Plasmonic MXene-based nanocomposites exhibiting photothermal therapeutic effects with lower acute toxicity than pure MXene

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.

Anticancer effects of doxorubicin-conjugated magnetite MXene/Callicarpa extract on MCF-7 breast cancer cell line

Cancer is the most dangerous disease and second leading cause of death worldwide. Doxorubicin (DOX) is the most effective chemotherapeutic agent used for treating cancers. DOX possesses the side effects and strong cytotoxicity. Thus, it is urgent to develop the bio-carriers for loading this drug. In this work, we reported a novel platform based on MXene functionalized with Callicarpa extract and iron oxide nanoparticles (EX-Fe3O4-MX) for loading and release of DOX at different times and pHs and revealing the cytotoxicity of DOX@EX-Fe3O4-MX on breast cancer cell line (MCF-7) by MTT assay. The Raman, UV-Vis, XRD and FT-IR spectroscopy and FE-SEM images revealed DOX onto EX-Fe3O4-MX hybrid. FE-SEM images showed Fe3O4 nanoparticles with main particle size of 34.7 ± 2.6 nm on MXene layers. The 100 ppm of EX-Fe3O4-MX and DOX@EX-Fe3O4-MX showed 0.91 ppm and 0.84 ppm phenols with DPPH radical scavenging of 86.84 % and 75.93 %, respectively. The DOX-efficient loading, 88 % (at pH 7.0 for 4 h), was seen on EX-Fe3O4-MX in comparison to MX and Fe3O4-MX due to the presence of extract phenolic groups. The behavior of DOX@EX-Fe3O4-MX hybrid provided a biphasic release pattern consisting of an initial burst release, followed by a sustained drug release. Upon the normal physiological pH 7.0, the DOX-release content was 24.6 % from the DOX@EX-Fe3O4-MX at 12 h, while 72.1 % of DOX was released at pH 4.0. The 30.5 % and 73.6 % contents of DOX could be released after 25 h at pH 7.0 and 4.0, respectively. Cytotoxicity tests assessed significant viability loss, 41 % and 22 % after 24 and 48 h exposure, respectively for 4 μg/mL of DOX@EX-Fe3O4-MX. The viability loss of DOX@EX-Fe3O4-MX was comparable to free DOX with IC50 of ∼1 μg/mL after 48 h. All these findings imply that EX-Fe3O4-MX carrier offers significant benefits for biomedical applications and the design DOX@EX-Fe3O4-MX based-hybrid exhibits strong anticancer effect because of its remarkable properties, large surface area, and synergistic effects.

Tailoring the synthesis of V0.25(Zr1.75)C MXene for sensitive SERS quantification of ciprofloxacin antibiotics: spectroscopic and DFT investigation

In recent years, bimetallic MXenes have emerged as a promising class of 2D transition metal carbides, noted for their exceptional properties and tunable surface chemistry. This study reports the green synthesis of V0.25(Zr1.75)CTx MXenes from its MAX phase using environmentally friendly etchants. We evaluated, experimentally and theoretically, the potential of the bimetallic MXene as an active surface-enhanced Raman scattering (SERS) substrate for detecting low concentrations of ciprofloxacin. The hybrid SERS substrate, leveraging coupled plasmonic effects, diffused Fermi levels, and enhanced inter-band charge transfer, achieved an outstanding enhancement factor on the order of 1010, enabling the detection of ciprofloxacin at an unprecedented limit of 1 × 10-14 M. The designed substrate exhibited a promising selectivity distinguishing ciprofloxacin from other possible interferents and achieved a high recovery rate of 98%. These findings highlight the significant role of bimetallic MXenes as a new and an effective class to develop SERS substrates for quantifying pharmaceutical compounds. This approach has promising implications for applications in biomedical diagnostics, environmental monitoring, and pharmaceutical quality control.

Engineering space dimension and surface chemistry of MXene-based nanocomposite photocatalysts for sustainable environmental applications

It is very urgent to solve the environmental pollution problem. MXene-based composite photocatalysts show great promise, and utilize solar energy for purification. MXenes have excellent electrical conductivity, a large surface area due to their 2D structure, and surface functional groups beneficial for photocatalysis. In this review, various synthesis methods to prepare MXenes with different properties for specific applications have been reviewed, such as hydrofluoric acid etching, substitute etching and molten fluoride etching. The influence of different groups on the performance of MXenes has been investigated. Modification strategies including heterojunction construction, doping, precious metal deposition and single atom anchoring have been explored to enhance the photocatalytic performance of MXene-based composites in photocatalytic reactions. It is found that MXenes can act as supports that limit photocatalyst size, enhance reactant adsorption, and function as cocatalysts loaded onto semiconductors to improve charge separation. Our perspectives on the key challenges and future directions of developing high-performance MXene-based composite photocatalysts for environmental applications are elaborated.

MXene-based nanocomposites: synthesis, optical properties, and biomedical applications

With the discovery and in-depth research of 2D carbide/nitride MXene, MXene-based nanocomposites have attracted widespread attention due to their unique enhancement and synergistic effects, demonstrating tremendous application potential in the biomedical field. Hence, this review provides a comprehensive discussion of the synthesis methods, optical properties, and biomedical applications of MXene-based nanocomposites. Firstly, it discusses and compares various synthesis methods for MXenes and MXene-based nanocomposites, and categorizes the combination types based on surface engineering strategies and distinct properties. Subsequently, the optical properties of MXene-based nanocomposites are summarized, including localized surface plasmon resonance (LSPR), surface-enhanced Raman scattering (SERS), and photothermal conversion efficiency (PCE). Furthermore, this review provides an in-depth discussion of the applications of MXene-based nanocomposites in biosensors, optical therapeutics, and bioimaging. Finally, we thoroughly explore the challenges and opportunities for the future development of MXene-based nanocomposites, aiming to offer a feasible approach for the development of high-performance materials for biomedical applications.

