Safety Assessment of 2D MXenes: In Vitro and In Vivo

MXenes as emerging materials to repair electroactive tissues and organs

Nanomaterials with electroactive properties have taken a big leap for tissue repair and regeneration due to their unique physiochemical properties and biocompatibility. MXenes, an emerging class of electroactive materials have generated considerable interest for their biomedical applications from bench to bedside. Recently, the application of these two-dimensional wonder materials have been extensively investigated in the areas of biosensors, bioimaging and repair of electroactive organs, owing to their outstanding electromechanical properties, photothermal capabilities, hydrophilicity, and flexibility. The currently available data reports that there is significant potential to employ MXene nanomaterials for repair, regeneration and functioning of electroactive tissues and organs such as brain, spinal cord, heart, bone, skeletal muscle and skin. The current review is the first report that compiles the most recent advances in the application of MXenes in bioelectronics and the development of biomimetic scaffolds for repair, regeneration and functioning of electroactive tissues and organs including heart, nervous system, skin, bone and skeletal muscle. The content in this article focuses on unique features of MXenes, synthesis process, with emphasis on MXene-based electroactive tissue engineering constructs, biosensors and wearable biointerfaces. Additionally, a section on the future of MXenes is presented with a focus on the clinical applications of MXenes.

Introduction to MXene chemistries in biology, medicine and sensing

Maksym Pogorielov, Açelya Yilmazer, Lucia Gemma Delogu and Yury Gogotsi introduce the cross-journal themed issue collection on MXene chemistries in biology, medicine and sensing, published in Nanoscale and Nanoscale Advances.

MXenes in healthcare: transformative applications and challenges in medical diagnostics and therapeutics

MXenes, a novel class of two-dimensional transition metal carbides, exhibit exceptional physicochemical properties that make them highly promising for biomedical applications. Their application has been explored in bioinstrumentation, tissue engineering, and infectious disease management. In bioinstrumentation, MXenes enhance the sensitivity and response time of wearable sensors, including piezoresistive, electrochemical, and electrophysiological sensors. They also function effectively as contrast agents in MRI and CT imaging for cancer diagnostics and therapy. In tissue engineering, MXenes contribute to both hard and soft tissue regeneration, playing a key role in neural, cardiac, skin and bone repair. Additionally, they offer innovative solutions in combating infectious and inflammatory diseases by facilitating antimicrobial surfaces and immune modulation. Despite their potential, several challenges hinder the clinical translation of MXene-based technologies. Issues related to synthesis, scalability, biocompatibility, and long-term safety must be addressed to ensure their practical implementation in medical applications. This review provides a comprehensive overview of MXenes in next-generation medical diagnostics, including the role they play in wearable sensors and imaging contrast agents. It further explores their applications in tissue engineering and infectious disease management, highlighting their antimicrobial and immunomodulatory properties. Finally, we discuss the key barriers to clinical translation and propose strategies for overcoming these limitations. This review aims to bridge current advancements with future opportunities for integration of MXenes in healthcare.

Revolutionizing MXene nanomaterials for hydrogen production and storage: Enhancing catalysis, storage, mechanical integrity, and ecosystem compatibility

Hydrogen holds a pivotal role in achieving net-zero emission targets. Serving as an energy carrier, it complements renewable energy sources in meeting clean energy transition goals and mitigating climate change issues. While many nations recognizes the potential of hydrogen, in the current energy scenario, there is an urgent need for rapid advancements in hydrogen production and storage methods. The advancements in hydrogen production and storage must utilize emission-free methods that are both cost-effective and scalable. Hydrogen as a portable power source, faces criticism due to its low volumetric energy density and the safety requirements associated with its storage. To unlock the full potential of hydrogen in the energy sector, it is imperative to address the challenges related to cost-effective, emission-free generation methods and storage options. In recent years, MXene, a two-dimensional material composed of transition metal carbides, nitrides, and carbonitrides, has garnered significant attention. Its excellent mechanical strength and chemical stability make it a promising material for hydrogen production and storage. Previous reviews have predominantly concentrated on either hydrogen production or storage capabilities of MXene; however, a comprehensive review of its potential in both domains is scarce. Understanding the importance and potential of MXene, the present study review the potential, technical barriers, and solutions for using MXene for both hydrogen production and storage. The challenges associated with MXenes, such as scalability of synthesis, environmental stability, limited hydrogen storage capacity, and catalytic efficiency for hydrogen evolution reactions (HER), are critically examined. Additionally, the review discusses MXene's mechanical and thermal properties, advantages, disadvantages, and environmental risks. Notably, it highlights MXene's application as a catalyst for advancing hydrogen production through gasification, thermochemical processes, and hydrocarbon reforming.

