Conducting metal nanowires can be assembled into thin films for flexible electronics and optoelectronics applications including transparent electrodes, nanocircuits, and electronic skin, however, the junction resistances and low aspect ratios still limit its performance. Herein we report high-quality silver nanofibers (AgNFs) synthesized by a gas-assistant solution spinning method. Compared with traditional Ag nanowires that usually have lengths below 100 μm, AgNFs are infinitely long and can be easily assembled into large-scale 2D and 3D flexible conductors with fused junctions between nanofibers. The AgNF networks showed high transparency, low sheet resistance (e. g, 6 Ω sq(-1) at ∼97% transparency), and high flexibility as transparent electrodes, whereas the 3D AgNF sponge could be used as a deformable and robust 3D conductor.
Ultrathin metal fibers can serve as highly conducting and flexible current and heat transport channels, which are essential for numerous applications ranging from flexible electronics to energy conversion. Although industrial production of metal fibers with diameters of down to 2 μm is feasible, continuous production of high-quality and low-cost nanoscale metal wires is still challenging. Herein, we report the continuous draw spinning of highly conductive silver submicron fibers with the minimum diameter of ∼200 nm and length of more than kilometers. We obtained individual AgNO/polymer fibers by continuous drawing from an aqueous solution at a speed of up to 8 m/s. With subsequent heat treatment, freestanding Ag submicron fibers with high mechanical flexibility and electric conductivity have been obtained. Woven mats of aligned Ag submicron fibers were used as transparent electrodes with high flexibility and high performance with sheet resistance of 7 Ω sq at a transparency of 96%. Continuous draw spinning opened new avenues for scalable, flexible, and ultralow-cost fabrication of extra-long conductive ultrathin metal fibers.
Transparent conductive film (TCF) has found wide applications. Indium tin oxide (ITO) is currently the most widely used transparent electrode. However, major problem of ITO is the lacking of flexibility, which totally limits its applications. Here, we report a highly flexible transparent electrode consisting of freestanding ITO nanofiber network fabricated by blow spinning, the advantage of which is its high-efficiency, low cost and safety. When the bending radius decreased to 0.5 mm, the resistance of the transparent electrodes only increased by 18.4%. Furthermore, the resistance was almost unchanged after thousands of bending cycles at 3.5 mm bending radius.
Protein drugs have great potential as targeted therapies, yet their application suffers from several drawbacks, such as instability, short half‐life, and adverse immune responses. Thus, protein delivery approaches based on stimuli‐responsive nanocarriers can provide effective strategies for selectively enhancing the availability and activation of proteins in targeted tissues. Herein, polymeric micelles with the ability of encapsulating proteins are developed via concurrent ion complexation and pH‐cleavable covalent bonding between proteins and block copolymers directed to pH‐triggered release of the protein payload. Carboxydimethylmaleic anhydride (CDM) is selected as the pH‐sensitive moiety, since the CDMamide bond is stable at physiological pH (pH 7.4), while it cleaves at pH 6.5, that is, the pathophysiological pH of tumors and inflammatory tissues. By using poly(ethylene glycol)‐poly(l‐lysine) block copolymers having 45% CDM addition, different proteins with various sizes and isoelectric points are loaded successfully. By using myoglobin‐loaded micelles (myo/m) as a model, the stability of the micelles in physiological conditions and the dissociation and release of functional myoglobin at pH 6.5 are successfully confirmed. Moreover, myo/m shows extended half‐life in blood compared to free myoglobin and micelles assembled solely by polyion complex, indicating the potential of this system for in vivo delivery of proteins.
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