MXene-Derived Multifunctional Biomaterials: New Opportunities for Wound Healing

The process of wound healing is frequently impeded by metabolic imbalances within the wound microenvironment. MXenes exhibit exceptional biocompatibility, biodegradability, photothermal conversion efficiency, conductivity, and adaptable surface functionalization, demonstrating marked potential in the development of multifunctional platforms for wound healing. Moreover, the integration of MXenes with other bioactive nanomaterials has been shown to enhance their therapeutic efficacy, paving the way for innovative approaches to wound healing. In this review, we provide a systematic exposition of the mechanisms through which MXenes facilitate wound healing and offer a comprehensive analysis of the current research landscape on MXene-based multifunctional bioactive composites in this field. By delving into the latest scientific discoveries, we identify the existing challenges and potential future trajectories for the advancement of MXenes. Our comprehensive evaluation aims to provide insightful guidance for the formulation of more effective wound healing strategies.

Au-decorated Ti3C2Tx/porous carbon immunoplatform for ECM1 breast cancer biomarker detection with machine learning computation for predictive accuracy

Electrochemical immunosensors, surpassing conventional diagnostics, exhibit significant potential for cancer biomarker detection. However, achieving a delicate balance between signal sensitivity and operational stability, especially at the heterostructure interface, is crucial for practical immunosensors. Herein, porous carbon (PC) integration with Ti3C2Tx-MXene (MX) and gold nanoparticles (Au NPs) constructs a versatile immunosensing platform for detecting extracellular matrix protein-1 (ECM1), a breast cancer-associated biomarker. The inclusion of PC provided robust structural support, enhancing electrolytic diffusion with an expansive surface area while synergistically facilitating charge transfer with Ti3C2Tx. The biosensor optimized with 1.0 mg PC demonstrates a robust electrochemical redox response to the surface-bound thionine (th) redox probe, utilizing an inhibition-based strategy for ECM1 detection. The robust antibody-antigen interactions across the PC-integrated Ti3C2Tx-Au NPs platform (MX-Au-C-1) enabled robust ECM1 detection within 0.1-7.5 nM, with a low limit of detection (LOD) of 0.012 nM. The constructed biosensor shows improved operational stability with a 98.6 % current retention over 1 h, surpassing MXene-integrated (MX-Au) and pristine Au NPs (63.2 % and 44.3 %, respectively) electrodes. Moreover, the successful adaptation of the artificial neural network (ANN) model for predictive analysis of the generated DPV data further validates the accuracy of the biosensor, promising its future application in AI-powered remote health monitoring.

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.

MXene-Polydopamine-antiCEACAM1 Antibody Complex as a Strategy for Targeted Ablation of Melanoma

Photothermal therapy (PTT) is a method for eradicating tumor tissues through the use of photothermal materials and photosensitizing agents that absorb light energy from laser sources and convert it into heat, which selectively targets and destroys cancer cells while sparing healthy tissue. MXenes have been intensively investigated as photosensitizing agents for PTT. However, achieving the selectivity of MXenes to the tumor cells remains a challenge. Specific antibodies (Ab) against tumor antigens can achieve homing of the photosensitizing agents toward tumor cells, but their immobilization on MXene received little attention. Here, we offer a strategy for the selective ablation of melanoma cells using MXene-polydopamine-antiCEACAM1 Ab complexes. We coated Ti3C2Tx MXene with polydopamine (PDA), a natural compound that attaches Ab to the MXene surface, followed by conjugation with an anti-CEACAM1 Ab. Our experiments confirm the biocompatibility of the Ti3C2Tx-PDA and Ti3C2Tx-PDA-antiCEACAM1 Ab complexes across various cell types. We also established a protocol for the selective ablation of CEACAM1-positive melanoma cells using near-infrared irradiation. The obtained complexes exhibit high selectivity and efficiency in targeting and eliminating CEACAM1-positive melanoma cells while sparing CEACAM1-negative cells. These results demonstrate the potential of MXene-PDA-Ab complexes for cancer therapy. They underline the critical role of targeted therapies in oncology, offering a promising avenue for the precise and safe treatment of melanoma and possibly other cancers characterized by specific biomarkers. Future research will aim to refine these complexes for clinical use, paving the way for new strategies for cancer treatment.

Gold nanoparticles-doped MXene heterostructure for ultrasensitive electrochemical detection of fumonisin B1 and ampicillin

Early transition metal carbides (MXene) hybridized by precious metals open a door for innovative electrochemical biosensing device design. Herein, we present a facile one-pot synthesis of gold nanoparticles (AuNPs)-doped two-dimensional (2D) titanium carbide MXene nanoflakes (Ti3C2Tx/Au). Ti3C2Tx MXene exhibits high electrical conductivity and yields synergistic signal amplification in conjunction with AuNPs leading to excellent electrochemical performance. Thus Ti3C2Tx/Au hybrid nanostructure can be used as an electrode platform for the electrochemical analysis of various targets. We used screen-printed electrodes modified with the Ti3C2Tx/Au electrode and functionalized with different biorecognition elements to detect and quantify an antibiotic, ampicillin (AMP), and a mycotoxin, fumonisin B1 (FB1). The ultralow limits of detection of 2.284 pM and 1.617 pg.mL-1, which we achieved respectively for AMP and FB1 are far lower than their corresponding maximum residue limits of 2.8 nM in milk and 2 to 4 mg kg-1 in corn products for human consumption set by the United States Food and Drug Administration. Additionally, the linear range of detection and quantification of AMP and FB1 were, respectively, 10 pM to 500 nM and 10 pg mL-1 to 1 µg mL-1. The unique structure and excellent electrochemical performance of Ti3C2Tx/Au nanocomposite suggest that it is highly suitable for anchoring biorecognition entities such as antibodies and oligonucleotides for monitoring various deleterious contaminants in agri-food products.

Transition Metal Oxide-Decorated MXenes as Drugless Nanoarchitectonics for Enriched Nanocatalytic Chemodynamic Treatment

Despite their unique characteristics, 2D MXenes with sole photothermal conversion ability are required to explore their superfluous abilities in biomedicine. The small-molecule-based chemotherapeutics suffer from various shortcomings of time-consuming and expensiveness concerning theoretical and performance (preclinical/clinical) checks. This study demonstrates the fabrication of Ti3C2 MXene nanosheets (TC-MX NSs) and subsequent decoration with transition metal oxides, that is, copper oxide (Cu2O/MX, CO-MX NCs) as drugless nanoarchitectonics for synergistic photothermal (PTT)-chemodynamic therapeutic (CDT) efficacies. Initially, the monolayer/few-layered TC-MX NSs are prepared using the chemical etching-assisted ultrasonic exfoliation method and then deposited with Cu2O nanoconstructs using the in situ reduction method. Further, the photothermal ablation under near-infrared (NIR)-II laser irradiation shows PTT effects of CO-MX NCs. The deposited Cu2O on TC-MX NSs facilitates the release of copper (Cu+) ions in the acidic microenvironment intracellularly for Fenton-like reaction-assisted CDT effects and enriched PTT effects synergistically. Mechanistically, these deadly free radicals intracellularly imbalance the glutathione (GSH) levels and result in mitochondrial dysfunction, inducing apoptosis of 4T1 cells. Finally, the in vivo investigations in BALB/c mice confirm the substantial ablation of breast carcinoma. Together, these findings demonstrate the potential synergistic PTT-CDT effects of the designed CO-MX NCs as drugless nanoarchitectonics against breast carcinoma.

