A Water‐Processable and Bioactive Multivalent Graphene Nanoink for Highly Flexible Bioelectronic Films and Nanofibers

Abstract

The capabilities of conductive nanomaterials to be produced in liquid form with well‐defined chemical, physical, and biological properties are highly important for the construction of next‐generation flexible bioelectronic devices. Although functional graphene nanomaterials can serve as attractive liquid nanoink platforms for the fabrication of bioelectronics, scalable synthesis of graphene nanoink with an integration of high colloidal stability, water processability, electrochemical activity, and especially bioactivity remains a major challenge. Here, a facile and scalable synthesis of supramolecular‐functionalized multivalent graphene nanoink (mGN‐ink) via [2+1] nitrene cycloaddition is reported. The mGN‐ink unambiguously displays a well‐defined and flat 2D morphology and shows good water processability and bioactivity. The uniquely chemical, physical, and biological properties of mGN‐ink endow the constructed bioelectronic films and nanofibers with high flexibility and durability, suitable conductivity and electrochemical activity, and most importantly, good cellular compatibility and a highly efficient control of stem‐cell spreading and orientation. Overall, for the first time, a water‐processable and bioactive mGN‐ink is developed for the design of flexible and electrochemically active bioelectronic composites and devices, which not only presents manifold possibilities for electronic‐cellular applications but also establishes a new pathway for adapting macroscopic usages of graphene nanomaterials in bionic, biomedical, electronic, and even energy fields.

Atomic Fe–Nx Coupled Open‐Mesoporous Carbon Nanofibers for Efficient and Bioadaptable Oxygen Electrode in Mg–Air Batteries

“…With the rapid development of lightweight, portable, flexible, and wearable electronics for diverse health and biomedical devices, there is an urgent need to explore new power sources that offer higher flexibility and human/tissue adaptability for these electronic devices, such as aqueous metal‐ion batteries, bio‐fuel cells, and metal–air batteries . Among them, the metal–air batteries are considered to be one of the most promising types of power sources due to their high‐energy capacities, high flexibility, and eco‐friendly and low cost fabrication process .…”

“…It can be assumed that the open‐mesoporous and interconnected structures will significantly boost the mass transport, thus enhancing the electrochemical performance . To assess the electrochemical capacitances of OM‐NCNF and OM‐NCNF‐FeN x in neutral electrolytes, cyclic voltammetry (CV) of these nanofibers has been performed in Dulbecco's phosphate‐buffered saline (DPBS) buffer as shown in Figure e and Figure S9 in the Supporting Information . Compared to NCNF, the OM‐NCNF and OM‐NCNF‐FeN x exhibit much higher electrochemical capacitance, indicating their better ionic conductivity and higher electrical double‐layer capacitance.…”

“…As shown in Figure h, i and Figures S10 and S11 in the Supporting Information, the OM‐NCNF and OM‐NCNF‐FeN x have significantly higher live cell numbers and a faster cell colonization speed compared to NCNF and tissue culture polystyrene (TCPS) from day 1 to 7. Therefore, the OM‐NCNF‐FeN x electrode not only shows high electrochemical capacitance but also excellent cytocompatibility, which guarantees its application potential in bio‐adaptable oxygen electrodes and many other bio‐electronic devices, such as biocapacitors, biocircuits, and human sensors …”

Direct Writing of Additive‐Free MXene‐in‐Water Ink for Electronics and Energy Storage

“…Rollerball pens have advantageous characteristics over fountain or brush style pens in that they are able to create ink patterns in a controllable manner due to the rotating ball dispensing a controlled flow of ink while minimizing any smearing effects . Direct writing of various functional materials including metal nanoparticles (Ag and Cu inks), carbon nanomaterials (carbon nanofiber inks, carbon nanotubes, graphene), conducting polymer (PEDOT:PSS), gallium‐based liquid metal, and enzymatic inks have been demonstrated previously. In most reports, inks developed for use in writing implements have been developed for use in passive circuitry or sensing elements .…”

“…In most reports, inks developed for use in writing implements have been developed for use in passive circuitry or sensing elements . Recently, Cheng et al, developed graphene nanomaterial based inks for designing flexible and electrochemically active bioelectronic composites . Developing solution processable conductive 2D nanomaterial ink formulations enables scalable fabrication of functional devices on unconventional substrates including paper and textiles .…”