Electrospinner: Adv Fiber Mater—Wet spinning of polyaniline/carbon nanotube fibers: a new breakthrough in sweat-driven electricity, sensing and detection to protect health!

Background

Peripheral nerve defects caused by trauma, tumors and other factors are common and difficult problems in clinical practice. Schwann cells are the most critical functional cells in the process of peripheral nerve regeneration. Their reduced proliferation ability and functional impairment in nerve scaffolds are the main obstacles to poor nerve defect effects.

Recently, the research results entitled "Bioactive MgO/MgCO3/Polycaprolactone Multi-gradient Fibers Facilitate Peripheral Nerve Regeneration by Regulating Schwann Cell Function and Activating Wingless/integrase-1 Signaling" were published in Advanced Fiber Materials by the collaboration of Professor Wang Deli of Peking University Shenzhen Hospital, Professor Li Ye of Hong Kong Polytechnic University, and Professor Zhang Jin of Fuzhou University. This work uses electrospinning technology to mix polycaprolactone (PCL) with magnesium-containing monomers (MgO, MgCO3) of different concentrations and different degradation efficiencies to prepare gradient nanofiber membranes with long-term sustained release of Mg2+. The regulation of the local nerve regeneration microenvironment is achieved by constructing a reasonable and effective Mg2+ sustained release system. The results of the study on the 10 mm sciatic nerve defect model of SD rats showed that the material can promote the myelination of regenerated axons, reinnervation of muscle tissue, and promote the regeneration of peripheral nerve function.

The main point of this paper

This study used single-walled carbon nanotubes (SWCNTs) to induce the orientation and extension of polyaniline (PANI) molecular chains, and prepared highly crystalline PANI/SWCNTs fibers by wet spinning. The sweat-stimulated battery constructed with the fiber as cathode and zinc as anode undergoes a rapid solid-liquid two-phase 4e− transfer reaction, and the power density is increased by 2 orders of magnitude compared with the traditional carbon fiber cathode. At the same time, it is integrated with the PANI/SWCNTs fiber-based electrochemical sensor to achieve visual real-time monitoring of pH, glucose and K+ concentration in sweat

During the wet spinning process, the shear force of the fluid induces the SWCNT and PANI in the spinning solution to be oriented along the fluid axis. At the same time, the π-π and hydrogen bond interactions between SWCNTs and PANI molecular chains can construct an interfacial interphase polymer layer, further induce the interface orientation between the PANI molecular chain and SWCNTs, and further improve the crystallinity of PANI. In addition, SWCNT acts as an interface bridge between PANI molecular chains, enhancing the electrical (195 S/cm) and mechanical properties (374 MPa) of the fiber.

The fiber battery is constructed with PANI/SWCNTs2‰ and Zn wire as the cathode and anode core layers, respectively, and hydrophilic cotton wire as the shell layer. Under 10 μL NaCl conditions, the battery can be excited within 1 s, with a voltage of up to 1.2 V and an output voltage of up to 1.07 V. During the electrochemical reaction, the PANI cathode is reduced from the ES state to the LEB state, and a 4e− transfer reaction occurs, overcoming the reduction of O2 at the cathode interface to produce OH−, and the battery system undergoes a rapid solid-liquid two-phase reaction. Even in 20 mmol/L NaCl electrolyte, the power density is still as high as 1.79 mW/cm2

After functionalizing the surface of PANI fiber, pH, glucose and K+ biosensors were constructed, with sensitivities of (62.1 ± 1.5) mV/pH, (4.2 ± 0.03) nA μmol/L and (41.9 ± 0.7) mV/dec, respectively, which are comparable to the sweat sensing electrodes reported so far. Even in a slightly changing pH environment, PANI/SWCNTs2‰ fiber still has excellent responsiveness and stability, and is expected to achieve highly sensitive monitoring of human sweat

After 4×8 series-parallel connections of PANI/SWCNTs||Zn self-powered batteries were woven into fabrics, and integrated with fiber sensors and printed circuit boards, the pH, glucose and K+ concentrations of sweat in human walking and running can be monitored in real time, which is expected to provide new ideas for future self-powered human health monitoring and flexible wearables

summary

In summary, the PANI/SWCNTs||Zn self-powered battery has high voltage and high power density. The PANI/SWCNTs-based biosensor has high sensitivity, high reversibility and stability. The effective integration of the two provides an effective strategy for sweat monitoring and has broad application prospects in daily health monitoring and clinical applications.