Two-dimensional self-healing hydrogen-bond-based supramolecular polymer film

Evolution of Musculoskeletal Electronics

The musculoskeletal system, constituting the largest human physiological system, plays a critical role in providing structural support to the body, facilitating intricate movements, and safeguarding internal organs. By virtue of advancements in revolutionized materials and devices, particularly in the realms of motion capture, health monitoring, and postoperative rehabilitation, "musculoskeletal electronics" has actually emerged as an infancy area, but has not yet been explicitly proposed. In this review, the concept of musculoskeletal electronics is elucidated, and the evolution history, representative progress, and key strategies of the involved materials and state-of-the-art devices are summarized. Therefore, the fundamentals of musculoskeletal electronics and key functionality categories are introduced. Subsequently, recent advances in musculoskeletal electronics are presented from the perspectives of "in vitro" to "in vivo" signal detection, interactive modulation, and therapeutic interventions for healing and recovery. Additionally, nine strategy avenues for the development of advanced musculoskeletal electronic materials and devices are proposed. Finally, concise summaries and perspectives are proposed to highlight the directions that deserve focused attention in this booming field.

AIEgen-Enabled Multicolor Visualization for the Formation of Supramolecular Polymer Networks

Extensive reports on the use of supramolecular polymer networks (SPNs) in self-healing materials, controlled release system and degradable products have led more researchers to tap their potential owing to the unique properties. Yet, the attendant efforts in the visualization through conventional luminescence methods during the formation of SPNs have been met with limited success. Herein, we designed a special type of SPNs prepared by PPMU polymer chains containing pyrene benzohydrazonate (PBHZ) molecules as AIEgens for the multicolor visualization with naked eyes. The complete detection of the formation process of the networks relied on the PBHZ molecules with aggregation-induced ratiometric emission (AIRE) effect, which enabled the fluorescence of the polymer networks transits from blue to cyan, and then to green with the increasing crosslinking degree derived from the hydrogen bonds between 2-ureido-4-pyrimidone (UPy) units of the polymer chains. Additionally, we certificated the stimuli-responsiveness of the obtained SPNs, and the fluorescence change, as well as observing the morphology transition. The AIEgen-enabled multicolor visualization of the formation of SPNs may provide better understanding of the details of the crosslinking interactions in the microstructural evolution, giving more inspiration for the multifunctional products based on SPNs.

A Comparative Study on the Self-Healing Characterizations and Formulation Optimization of Polyurea Coating

Self-healing materials, especially self-healing polyurea/polyurethane, to replace traditional coating has been of increasing interest in the past decade. The frequency of regular maintenance work can also be reduced as the coating is capable of forming bonds at ruptured sites. This reduces the cost of maintenance and the risk involved in workers engaging in maintenance work. The extremely short curing time of polyurea coating could potentially outweigh the cost due to its short down time. With a high self-healing efficiency, self-healing polyurea could be the ultimate choice of protective coating. This report aims to find the optimum formulation for fabrication of polyurea with a high self-healing efficiency. This is conducted by changing the composition of the components chosen for formulation of polyurea. The choice of isocyanate and amine is varied to explore its impact on chain mobility and microphase separation, which are important factors affecting self-healing efficiency. A series of characterizations, including ATR-FTIR, DSC, optical microscope and mechanical tester, is used to analyze the factors affecting the self-healing efficiency of fabricated polyurea and to eventually determine the best formulation. The ideal formulation of toluene 2,4 diisocyanate-amine (TDI-P1000) polyurea managed to achieve a self-healing of 42%. Further studies could be done to include multiple healing mechanisms after different area of polyurea to boost its self-healing efficiency after repeated healing.