Biogenic crocetin-crosslinked chitosan nanoparticles with high stability and drug loading for efficient radioprotection

The risk of radiation exposure increases with the development of nuclear energy and technology, and radiation protection receives more and more attention from public health and safety. However, the numerous adverse effects and low drug utilization limit the practical applications of radioprotective agents. In this study, we developed a biogenic crocetin-crosslinked chitosan nanoparticle with high stability and drug loading for efficient radioprotection. In detail, the nanoparticles were prepared using the natural antioxidant crocetin as a cross-linking reagent in amidation reactions of chitosan and mPEG-COOH. The nanoparticles exhibit a quick scavenging ability for common reactive oxygen species and reactive nitrogen in vitro. Meanwhile, cellular experiments demonstrate the good biocompatibility of the nanoparticles and the alleviation of radiation damage by scavenging reactive oxygen species, reducing apoptosis, and inhibiting DNA damage, etc. Importantly, the nanoparticles are effective in mitigating oxidative damage in major organs and maintaining peripheral blood cell content. In addition, they perform better radioprotective properties than free drug due to the significant extension of the blood half-life of crocetin in vivo from 10 min to 5 h. This work proposes a drug-crosslinking strategy for the design of a highly efficient radioprotective agent, which exhibits a promising prospect in the fields of nuclear emergency and public health.

MXene: A wonderful nanomaterial in antibacterial

Increasing bacterial infections and growing resistance to available drugs pose a serious threat to human health and the environment. Although antibiotics are crucial in fighting bacterial infections, their excessive use not only weakens our immune system but also contributes to bacterial resistance. These negative effects have caused doctors to be troubled by the clinical application of antibiotics. Facing this challenge, it is urgent to explore a new antibacterial strategy. MXene has been extensively reported in tumor therapy and biosensors due to its wonderful performance. Due to its large specific surface area, remarkable chemical stability, hydrophilicity, wide interlayer spacing, and excellent adsorption and reduction ability, it has shown wonderful potential for biopharmaceutical applications. However, there are few antimicrobial evaluations on MXene. The current antimicrobial mechanisms of MXene mainly include physical damage, induced oxidative stress, and photothermal and photodynamic therapy. In this paper, we reviewed MXene-based antimicrobial composites and discussed the application of MXene in bacterial infections to guide further research in the antimicrobial field.

A biosensor based on Fe3O4@MXene-Au nanocomposites with high peroxidase-like activity for colorimetric and smartphone-based detection of glucose

A novel magnetic nanozyme Fe₃O₄@MXene-Au nanocomposite, which possessed higher peroxidase-like activity than that of Fe₃O₄ nanoparticles and Fe₃O₄@MXene nanocomposites, was developed. The outstanding magnetic properties of the nanozyme endowed it with the ability of simple and rapid separation, achieving great recyclability. Based on Fe₃O₄@MXene-Au nanocomposites and glucose oxidase (Glu Ox), a highly selective colorimetric biosensor for glucose detection was developed. Fe₃O₄@MXene-Au nanocomposites can catalyze H₂O₂ produced from glucose catalyzed by glucose oxidase to ·OH and oxidize colorless 3,3',5,5'-tetramethylbenzidine (TMB) to blue oxidized TMB (oxTMB) with a significant absorbance at 652 nm. The linear range of glucose was 0-1.4 mM under optimal conditions, with a limit of detection (LOD) of 0.11 mM. Glucose in human whole blood was successfully detected with satisfactory recoveries. Furthermore, a facile agarose hydrogel detection platform was designed. With smartphone software, glucose detection can be realized by the agarose hydrogel platform, demonstrating the potential in on-site and visual detection of glucose.

Advances in the application of Mxene nanoparticles in wound healing

Skin is the largest organ of the human body. It plays a vital role as the body's first barrier: stopping chemical, radiological damage and microbial invasion. The importance of skin to the human body can never be overstated. Delayed wound healing after a skin injury has become a huge challenge in healthcare. In some situations, this can have very serious and even life-threatening effects on people's health. Various wound dressings have been developed to promote quicker wound healing, including hydrogels, gelatin sponges, films, and bandages, all work to prevent the invasion of microbial pathogens. Some of them are also packed with bioactive agents, such as antibiotics, nanoparticles, and growth factors, that help to improve the performance of the dressing it is added to. Recently, bioactive nanoparticles as the bioactive agent have become widely used in wound dressings. Among these, functional inorganic nanoparticles are favored due to their ability to effectively improve the tissue-repairing properties of biomaterials. MXene nanoparticles have attracted the interest of scholars due to their unique properties of electrical conductivity, hydrophilicity, antibacterial properties, and biocompatibility. The potential for its application is very promising as an effective functional component of wound dressings. In this paper, we will review MXene nanoparticles in skin injury repair, particularly its synthesis method, functional properties, biocompatibility, and application.

Crafting two-dimensional materials for contrast agents, drug, and heat delivery applications through green technologies

The development of two-dimensional (2D) materials for biomedical applications has accelerated exponentially. Contrary to their bulk counterparts, the exceptional properties of 2D materials make them highly prospective for contrast agents for bioimage, drug, and heat delivery in biomedical treatment. Nevertheless, empty space in the integration and utilisation of 2D materials in living biological systems, potential toxicity, as well as required complicated synthesis and high-cost production limit the real application of 2D materials in those advance medical treatments. On the other hand, green technology appears to be one of strategy to shed a light on the blurred employment of 2D in medical applications, thus, with the increasing reports of green technology that promote advanced technologies, here, we compile, summarise, and synthesise information on the biomedical technology of 2D materials through green technology point of view. Beginning with a fundamental understanding, of crystal structures, the working mechanism, and novel properties, this article examines the recent development of 2D materials. As well as 2D materials made from natural and biogenic resources, a recent development in green-related synthesis was also discussed. The biotechnology and biomedical-related application constraints are also discussed. The challenges, solutions, and prospects of the so-called green 2D materials are outlined.

