Nanomedicine-Enabled Photonic Thermogaseous Cancer Therapy

Elucidation of Potential Genotoxicity of MXenes Using a DNA Comet Assay

MXenes are among the most diverse and prominent 2D materials. They are being explored in almost every field of science and technology, including biomedicine. In particular, they are being investigated for photothermal therapy, drug delivery, medical imaging, biosensing, tissue engineering, blood dialysis, and antibacterial coatings. Despite their proven biocompatibility and low cytotoxicity, their genotoxicity has not been addressed. To investigate whether MXenes interfere with DNA integrity in cultured cells, we loaded the cells with MXenes and examined the fragmentation of their chromosomal DNA by a DNA comet assay. The presence of both Ti3C2Tx and Nb4C3Tx MXenes generated DNA comets, suggesting a strong genotoxic effect in murine melanoma and human fibroblast cells. However, no corresponding cytotoxicity was observed, confirming that MXenes were well tolerated by the cells. The lateral size of the MXene flakes was critical for developing the DNA comets; submicrometer flakes induced the DNA comets, while larger flakes did not. MXenes did not induce DNA comets in dead cells. Moreover, the extraction of the chromosomal DNA from the MXene-loaded cells or mixing the purified DNA with MXenes showed no signs of DNA fragmentation. Unconstrained living MXene-loaded cells did not show cleavage of the DNA with MXenes under electrophoresis conditions. Thus, the DNA comet assay showed the ability of submicrometer MXene particles to penetrate living cells and induce DNA fragmentation under the applied field. The most probable mechanism of DNA comet formation is the rotation and movement of submicrometer MXene flakes inside cells in an electric field, leading to cleavage and DNA shredding by MXene's razor-sharp edges. Under all other conditions of interest, titanium- and niobium-carbide-based MXenes showed excellent biocompatibility and no signs of cytotoxicity or genotoxicity. These findings may contribute to the development of strategies for cancer therapy.

Corrole-based photothermal nanocomposite hydrogel with nitric oxide release for diabetic wound healing

The management of chronic diabetic wounds remains a significant challenge due to persistent bacterial infections and impaired angiogenesis. Herein, we reported a nanocomposite hydrogel (M/P-SNO/G) incorporated with M/P-SNO nanoparticles engineered by supramolecular assembly of the photosensitizing mono-carboxyl corrole (MCC) and S-nitrosothiol-modified polyethylene glycol (mPEG-SNO) for synergistic photothermal therapy (PTT)/nitric oxide (NO) treatment of diabetic wounds. The strong π-π interaction among aggregated MCC in M/P-SNO enhances the optical absorption and photothermal ability, thereby facilitating the precise release of NO upon laser irradiation. The hydrogel matrix, composed of oxidized hyaluronic acid and carboxymethyl chitosan crosslinked by Schiff-base, demonstrates good injectability and self-healing characteristics, providing an ideal environment for wound repair. As expected, M/P-SNO/G exhibits a desirable photothermal performance and a controlled laser-responsive NO release, realizing enhanced bactericidal effect and anti-biofilm ability in vitro. In a full-thickness skin defect model on diabetic mice, M/P-SNO/G has proven effective in bacteria clearance and angiogenesis, significantly accelerating wound healing. This study presents a feasible supramolecular strategy to develop diabetic wound dressings with synergistic PTT/NO treatment. STATEMENT OF SIGNIFICANCE: Developing advanced dressings that simultaneously eliminate bacteria and accelerate wound recovery is essential for treating diabetic wounds. This study developed a nanocomposite hydrogel (M/P-SNO/G) featuring the synergistic effect of photothermal therapy (PTT) and nitric oxide (NO) treatment to accelerate infected diabetic wound healing. M/P-SNO nanoparticles within the hydrogel are self-assembled through the hydrophobic photosensitizing mono-carboxyl corrole (MCC) and the hydrophilic NO-releasing polymer (mPEG-SNO), where highly aggregated MCC molecules ensure superior photothermal performance. Meanwhile, the temperature increase induced by the photothermal effect activates NO release from the hydrogel. Under 660 nm laser irradiation, M/P-SNO/G demonstrates a PTT/NO synergy to effectively inhibit bacterial proliferation and promote angiogenesis, offering significant benefits in diabetic wound repair and further expanding the biomedical applications of corroles.

2D MXene Biomaterials for Catalytic Medical Applications

In recent years, two-dimensional transition metal carbides, nitrides, and carbonitrides, termed as MXenes, have been widely applied in energy storage, photocatalysis and biomedicine owing to their unique physicochemical properties of large specific surface area, high electrical conductivity, excellent optical performance, good stability, etc. Moreover, due to their strong light absorption capacity in the first and second near-infrared bio-window, and their ability of being simply functionalized with multiple organic/inorganic materials, MXene biomaterials have shown great potential in the field of catalytic therapy. This review will summarize the common catalytic mechanism of MXene biomaterials and their latest applications in catalytic medicine such as tumor therapy, antibacterial and anti-inflammatory, and present the current challenges and opportunities in clinical translation for future development to promote the advancement of MXene biomaterials in the field of catalytic medicine.