Mini-Review of Self-Healing Mechanism and Formulation Optimization of Polyurea Coating

Self-healing polymers are categorized as smart materials that are capable of surface protection and prevention of structural failure. Polyurethane/polyurea, as one of the representative coatings, has also attracted attention for industrial applications. Compared with polyurethane, polyurea coating, with a similar formation process, provides higher tensile strength and requires shorter curing time. In this paper, extrinsic and intrinsic mechanisms are reviewed to address the efficiency of the self-healing process. Moreover, formulation optimization and strategic improvement to ensure self-healing within a shorter period of time with acceptable recovery of mechanical strength are also discussed. The choice and ratio of diisocyanates, as well as the choice of chain extender, are believed to have a crucial effect on the acceleration of the self-healing process and enhance self-healing efficiency during the preparation of polyurea coatings.

Two-Dimensional Field-Effect Transistor Sensors: The Road toward Commercialization

The evolutionary success in information technology has been sustained by the rapid growth of sensor technology. Recently, advances in sensor technology have promoted the ambitious requirement to build intelligent systems that can be controlled by external stimuli along with independent operation, adaptivity, and low energy expenditure. Among various sensing techniques, field-effect transistors (FETs) with channels made of two-dimensional (2D) materials attract increasing attention for advantages such as label-free detection, fast response, easy operation, and capability of integration. With atomic thickness, 2D materials restrict the carrier flow within the material surface and expose it directly to the external environment, leading to efficient signal acquisition and conversion. This review summarizes the latest advances of 2D-materials-based FET (2D FET) sensors in a comprehensive manner that contains the material, operating principles, fabrication technologies, proof-of-concept applications, and prototypes. First, a brief description of the background and fundamentals is provided. The subsequent contents summarize physical, chemical, and biological 2D FET sensors and their applications. Then, we highlight the challenges of their commercialization and discuss corresponding solution techniques. The following section presents a systematic survey of recent progress in developing commercial prototypes. Lastly, we summarize the long-standing efforts and prospective future development of 2D FET-based sensing systems toward commercialization.

Real-Time Visual Monitoring of Kinetically Controlled Self-Assembly

The construction of artificial structures through hierarchical self-assembly based on noncovalent interactions, as well as monitoring during the self-assembly process, are important aspects of dynamic supramolecular chemistry. Herein we describe the complex dynamics of chiral N,N'-diphenyl dihydrodibenzo[a,c]phenazine derivatives (S)/(R)-DPAC, whose different assemblies were found to have distinct optical and morphological characteristics. With ratiometric fluorescence originating from vibration-induced emission (VIE), the self-assembly process from kinetic traps to the thermodynamic equilibrium state could be monitored in real time by optical spectrometry. During the morphology transformation from particles to nanobricks, strong circularly polarized luminescence was induced with g_lum =1.6×10^-2 . The excited-state characteristics of the self-assemblies enabled investigation of the relationship between molecular aggregation and conformational change, thus allowing effective monitoring of the sophisticated supramolecular self-assembly process.

Niacin Metal-Organic Framework-Laden Self-Healing Hydrogel for Wound Healing

Bacterial infection is one of the most significant impediments to wound healing. To treat wounds, non-biological and non-pharmacological interventions have gained increasing importance as they are easily translatable into clinical products. In this study, we developed a niacin metal-organic frameworks (NOFs)-laden hybrid hydrogel with self-healing ability for better wound healing. The copper based-NOFs (Cu-NOFs) and zinc based-NOFs (Zn-NOFs) were constructed and encapsulated into the self-healing hydrogels, which could prevent NOFs from directly interacting with protein-containing solutions (e. g., tissue fluid). The hydrogel was prepared by using four-armed benzaldehyde-terminated polyethylene glycol (BAPEG) and carboxymethyl chitosan (CMC). Our results showed that the hydrogel gained self-healing ability through reversible Schiff base reaction. In addition, after loading NOFs, the hybrid hydrogel exerted significant effects on antibacterial and antioxidant activities. The in vivo studies demonstrated that the hybrid hydrogel could alleviate inflammation and enhance the formation of granulation tissue, collagen and vascular tissue, thereby promoting wound closure in rats with E. coli -infected wounds. Overall, this study highlights the tremendous potential for the clinical implementation of NOFs-laden hydrogel with good self-healing, antibacterial and antioxidant properties in wound healing.