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.

Roles of MXenes in biomedical applications: recent developments and prospects

....With the development of nanomedical technology, the application of various novel nanomaterials in the biomedical field has been greatly developed in recent years. MXenes, which are new inorganic nanomaterials with ultrathin atomic thickness, consist of layered transition metal carbides and nitrides or carbonitrides and have the general structural formula Mn+1XnTx (n = 1-3). Based on the unique structural features of MXenes, such as ultrathin atomic thickness and high specific surface area, and their excellent physicochemical properties, such as high photothermal conversion efficiency and antibacterial properties, MXenes have been widely applied in the biomedical field. This review systematically summarizes the application of MXene-based materials in biomedicine. The first section is a brief summary of their synthesis methods and surface modification strategies, which is followed by a focused overview and analysis of MXenes applications in biosensors, diagnosis, therapy, antibacterial agents, and implants, among other areas. We also review two popular research areas: wearable devices and immunotherapy. Finally, the difficulties and research progress in the clinical translation of MXene-based materials in biomedical applications are briefly discussed.

Functional two-dimensional MXenes as cancer theranostic agents

Recently, MXenes, as a kind of two-dimensional (2D) layered materials with exceptional performance, have become the research hotspots owing to their unique structural, electronic, and chemical properties. They have potential applications in electrochemical storage, photocatalysis, and biosensors. Furthermore, they have certain characteristics such as large surface area, favorable biocompatibility, and ideal mechanical properties, which can expand their applications in biomedical fields, especially in cancer therapy. To date, several researchers have explored the applications of MXenes in tumor elimination, which exhibited other fantastic properties of those 2D MXenes, such as efficient in vivo photothermal ablation, low phototoxicity, high biocompatibility, etc. In this review, the structures, properties, modifications, and preparation methods are introduced respectively. More importantly, the multifunctional platforms for cancer therapy based on MXenes nanosheets (NSs) are reviewed in detail, including single-modality and combined-modality cancer therapy. Finally, the prospects and challenges of MXenes are prospected and discussed. STATEMENT OF SIGNIFICANCE: In this review, the structures, properties, modifications, and preparation methods of MXenes nanomaterials are introduced, respectively. In addition, the preparation conditions and morphological characterizations of some common MXenes for therapeutic platforms are also summarized. More importantly, the practical applications of MXenes-based nanosheets are reviewed in detail, including drug delivery, biosensing, bioimaging, and multifunctional tumor therapy platforms. Finally, the future prospects and challenges of MXenes are prospected and discussed.

Towards Greener and More Sustainable Synthesis of MXenes: A Review

The unique properties of MXenes have been deemed to be of significant interest in various emerging applications. However, MXenes provide a major drawback involving environmentally harmful and toxic substances for its general fabrication in large-scale production and employing a high-temperature solid-state reaction followed by selective etching. Meanwhile, how MXenes are synthesized is essential in directing their end uses. Therefore, making strategic approaches to synthesize greener, safer, more sustainable, and more environmentally friendly MXenes is imperative to commercialize at a competitive price. With increasing reports of green synthesis that promote advanced technologies and non-toxic agents, it is critical to compile, summarize, and synthesize the latest development of the green-related technology of MXenes. We review the recent progress of greener, safer, and more sustainable MXene synthesis with a focus on the fundamental synthetic process, the mechanism, and the general advantages, and the emphasis on the MXene properties inherited from such green synthesis techniques. The emerging use of the so-called green MXenes in energy conversion and storage, environmental remediation, and biomedical applications is presented. Finally, the remaining challenges and prospects of greener MXene synthesis are discussed.

MXene-Chitosan Composites and Their Biomedical Potentials

Today, MXenes with fascinating electronic, thermal, optical, and mechanical features have been broadly studied for biomedical applications, such as drug/gene delivery, photothermal/photodynamic therapy, antimicrobials/antivirals, sensing, tissue engineering, and regenerative medicine. In this context, various MXene-polymer composites have been designed to improve the characteristics such as physiological stability, sustained/controlled release behaviors, biodegradability, biocompatibility, selectivity/sensitivity, and functionality. Chitosan with advantages of ease of modification, biodegradability, antibacterial activities, non-toxicity, and biocompatibility can be considered as attractive materials for designing hybridized composites together with MXenes. These hybrid composites ought to be further explored for biomedical applications because of their unique properties such as high photothermal conversion efficiency, improved stability, selectivity/sensitivity, stimuli-responsiveness behaviors, and superior antibacterial features. These unique structural, functional, and biological attributes indicate that MXene-chitosan composites are attractive alternatives in biomedical engineering. However, several crucial aspects regarding the surface functionalization/modification, hybridization, nanotoxicological analyses, long-term biosafety assessments, biocompatibility, in vitro/in vivo evaluations, identification of optimization conditions, implementation of environmentally-benign synthesis techniques, and clinical translation studies are still need to be examined by researchers. Although very limited studies have revealed the great potentials of MXene-chitosan hybrids in biomedicine, the next steps should be toward the extensive research and detailed analyses in optimizing their properties and improving their functionality with a clinical and industrial outlook. Herein, recent developments in the use of MXene-chitosan composites with biomedical potentials are deliberated, with a focus on important challenges and future perspectives. In view of the fascinating properties and multifunctionality of MXene-chitosan composites, these hybrid materials can open significant new opportunities in the future for bio- and nano-medicine arena.

Application of MXene in the diagnosis and treatment of breast cancer: A critical overview

Breast cancer is the second most common cancer worldwide. Prognosis and timely treatment can reduce the illness or improve it. The use of nanomaterials leads to timely diagnosis and effective treatment. MXenes are a 2D material with a unique composition of attributes, containing significant electrical conductance, high optical characteristics, mechanical consistency, and excellent optical properties. Current advances and insights show that MXene is far more promising in biotechnology applications than current nanobiotechnology systems. MXenes have various applications in biotechnology and biomedicine, such as drug delivery/loading, biosensor, cancer treatment, and bioimaging programs due to their high surface area, excellent biocompatibility, and physicochemical properties. Surface modifications MXenes are not only biocompatible but also have multifunctional properties, such as aiming ligands for preferential agglomeration at the tumor sites for photothermal treatment. Studies have shown that these nanostructures, detection, and breast cancer therapy are more acceptable than present nanosystems in in vivo and in vitro. This review article aims to investigate the structure of MXene, its various synthesis methods, its application to cancer diagnosis, cytotoxicity, biodegradability, and cancer treatment by the photothermal process (in-vivo and in-vitro).