Exploring the revolutionary potential of MXene nanoparticles in breast Cancer therapy: A review of applications and future prospects

Breast cancer is a leading cause of cancer-related deaths in women worldwide. Early detection and accurate diagnosis are crucial for successful treatment and improving patient outcomes. Nanoparticles, such as MXenes, have emerged as a promising tool for various breast cancer applications due to their unique properties. MXenes possess a high surface area and excellent biocompatibility, and can be engineered to enhance targeting ability, as well as mechanical, electrochemical, and optical properties. This review article explores the potential of MXenes in breast cancer detection and treatment, including miRNA detection, MRI-guided photothermal therapy, combined therapy, and immunotherapy. MXenes can be used for miRNA detection, which has shown promise as a biomarker for breast cancer. MXenes can also be used for MRI-guided photothermal therapy, where they can absorb light and convert it into heat to destroy cancer cells. Additionally, MXenes can be used in combination therapy with other drugs to enhance their efficacy. MXenes can also be used for immunotherapy by enhancing the immune response against cancer cells. The article also discusses the future prospects of MXenes in breast cancer research and their cytotoxicity effects. The use of MXenes in breast cancer research is a novel approach with great potential for improving patient outcomes.

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.

Cytotoxicity and antibacterial activity of polyhedral oligomeric silsesquioxane modified Ti3C2Tx MXene films

Bioactive antimicrobial films play important roles in various fields, such as biodegradable interfaces, tissue regeneration, and biomedical applications where preventing infection, biocompatibility, and immune rejection are important. In the present study, bioactive POSS-doped Ti3C2Tx MXene filled PLA composite film was prepared using the solution casting method for biomedical applications. The contact angle tests were investigated to reveal the usability of the thin films in biomedical applications. The angle decreased from 85.92° degrees in pure PLA thin films to 72.23° on POSS-doped Ti3C2Tx MXene films. The antibacterial performance, cytotoxicity and cell viability assessments of the prepared films have also been thoroughly investigated. Antibacterial tests revealed that the POSS-doped Ti3C2Tx MXene films effectively inhibited the growth of E. coli and S. aureus by 65.93% and 80.63%, respectively, within 4 h. These inhibition rates were observed as 58.32% and 54.97% for E. coli and S. aureus, respectively, after 24 h. Cytotoxicity assessments demonstrated that PMPs consistently showed higher cell viability due to the combination of POSS and Ti3C2Tx MXene. The obtained results suggest that the POSS-doped Ti3C2Tx MXene film is a promising candidate in cases where bacterial inhibition and high biocompatibility are of critical importance.

MXene-Based Electrochemical Biosensors: Advancing Detection Strategies for Biosensing (2020-2024)

MXenes, a class of two-dimensional materials, have emerged as promising candidates for developing advanced electrochemical biosensors due to their exceptional electrical conductivity, large surface area, and rich surface chemistry. These unique properties enable high sensitivity, rapid response, and versatile functionalization, making MXene-based biosensors highly suitable for detecting biomolecules and pathogens in biomedical applications. This review explores recent advancements in MXene-based electrochemical biosensors from 2020 to 2024, focusing on their design principles, fabrication strategies, and integration with microfluidic platforms for enhanced performance. The potential of MXene sensors to achieve real-time and multiplexed detection is highlighted, alongside the associated challenges. Emphasis is placed on the role of MXenes in addressing critical needs in disease diagnostics, personalized medicine, and point-of-care testing, providing insights into future trends and transformative possibilities in the field of biomedical sensing technologies.