A Diketopyrrolopyrrole-Based All-in-One Nanoplatform for Self-Reinforcing Mild Photothermal Therapy Cascade Immunotherapy for Tumors

Mild photothermal therapy (PTT) has attracted attention for effectively avoiding the severe side effects associated with high-temperature tumor ablation. However, its progress is hindered by the limited availability of high-performance photothermal agents (PTAs) and the thermoresistance of cancer cells induced by heat shock reactions. Herein, this work proposes a new strategy to expand the library of high-performance organic small-molecule PTAs and utilize it to construct a multifunctional nano-theranostic platform. By incorporating additional acceptors and appropriate π-bridges, a diketopyrrolopyrrole-based dye BDB is developed, which exhibits strong absorption and bright fluorescence emission in the near-infrared (NIR) region. Subsequently, BDB is co-coated with the heat shock protein (HSP) inhibitor tanespimycin (17-AAG) using the functional amphiphilic polymers DSPE-Hyd-PEG2000-cRGD to form an all-in-one nanoplatform BAG NPs. As a result, BAG NPs can precisely target tumor tissue, guide the treatment process in real-time through NIR-II fluorescence/photoacoustic/photothermal imaging, and release 17-AAG on demand to enhance mild PTT. Additionally, the mild PTT has been demonstrated to induce immunogenic cell death (ICD) and activate a systemic anti-tumor immune response, thereby suppressing both primary and distant tumors. Overall, this study presents a multifunctional nanoplatform designed for precise mild PTT combined with immunotherapy for effective tumor treatment.

Fabrication Methods, Structural, Surface Morphology and Biomedical Applications of MXene: A Review

Recently, two-dimensional (2-D) layered materials have revealed outstanding properties and play a crucial role for numerous advanced applications. The emerging transition metal carbides and nitrides, known as MXene with empirical formula Mn+1XnTx, have generated widespread attention and demonstrated impressive potential in various fields. The fabrication of 2-D novel MXene and its composites and their characterizations are applicable to vast applications in different areas such as energy storage, gas sensors, catalysis, and biomedical applications. In this review, the main focus is on the various synthesis methods, their properties, and biomedical applications. This review provides detailed illustrations of MXenes for many biomedical applications, including bioimaging, drug delivery, therapies, biosensors, tissue engineering, and antibacterial reagents. The challenges and future prospects were highlighted in a comprehensive manner, and the existing problems and potential for MXene-based biomaterials were analyzed with the goal of accelerating their use in the biomedical field.

Engineered Niobium Carbide MXenzyme-Integrated Self-Adaptive Coatings Inhibiting Periprosthetic Osteolysis by Orchestrating Osteogenesis-Osteoclastogenesis Balance

Periprosthetic osteolysis induced by the ultrahigh-molecular-weight polyethylene (UHMWPE) wear particles is a major complication associated with the sustained service of artificial joint prostheses and often necessitates revision surgery. Therefore, a smart implant with direct prevention and repair abilities is urgently developed to avoid painful revision surgery. Herein, we fabricate a phosphatidylserine- and polyethylenimine-engineered niobium carbide (Nb2C) MXenzyme-coated micro/nanostructured titanium implant (PPN@MNTi) that inhibits UHMWPE particle-induced periprosthetic osteolysis. The specific mechanism by which PPN@MNTi operates involves the bioresponsive release of nanosheets from the MNTi substrate within an osteolysis microenvironment, initiated by the cleavage of a thioketal-dopamine molecule sensitive to reactive oxygen species (ROS). Subsequently, functionalized Nb2C MXenzyme could target macrophages and escape from lysosomes, effectively scavenging intracellular ROS through its antioxidant nanozyme-mimicking activities. This further achieves the suppression of osteoclastogenesis by inhibiting NF-κB/MAPK and autophagy signaling pathways. Simultaneously, based on the synergistic effect of MXenzyme-integrated coatings and micro/nanostructured topography, the designed implant promotes the osteogenic differentiation of bone mesenchymal stem cells to regulate bone homeostasis, further achieving advanced osseointegration and alleviable periprosthetic osteolysis in vivo. This study provides a precise prevention and repair strategy of periprosthetic osteolysis, offering a paradigm for the development of smart orthopedic implants.

Spatially Confined Nanoreactors Designed for Biological Applications

The applications of nanoreactors in biology are becoming increasingly significant and prominent. Specifically, nanoreactors with spatially confined, due to their exquisite design that effectively limits the spatial range of biomolecules, attracted widespread attention. The main advantage of this structure is designed to improve reaction selectivity and efficiency by accumulating reactants and catalysts within the chambers, thus increasing the frequency of collisions between reactants. Herein, the recent progress in the synthesis of spatially confined nanoreactors and their biological applications is summarized, covering various kinds of nanoreactors, including porous inorganic materials, porous crystalline materials with organic components and self-assembled polymers to construct nanoreactors. These design principles underscore how precise reaction control could be achieved by adjusting the structure and composition of the nanoreactors to create spatial confined. Furthermore, various applications of spatially confined nanoreactors are demonstrated in the biological fields, such as biocatalysis, molecular detection, drug delivery, and cancer therapy. These applications showcase the potential prospects of spatially confined nanoreactors, offering robust guidance for future research and innovation.

