic molecule modified graphene materials, and excellent selectivity and reliable reversibility at room temperature. Furthermore, as revealed through the charge density difference calculation, it is the effective enhancement of charge transfer between ANS and graphene that should be responsible for the sharp improvement of NO gas response of the material. Thus, for the first time, we demonstrate that supramolecular assembly of a D-π-A molecule and graphene provides a facile and effective approach to fabrication of high performance graphene-based gas sensors.

Some advances toward realizing higher efficiency and large-scale the fabrication of fog harvesting materials based on bioinspired ideas.

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