Isolation of Biomolecules Using MXenes

Biomolecule isolation is a crucial process in diverse biomedical and biochemical applications, including diagnostics, therapeutics, research, and manufacturing. Recently, MXenes, a novel class of two-dimensional nanomaterials, have emerged as promising adsorbents for this purpose due to their unique physicochemical properties. These biocompatible and antibacterial nanomaterials feature a high aspect ratio, excellent conductivity, and versatile surface chemistry. This timely review explores the potential of MXenes for isolating a wide range of biomolecules, such as proteins, nucleic acids, and small molecules, while highlighting key future research trends and innovative applications poised to transform the field. This review provides an in-depth discussion of various synthesis methods and functionalization techniques that enhance the specificity and efficiency of MXenes in biomolecule isolation. In addition, the mechanisms by which MXenes interact with biomolecules are elucidated, offering insights into their selective adsorption and customized separation capabilities. This review also addresses recent advancements, identifies existing challenges, and examines emerging trends that may drive the next wave of innovation in this rapidly evolving area.

MXene-Reinforced Composite Cryogel Scaffold for Neural Tissue Repair

The development of effective materials for neural tissue repair remains a major challenge in regenerative medicine. In this study, we present a novel MXene-reinforced composite cryogel scaffold designed for neural tissue regeneration. MXenes, a class of two-dimensional materials with high conductivity and biocompatibility, were integrated into a polyvinyl alcohol (PVA) matrix via cryopolymerization to form a macroporous, mechanically stable scaffold. The morphology, mechanical properties, and swelling behavior of the cryogel with different MXene contents have been assessed. The effects of MXene on the viability/proliferation and differentiation of neural cells (PC-12) cultured in the composite cryogel were elucidated. The MXene/PVA cryogel demonstrated excellent cell-supporting potential, with MXene not only showing no toxicity but also promoting the proliferation of cultured PC-12. Additionally, MXene induced a neuritogenesis-like process in the cells as evidenced by morphological changes and the enhanced expression of the neural marker β-III-tubulin. The neuroprotective properties of the MXene component were revealed by the alleviation of oxidative stress and reduction of intracellular ROS levels. These findings highlight the potential of MXene-embedded PVA cryogel as a promising material that can be further used in conjunction with electrostimulation therapy for advancing strategies in neural tissue engineering.

Maximizing the safety and sustainability of MXenes

Safe and Sustainable by Design (SSbD) is a new regulatory concept guiding chemical and material innovation. The European Commission has recommended a two-stage SSbD framework and plan to revise it based on stakeholder feedback. The framework involves establishing key (re)design SSbD principles and assessment of the final innovation, however the applicability of the framework to advanced materials remains to be addressed. Here, we applied the SSbD framework on Ti3C2Tx MXenes, an emerging advanced material, by (1) reviewing health, environmental and safety information; (2) characterizing MXenes transformation/dissolution in different media; (3) conducting (eco)toxicological experiments, and (4) completing a prospective life-cycle assessment. Our analysis suggests that Ti3C2Tx is safe and sustainable when applying the SSbD framework. Further research is needed regarding long-term hazardous effects of Ti3C2Tx and the sustainable production of the titanium precursor. Guidance is also needed on how much weight one should assign to the different lines of evidence in the overall SSbD assessment.

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.

Synergistic integration of MXene nanostructures into electrospun fibers for advanced biomedical engineering applications

MXene-based architectures have paved the way in various fields, particularly in healthcare area, owing to their remarkable physiochemical and electromagnetic characteristics. Moreover, the modification of MXene structures and their combination with polymeric networks have gained considerable prominence to further develop their features. The combination of electrospun fibers with MXenes would be promising in this regard since electrospinning is a well-established technique that is now being directed toward commercial biomedical applications. The introduction of MXenes into electrospun fibrous frameworks has highlighted outcomes in various biomedical applications, including cancer therapy, controlled drug delivery, antimicrobial targets, sensors, and tissue engineering. Correspondingly, this review describes the employed strategies for the preparation of electrospun configurations in tandem with MXene nanostructures with remarkable characteristics. Next, the advantages of MXene-decorated electrospun fibers for use in biomedical applications are comprehensively discussed. According to the investigations, rich surface functional groups, hydrophilicity, large surface area, photothermal features, and antimicrobial and antibacterial activities of MXenes could synergize the performance of electrospun layers to engineer versatile biomedical targets. Moreover, the future of this path is clarified to combat the challenges related to the electrospun fibers decorated with MXene nanosheets.