Large-Scale, Mechanically Robust, Solvent-Resistant, and Antioxidant MXene-Based Composites for Reliable Long-Term Infrared Stealth

MXene-based thermal camouflage materials have gained increasing attention due to their low emissivity, however, the poor anti-oxidation restricts their potential applications under complex environments. Various modification methods and strategies, e.g., the addition of antioxidant molecules and fillers have been developed to overcome this, but the realization of long-term, reliable thermal camouflage using MXene network (coating) with excellent comprehensive performance remains a great challenge. Here, a MXene-based hybrid network comodified with hyaluronic acid (HA) and hyperbranched polysiloxane (HSi) molecules is designed and fabricated. Notably, the presence of appreciated HA molecules restricts the oxidation of MXene sheets without altering infrared stealth performance, superior to other water-soluble polymers; while the HSi molecules can act as efficient cross-linking agents to generate strong interactions between MXene sheets and HA molecules. The optimized MXene/HA/HSi composites exhibit excellent mechanical flexibility (folded into crane structure), good water/solvent resistance, and long-term stable thermal camouflage capability (with low infrared emissivity of ≈0.29). The long-term thermal camouflage reliability (≈8 months) under various outdoor weathers and the scalable coating capability of the MXene-coated textile enable them to disguise the IR signal of various targets in complex environments, indicating the great promise of achieved material for thermal camouflage, IR stealth, and counter surveillance.

Nanomedicine-induced cell pyroptosis to enhance antitumor immunotherapy

Immunotherapy is a therapeutic modality designed to elicit or augment an immune response against malignancies. Despite the immune system's ability to detect and eradicate neoplastic cells, certain neoplastic cells can elude immune surveillance and elimination through diverse mechanisms. Therefore, antitumor immunotherapy has emerged as a propitious strategy. Pyroptosis, a type of programmed cell death (PCD) regulated by Gasdermin (GSDM), is associated with cytomembrane rupture due to continuous cell expansion, which results in the release of cellular contents that can trigger robust inflammatory and immune responses. The field of nanomedicine has made promising progress, enabling the application of nanotechnology to enhance the effectiveness and specificity of cancer therapy by potentiating, enabling, or augmenting pyroptosis. In this review, we comprehensively examine the paradigms underlying antitumor immunity, particularly paradigms related to nanotherapeutics combined with pyroptosis; these treatments include chemotherapy (CT), hyperthermia therapy, photodynamic therapy (PDT), chemodynamic therapy (CDT), ion-interference therapy (IIT), biomimetic therapy, and combination therapy. Furthermore, we thoroughly discuss the coordinated mechanisms that regulate these paradigms. This review is expected to enhance the understanding of the interplay between pyroptosis and antitumor immunotherapy, broaden the utilization of diverse nanomaterials in pyroptosis-based antitumor immunotherapy, and facilitate advancements in clinical tumor therapy.

Potential Biosafety of Mxenes: Stability, Biodegradability, Toxicity and Biocompatibility

MXenes are two-dimensional nanomaterials with unique properties that are widely used in various fields of research, mostly in the field of energy. Fewer publications are devoted to MXene application in biomedicine and the question is: are MXenes safe for use in biological systems? The sharp edges of MXenes provide the structure of "nanoknives" which cause damage in direct physical contact with cells. This is effectively used for antibacterial research. However, on the other hand, most studies in cultured cells and rodents report that they do not cause obvious signs of cytotoxicity and are fully biocompatible. The aim of our review was to consider whether MXenes can really be considered non-toxic and biocompatible. Often the last two concepts are confused. We first reviewed aspects such as the stability and biodegradation of MXenes, and then analyzed the mechanisms of toxicity and their consequences for bacteria, cultured cells, and rodents, with subsequent conclusions regarding their biocompatibility.

Two-dimensional nanomaterials induced nano-bio interfacial effects and biomedical applications in cancer treatment

Two-dimensional nanomaterials (2D NMs), characterized by a large number of atoms or molecules arranged in one dimension (typically thickness) while having tiny dimensions in the other two dimensions, have emerged as a pivotal class of materials with unique properties. Their flat and sheet-like structure imparts distinctive physical, chemical, and electronic attributes, which offers several advantages in biomedical applications, including enhanced surface area for efficient drug loading, surface-exposed atoms allowing precise chemical modifications, and the ability to form hierarchical multilayer structures for synergistic functionality. Exploring their nano-bio interfacial interactions with biological components holds significant importance in comprehensively and systematically guiding safe applications. However, the current lack of in-depth analysis and comprehensive understanding of interfacial effects on cancer treatment motivates our ongoing efforts in this field. This study provides a comprehensive survey of recent advances in utilizing 2D NMs for cancer treatment. It offers insights into the structural characteristics, synthesis methods, and surface modifications of diverse 2D NMs. The investigation further delves into the formation of nano-bio interfaces during their in vivo utilization. Notably, the study discusses a wide array of biomedical applications in cancer treatment. With their potential to revolutionize therapeutic strategies and outcomes, 2D NMs are poised at the forefront of cancer treatment, holding the promise of transformative advancements.

