Ultrathin and Smooth Pheomelanin-like Photoconductive Film

This study introduces a facile method for the substrate-independent deposition of pheomelanin-like films, revealing unique and promising electrical characteristics. The conventional darkening of a dopamine solution at a basic pH was significantly delayed by the addition of l-cysteine, resulting in a distinctive temporal pattern: an initial quiescent period without apparent color change followed by an abrupt and explosive burst. Surprisingly, within the quiescent period, the deposition of ultrathin and smooth pheomelanin-like films was observed, in addition to rough and thick films formed after the burst. Regardless of thickness or texture, these films exhibited common chemical properties, including moisture-capturing capability and dark- and bright-state conductivities. Particularly noteworthy were consistent photocurrent responses under bias voltage across various pheomelanin-like films, which were not observed in polydopamine films, highlighting the influential role of l-cysteine addition. These findings present a novel avenue for the potential application of pheomelanin-like films in bioelectronics, emphasizing their distinct electrical characteristics and prompting further exploration into their intricate conductive mechanisms. The study contributes to advancing our understanding of melanin-based materials and their potential in diverse scientific and technological domains.

Elastic and Conductive Melanin/Poly(Vinyl Alcohol) Composite Hydrogel for Enhancing Repair Effect on Myocardial Infarction

Heart failure caused by acute myocardial infarction (MI) still remains the main cause of death worldwide. Development of conductive hydrogels provided a promising approach for the treatment of myocardial infarction. However, the therapeutic potential of these hydrogels is still limited by material toxicity or low conductivity. The latter directly affects the coupling and the propagation of electrical signals between cells. Here, a functional conductive hydrogel by combining hydrophilic and biocompatible poly(vinyl alcohol) (PVA) with conductive melanin nanoparticles under physical crosslinking conditions is prepared. The composite hydrogels prepared by a facile fabrication process of five freeze/thaw cycles possessed satisfying mechanical properties and conductivity close to those of the natural heart. The physical properties and biocompatibility are evaluated in vitro experiments, showing that the introduction of melanin particles successfully improved the elasticity, conductivity, and cell adhesion of PVA hydrogel. In vivo, the composite hydrogels can enhance the cardiac repair effect by reducing MI area, slowing down ventricular wall thinning, and promoting the vascularization of infarct area in MI rat model. It is believed that the melanin/PVA composite hydrogel may be a suitable candidate material for MI repair.

Highlights on Advancing Frontiers in Tissue Engineering

The field of tissue engineering continues to advance, sometimes in exponential leaps forward, but also sometimes at a rate that does not fulfill the promise that the field imagined a few decades ago. This review is in part a catalog of success in an effort to inform the process of innovation. Tissue engineering has recruited new technologies and developed new methods for engineering tissue constructs that can be used to mitigate or model disease states for study. Key to this antecedent statement is that the scientific effort must be anchored in the needs of a disease state and be working toward a functional product in regenerative medicine. It is this focus on the wildly important ideas coupled with partnered research efforts within both academia and industry that have shown most translational potential. The field continues to thrive and among the most important recent developments are the use of three-dimensional bioprinting, organ-on-a-chip, and induced pluripotent stem cell technologies that warrant special attention. Developments in the aforementioned areas as well as future directions are highlighted in this article. Although several early efforts have not come to fruition, there are good examples of commercial profitability that merit continued investment in tissue engineering. Impact statement Tissue engineering led to the development of new methods for regenerative medicine and disease models. Among the most important recent developments in tissue engineering are the use of three-dimensional bioprinting, organ-on-a-chip, and induced pluripotent stem cell technologies. These technologies and an understanding of them will have impact on the success of tissue engineering and its translation to regenerative medicine. Continued investment in tissue engineering will yield products and therapeutics, with both commercial importance and simultaneous disease mitigation.

Multifunctional Polydopamine Particles as a Thermal Stability Modifier to Prepare Antifouling Melt Blend Composite Membranes

This study reports a novel, multifunctional, and easily obtained modifier to support the rapid advancements in the field of filtration. Polydopamine (PDA) particles (PDAPs) have been reported as a filler for constructing polymer composites, but because of their poor thermal stability, the use of PDAPs in high-temperature blend melt systems to construct antifouling membranes was rare. In this paper, high-thermal-stability methoxy polyethylene glycol amine (mPEG-NH₂)-functionalized PDA nanoparticles (mPDAPs) were first used as a modifier in high-temperature blend melt polymer composites to construct antifouling composite membranes. First, high-thermal-stability mPDAPs with an average diameter of about 390 nm were prepared by immobilized mPEG-NH₂ on the PDAP surface, then melt blend mPDAPs with ultrahigh-molecular-weight polyethylene/liquid paraffin (LP) solution and thermally reduced phase separation (TIPS) to construct antifouling membranes. A combination of properties including mechanical properties, filtration efficiency, and antifouling properties of hybrid composite membranes was investigated and demonstrated that mPDAPs were an efficient modifier for high-temperature melt blending systems. The aim of this study was to provide an effective approach to improve the membrane filtration performance by bulk hybrid modification of multifunctional nanoparticles.

Recent advances in self-actuation and self-sensing materials: State of the art and future perspectives

The contradiction between human's strong demand of fossil fuels and their limited reserves becomes increasingly severe. Without external power input, intelligent materials responding sharply and reversibly to various external stimuli are the topic of intense research these years, especially the self-actuation and self-sensing materials. The promising family of these materials will play a significant role in energy-saving, low-cost and environment-friendly intelligent systems in the future. This review summarizes the latest advances in self-actuation and self-sensing materials. The synthetic strategies, morphologies and performance of these materials are introduced, as well as their applications in energy harvest, self-powering sensors, wearable devices, etc. Finally, tentative conclusions and assessments regarding the opportunities and challenges for the future development of these materials are presented.