Photothermal Excitation of Neurons Using MXene: Cellular Stress and Phototoxicity Evaluation

Understanding the communication of individual neurons necessitates precise control of neural activity. Photothermal modulation is a remote and non-genetic technique to control neural activity with high spatiotemporal resolution. The local heat release by photothermally active nanomaterial will change the membrane properties of the interfaced neurons during light illumination. Recently, it is demonstrated that the two-dimensional Ti3C2Tx MXene is an outstanding candidate to photothermally excite neurons with low incident energy. However, the safety of using Ti3C2Tx for neural modulation is unknown. Here, the biosafety of Ti3C2Tx-based photothermal modulation is thoroughly investigated, including assessments of plasma membrane integrity, mitochondrial stress, and oxidative stress. It is demonstrated that culturing neurons on 25 µg cm-2 Ti3C2Tx films and illuminating them with laser pulses (635 nm) with different incident energies (2-10 µJ per pulse) and different pulse frequencies (1 pulse, 1 Hz, and 10 Hz) neither damage the cell membrane, induce cellular stress, nor generate oxidative stress. The threshold energy to cause damage (i.e., 14 µJ per pulse) exceeded the incident energy for neural excitation (<10 µJ per pulse). This multi-assay safety evaluation provides crucial insights for guiding the establishment of light conditions and protocols in the clinical translation of photothermal modulation.

Soft, Multifunctional MXene-Coated Fiber Microelectrodes for Biointerfacing

Flexible fiber-based microelectrodes allow safe and chronic investigation and modulation of electrically active cells and tissues. Compared to planar electrodes, they enhance targeting precision while minimizing side effects from the device-tissue mechanical mismatch. However, the current manufacturing methods face scalability, reproducibility, and handling challenges, hindering large-scale deployment. Furthermore, only a few designs can record electrical and biochemical signals necessary for understanding and interacting with complex biological systems. In this study, we present a method that utilizes the electrical conductivity and easy processability of MXenes, a diverse family of two-dimensional nanomaterials, to apply a thin layer of MXene coating continuously to commercial nylon filaments (30-300 μm in diameter) at a rapid speed (up to 15 mm/s), achieving a linear resistance below 10 Ω/cm. The MXene-coated filaments are then batch-processed into free-standing fiber microelectrodes with excellent flexibility, durability, and consistent performance even when knotted. We demonstrate the electrochemical properties of these fiber electrodes and their hydrogen peroxide (H2O2) sensing capability and showcase their applications in vivo (rodent) and ex vivo (bladder tissue). This scalable process fabricates high-performance microfiber electrodes that can be easily customized and deployed in diverse bioelectronic monitoring and stimulation studies, contributing to a deeper understanding of health and disease.

Recent Advances in Two-Dimensional Nanomaterials for Healthcare Monitoring

The development of advanced technologies for the fabrication of functional nanomaterials, nanostructures, and devices has facilitated the development of biosensors for analyses. Two-dimensional (2D) nanomaterials, with unique hierarchical structures, a high surface area, and the ability to be functionalized for target detection at the surface, exhibit high potential for biosensing applications. The electronic properties, mechanical flexibility, and optical, electrochemical, and physical properties of 2D nanomaterials can be easily modulated, enabling the construction of biosensing platforms for the detection of various analytes with targeted recognition, sensitivity, and selectivity. This review provides an overview of the recent advances in 2D nanomaterials and nanostructures used for biosensor and wearable-sensor development for healthcare and health-monitoring applications. Finally, the advantages of 2D-nanomaterial-based devices and several challenges in their optimal operation have been discussed to facilitate the development of smart high-performance biosensors in the future.

Multifunctional MXene-Based Platforms for Soft and Bone Tissue Regeneration and Engineering

MXenes and their composites hold great promise in the field of soft and bone tissue regeneration and engineering (TRE). However, there are challenges that need to be overcome, such as ensuring biocompatibility and controlling the morphologies of MXene-based scaffolds. The future prospects of MXenes in TRE include enhancing biocompatibility through surface modifications, developing multifunctional constructs, and conducting in vivo studies for clinical translation. The purpose of this perspective about MXenes and their composites in soft and bone TRE is to critically evaluate their potential applications and contributions in this field. This perspective aims to provide a comprehensive analysis of the challenges, advantages, limitations, and future prospects associated with the use of MXenes and their composites for soft and bone TRE. By examining the existing literature and research, the review seeks to consolidate the current knowledge and highlight the key findings and advancements in MXene-based TRE. It aims to contribute to the understanding of MXenes' role in promoting soft and bone TRE, addressing the challenges faced in terms of biocompatibility, morphology control, and tissue interactions.