Recent Advances in Photothermal Therapy at Near-Infrared-II Based on 2D MXenes

The use of photothermal therapy (PTT) with the near-infrared II region (NIR-II: 1000-1700 nm) is expected to be a powerful cancer treatment strategy. It retains the noninvasive nature and excellent temporal and spatial controllability of the traditional PTT, and offers significant advantages in terms of tissue penetration depth, background noise, and the maximum permissible exposure standards for skin. MXenes, transition-metal carbides, nitrides, and carbonitrides are emerging inorganic nanomaterials with natural biocompatibility, wide spectral absorption, and a high photothermal conversion efficiency. The PTT of MXenes in the NIR-II region not only provides a valuable reference for exploring photothermal agents that respond to NIR-II in 2D inorganic nanomaterials, but also be considered as a promising biomedical therapy. First, the synthesis methods of 2D MXenes are briefly summarized, and the laser light source, mechanism of photothermal conversion, and evaluation criteria of photothermal performance are introduced. Second, the latest progress of PTT based on 2D MXenes in NIR-II are reviewed, including titanium carbide (Ti3 C2 ), niobium carbide (Nb2 C), and molybdenum carbide (Mo2 C). Finally, the main problems in the PTT application of 2D MXenes to NIR-II and future research directions are discussed.

Current trends in gas-synergized phototherapy for improved antitumor theranostics

Phototherapy, such as photothermal therapy (PTT) and photodynamic therapy (PDT), has been considered an elegant solution to eradicate tumors due to its minimal invasiveness and low systemic toxicity. Nevertheless, it is still challenging for phototherapy to achieve ideal outcomes and clinical translation due to its inherent drawbacks. Owing to the unique biological functions, diverse gases have attracted growing attention in combining with phototherapy to achieve super-additive therapeutic effects. Specifically, gases such as nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) have been proven to kill tumor cells by inducing mitochondrial damage in synergy with phototherapy. Additionally, several gases not only enhance the thermal damage in PTT and the reactive oxygen species (ROS) production in PDT but also improve the tumor accumulation of photoactive agents. The inflammatory responses triggered by hyperthermia in PTT are also suppressed by the combination of gases. Herein, we comprehensively review the latest studies on gas-synergized phototherapy for cancer therapy, including (1) synergistic mechanisms of combining gases with phototherapy; (2) design of nanoplatforms for gas-synergized phototherapy; (3) multimodal therapy based on gas-synergized phototherapy; (4) imaging-guided gas-synergized phototherapy. Finally, the current challenges and future opportunities of gas-synergized phototherapy for tumor treatment are discussed. STATEMENT OF SIGNIFICANCE: 1. The novelty and significance of the work with respect to the existing literature. (1) Strategies to design nanoplatforms for gas-synergized anti-tumor phototherapy have been summarized for the first time. Meanwhile, the integration of various imaging technologies and therapy modalities which endow these nanoplatforms with advanced theranostic capabilities has been summarized. (2) The mechanisms by which gases synergize with phototherapy to eradicate tumors are innovatively and comprehensively summarized. 2. The scientific impact and interest. This review elaborates current trends in gas-synergized anti-tumor phototherapy, with special emphases on synergistic anti-tumor mechanisms and rational design of therapeutic nanoplatforms to achieve this synergistic therapy. It aims to provide valuable guidance for researchers in this field.

POSS Engineering of Multifunctional Nanoplatforms for Chemo-Mild Photothermal Synergistic Therapy