Recent Advancements on Photothermal Conversion and Antibacterial Applications over MXenes-Based Materials

HIGHLIGHTS

Fabrication, characterizations and photothermal properties of MXenes are systematically described. Photothermal-derived antibacterial performances and mechanisms of MXenes-based materials are summarized and reviewed. Recent advances in the derivative applications relying on antibacterial properties of MXenes-based materials, including in vitro and in vivo sterilization, solar water evaporation and purification, and flexible antibacterial fabrics, are investigated.

ABSTRACT

The pernicious bacterial proliferation and emergence of super-resistant bacteria have already posed a great threat to public health, which drives researchers to develop antibiotic-free strategies to eradicate these fierce microbes. Although enormous achievements have already been achieved, it remains an arduous challenge to realize efficient sterilization to cut off the drug resistance generation. Recently, photothermal therapy (PTT) has emerged as a promising solution to efficiently damage the integrity of pathogenic bacteria based on hyperthermia beyond their tolerance. Until now, numerous photothermal agents have been studied for antimicrobial PTT. Among them, MXenes (a type of two-dimensional transition metal carbides or nitrides) are extensively investigated as one of the most promising candidates due to their high aspect ratio, atomic-thin thickness, excellent photothermal performance, low cytotoxicity, and ultrahigh dispersibility in aqueous systems. Besides, the enormous application scenarios using their antibacterial properties can be tailored via elaborated designs of MXenes-based materials. In this review, the synthetic approaches and textural properties of MXenes have been systematically presented first, and then the photothermal properties and sterilization mechanisms using MXenes-based materials are documented. Subsequently, recent progress in diverse fields making use of the photothermal and antibacterial performances of MXenes-based materials are well summarized to reveal the potential applications of these materials for various purposes, including in vitro and in vivo sterilization, solar water evaporation and purification, and flexible antibacterial fabrics. Last but not least, the current challenges and future perspectives are discussed to provide theoretical guidance for the fabrication of efficient antimicrobial systems using MXenes. [Image: see text]

MXene-Assisted Ablation of Cells with a Pulsed Near-Infrared Laser

Innovative therapies are urgently needed to combat cancer. Thermal ablation of tumor cells is a promising minimally invasive treatment option. Infrared light can penetrate human tissues and reach superficial malignancies. MXenes are a class of 2D materials that consist of carbides/nitrides of transition metals. The transverse surface plasmons of MXenes allow for efficient light absorption and light-to-heat conversion, making MXenes promising agents for photothermal therapy (PTT). To date, near-infrared (NIR) light lasers have been used in PTT studies explicitly in a continuous mode. We hypothesized that pulsed NIR lasers have certain advantages for the development of tailored PTT treatment targeting tumor cells. The pulsed lasers offer a wide range of controllable parameters, such as power density, duration of pulses, pulse frequency, and so on. Consequently, they can lower the total energy applied and enable the ablation of tumor cells while sparing adjacent healthy tissues. We show for the first time that a pulsed 1064 nm laser could be employed for selective ablation of cells loaded with Ti₃C₂T_x MXene. We demonstrate both low toxicity and good biocompatibility of this MXene in vitro, as well as a favorable safety profile based on the experiments in vivo. Furthermore, we analyze the interaction of MXene with cells in several cell lines and discuss possible artifacts of commonly used cellular metabolic assays in experiments with MXenes. Overall, these studies provide a basis for the development of efficient and safe protocols for minimally invasive therapies for certain tumors.

Synthesis, Toxicity Assessment, Environmental and Biomedical Applications of MXenes: A Review

MXenes are a family of two-dimensional (2D) composite materials based on transition metal carbides, nitrides and carbonitrides that have been attracting attention since 2011. Combination of electrical and mechanical properties with hydrophilicity makes them promising materials for biomedical applications. This review briefly discusses methods for the synthesis of MXenes, their potential applications in medicine, ranging from sensors and antibacterial agents to targeted drug delivery, cancer photo/chemotherapy, tissue engineering, bioimaging, and environmental applications such as sensors and adsorbents. We focus on in vitro and in vivo toxicity and possible mechanisms. We discuss the toxicity analogies of MXenes and other 2D materials such as graphene, mentioning the greater biocompatibility of MXenes. We identify existing barriers that hinder the formation of objective knowledge about the toxicity of MXenes. The most important of these barriers are the differences in the methods of synthesis of MXenes, their composition and structure, including the level of oxidation, the number of layers and flake size; functionalization, test concentrations, duration of exposure, and individual characteristics of biological test objects Finally, we discuss key areas for further research that need to involve new methods of nanotoxicology, including predictive computational methods. Such studies will bring closer the prospect of widespread industrial production and safe use of MXene-based products.

Two-dimensional nanomaterials-added dynamism in 3D printing and bioprinting of biomedical platforms: Unique opportunities and challenges

The nanomaterials research spectrum has seen the continuous emergence of two-dimensional (2D) materials over the years. These highly anisotropic and ultrathin materials have found special attention in developing biomedical platforms for therapeutic applications, biosensing, drug delivery, and regenerative medicine. Three-dimensional (3D) printing and bioprinting technologies have emerged as promising tools in medical applications. The convergence of 2D nanomaterials with 3D printing has extended the application dynamics of available biomaterials to 3D printable inks and bioinks. Furthermore, the unique properties of 2D nanomaterials have imparted multifunctionalities to 3D printed constructs applicable to several biomedical applications. 2D nanomaterials such as graphene and its derivatives have long been the interest of researchers working in this area. Beyond graphene, a range of emerging 2D nanomaterials, such as layered silicates, black phosphorus, transition metal dichalcogenides, transition metal oxides, hexagonal boron nitride, and MXenes, are being explored for the multitude of biomedical applications. Better understandings on both the local and systemic toxicity of these materials have also emerged over the years. This review focuses on state-of-art 3D fabrication and biofabrication of biomedical platforms facilitated by 2D nanomaterials, with the comprehensive summary of studies focusing on the toxicity of these materials. We highlight the dynamism added by 2D nanomaterials in the printing process and the functionality of printed constructs.

