MXene and Xene: promising frontier beyond graphene in tissue engineering and regenerative medicine

MXenes in healthcare: synthesis, fundamentals and applications

Since their discovery over a decade ago, MXenes have transformed the field of "materials for healthcare", stimulating growing interest in their healthcare-related applications. These developments have also driven significant advancements in MXenes' synthesis. This review systematically examines the synthesis of MXenes and their applications in sensing and biomedical fields, underscoring their pivotal role in addressing critical challenges in modern healthcare. We describe the experimental synthesis of MXenes by combining appropriate laboratory modules with the mechanistic principles underlying each synthesis step. In addition, we provide extensive details on the experimental parameters, critical considerations, and essential instructions for successful laboratory synthesis. Various healthcare applications including sensing, biomedical imaging, synergistic therapies, regenerative medicine, and wearable devices have been explored. We further highlight the emerging trends of MXenes, viz., their role as nanovehicles for drug delivery, vectors for gene therapy, and tools for immune profiling. By identifying the important parameters that define the utility of MXenes in biomedical applications, this review outlines strategies to regulate their biomedical profile, thereby serving as a valuable guide to design MXenes with application-specific properties. The final section integrates experimental research with theoretical studies to provide a comprehensive understanding of the field. It examines the role of emerging technologies, such as artificial intelligence (AI) and machine learning (ML), in accelerating material discovery, structure-property optimization, and automation. Complemented by detailed supplementary information on synthesis, stability, biocompatibility, environmental impact, and theoretical insights, this review offers a profound knowledge base for understanding this diverse family of 2D materials. Finally, we compared the potential of MXenes with that of other 2D materials to underscore the existing challenges and prioritize interdisciplinary collaboration. By synthesizing key studies from its discovery to current trends (especially from 2018 onward), this review provides a cohesive assessment of MXene synthesis with theoretical foundations and their prospects in the healthcare sector.

Engineered MXene Biomaterials for Regenerative Medicine

MXene-based materials have attracted significant interest due to their distinct physical and chemical properties, which are relevant to fields such as energy storage, environmental science, and biomedicine. MXene has shown potential in the area of tissue regenerative medicine. However, research on its applications in tissue regeneration is still in its early stages, with a notable absence of comprehensive reviews. This review begins with a detailed description of the intrinsic properties of MXene, followed by a discussion of the various nanostructures that MXene can form, spanning from 0 to 3 dimensions. The focus then shifts to the applications of MXene-based biomaterials in tissue engineering, particularly in immunomodulation, wound healing, bone regeneration, and nerve regeneration. MXene's physicochemical properties, including conductivity, photothermal characteristics, and antibacterial properties, facilitate interactions with different cell types, influencing biological processes. These interactions highlight its potential in modulating cellular functions essential for tissue regeneration. Although the research on MXene in tissue regeneration is still developing, its versatile structural and physicochemical attributes suggest its potential role in advancing regenerative medicine.

Non-Ti MXenes: new biocompatible and biodegradable candidates for biomedical applications

MXenes are a class of two-dimensional nanomaterials with the general formula Mn+1XnTx, where M denotes a transition metal, X denotes either carbon or nitrogen and Tx refers to surface terminations, such as -OH, -O, -F or -Cl. The unique properties of MXenes, including their tunable surface chemistry and high surface area-to-volume ratio, make them promising candidates for various biomedical applications, such as targeted drug delivery, photothermal therapy and so on. Among the family of MXenes, titanium (Ti)-based MXenes, especially Ti3C2Tx, have been extensively explored for biomedical applications. However, despite their potential, Ti-based MXenes have shown some limitations, such as low biocompatibility. Recent studies have also indicated that Ti MXenes may disrupt spermatogenesis and accumulate in the uterus. Non-Ti MXenes are emerging as promising alternatives to Ti-based MXenes due to their superior biodegradability and enhanced biocompatibility. Recently, non-Ti MXenes have been explored for a range of biomedical applications, including drug delivery, photothermal therapy, chemodynamic therapy and sonodynamic therapy. In addition, some non-Ti MXenes exhibit enzyme-mimicking activity, such as superoxide dismutase and peroxidase-like functions, which play a major role in scavenging reactive oxygen species (ROS). This review discusses the properties of non-Ti MXenes, such as biocompatibility, biodegradability, antibacterial activity, and neuroprotective effects, highlighting their potential in various biomedical applications. These properties can be leveraged to mitigate oxidative stress and develop safe and innovative strategies for managing chronic diseases. This review provides a comprehensive analysis of the various biomedical applications of non-Ti MXenes, including their use in drug delivery and combinatorial therapies and as nanozymes for sensing and therapeutic purposes. The theranostic applications of non-Ti MXenes are also discussed. Finally, the antibacterial properties of non-Ti MXenes and the proposed mechanisms are discussed. The review concludes with a summary of the key findings and future perspectives. In short, this review provides a thorough analysis of the biomedical applications of non-Ti MXenes, emphasizing their unique properties, potential opportunities and challenges in the field.