Chemo-mild photothermal synergistic therapy can effectively inhibit tumor growth under mild hyperthermia, minimizing damage to nearby healthy tissues and skin while ensuring therapeutic efficacy. In this paper, we develop a multifunctional study based on polyhedral oligomeric sesquisiloxane (POSS) that exhibits a synergistic therapeutic effect through mild photothermal and chemotherapy treatments (POSS-SQ-DOX). The nanoplatform utilizes SQ-N as a photothermal agent (PTA) for mild photothermal, while doxorubicin (DOX) serves as the chemotherapeutic drug for chemotherapy. By incorporating POSS into the nanoplatform, we successfully prevent the aggregation of SQ-N in aqueous solutions, thus maintaining its excellent photothermal properties both in vitro and in vivo. Furthermore, the introduction of polyethylene glycol (PEG) significantly enhances cell permeability, which contributes to the remarkable therapeutic effect of POSS-SQ-DOX NPs. Our studies on the photothermal properties of POSS-SQ-DOX NPs demonstrate their high photothermal conversion efficiency (62.3%) and stability, confirming their suitability for use in mild photothermal therapy. A combination index value (CI = 0.72) verified the presence of a synergistic effect between these two treatments, indicating that POSS-SQ-DOX NPs exhibited significantly higher cell mortality (74.7%) and tumor inhibition rate (72.7%) compared to single chemotherapy and mild photothermal therapy. This observation highlights the synergistic therapeutic potential of POSS-SQ-DOX NPs. Furthermore, in vitro and in vivo toxicity tests suggest that the absence of cytotoxicity and excellent biocompatibility of POSS-SQ-DOX NPs provide a guarantee for clinical applications. Therefore, utilizing near-infrared light-triggering POSS-SQ-DOX NPs can serve as chemo-mild photothermal PTA, while functionalized POSS-SQ-DOX NPs hold great promise as a novel nanoplatform that may drive significant advancements in the field of chemo-mild photothermal therapy.

Functionalized MoS2-nanosheets with NIR-Triggered nitric oxide delivery and photothermal activities for synergistic antibacterial and regeneration-promoting therapy

Bacterial infection in skin and soft tissue has emerged as a critical concern. Overreliance on antibiotic therapy has led to numerous challenges, including the emergence of multidrug-resistant bacteria and adverse drug reactions. It is imperative to develop non-antibiotic treatment strategies that not only exhibit potent antibacterial properties but also promote rapid wound healing and demonstrate biocompatibility. Herein, a novel multimodal synergistic antibacterial system (SNO-CS@MoS2) was developed. This system employs easily surface-modified thin-layer MoS2 as photothermal agents and loaded with S-nitrosothiol-modified chitosan (SNO-CS) via electrostatic interactions, thus realizing the combination of NO gas therapy and photothermal therapy (PTT). Furthermore, this surface modification renders SNO-CS@MoS2 highly stable and capable of binding with bacteria. Through PTT's thermal energy, SNO-CS@MoS2 rapidly generates massive NO, collaborating with PTT to achieve antibacterial effects. This synergistic therapy can swiftly disrupt the bacterial membrane, causing protein leakage and ATP synthesis function damage, ultimately eliminating bacteria. Notably, after effectively eliminating all bacteria, the residual SNO-CS@MoS2 can create trace NO to promote fibroblast migration, proliferation, and vascular regeneration, thereby accelerating wound healing. This study concluded that SNO-CS@MoS2, a novel multifunctional nanomaterial with outstanding antibacterial characteristics and potential to promote wound healing, has promising applications in infected soft tissue wound treatment.

Multifunctional mesoporous silica nanoparticles for biomedical applications

Mesoporous silica nanoparticles (MSNs) are recognized as a prime example of nanotechnology applied in the biomedical field, due to their easily tunable structure and composition, diverse surface functionalization properties, and excellent biocompatibility. Over the past two decades, researchers have developed a wide variety of MSNs-based nanoplatforms through careful design and controlled preparation techniques, demonstrating their adaptability to various biomedical application scenarios. With the continuous breakthroughs of MSNs in the fields of biosensing, disease diagnosis and treatment, tissue engineering, etc., MSNs are gradually moving from basic research to clinical trials. In this review, we provide a detailed summary of MSNs in the biomedical field, beginning with a comprehensive overview of their development history. We then discuss the types of MSNs-based nanostructured architectures, as well as the classification of MSNs-based nanocomposites according to the elements existed in various inorganic functional components. Subsequently, we summarize the primary purposes of surface-functionalized modifications of MSNs. In the following, we discuss the biomedical applications of MSNs, and highlight the MSNs-based targeted therapeutic modalities currently developed. Given the importance of clinical translation, we also summarize the progress of MSNs in clinical trials. Finally, we take a perspective on the future direction and remaining challenges of MSNs in the biomedical 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.

2D Nanomaterials and Their Drug Conjugates for Phototherapy and Magnetic Hyperthermia Therapy of Cancer and Infections

Photothermal therapy (PTT) and magnetic hyperthermia therapy (MHT) using 2D nanomaterials (2DnMat) have recently emerged as promising alternative treatments for cancer and bacterial infections, both important global health challenges. The present review intends to provide not only a comprehensive overview, but also an integrative approach of the state-of-the-art knowledge on 2DnMat for PTT and MHT of cancer and infections. High surface area, high extinction coefficient in near-infra-red (NIR) region, responsiveness to external stimuli like magnetic fields, and the endless possibilities of surface functionalization, make 2DnMat ideal platforms for PTT and MHT. Most of these materials are biocompatible with mammalian cells, presenting some cytotoxicity against bacteria. However, each material must be comprehensively characterized physiochemically and biologically, since small variations can have significant biological impact. Highly efficient and selective in vitro and in vivo PTTs for the treatment of cancer and infections are reported, using a wide range of 2DnMat concentrations and incubation times. MHT is described to be more effective against bacterial infections than against cancer therapy. Despite the promising results attained, some challenges remain, such as improving 2DnMat conjugation with drugs, understanding their in vivo biodegradation, and refining the evaluation criteria to measure PTT or MHT effects.