A critical overview of MXenes adsorption behavior toward heavy metals

In recent years, tremendous interest has been generated in MXenes as a fast-growing and diversified family of two-dimensional (2D) materials with a wide range of potential uses. MXenes exhibit many unique structural and physicochemical properties that make them particularly attractive as adsorbents for removing heavy metals from aqueous media, including a large surface area, abundant surface terminations, electron-richness, and hydrophilic nature. In light of the adsorption capabilities of MXenes at the ever-increasing rate of expansion, this review investigates the recent computational predictions for the adsorption capabilities of MXenes and the effect of synthesis of different MXene on their remediation behavior toward heavy metals. The influence of MXene engineering strategies such as alkalization, acidification, and incorporation into organic and inorganic hosts on their surface properties and adsorption capacity is compared to provide critical insights for designing effective MXene adsorbents. Additionally, the review discusses MXenes' adsorption mechanisms, the effect of coexisting ions on MXenes' selectivity, the regeneration of exhausted MXenes, and provides an overview of MXenes' stability and biocompatibility to demonstrate their potentiality for wastewater remediation. Finally, the review identifies current flaws and offers recommendations for further research.

Harnessing the Immunogenic Potential of Gold Nanoparticle-Based Platforms as a Therapeutic Strategy in Breast Cancer Immunotherapy: A Mini Review

Breast cancer remains the most common malignancy among women worldwide. Although the implementation of mammography has dramatically increased the early detection rate, conventional treatments like chemotherapy, radiation therapy, and surgery, have significantly improved the prognosis for breast cancer patients. However, about a third of treated breast cancer patients are known to suffer from disease recurrences and progression to metastasis. Immunotherapy has recently gained traction due to its ability to establish long-term immune surveillance, and response for the prevention of disease recurrence and extension of patient survival. Current research findings have revealed that gold nanoparticles can enhance the safety and efficacy of cancer immunotherapy, through their unique intrinsic properties of good biocompatibility, durability, convenient surface modification, as well as enhanced permeability and retention effect. Gold nanoparticles are also able to induce innate immune responses through the process of immunogenic cell death, which can lead to the establishment of lasting adaptive immunity. As such gold nanoparticles are considered as good candidates for next generation immunotherapeutic strategies. This mini review gives an overview of gold nanoparticles and their potential applications in breast cancer immunotherapeutic strategies.

MXene-Enhanced Chitin Composite Sponges with Antibacterial and Hemostatic Activity for Wound Healing

This study shows the effective use of MXene-based nanomaterials to improve the performance of biocomposite sponges in wound healing. In this way, diverse chitin/MXene composite sponges are fabricated by incorporating MXene-based nanomaterials with various morphology (accordion-shaped, intercalated, single-layer, gold nanoparticles (AuNPs)-loaded single-layer) into the network of chitin sponge (CH), which can prevent massive blood losses and promote the healing process of bacterial-infected wounds. With the addition of MXene-based nanomaterials, the hemostatic efficacy of CH is enhanced due to the improved hemophilicity and accelerated blood coagulation kinetics. Furthermore, the composite sponges show a predominant antibacterial activity through the synergy between the capture and the photothermal effects. Importantly, the addition of AuNPs to composite sponges further improves hemostatic performance and promotes normal skin cell migration to heal the infected wound, achieving wound closure rates of 84% on day 9. These initial studies expand the applications of MXene-based nanomaterials in biomedical fields.

The 10th anniversary of MXenes: Challenges and prospects for their surface modification toward future biotechnological applications

A broad family of two-dimensional (2D) materials - carbides, nitrides, and carbonitrides of early transition metals, called MXenes, became a newcomer in the flatland at the turn of 2010 and 2011 (over ten years ago). Their unique physicochemical properties made them attractive for many applications, highly boosting the development of various fields, including biotechnological. However, MXenes' functional features that impact their bioactivity and toxicity are still not fully well understood. This study discusses the essentials for MXenes's surface modifications toward their application in modern biotechnology and nanomedicine. We survey modification strategies in context of cytotoxicity, biocompatibility, and most prospective applications ready to implement in medical practice. We put the discussion on the material-structure-chemistry-property relationship into perspective and concentrate on overarching challenges regarding incorporating MXenes into nanostructured organic/inorganic bioactive architectures. It is another emerging group of materials that are interesting from the biomedical point of view as well. Finally, we present an influential outlook on the growing demand for future research in this field.

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

MXenes, representing a new class of two-dimensional nanomaterial, have attracted intense interest in a variety of fields as supercapacitors, catalysts, and sensors, and in biomedicine. The assessment of the safety of MXenes and related materials in biological systems is thus an issue that requires significant attention. In this review, the toxic effects of MXenes and their derivatives are summarized through the discussion of current research into their behaviors in mammalian cells, animals and plants. Numerous studies have shown that MXenes have generally low cytotoxicity and good biocompatibility. However, a few studies have indicated that MXenes are toxic to stem cells and embryos. These in vitro and in vivo toxic effects are strongly associated with the dose of material, the cell type, the mode of exposure, and the specific type of MXene. In addition, surface modifications alter the toxic effects of MXenes. The stability of MXenes must be considered during toxicity evaluation, as degradation can lead to potentially toxic byproducts. Although research concerning the toxicity of MXenes is limited, this review provides an overview of the current understanding of interactions of MXenes with biological systems and suggests future research directions.

MXene (Ti3C2Tx)-Embedded Nanocomposite Hydrogels for Biomedical Applications: A Review

Polymeric nanocomposites have been outstanding functional materials and have garnered immense attention as sustainable materials to address multi-disciplinary problems. MXenes have emerged as a newer class of 2D materials that produce metallic conductivity upon interaction with hydrophilic species, and their delamination affords monolayer nanoplatelets of a thickness of about one nm and a side size in the micrometer range. Delaminated MXene has a high aspect ratio, making it an alluring nanofiller for multifunctional polymer nanocomposites. Herein, we have classified and discussed the structure, properties and application of major polysaccharide-based electroactive hydrogels (hyaluronic acid (HA), alginate sodium (SA), chitosan (CS) and cellulose) in biomedical applications, starting with the brief historical account of MXene's development followed by successive discussions on the synthesis methods, structures and properties of nanocomposites encompassing polysaccharides and MXenes, including their biomedical applications, cytotoxicity and biocompatibility aspects. Finally, the MXenes and their utility in the biomedical arena is deliberated with an eye on potential opportunities and challenges anticipated for them in the future, thus promoting their multifaceted applications.

