Electrochemically Mediated Surface-Initiated de Novo Growth of Polymers for Amplified Electrochemical Detection of DNA

The development of convenient and efficient strategies without involving any complex nanomaterials or enzymes for signal amplification is of great importance in bioanalytical applications. In this work, we report the use of electrochemically mediated surface-initiated atom transfer radical polymerization (SI-eATRP) as a novel amplification strategy based on the de novo growth of polymers (dnGOPs) for the electrochemical detection of DNA. Specifically, the capture of target DNA (tDNA) by the immobilized peptide nucleic acid (PNA) probes provides a high density of phosphate groups for the subsequent attachment of ATRP initiators onto the electrode surface by means of the phosphate-Zr⁴⁺-carboxylate chemistry, followed by the de novo growth of electroactive polymer via the SI-eATRP. De novo growth of long polymeric chains enables the labeling of numerous electroactive probes, which in turn greatly improves the electrochemical response. Moreover, it circumvents the slow kinetics and poor coupling efficiency encountered when nanomaterials or preformed polymers are used and features sufficient flexibility and simplicity in controlling the degree of signal amplification. Under optimal conditions, it allows a highly sensitive and selective detection of tDNA within a broad linear range from 0.1 fM to 0.1 nM (<i>R</i>² = 0.996), with the detection limit down to 0.072 fM. Compared with the unamplified method, more than 1.2 × 10⁶-fold sensitivity improvement in DNA detection can be achieved. By virtue of its simplicity, high efficiency, and cost-effectiveness, the proposed dnGOPs-based signal amplification strategy holds great potential in bioanalytical applications for the sensitive detection of biological molecules

Synergistic Ion Sieve and Solvation Regulation by Recyclable Clay-Based Electrolyte Membrane for Stable Zn-Iodine Battery

The high dissolution of polyiodides and unstable interface at the anode/electrolyte severely restrict the practical applications of rechargeable aqueous Zn-iodine batteries. Herein, we develop a zinc ion-based montmorillonite (ZMT) electrolyte membrane for synergizing ion sieve and solvation regulation to achieve highly stable Zn-iodine batteries. The rich M–O band and special cation-selective transport channel in ZMT locally tailor the solvation sheath around Zn2+ and therefore achieve high transference number (t+ = 0.72), benefiting for uniform and reversible deposition/stripping of Zn. Meanwhile, the mechanisms for three-step polyiodide generation and shuttle-induced Zn corrosion are highlighted by in situ characterization techniques. It is confirmed that the strong chemical adsorption between O atoms in ZMT and polyiodides species is the key to effectively inhibit the shuffle effect and side reactions. Consequently, the ZMT-based Zn-iodine battery delivers a high capacity of 0.45 mAh cm–2 at 1 mA cm–2 with a much improved Coulombic efficiency of 99.5% and outstanding capacity retention of 95% after 13 500 cycles at 10 mA cm–2. Moreover, owing to its high durability and chemical inertness and structural stability, ZMT-based electrolyte membranes can be recycled and applied in double-sided pouch cells, delivering a high areal capacity of 2.4 mAh cm–2 at 1 mA cm–2

Design of Amorphous Manganese Oxide@Multiwalled Carbon Nanotube Fiber for Robust Solid-State Supercapacitor

Solid-state fiber-based supercapacitors have been considered promising energy storage devices for wearable electronics due to their lightweight and amenability to be woven into textiles. Efforts have been made to fabricate a high performance fiber electrode by depositing pseudocapacitive materials on the outer surface of carbonaceous fiber, for example, crystalline manganese oxide/multiwalled carbon nanotubes (MnO₂/MWCNTs). However, a key challenge remaining is to achieve high specific capacitance and energy density without compromising the high rate capability and cycling stability. In addition, amorphous MnO₂ is actually preferred due to its disordered structure and has been proven to exhibit superior electrochemical performance over the crystalline one. Herein, by incorporating amorphous MnO₂ onto a well-aligned MWCNT sheet followed by twisting, we design an amorphous MnO₂@MWCNT fiber, in which amorphous MnO₂ nanoparticles are distributed in MWCNT fiber uniformly. The proposed structure gives the amorphous MnO₂@MWCNT fiber good mechanical reliability, high electrical conductivity, and fast ion-diffusion. Solid-state supercapacitor based on amorphous MnO₂@MWCNT fibers exhibits improved energy density, superior rate capability, exceptional cycling stability, and excellent flexibility. This study provides a strategy to design a high performance fiber electrode with microstructure control for wearable energy storage devices