Advancements in MXene-based composites for electronic skins

MXenes are a class of two-dimensional (2D) materials that have gained significant attention in the field of electronic skins (E-skins). MXene-based composites offer several advantages for E-skins, including high electrical conductivity, mechanical flexibility, transparency, and chemical stability. Their mechanical flexibility allows for conformal integration onto various surfaces, enabling the creation of E-skins that can closely mimic human skin. In addition, their high surface area facilitates enhanced sensitivity and responsiveness to external stimuli, making them ideal for sensing applications. Notably, MXene-based composites can be integrated into E-skins to create sensors that can detect various stimuli, such as temperature, pressure, strain, and humidity. These sensors can be used for a wide range of applications, including health monitoring, robotics, and human-machine interfaces. However, challenges related to scalability, integration, and biocompatibility need to be addressed. One important challenge is achieving long-term stability under harsh conditions such as high humidity. MXenes are susceptible to oxidation, which can degrade their electrical and mechanical properties over time. Another crucial challenge is the scalability of MXene synthesis, as large-scale production methods need to be developed to meet the demand for commercial applications. Notably, the integration of MXenes with other components, such as energy storage devices or flexible electronics, requires further developments to ensure compatibility and optimize overall performance. By addressing issues related to material stability, mechanical flexibility, scalability, sensing performance, and power supply, MXene-based E-skins can develop the fields of healthcare monitoring/diagnostics, prosthetics, motion monitoring, wearable electronics, and human-robot interactions. The integration of MXenes with emerging technologies, such as artificial intelligence or internet of things, can unlock new functionalities and applications for E-skins, ranging from healthcare monitoring to virtual reality interfaces. This review aims to examine the challenges, advantages, and limitations of MXenes and their composites in E-skins, while also exploring the future prospects and potential advancements in this field.

Acoustic platforms meet MXenes - a new paradigm shift in the palette of biomedical applications

The wide applicability of acoustics in the life of mankind spread over health, energy, environment, and others. These acoustic technologies rely on the properties of the materials with which they are made of. However, traditional devices have failed to develop into low-cost, portable devices and need to overcome issues like sensitivity, tunability, and applicability in biological in vivo studies. Nanomaterials, especially 2D materials, have already been proven to produce high optical contrast in photoacoustic applications. One such wonder kid in the materials family is MXenes, which are transition metal carbides, that are nowadays flourishing in the materials world. Recently, it has been demonstrated that MXene nanosheets and quantum dots can be synthesized by acoustic excitations. In addition, MXene can be used as a mechanical sensing material for building piezoresistive sensors to realize sound detection as it produces a sensitive response to pressure and vibration. It has also been demonstrated that MXene nanosheets show high photothermal conversion capability, which can be utilized in cancer treatment and photoacoustic imaging (PAI). In this review, we have rendered the role of acoustics in the palette of MXene, including acoustic synthetic strategies of MXenes, applications such as acoustic sensors, PAI, thermoacoustic devices, sonodynamic therapy, artificial ear drum, and others. The review also discusses the challenges and future prospects of using MXene in acoustic platforms in detail. To the best of our knowledge, this is the first review combining acoustic science in MXene research.

Environmental implications of metal-organic frameworks and MXenes in biomedical applications: a perspective