Application of MXenes for water treatment and energy-efficient desalination: A review

MXenes are a new type of two-dimensional (2D) material which are rapidly gaining traction for a range of environmental, chemical and medical applications. MXenes and MXene-composites exhibit high surface area, superlative chemical stability, thermal conductivity, hydrophilicity and are environmentally compatible. Consequently, MXenes have been successfully employed for hydrogen storage, semiconductor manufacture and lithium ion batteries. In recent years, MXenes have been utilized in numerous environmental applications for treating contaminated surface waters, ground and industrial/ municipal wastewaters and for desalination, often outperforming conventional materials in each field. MXene-composites can adsorb multiple organic and inorganic contaminants, and undergo Faradaic capacitive deionization (CDI) when utilized for electrochemical applications. This approach allows for a significant decrease in the energy demand by overcoming the concentration polarization limitation of conventional CDI electrodes, offering a solution for low-energy desalination of brackish waters. This article presents a state-of-the-art review on water treatment and desalination applications of MXenes and MXene-composites. An investigation into the kinetics and isotherms is presented, as well as the impact of water constituents and operating conditions are also discussed. The applications of MXenes for CDI, pervaporation desalination and solar thermal desalination are also examined based on the reviewed literature. The effects of the water composition and operational protocols on the regeneration efficacy and long-term usage are also highlighted.

Constructing virus-like SiOx/CeO2/VOx nanozymes for 1064 nm light-triggered mild-temperature photothermal therapy and nanozyme catalytic therapy

The construction of nanoplatforms with combined photothermal properties and cascading enzymatic activities has become an active area of anticancer research. However, the overheating of photothermal therapy (PTT) and the specific properties of tumor microenvironment (TME) greatly impaired the therapeutic efficiency. Herein, we rationally fabricated a virus-like SiO_x/CeO₂/VO_x (SCV) nanoplatform for 1064 nm near-infrared (NIR) triggered mild-temperature PTT and nanozyme catalytic therapy. Firstly, the virus-like shape of SiO_x/CeO₂/VO_x made it favorable for cell adhesion and improved its phagocytosis in cells, and the SCV generated an effective PTT effect upon 1064 nm laser irradiation. Particularly, the produced VO²⁺ in TME could be used as a heat shock protein inhibitor to inhibit the expression of heat shock protein 60 (HSP60) to enhance the PTT efficiency. Moreover, the SCV nanozyme exhibited obvious peroxidase-mimic (POD) catalytic activity, which could generate highly toxic free radical ions (˙OH) under acidic conditions. The mild-temperature heat and ˙OH produced by enzymatic catalysis effectively blocked the tumor growth, as verified firmly by in vitro and in vivo tests. Our designed virus-like SCV nanozyme with POD mimic enzyme activity and a mild photothermal effect may provide a new way of thinking about the combination therapy model.

MXenes-A New Class of Two-Dimensional Materials: Structure, Properties and Potential Applications

A new class of two-dimensional nanomaterials, MXenes, which are carbides/nitrides/carbonitrides of transition and refractory metals, has been critically analyzed. Since the synthesis of the first family member in 2011 by Yury Gogotsi and colleagues, MXenes have quickly become attractive for a variety of research fields due to their exceptional properties. Despite the fact that this new family of 2D materials was discovered only about ten years ago, the number of scientific publications related to MXene almost doubles every year. Thus, in 2021 alone, more than 2000 papers are expected to be published, which indicates the relevance and prospects of MXenes. The current paper critically analyzes the structural features, properties, and methods of synthesis of MXenes based on recent available research data. We demonstrate the recent trends of MXene applications in various fields, such as environmental pollution removal and water desalination, energy storage and harvesting, quantum dots, sensors, electrodes, and optical devices. We focus on the most important medical applications: photo-thermal cancer therapy, diagnostics, and antibacterial treatment. The first results on obtaining and studying the structure of high-entropy MXenes are also presented.

Characterization of MXene as a Cancer Photothermal Agent Under Physiological Conditions

A growing interest has recently emerged in the use of nanomaterials in medical applications. Nanomaterials, such as MXene, have unique properties due to their 2D ultra-thin structure, which is potentially useful in cancer photothermal therapy. To be most effective, photothermal agents need to be internalized by the cancer cells. In this study, MXene was fabricated using chemical reactions and tested as a photothermal agent on MDA-231 breast cancer cells under static and physiological conditions. Fluid shear stress (∼0.1 Dyn/cm2) was applied using a perfusion system to mimic the physiological tumor microenvironment. The uptake of MXene was analyzed under fluid flow compared to static culture using confocal microscopy, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and transmission electron microscopy (TEM). Furthermore, a viability assay was used to assess cell’s survival after exposing the treated cells to photothermal laser at different power densities and durations. We showed that when incubated with cancer cells, 2D MXene nanoparticles were successfully internalized into the cells resulting in increased intracellular temperatures when exposed to NIR laser. Interestingly, dynamic culture alone did not result in a significant increase in uptake suggesting the need for surface modifications for enhanced cellular uptake under shear stress.

A decade of exploring MXenes as aquatic cleaners: Covering a broad range of contaminants, current challenges and future trends

Clean water, the elixir of life, is of tremendous importance in achieving environmental sustainability and the balanced functioning of our ecosystem. Coupled with population growth, several anthropogenic activities and environmental catastrophes have together contributed to an alarming increase in the concentration of toxic pollutants in water bodies. Diversified physiochemical conditions of water matrices, ranging from mining drainage to seawater, is the critical challenge in designing adsorbents. MXenes, a new class of 2D layered materials, are transition metal nitrides, carbides, carbonitrides or borides formed through selective etching process. MXenes are known to have high surface area and activity with biological compatibility and chemical stability and therefore are promising adsorbents and have been explored for a broad range of contaminants. This review starts with a brief about environmental contaminants followed by synthesis and modifications of MXenes. It then revolves around their so far explored adsorbing and degradation properties for different contaminants ranging from toxic metals, inorganic ions, and radionuclides to various organic pollutants, including dyes, pharmaceuticals, aromatic hydrocarbons, and pesticides, etc. Finally, we have discussed associated toxicity, secondary contamination, future trends, and challenges in ascertaining scalability and wide-range applicability of MXenes in natural environmental conditions to make them a warrior of water sustainability.

