Adaptive Self-Organization of Nanomaterials Enables Strain-Insensitive Resistance of Stretchable Metallic Nanocomposites

© 2022 Wiley-VCH GmbH.Highly conductive and stretchable nanocomposites are promising material candidates for skin electronics. However, the resistance of stretchable metallic nanocomposites highly depends on external strains, often deteriorating the performance of fabricated electronic devices. Here, a material strategy for the highly conductive and stretchable nanocomposites comprising metal nanomaterials of various dimensions and a viscoelastic block-copolymer matrix is presented. The resistance of the nanocomposites can be well retained under skin deformations (<50% strain). It is demonstrated that silver nanomaterials can self-organize inside the viscoelastic media in response to external strain when their surface is conjugated with 1-decanethiol. Distinct self-organization behaviors associated with nanomaterial dimensions and strain conditions are found. Adopting the optimum composition of 0D/1D/2D silver nanomaterials can render the resistance of the nanocomposites insensitive to uniaxial or biaxial strains. As a result, the resistance can be maintained with a variance of < 1% during 1000 stretching cycles under uniaxial and biaxial strains of <50% while a high conductivity of ≈31 000 S cm−1 is achieved.11Nsciescopu

Stretchable Low-Impedance Nanocomposite Comprised of Ag–Au Core–Shell Nanowires and Pt Black for Epicardial Recording and Stimulation

© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimCardiac resynchronization therapy (CRT) presents effective means to modulate cardiac conduction and related functions in heart failure patients. However, the conventional CRT delivers electric current at only two points on the heart, therefore, it is unable to provide comprehensive electrical support to the heart. Additionally, the CRT-device structure faces several issues, such as those associated with the endocardial screw tip, which may cause myocardial degeneration, and the metal lead wire, which may lead to intravascular thrombosis and lead infection. Moreover, the conventional CRT has limitations in mechanically improving the cardiac contractility, which often cannot prevent further ventricular dilation. Here, a fabrication of an elastoconductive epicardial mesh using a stretchable low-impedance nanocomposite comprising Ag–Au core–shell nanowires and platinum black (Pt black) in elastomer to provide a potential solution to the above-mentioned clinical issues is reported. The proposed nanocomposite structure exhibits high stretchability, conductivity, and biocompatibility in combination with low impedance. These features facilitate the realization of high signal-to-noise ratios in electrocardiogram recordings, and high-quality electrical stimulations. The proposed epicardial mesh is implanted on the surface of an animal heart with minimum traumatic stress, and is consequently able to conduct high-quality cardiac recording and electrical stimulation in rodent

Stretchable Low-Impedance Nanocomposite Comprised of Ag-Au Core-Shell Nanowires and Pt Black for Epicardial Recording and Stimulation

Cardiac resynchronization therapy (CRT) presents effective means to modulate cardiac conduction and related functions in heart failure patients. However, the conventional CRT delivers electric current at only two points on the heart, therefore, it is unable to provide comprehensive electrical support to the heart. Additionally, the CRT-device structure faces several issues, such as those associated with the endocardial screw tip, which may cause myocardial degeneration, and the metal lead wire, which may lead to intravascular thrombosis and lead infection. Moreover, the conventional CRT has limitations in mechanically improving the cardiac contractility, which often cannot prevent further ventricular dilation. Here, a fabrication of an elastoconductive epicardial mesh using a stretchable low-impedance nanocomposite comprising Ag-Au core-shell nanowires and platinum black (Pt black) in elastomer to provide a potential solution to the above-mentioned clinical issues is reported. The proposed nanocomposite structure exhibits high stretchability, conductivity, and biocompatibility in combination with low impedance. These features facilitate the realization of high signal-to-noise ratios in electrocardiogram recordings, and high-quality electrical stimulations. The proposed epicardial mesh is implanted on the surface of an animal heart with minimum traumatic stress, and is consequently able to conduct high-quality cardiac recording and electrical stimulation in rodents.

Adaptive Self-Organization of Nanomaterials Enables Strain-Insensitive Resistance of Stretchable Metallic Nanocomposites

Highly conductive and stretchable nanocomposites are promising material candidates for skin electronics. However, the resistance of stretchable metallic nanocomposites highly depends on external strains, often deteriorating the performance of fabricated electronic devices. Here, a material strategy for the highly conductive and stretchable nanocomposites comprising metal nanomaterials of various dimensions and a viscoelastic block-copolymer matrix is presented. The resistance of the nanocomposites can be well retained under skin deformations (&lt;50% strain). It is demonstrated that silver nanomaterials can self-organize inside the viscoelastic media in response to external strain when their surface is conjugated with 1-decanethiol. Distinct self-organization behaviors associated with nanomaterial dimensions and strain conditions are found. Adopting the optimum composition of 0D/1D/2D silver nanomaterials can render the resistance of the nanocomposites insensitive to uniaxial or biaxial strains. As a result, the resistance can be maintained with a variance of &lt; 1% during 1000 stretching cycles under uniaxial and biaxial strains of &lt;50% while a high conductivity of approximate to 31 000 S cm(-1) is achieved.N

Facile and Scalable Synthesis of Whiskered Gold Nanosheets for Stretchable, Conductive, and Biocompatible Nanocomposites

