Hanqing Dai
11 records found
1
From Short Circuit to Completed Circuit
Conductive Hydrogel Facilitating Oral Wound Healing
The primary challenges posed by oral mucosal diseases are their high incidence and the difficulty in managing symptoms. Inspired by the ability of bioelectricity to activate cells, accelerate metabolism, and enhance immunity, a conductive polyacrylamide/sodium alginate crosslinked hydrogel composite containing reduced graphene oxide (PAA-SA@rGO) is developed. This composite possesses antibacterial, anti-inflammatory, and antioxidant properties, serving as a bridge to turn the “short circuit” of the injured site into a “completed circuit,” thereby prompting fibroblasts in proximity to the wound site to secrete growth factors and expedite tissue regeneration. Simultaneously, the PAA-SA@rGO hydrogel effectively seals wounds to form a barrier, exhibits antibacterial and anti-inflammatory properties, and prevents foreign bacterial invasion. As the electric field of the wound is rebuilt and repaired by the PAA-SA@rGO hydrogel, a 5 × 5 mm2 wound in the full-thickness buccal mucosa of rats can be expeditiously mended within mere 7 days. The theoretical calculations indicate that the PAA-SA@rGO hydrogel can aggregate and express SOX2, PITX1, and PITX2 at the wound site, which has a promoting effect on rapid wound healing. Importantly, this PAA-SA@rGO hydrogel has a fast curative effect and only needs to be applied for the first three days, which significantly improves patient satisfaction during treatment.
@enIn recent years, various functional fabrics capable of responding to multistimuli have been widely recognized as promising wearable devices. However, the obtained composite functional fabrics have only been applied in a few scenarios, rendering the achievement of multifunctional wearable application scenarios a difficult goal. Therefore, there is an urgent need to expand the diversity of wearable applications for functional fabrics. Herein, we design hydrogel composite fabrics capable of responding to multiple stimuli, including vibration, temperature, strain, and pressure, to enable wearable multiapplication scenarios. The hydrogel composite fabrics, based on nylon fabrics (NFs), are fabricated with polyacrylamide (PAM)-poly(vinyl alcohol) (PVA)-sodium alginate (SA)-reduced graphene oxide (rGO)/NFs (PAM-PVA-SA-rGO/NFs). The PAM-PVA-SA-rGO/NFs exhibit a higher elastic stiffness coefficient (2.79 N cm-1) than the blank NFs (1.76 N cm-1), good temperature sensitivity in the range of 30-80 °C, and excellent detecting ability for urine presence with a threshold of unit area of 2.55 × 10-3 mL cm-2. The PAM-PVA-SA-rGO/NFs can not only respond to multiple stimuli but also be integrated into clothing for wearable multiapplication scenarios, such as detecting human speaking and breathing, intelligent sleeves, and diaper alarms. Additionally, the mechanisms of the above phenomena are revealed. These results indicate that the PAM-PVA-SA-rGO/NFs will provide inspiration for the development of intelligence systems, feedback devices, soft robotics, wearable devices, etc.
@enSulfide minerals hold significant importance in both fundamental science and industrial advancement. However, certain natural sulfide minerals, such as NaFe3S5·2H2O (NFS), pose great challenges for exploitation and synthesis due to their high susceptibility to oxidation. To date, no successful precedent exists for synthesizing NFS. Here, a novel approach to synthesizing low-cost and pollution-free NFS with high stability using the high-pressure hydrothermal method based solely on knowledge of its chemical formula is presented. Moreover, an innovative strategy inspired by the cicada's molting process to develop unstable natural materials is proposed. The mechanical, thermal, optical, electrochemical, and magnetic properties of the NFS are thoroughly investigated. The storage of lithium, sodium, and potassium ions is primarily concentrated in the gap between (0 0 1) crystal planes. Additionally, as a catalyst for hydrogen evolution reaction (HER) at 10 mA cm−2, micron-sized NFS exhibits an excellent overpotential of 6.5 mV at 90 °C, surpassing those of reported HER catalysts of similar size. This research bridges the gap in the sulfide mineral family, overcomes limitations of the high-pressure hydrothermal method, and paves the way for future synthesis of natural minerals, lunar minerals, and Martian minerals.
@enHydrogel materials have biocompatibility, flexibility, transparency, self-healing ability, adhesion with various substrates, anti-freeze ability, and high-temperature resistance. However, the existing hydrogel devices cannot continue to operate in the case of damage, and they cannot work during the repair period, which brings great challenges and threats to life safety. Herein, we have designed a bio-inspired combinable low-power device by imitating the generation of nerve signals whose components can be disassembled and can continue to operate during the period of reconstruction. And the mechanism and determinants of the above phenomena are revealed. The results indicate that this device can establish some information interaction relationships with the body or its surroundings to reflect and identify certain changes, implying that it will possess promising potential in feedback systems, power transformers, intelligence systems, soft robotics, wearable devices, implanted electronics with flexible characteristics matching biological tissues, etc.