All-Graphene-Based Highly Flexible Noncontact Electronic Skin

Noncontact electronic skin (e-skin), which possesses superior long-range and high-spatial-resolution sensory properties, is becoming indispensable in fulfilling the emulation of human sensation via prosthetics. Here, we present an advanced design and fabrication of all-graphene-based highly flexible noncontact e-skins by virtue of femtosecond laser direct writing (FsLDW). The photoreduced graphene oxide patterns function as the conductive electrodes, whereas the pristine graphene oxide thin film serves as the sensing layer. The as-fabricated e-skins exhibit high sensitivity, fast response–recovery behavior, good long-term stability, and excellent mechanical robustness. In-depth analysis reveals that the sensing mechanism is attributed to proton and ionic conductivity in the low and high humidity conditions, respectively. By taking the merits of the FsLDW, a 4 × 4 sensing matrix is facilely integrated in a single-step, eco-friendly, and green process. The light-weight and in-plane matrix shows high-spatial-resolution sensing capabilities over a long detection range in a noncontact mode. This study will open up an avenue to innovations in the noncontact e-skins and hold a promise for applications in wearable human–machine interfaces, robotics, and bioelectronics

All-Graphene-Based Highly Flexible Noncontact Electronic Skin

Noncontact electronic skin (e-skin), which possesses superior long-range and high-spatial-resolution sensory properties, is becoming indispensable in fulfilling the emulation of human sensation via prosthetics. Here, we present an advanced design and fabrication of all-graphene-based highly flexible noncontact e-skins by virtue of femtosecond laser direct writing (FsLDW). The photoreduced graphene oxide patterns function as the conductive electrodes, whereas the pristine graphene oxide thin film serves as the sensing layer. The as-fabricated e-skins exhibit high sensitivity, fast response–recovery behavior, good long-term stability, and excellent mechanical robustness. In-depth analysis reveals that the sensing mechanism is attributed to proton and ionic conductivity in the low and high humidity conditions, respectively. By taking the merits of the FsLDW, a 4 × 4 sensing matrix is facilely integrated in a single-step, eco-friendly, and green process. The light-weight and in-plane matrix shows high-spatial-resolution sensing capabilities over a long detection range in a noncontact mode. This study will open up an avenue to innovations in the noncontact e-skins and hold a promise for applications in wearable human–machine interfaces, robotics, and bioelectronics

General Metal-Ion Mediated Method for Functionalization of Graphene Fiber

Graphene fibers (GFs) are attractive materials for wearable electronics because of their lightness, superior flexibility, and electrical conductivity. However, the hydrophobic nature and highly stacked structure endow GFs similar characteristics in nature to solid carbon fibers. Therefore, the interior functionalization of GFs so as to achieve synergistic interaction between graphene nanosheets and active materials thus enhance the performance of hybrid fibers remains a challenge. Herein, a general metal-ion mediated strategy is developed to functionalize GFs and nanoparticles of Cu, Fe₂O₃, NiO, and CoO are successfully incorporated into GFs, respectively. As proof-of-concept applications, the obtained functionalized GFs are used as electrodes for electrochemical sensors and supercapacitors. The performances of thus-devised fiber sensor and supercapacitor are greatly improved

Dual-Function Metal–Organic Framework-Based Wearable Fibers for Gas Probing and Energy Storage

Metal–organic frameworks (MOFs) coupled with multiwalled carbon nanotubes (MWCNTs) have been developed with an ultrahigh sensitivity for hazardous gas monitoring. Both the MOF/MWCNT and as-derived metal oxides (MOs)/MWCNTs hybrid fibers deliver an ultralow detection limit for NO₂ down to 0.1 ppm without external heating, and they can be further bent into different angles without loss of sensing performance. Also, a high specific capacitance of 110 F cm^–3 can also be obtained for MO/MWCNT hybrid fibers, demonstrating promising application for integrated wearable devices