Noble metal nanomaterials have been studied as conductive fillers for stretchable, conductive, and biocompatible nanocomposites. However, their performance as conductive filler materials is far from ideal because of their high percolation threshold and low intrinsic conductivity. Moreover, the difficulty in large-scale production is another critical hurdle in their practical applications. Here we report a method for the facile and scalable synthesis of whiskered gold nanosheets (WAuNSs) for stretchable, conductive, and biocompatible nano composites and their application to stretchable bioelectrodes. W-AuNSs show a lower percolation threshold (1.56 vol %) than those of gold nanoparticles (5.02 vol %) and gold nanosheets (2.74 vol %), which enables the fabrication of W-AuNS-based stretchable nanocomposites with superior conductivity and high stretchability. Addition of platinum-coated W-AuNSs (WAuNSs@Pt) to the prepared nanocomposite significantly reduces the impedance and improved charge storage capacity. Such enhanced performance of the stretchable nanocomposite enables us to fabricate stretchable bioelectrodes whose performance is demonstrated through animal experiments including electrophysiological recording and electrical stimulation in vivo.11Nsciescopu

Enhanced Chemodynamic Therapy by Cu-Fe Peroxide Nanoparticles: Tumor Microenvironment-Mediated Synergistic Fenton Reaction

© An urgent need in chemodynamic therapy (CDT) is to achieve high Fenton catalytic efficiency at small doses of CDT agents. However, simple general promotion of the Fenton reaction increases the risk of damaging normal cells along with the cancer cells. Therefore, a tailored strategy to selectively enhance the Fenton reactivity in tumors, for example, by taking advantage of the characteristics of the tumor microenvironment (TME), is in high demand. Herein, a heterogeneous CDT system based on copper-iron peroxide nanoparticles (CFp NPs) is designed for TME-mediated synergistic therapy. CFp NPs degrade under the mildly acidic conditions of TME, self-supply H2O2, and the released Cu and Fe ions, with their larger portions at lower oxidation states, cooperatively facilitate hydroxyl radical production through a highly efficient catalytic loop to achieve an excellent tumor therapeutic efficacy. This is distinct from previous heterogeneous CDT systems in that the synergism is closely coupled with the Cu+-assisted conversion of Fe3+ to Fe2+ rather than their independent actions. As a result, almost complete ablation of tumors at a minimal treatment dose is demonstrated without the aid of any other therapeutic modality. Furthermore, CFp NPs generate O2 during the catalysis and exhibit a TME-responsive T1 magnetic resonance imaging contrast enhancement, which are useful for alleviating hypoxia and in vivo monitoring of tumors, respectively.11Nsciescopu

Epitaxially Strained CeO2/Mn3O4 Nanocrystals as an Enhanced Antioxidant for Radioprotection

© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Nanomaterials with antioxidant properties are promising for treating reactive oxygen species (ROS)-related diseases. However, maintaining efficacy at low doses to minimize toxicity is a critical for clinical applications. Tuning the surface strain of metallic nanoparticles can enhance catalytic reactivity, which has rarely been demonstrated in metal oxide nanomaterials. Here, it is shown that inducing surface strains of CeO2/Mn3O4 nanocrystals produces highly catalytic antioxidants that can protect tissue-resident stem cells from irradiation-induced ROS damage. Manganese ions deposited on the surface of cerium oxide (CeO2) nanocrystals form strained layers of manganese oxide (Mn3O4) islands, increasing the number of oxygen vacancies. CeO2/Mn3O4 nanocrystals show better catalytic activity than CeO2 or Mn3O4 alone and can protect the regenerative capabilities of intestinal stem cells in an organoid model after a lethal dose of irradiation. A small amount of the nanocrystals prevents acute radiation syndrome and increases the survival rate of mice treated with a lethal dose of total body irradiation11sci

Highly conductive and elastic nanomembrane for skin electronics

Skin electronics require stretchable conductors that satisfy metallike conductivity, high stretchability, ultrathin thickness, and facile patternability, but achieving these characteristics simultaneously is challenging. We present a float assembly method to fabricate a nanomembrane that meets all these requirements. The method enables a compact assembly of nanomaterials at the water-oil interface and their partial embedment in an ultrathin elastomer membrane, which can distribute the applied strain in the elastomer membrane and thus lead to a high elasticity even with the high loading of the nanomaterials. Furthermore, the structure allows cold welding and bilayer stacking, resulting in high conductivity. These properties are preserved even after high-resolution patterning by using photolithography. A multifunctional epidermal sensor array can be fabricated with the patterned nanomembranes.

Epitaxially Strained CeO 2

© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Nanomaterials with antioxidant properties are promising for treating reactive oxygen species (ROS)-related diseases. However, maintaining efficacy at low doses to minimize toxicity is a critical for clinical applications. Tuning the surface strain of metallic nanoparticles can enhance catalytic reactivity, which has rarely been demonstrated in metal oxide nanomaterials. Here, it is shown that inducing surface strains of CeO2/Mn3O4 nanocrystals produces highly catalytic antioxidants that can protect tissue-resident stem cells from irradiation-induced ROS damage. Manganese ions deposited on the surface of cerium oxide (CeO2) nanocrystals form strained layers of manganese oxide (Mn3O4) islands, increasing the number of oxygen vacancies. CeO2/Mn3O4 nanocrystals show better catalytic activity than CeO2 or Mn3O4 alone and can protect the regenerative capabilities of intestinal stem cells in an organoid model after a lethal dose of irradiation. A small amount of the nanocrystals prevents acute radiation syndrome and increases the survival rate of mice treated with a lethal dose of total body irradiation11sci