Recent advances in two-dimensional materials for drug delivery

Two-dimensional (2D) materials exhibit significant potential in biomedical applications, particularly as drug carriers. Thus, 2D materials, including graphene, black phosphorus, transition metal dichalcogenides, transition metal carbides/nitrides, and hexagonal boron nitride, have been extensively studied. Their large specific surface area, abundant surface active sites, and excellent biocompatibility and biodegradability make them ideal platforms for drug loading and delivery. By optimizing the physicochemical properties and methods for the surface modification of 2D materials, improved drug release mechanisms and enhanced combination therapy effects can be achieved, providing a reliable foundation for efficient cancer treatment. This review provides a comprehensive analysis of the recent advances in the utilization of 2D materials for drug delivery. It systematically categorizes and summarizes the preparation methodologies, surface modification strategies, application domains, primary advantages and potential drawbacks of various 2D materials in the biomedical field. Furthermore, it provides an extensive overview of current challenges in this field and outlines potential future research directions for 2D materials in drug delivery based on existing issues.

2D MXene Nanosheets with ROS Scavenging Ability Effectively Delay Osteoarthritis Progression

MXenes nanosheets with high conductivity, hydrophilicity, and excellent reactive oxygen species (ROS) scavenging ability have shown promise in treating various degenerative diseases correlated with abnormal ROS accumulation. Herein, the therapeutic potential of Ti3C2Tx nanosheets, which is the most widely investigated MXene material, in delaying osteoarthritis (OA) progression is demonstrated. In vitro experiments indicate the strong ROS scavenging capacity of Ti3C2Tx nanosheets and their acceptable biocompatibility. Ti3C2Tx nanosheets effectively protect chondrocytes from cell death induced by oxidative stress. In addition, Ti3C2Tx nanosheets demonstrate a prominent anti-inflammatory effect and the ability to restore homeostasis between anabolic activities and catabolic activities in chondrocytes. Furthermore, RNA sequencing reveals the potential mechanism underlying the Ti3C2Tx nanosheet-mediated therapeutic effect. Finally, the in vivo curative effect of Ti3C2Tx nanosheets is verified using a rat OA model. Histological staining and immunohistochemical analyses indicate that Ti3C2Tx nanosheets effectively ameliorate OA progression. Conclusively, the in vitro and in vivo experiments suggest that Ti3C2Tx nanosheets could be a promising and effective option for OA treatment.

Study on 3D printed MXene-berberine-integrated scaffold for photo-activated antibacterial activity and bone regeneration

The repair of mandibular defects is a challenging clinical problem, and associated infections often hinder the treatment, leading to failure in bone regeneration. Herein, a multifunctional platform is designed against the shortages of existing therapies for infected bone deficiency. 2D Ti3C2 MXene and berberine (BBR) are effectively loaded into 3D printing biphasic calcium phosphate (BCP) scaffolds. The prepared composite scaffolds take the feature of the excellent photothermal capacity of Ti3C2 as an antibacterial, mediating NIR-responsive BBR release under laser stimuli. Meanwhile, the sustained release of BBR enhances its antibacterial effect and further accelerates the bone healing process. Importantly, the integration of Ti3C2 improves the mechanical properties of the 3D scaffolds, which are beneficial for new bone formation. Their remarkable biomedical performances in vitro and in vivo present the outstanding antibacterial and osteogenic properties of the Ti3C2-BBR functionalized BCP scaffolds. The synergistic therapy makes it highly promising for repairing infected bone defects and provides insights into a wide range of applications of 2D nanosheets in biomedicine.