Bioorthogonal chemistry for prodrug activation in vivo

Prodrugs have emerged as a major strategy for addressing clinical challenges by improving drug pharmacokinetics, reducing toxicity, and enhancing treatment efficacy. The emergence of new bioorthogonal chemistry has greatly facilitated the development of prodrug strategies, enabling their activation through chemical and physical stimuli. This "on-demand" activation using bioorthogonal chemistry has revolutionized the research and development of prodrugs. Consequently, prodrug activation has garnered significant attention and emerged as an exciting field of translational research. This review summarizes the latest advancements in prodrug activation by utilizing bioorthogonal chemistry and mainly focuses on the activation of small-molecule prodrugs and antibody-drug conjugates. In addition, this review also discusses the opportunities and challenges of translating these advancements into clinical practice.

A Gas/phototheranostic Nanocomposite Integrates NIR-II-Peak Absorbing Aza-BODIPY with Thermal-Sensitive Nitric Oxide Donor for Atraumatic Osteosarcoma Therapy

Photothermal therapy (PTT) has received increasing interest in cancer therapeutics owing to its excellent efficacy and controllability. However, there are two major limitations in PTT applications, which are the tissue penetration depth of lasers within the absorption range of photothermal agents and the unavoidable tissue empyrosis induced by high-energy lasers. Herein, a gas/phototheranostic nanocomposite (NA1020-NO@PLX) is engineered that integrates the second near-infrared-peak (NIR-II-peak) absorbing aza-boron-dipyrromethenes (aza-BODIPY,NA1020) with the thermal-sensitive nitric oxide (NO) donor (S-nitroso-N-acetylpenicillamine, SNAP). An enhanced intramolecular charge transfer mechanism is proposed to achieve the NIR-II-peak absorbance (λmax = 1020 nm) on NA1020, thereby obtaining its deep tissue penetration depth. The NA1020 exhibits a remarkable photothermal conversion, making it feasible for the deep-tissue orthotopic osteosarcoma therapy and providing favorable NIR-II emission to precisely pinpoint the tumor for a visible PTT process. The simultaneously investigated atraumatic therapeutic process with an enhanced cell apoptosis mechanism indicates the feasibility of the synergistic NO/low-temperature PTT for osteosarcoma. Herein, this gas/phototheranostic strategy optimizes the existing PTT to present a repeatable and atraumatic photothermal therapeutic process for deep-tissue tumors, validating its potential clinical applications.

Biodegradable FePS3 nanoplatform for efficient treatment of osteosarcoma by combination of gene and NIR-II photothermal therapy

As a common tumor with high incidence, osteosarcoma possesses extremely poor prognosis and high mortality. Improving the survival of osteosarcoma patients is still a great challenge due to the precipice of advancement in treatment. In this study, a combination strategy of gene therapy and photothermal therapy (PTT) is developed for efficient treatment of osteosarcoma. Two-dimensional (2D) FePS₃ nanosheets are synthesized and functionalized by poly-L-lysine-PEG-folic acid (PPF) to fabricate a multifunctional nanoplatform (FePS@PPF) for further loading microRNAs inhibitor, miR-19a inhibitor (anti-miR-19a). The photothermal conversion efficiency of FePS@PPF is up to 47.1% under irradiation by 1064 nm laser. In vitro study shows that anti-miR-19a can be efficiently internalized into osteosarcoma cells through the protection and delivery of FePS@PPF nanaocarrier, which induces up-regulation of PTEN protein and down-regulation p-AKT protein. After intravenous injection, the FePS@PPF nanoplatform specifically accumulates to tumor site of osteosarcoma-bearing mice. The in vitro and in vivo investigations reveal that the combined PTT-gene therapy displays most significant tumor ablation compared with monotherapy. More importantly, the good biodegradability promotes FePS@PPF to be cleared from body avoiding potential toxicity of long-term retention. Our work not only develops a combined strategy of NIR-II PTT and gene therapy mediated by anti-miR-19a/FePS@PPF but also provides insights into the design and applications of other nanotherapeutic platforms.