Metal-organic frameworks (MOFs) and MXenes have demonstrated immense potential for biomedical applications, offering a plethora of advantages. MXenes, in particular, exhibit robust mechanical strength, hydrophilicity, large surface areas, significant light absorption potential, and tunable surface terminations, among other remarkable characteristics. Meanwhile, MOFs possess high porosity and large surface area, making them ideal for protecting active biomolecules and serving as carriers for drug delivery, hence their extensive study in the field of biomedicine. However, akin to other (nano)materials, concerns regarding their environmental implications persist. The number of studies investigating the toxicity and biocompatibility of MXenes and MOFs is growing, albeit further systematic research is needed to thoroughly understand their biosafety issues and biological effects prior to clinical trials. The synthesis of MXenes often involves the use of strong acids and high temperatures, which, if not properly managed, can have adverse effects on the environment. Efforts should be made to minimize the release of harmful byproducts and ensure proper waste management during the production process. In addition, it is crucial to assess the potential release of MXenes into the environment during their use in biomedical applications. For the biomedical applications of MOFs, several challenges exist. These include high fabrication costs, poor selectivity, low capacity, the quest for stable and water-resistant MOFs, as well as difficulties in recycling/regeneration and maintaining chemical/thermal/mechanical stability. Thus, careful consideration of the biosafety issues associated with their fabrication and utilization is vital. In addition to the synthesis and manufacturing processes, the ultimate utilization and fate of MOFs and MXenes in biomedical applications must be taken into account. While numerous reviews have been published regarding the biomedical applications of MOFs and MXenes, this perspective aims to shed light on the key environmental implications and biosafety issues, urging researchers to conduct further research in this field. Thus, the crucial aspects of the environmental implications and biosafety of MOFs and MXenes in biomedicine are thoroughly discussed, focusing on the main challenges and outlining future directions.

Oxidation engineering triggered peroxidase-like activity of VOxC for detection of dopamine and glutathione

MXenes, two-dimensional nanomaterials, are gaining traction in catalysis and biomedicine. Yet, their oxidation instability poses significant functional constraints. Gaining insight into this oxidation dynamic is pivotal for designing MXenes with tailored functionalities. Herein, we crafted VOxC nanosheets by oxidatively engineering V4C3 MXene. Interestingly, while pristine V4C3 displays pronounced antioxidant behavior, its derived VOxC showcases enhanced peroxidase-like activity, suggesting the crossover between antioxidant and pro-oxidant capability. The mixed valence states and balanced composition of V in VOxC drive the Fenton reaction through multiple pathways to continually generate hydroxyl radicals, which was proposed as the mechanism underlying the peroxidase-like activity. Furthermore, this unique activity rendered VOxC effective in dopamine and glutathione detection. These findings underscore the potential of modulating MXenes' oxidation state to elicit varied catalytic attributes, providing an avenue for the judicious design of MXenes and derivatives for bespoke applications.

V4 C3 MXene Immune Profiling and Modulation of T Cell-Dendritic Cell Function and Interaction

Although vanadium-based metallodrugs are recently explored for their effective anti-inflammatory activity, they frequently cause undesired side effects. Among 2D nanomaterials, transition metal carbides (MXenes) have received substantial attention for their promise as biomedical platforms. It is hypothesized that vanadium immune properties can be extended to MXene compounds. Therefore, vanadium carbide MXene (V4 C3 ) is synthetized, evaluating its biocompatibility and intrinsic immunomodulatory effects. By combining multiple experimental approaches in vitro and ex vivo on human primary immune cells, MXene effects on hemolysis, apoptosis, necrosis, activation, and cytokine production are investigated. Furthermore, V4 C3 ability is demonstrated to inhibit T cell-dendritic cell interactions, evaluating the modulation of CD40-CD40 ligand interaction, two key costimulatory molecules for immune activation. The material biocompatibility at the single-cell level on 17 human immune cell subpopulations by single-cell mass cytometry is confirmed. Finally, the molecular mechanism underlying V4 C3 immune modulation is explored, demonstrating a MXene-mediated downregulation of antigen presentation-associated genes in primary human immune cells. The findings set the basis for further V4 C3 investigation and application as a negative modulator of the immune response in inflammatory and autoimmune diseases.

MXenes Antibacterial Properties and Applications: A Review and Perspective

The mutations of bacteria due to the excessive use of antibiotics, and generation of antibiotic-resistant bacteria have made the development of new antibacterial compounds a necessity. MXenes have emerged as biocompatible transition metal carbide structures with extensive biomedical applications. This is related to the MXenes' unique combination of properties, including multifarious elemental compositions, 2D-layered structure, large surface area, abundant surface terminations, and excellent photothermal and photoelectronic properties. The focus of this review is the antibacterial application of MXenes, which has attracted the attention of researchers since 2016. A quick overview of the synthesis strategies of MXenes is provided and then summarizes the effect of various factors (including structural properties, optical properties, surface charges, flake size, and dispersibility) on the biocidal activity of MXenes. The main mechanisms for deactivating bacteria by MXenes are discussed in detail including rupturing of the bacterial membrane by sharp edges of MXenes nanoflakes, generating the reactive oxygen species (ROS), and photothermal deactivating of bacteria. Hybridization of MXenes with other organic and inorganic materials can result in materials with improved biocidal activities for different applications such as wound dressings and water purification. Finally, the challenges and perspectives of MXene nanomaterials as biocidal agents are presented.