Gold Nanoparticles; Potential Nanotheranostic Agent in Breast Cancer: A Comprehensive Review with Systematic Search Strategy

BACKGROUND

Breast cancer is a heterogeneous disease typically prevalent among women and is the second-largest cause of death worldwide. Early diagnosis is the key to minimize the cancer-induced complication, however, the conventional diagnostic strategies have been sluggish, complex, and, to some extent, non-specific. Therapeutic tools are not so convenient and side effects of current therapies offer the development of novel theranostic tool to combat this deadly disease.

OBJECTIVE

This article aims to summarize the advances in the diagnosis and treatment of breast cancer with gold nanoparticles (GNP or AuNP).

METHODS

A systematic search was conducted in the three popular electronic online databases including PubMed, Google Scholar, and Web of Science, regarding GNP as breast cancer theranostics.

RESULTS

Published literature demonstrated that GNPs tuned with photosensitive moieties, nanomaterials, drugs, peptides, nucleotide, peptides, antibodies, aptamer, and other biomolecules improve the conventional diagnostic and therapeutic strategies of breast cancer management with minimum cytotoxic effect. GNP derived diagnosis system assures reproducibility, reliability, and accuracy cost-effectively. Additionally, surface-modified GNP displayed theranostic potential even in the metastatic stage of breast cancer.

CONCLUSION

Divergent strategies have shown the theranostic potential of surface tuned GNPs against breast cancer even in the metastatic stage with minimum cytotoxic effects both in vitro and in vivo.

Fascinating MXene nanomaterials: emerging opportunities in the biomedical field

In recent years, there has been rapid progress in MXene research due to its distinctive two-dimensional structure and outstanding properties. Especially in biomedical applications, MXenes have attracted widespread favor with numerous studies on biosafety, bioimaging, therapy, and biosensing, although their development is still in the experimental stage. A comprehensive understanding of the current status of MXenes in biomedicine will promote their use in clinical applications. Here, we review advances in MXene research. First, we introduce the methods of synthesis, surface modification and functionalization of MXenes. Then, we summarize the biosafety and biocompatibility, paving the way for specific biomedical applications. On this basis, MXene nanostructures are described with respect to their use in antibacterial, bioimaging, cancer therapy, tissue regeneration and biosensor applications. Finally, we discuss MXene as a promising candidate material for further applications in biomedicine.

Chitosan/hyaluronic acid based hollow microcapsules equipped with MXene/gold nanorods for synergistically enhanced near infrared responsive drug delivery

Ti₃C₂ MXenes, a novel two-dimensional material, have attracted lots of attention in biomedical filed for its large surface area and excellent near-infrared (NIR) responsiveness. In this paper, a pH/near-infrared (NIR) multi-responsive drug delivery platform consisted of hollow hydroxyapatite (HAP), chitosan (CS)/hyaluronic acid (HA) multilayers, gold nanorods (AuNRs) and MXene had been fabricated via a layer-by-layer (LbL) approach. Chitosan/hyaluronic acid multilayers were deposited on the surface of hollow HAP to retard the burst release of DOX in the initial delivery stage. MXenes and AuNRs equipped on the surface of hybrid matrix greatly enhanced the photothermal conversion efficiency of the microcapsules. Due to the collapse of electrostatic force among chitosan/hyaluronic acid multilayers and the dissolution of HAP under acidic condition, as well as the synergistically enhanced photothermal effect between MXene and AuNRs, HAP/CS/HA/MXene/AuNRs microcapsules exhibited outstanding pH-/NIR-responsive drug delivery properties. The present paper provides an attractive method to prepare chitosan/hyaluronic acid based pH/NIR multi-responsive hybrid microcapsules with excellent photothermal conversion efficiency and biocompatibility, which has great potential in the field of remotely controlled drug delivery.

Surface-Related Features Responsible for Cytotoxic Behavior of MXenes Layered Materials Predicted with Machine Learning Approach

To speed up the implementation of the two-dimensional materials in the development of potential biomedical applications, the toxicological aspects toward human health need to be addressed. Due to time-consuming and expensive analysis, only part of the continuously expanding family of 2D materials can be tested in vitro. The machine learning methods can be used-by extracting new insights from available biological data sets, and provide further guidance for experimental studies. This study identifies the most relevant highly surface-specific features that might be responsible for cytotoxic behavior of 2D materials, especially MXenes. In particular, two factors, namely, the presence of transition metal oxides and lithium atoms on the surface, are identified as cytotoxicity-generating features. The developed machine learning model succeeds in predicting toxicity for other 2D MXenes, previously not tested in vitro, and hence, is able to complement the existing knowledge coming from in vitro studies. Thus, we claim that it might be one of the solutions for reducing the number of toxicological studies needed, and allows for minimizing failures in future biological applications.

Resveratrol Inhibits Oxidative Stress and Prevents Mitochondrial Damage Induced by Zinc Oxide Nanoparticles in Zebrafish (Danio rerio)

Despite their wide industrial use, Zinc oxide (ZnO) nanoparticles (NPs) exhibit a high toxic potential while concerns of their health-related risks are still present, urging additional in vivo clarification studies. Oxidative stress is recognized as the primary trigger of NP-associated toxicity, suggesting antioxidants as a promising counteractive approach. Here, we investigated the protective effect of the natural antioxidant resveratrol against ZnO NP-induced toxicity in vivo using the zebrafish model. Our findings demonstrate that resveratrol counteracts ZnO NP-induced zebrafish lethality preventing cardiac morphological and functional damage. NP-induced vascular structural abnormalities during embryonic fish development were significantly counteracted by resveratrol treatment. Mechanistically, we further showed that resveratrol inhibits ROS increase, prevents mitochondrial membrane potential dysfunction, and counteracts cell apoptosis/necrosis elicited by ZnO NP. Overall, our data provide further evidence demonstrating the primary role of oxidative stress in NP-induced damage, and highlight new insights concerning the protective mechanism of antioxidants against nanomaterial toxicity.