NIR-II Responsive Nanohybrids Incorporating Thermosensitive Hydrogel as Sprayable Dressing for Multidrug-Resistant-Bacteria Infected Wound Management

Developing an effective dressing against bacterial infection and synchronously addressing wound complications, such as bleeding, long-term inflammation, and reinfection, are highly desirable in clinical practice. In this work, a second near-infrared (NIR-II) responsive nanohybrid consisting of imipenem encapsulated liposome with gold-shell and lipopolysaccharide (LPS)-targeting aptamer, namely ILGA, is constructed for bacteria elimination. Benefiting from the delicate structure, ILGA exhibits strong affinity and a reliable photothermal/antibiotic therapeutic effect toward multidrug-resistant Pseudomonas aeruginosa (MDR-PA). Furthermore, by incorporating ILGA with a thermosensitive hydrogel poly(lactic-co-glycolic acid)-polyethylene glycol-poly(lactic-co-glycolic acid) (PLGA-PEG-PLGA), a sprayable dressing ILGA@Gel was prepared, which enables a quick on-demand gelation (10 s) for wound hemostasis and offers excellent photothermal/antibiotic efficacy to sterilize the infected wound. Additionally, ILGA@Gel provides satisfactory wound-healing environments by reeducating wound-associated macrophages for inflammation alleviation and forming a gel layer to block exogenous bacterial reinfection. This biomimetic hydrogel reveals excellent bacteria eradication and wound recovery effectiveness, demonstrating its promising potential for managing complicated infected wounds.

Commercial and novel anticoagulant ECMO coatings: a review

Extracorporeal membrane oxygenation (ECMO) is an invasive and last-resort treatment for circulatory and respiratory failure. Prolonged ECMO support can disrupt the coagulation and anticoagulation systems in a patient, leading to adverse consequences, such as bleeding and thrombosis. To address this problem, anticoagulation coatings have been developed for use in ECMO circuits. This article reviews commonly used commercial and novel anticoagulant coatings developed in recent years and proposes a new classification of coatings based on the current state. While commercial coatings have been used clinically for decades, this review focuses on comparing the effectiveness and stability of coatings to support clinical selections. Furthermore, novel anticoagulation coatings often involve complex mechanisms and elaborate design strategies, and this review summarises representative studies on mainstream anticoagulation coatings to provide a point of reference for future studies.

Second Near-Infrared (NIR-II) Window for Imaging-Navigated Modulation of Brain Structure and Function

For a long time, optical imaging of the deep brain with high resolution has been a challenge. Recently, with the advance in second near-infrared (NIR-II) bioimaging techniques and imaging contrast agents, NIR-II window bioimaging has attracted great attention to monitoring deeper biological or pathophysiological processes with high signal-to-noise ratio (SNR) and spatiotemporal resolution. Assisted with NIR-II bioimaging, the modulation of structure and function of brain is promising to be noninvasive and more precise. Herein, in this review, first the advantage of NIR-II light in brain imaging from the interaction between NIR-II and tissue is elaborated. Then, several specific NIR-II bioimaging technologies are introduced, including NIR-II fluorescence imaging, multiphoton fluorescence imaging, and photoacoustic imaging. Furthermore, the corresponding contrast agents are summarized. Next, the application of various NIR-II bioimaging technologies in visualizing the characteristics of cerebrovascular network and monitoring the changes of the pathology signals will be presented. After that, the modulation of brain structure and function based on NIR-II bioimaging will be discussed, including treatment of glioblastoma, guidance of cell transplantation, and neuromodulation. In the end, future perspectives that would help improve the clinical translation of NIR-II light are proposed.

Recent trends in MXene-based material for biomedical applications

MXene is a magical class of 2D nanomaterials and emerging in many applications in diverse fields. Due to the multiple advantageous characteristics of its fundamental components, such as structural, physicochemical, optical, and occasionally even biological characteristics. However, it is limited in the biomedical industry due to poor physiological stability, decomposition rate, and lack of controlled and sustained drug release. These limitations can be overcome when MXene forms composites with other 2D materials. The efficiency of pure MXene in biomedicine is inferior to that of MXene-based composites. The availability of functionality on the exterior part of MXene has a key role in the modification of their surface and their characteristics. This review provides an extensive discussion on the synthesizing of MXene and the role of the surface functionalities on the efficiency of MXene. In addition, a detailed discussion of the biomedical applications of MXene, including antibacterial activity, regenerative medicine, CT scan capability, drug delivery, diagnostics, MRI and biosensing capability. Furthermore, an outline of the future problems and challenges of MXene-based materials for biomedical applications was narrated. Thus, these salient features showcase the potential of MXene-based material and will be a breakthrough in biomedical applications in the near future.

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.

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).

C. D, Karki B, Samatha K, Kim AA, Park M, Pant B. Advancements in MXene-Polymer Nanocomposites in Energy Storage and Biomedical Applications