@enAdvanced Composites Inspired by Biological Structures and Functions in Nature
Architecture Design, Strengthening Mechanisms, and Mechanical-Functional Responses
The natural design and coupling of biological structures are the root of realizing the high strength, toughness, and unique functional properties of biomaterials. Advanced architecture design is applied to many materials, including metal materials, inorganic nonmetallic materials, polymer materials, and so on. To improve the performance of advanced materials, the designed architecture can be enhanced by bionics of biological structure, optimization of structural parameters, and coupling of multiple types of structures. Herein, the progress of structural materials is reviewed, the strengthening mechanisms of different types of structures are highlighted, and the impact of architecture design on the performance of advanced materials is discussed. Architecture design can improve the properties of materials at the micro level, such as mechanical, electrical, and thermal conductivity. The synergistic effect of structure makes traditional materials move toward advanced functional materials, thus enriching the macroproperties of materials. Finally, the challenges and opportunities of structural innovation of advanced materials in improving material properties are discussed.
@enHuman skin, with beneficial elasticity and reparability, could sense the changes of the external environment through different receptors. Imitating these mechanical properties and perception of bionic skin with power supply function is an enormous challenge in the field of Internet of things and artificial intelligence. Herein, the neural signal transmission of human skin is imitated to create a smart self-powered bionic skin fragment integrating skin and power supply functions. Unlike the traditional bionic skin in essence, it can intelligently perceive the outside world by using anion-selective and cation-selective gels to control exchangeable anions and cations to realize the change of resting current and action current, and it can maintain the relatively stable self-powered current of 0.5 µA for nearly 2.2 h. Moreover, its mechanisms of current and voltage changes are systematically investigated. These results reveal that it can be applied to the synchronous transmission of signals for the next-generation neurologically integrated soft engineering systems such as bionic sensors, or prosthetic devices in hybrids of living and nonliving systems.
@enNaTi2(PO4)3 (NTP), a well-known anode material, could be used as a solid wide-band gap electrolyte. Herein, a novel solid-state sodium-ion battery (SSIB) with the thickness of electrolyte up to the millimeter level is proposed. The results of the difference in charge density investigated by the first-principles calculations imply that using the NTP nanocrystals as electrolytes to transport sodium ions is feasible. Moreover, the SSIB exhibits a high initial discharge capacity of 3250 mAh g-1 at the current density of 50 mA g-1. As compared with other previously reported SSIBs, our results are better than those reported and suggest that the NTP nanocrystals have potential application in SSIBs as solid electrolytes.
@enPreviously, α-Fe2O3 nanocrystals are recognized as anode materials owing to their high capacity and multiple properties. Now, this work provides high-voltage α-Fe2O3 nanoceramics cathodes fabricated by the solvothermal and calcination processes for sodium-ion batteries (SIBs). Then, their structure and electrical conductivity were investigated by the first-principles calculations. Also, the SIB with the α-Fe2O3 nanoceramics cathode exhibits a high initial charge-specific capacity of 692.5 mA h g-1 from 2.0 to 4.5 V at a current density of 25 mA g-1. After 800 cycles, the discharge capacity is still 201.8 mA h g-1, well exceeding the one associated with the present-state high-voltage SIB. Furthermore, the effect of the porous structure of the α-Fe2O3 nanoceramics on sodium ion transport and cyclability is investigated. This reveals that α-Fe2O3 nanoceramics will be a remarkably promising low-cost and pollution-free high-voltage cathode candidate for high-voltage SIBs.
@enAll-solid-state sodium-ion batteries (SIBs) possess the advantages of rich resources, low price, and high security, which are one of the best alternatives for large-scale energy storage systems in the future. Also, the chalcogenide solid electrolytes (CSEs) of SIBs have the characteristics of excellent room-temperature ionic conductivity (10−3-10−2 S cm−1), low activation energy (<0.6 eV), easy cold-pressing consolidation, etc. Hence, CSEs have become a very active area of all-solid-state SIB research in recent years. In this review, the modification methods and implementation technologies of CSEs are summarized, and the structure and electrochemical performance of the CSEs are discussed. Furthermore, the auxiliary function of first-principle calculations for modification is introduced. Ultimately, we describe the challenges regarding CSEs and propose some strategic suggestions.
@enAll-solid-state sodium-ion battery (ASSIB) is a promising new energy storage device due to the excellent thermal stability, low flammability, high impermeability and nonvolatility, as well as riskless fire and explosion properties. The solid electrolyte plays a core role in the ASSIBs to determine their electrochemical performance. Herein, close attention is paid to effective approaches to improve the performance of solid electrolytes, including ion doping and substitution, composite method, coating method, crystal transformation method, ceramization and vitrification, etc. In particular, electrochemical window, ionic conductivity, electrochemical stability, and structural stability are also reviewed. The future development of solid electrolytes and the possible directions for improving the properties of the ASSIBs in practical applications are also prospects. This review will guide the development of solid electrolytes for the ASSIBs in future.
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