State-of-the-art: MXene structures in nano-oncology

Cancer nanomedicine has been investigated widely and boomed in the last two decades, resulting in designing nanostructures with biofunctionalization, giving rise to an "All-in-One" multifunctional platform. The development of rational design technology with extended functionalities brought interdisciplinary researchers to work continuously, aiming to find a prevent or effectively treat the deadly disease of the century. Thus, it led to some Food and Drug Administration (FDA)-approving nano-based formulations for cancer treatment and opening a vast area of promising discoveries by exploiting different nanomaterials. Two-dimensional (2D) materials have recently gained tremendous interest among scientists because of their outstanding structural, optical, electronic, thermal, and mechanical characteristics. Among various 2D nanomaterials, MXenes are a widely studied nanosystem because of their close similarity to graphene analogs. So, it is synthesized using multiple approaches and exploits their inherited properties. But in most cases, surface functionalization techniques are carried out for targeting, site-specific drug clearance, renal clearance, and biocompatible with healthy cells. Thus, fabricating a multimodal agent for mono or combined therapies is also an image-guided diagnostic agent. This review will explain the recent and emerging advancements of MXenes-based composites as a multifunctional theragnostic agent and discuss the possibilities of transferring laboratory research to clinical translation.

Novel MXene-Modified Polyphenyl Sulfone Membranes for Functional Nanofiltration of Heavy Metals-Containing Wastewater

In this work, MXene as a hydrophilic 2D nanosheet has been suggested to tailor the polyphenylsulfone (PPSU) flat sheet membrane characteristics via bulk modification. The amount of MXene varied in the PPSU casting solution from 0-1.5 wt.%, while a series of characterization tools have been employed to detect the surface characteristics changes. This included atomic force microscopy (AFM), scanning electron microscopy (SEM), contact angle, pore size and porosity, and Fourier-transform infrared spectroscopy (FTIR). Results disclosed that the MXene content could significantly influence some of the membranes' surface characteristics while no effect was seen on others. The optimal MXene content was found to be 0.6 wt.%, as revealed by the experimental work. The roughness parameters of the 0.6 wt.% nanocomposite membrane were notably enhanced, while greater hydrophilicity has been imparted compared to the nascent PPSU membrane. This witnessed enhancement in the surface characteristics of the nanocomposite was indeed reflected in their performance. A triple enhancement in the pure water flux was witnessed without compromising the retention of the membranes against the Cu²⁺, Cd²⁺ and Pd²⁺ feed. In parallel, high, and comparable separation rates (>92%) were achieved by all membranes regardless of the MXene content. In addition, promising antifouling features were observed with the nanocomposite membranes, disclosing that these nanocomposite membranes could offer a promising potential to treat heavy metals-containing wastewater for various applications.

Cytocompatibility of Ti3C2Tx MXene with Red Blood Cells and Human Umbilical Vein Endothelial Cells and the Underlying Mechanisms

Two-dimensional (2D) nanomaterials have been widely used in biomedical applications because of their biocompatibility. Considering the high risk of exposure of the circulatory system to Ti3C2Tx, we studied the cytocompatibility of Ti3C2Tx MXene with red blood cells (RBCs) and human umbilical vein endothelial cells (HUVECs) and showed that Ti3C2Tx had excellent compatibility with the two cell lines. Ti3C2Tx at a concentration as high as 200 μg/mL caused a negligible percent hemolysis of 0.8%. By contrast, at the same treatment concentration, graphene oxide (GO) caused a high percent hemolysis of 50.8%. Scanning electron microscopy revealed that RBC structures remained intact in the Ti3C2Tx treatment group, whereas those in the GO group completely deformed, sunk, and shrunk, which resulted in the release of cell contents. This difference can be largely ascribed to the distinct surficial properties of the two nanosheets. In specific, the fully covered surface-terminating -O and -OH groups leading to Ti3C2Tx had a very hydrophilic surface, thereby hindering its penetration into the highly hydrophobic interior of the cell membrane. However, the strong direct van der Waals attractions coordinated with hydrophobic interactions between the unoxidized regions of GO and the lipid hydrophobic tails can still damage the integrity of the cell membranes. In addition, the sharp and keen-edged corners of GO may also facilitate its relatively strong cell membrane damage effects than Ti3C2Tx. Thus, the excellent cell membrane compatibility of Ti3C2Tx nanosheets and their ultraweak capacity to provoke excessive ROS generation endowed them with much better compatibility with HUVECs than GO nanosheets. These results indicate that Ti3C2Tx has much better cytocompatibility than GO and provide a valuable reference for the future biomedical applications of Ti3C2Tx.

Liquid Metal Patterning and Unique Properties for Next-Generation Soft Electronics

Room-temperature liquid metal (LM)-based electronics is expected to bring advancements in future soft electronics owing to its conductivity, conformability, stretchability, and biocompatibility. However, various difficulties arise when patterning LM because of its rheological features such as fluidity and surface tension. Numerous attempts are made to overcome these difficulties, resulting in various LM-patterning methods. An appropriate choice of patterning method based on comprehensive understanding is necessary to fully utilize the unique properties. Therefore, the authors aim to provide thorough knowledge about patterning methods and unique properties for LM-based future soft electronics. First, essential considerations for LM-patterning are investigated. Then, LM-patterning methods-serial-patterning, parallel-patterning, intermetallic bond-assisted patterning, and molding/microfluidic injection-are categorized and investigated. Finally, perspectives on LM-based soft electronics with unique properties are provided. They include outstanding features of LM such as conformability, biocompatibility, permeability, restorability, and recyclability. Also, they include perspectives on future LM-based soft electronics in various areas such as radio frequency electronics, soft robots, and heterogeneous catalyst. LM-based soft devices are expected to permeate the daily lives if patterning methods and the aforementioned features are analyzed and utilized.

Advances and emerging challenges in MXenes and their nanocomposites for biosensing applications

Two-dimensional materials have unique properties and their better functionality has created new paradigms in the field of sensing. Over the past decade, a new family of 2D materials known as MXenes has emerged as a promising material for numerous applications, including biosensing. Their metallic conductivity, rich surface chemistry, hydrophilicity, good biocompatibility, and high anchoring capacity for biomaterials make them an attractive candidate to detect a variety of analytes. Despite such notable properties, there are certain limitations associated with them. This review aims to present a detailed survey of MXene's synthesis; in particular, their superiority in the field of biosensing as compared to other 2D materials is addressed. Their low oxidative stability is still an open challenge, and recent investigations on MXene's oxidation are summarized. The hexagonal stacking network of MXenes acts as a distinctive matrix to load nanoparticles, and the embedded nanoparticles can bind an excess number of biomolecules (e.g., antibodies) thereby improving biosensor performance. We will also discuss the synthesis and corresponding performance of MXenes nanocomposites with noble metal nanoparticles and magnetic nanoparticles. Furthermore, Nb and Ti2C-based MXenes, and Ti3C2-MXene sandwich immunoassays are also reviewed in view of their importance. Different aspects and challenges associated with MXenes (from their synthesis to final applications) and the future perspectives described give new directions to fabricate novel biosensors.

New Polymeric Composites Based on Two-Dimensional Nanomaterials for Biomedical Applications

The constant evolution and advancement of the biomedical field requires robust and innovative research. Two-dimensional nanomaterials are an emerging class of materials that have risen the attention of the scientific community. Their unique properties, such as high surface-to-volume ratio, easy functionalization, photothermal conversion, among others, make them highly versatile for a plethora of applications ranging from energy storage, optoelectronics, to biomedical applications. Recent works have proven the efficiency of 2D nanomaterials for cancer photothermal therapy (PTT), drug delivery, tissue engineering, and biosensing. Combining these materials with hydrogels and scaffolds can enhance their biocompatibility and improve treatment for a variety of diseases/injuries. However, given that the use of two-dimensional nanomaterials-based polymeric composites for biomedical applications is a very recent subject, there is a lot of scattered information. Hence, this review gathers the most recent works employing these polymeric composites for biomedical applications, providing the reader with a general overview of their potential.