MXenes are 2D ceramic materials, especially carbides, nitrides, and carbonitrides derived from their parent 'MAX' phases by the etching out of 'A' and are famous due to their conducting, hydrophilic, biocompatible, and tunable properties. However, they are hardly stable in the outer environment, have low biodegradability, and have difficulty in drug release, etc., which are overcome by MXene/Polymer nanocomposites. The MXenes terminations on MXene transferred to the polymer after composite formation makes it more functional. With this, there is an increment in photothermal conversion efficiency for cancer therapy, higher antibacterial activity, biosensors, selectivity, bone regeneration, etc. The hydrophilic surfaces become conducting in the metallic range after the composite formation. MXenes can effectively be mixed with other materials like ceramics, metals, and polymers in the form of nanocomposites to get improved properties suitable for advanced applications. In this paper, we review different properties like electrical and mechanical, including capacitances, dielectric losses, etc., of nanocomposites more than those like Ti3C2Tx/polymer, Ti3C2/UHMWPE, MXene/PVA-KOH, Ti3C2Tx/PVA, etc. along with their applications mainly in energy storing and biomedical fields. Further, we have tried to enlist the MXene-based nanocomposites and compare them with conducting polymers and other nanocomposites. The performance under the NIR absorption seems more effective. The MXene-based nanocomposites are more significant in most cases than other nanocomposites for the antimicrobial agent, anticancer activity, drug delivery, bio-imaging, biosensors, micro-supercapacitors, etc. The limitations of the nanocomposites, along with possible solutions, are mentioned.

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.

Advances of MXenes; Perspectives on Biomedical Research

The last decade witnessed the emergence of a new family of 2D transition metal carbides and nitrides named MXenes, which quickly gained momentum due to their exceptional electrical, mechanical, optical, and tunable functionalities. These outstanding properties also rendered them attractive materials for biomedical and biosensing applications, including drug delivery systems, antimicrobial applications, tissue engineering, sensor probes, auxiliary agents for photothermal therapy and hyperthermia applications, etc. The hydrophilic nature of MXenes with rich surface functional groups is advantageous for biomedical applications over hydrophobic nanoparticles that may require complicated surface modifications. As an emerging 2D material with numerous phases and endless possible combinations with other 2D materials, 1D materials, nanoparticles, macromolecules, polymers, etc., MXenes opened a vast terra incognita for diverse biomedical applications. Recently, MXene research picked up the pace and resulted in a flood of literature reports with significant advancements in the biomedical field. In this context, this review will discuss the recent advancements, design principles, and working mechanisms of some interesting MXene-based biomedical applications. It also includes major progress, as well as key challenges of various types of MXenes and functional MXenes in conjugation with drug molecules, metallic nanoparticles, polymeric substrates, and other macromolecules. Finally, the future possibilities and challenges of this magnificent material are discussed in detail.

Scalable Manufacture of Curcumin-Loaded Chitosan Nanocomplex for pH-Responsive Delivery by Coordination-Driven Flash Nanocomplexation

Metal coordination-driven nanocomplexes are known to be responsive to physiologically relevant stimuli such as pH, redox, temperature or light, making them well-suited for antitumor drug delivery. The ever-growing demand for such nanocomplexes necessitates the design of a scalable approach for their production. In this study, we demonstrate a novel coordination self-assembly strategy, termed flash nanocomplexation (FNC), which is rapid and efficient for the fabrication of drug-loaded nanoparticles (NPs) in a continuous manner. Based on this strategy, biocompatible chitosan (CS) and Cu2+ can be regarded anchors to moor the antitumor drug (curcumin, Cur) through coordination, resulting in curcumin-loaded chitosan nanocomplex (Cur-loaded CS nanocomplex) with a narrow size distribution (PDI < 0.124) and high drug loading (up to 41.75%). Owing to the excellent stability of Cur-loaded CS nanocomplex at neutral conditions (>50 days), premature Cur leakage was limited to lower than 1.5%, and pH-responsive drug release behavior was realized in acidic tumor microenvironments. An upscaled manufacture of Cur-loaded CS nanocomplex is demonstrated with continuous FNC, which shows an unprecedented method toward practical applications of nanomedicine for tumor therapy. Furthermore, intracellular uptake study and cytotoxicity experiments toward H1299 cells demonstrates the satisfied anticancer efficacy of the Cur-loaded CS nanocomplex. These results confirm that coordination-driven FNC is an effective method that enables the rapid and scalable fabrication of antitumor drugs.

Two-Dimensional Nanomaterial-based catalytic Medicine: Theories, advanced catalyst and system design

Two-dimensional nanomaterial-based catalytic medicines that associate the superiorities of novel catalytic mechanisms with nanotechnology have emerged as absorbing therapeutic strategies for cancer therapy. Catalytic medicines featuring high efficiency and selectivity have been widely used as effective anticancer strategies without applying traditional nonselective and highly toxic chemodrugs. Moreover, two-dimensional nanomaterials are characterized by distinctive physicochemical properties, such as a sizeable bandgap, good conductivity, fast electron transfer and photoelectrochemical activity. The introduction of two-dimensional nanomaterials into catalytic medicine provides a more effective, controllable, and precise antitumor strategy. In this review, different types of two-dimensional nanomaterial-based catalytic nanomedicines are generalized, and their catalytic theories, advanced catalytic pathways and catalytic nanosystem design are also discussed in detail. Notably, future challenges and obstacles in the design and further clinical transformation of two-dimensional nanomaterial-based catalytic nanomedicine are prospected.

Biomedical engineering of two-dimensional MXenes

The emergence of two-dimensional (2D) transition metal carbides, carbonitrides and nitrides, referred to MXenes, with a general chemical formula of M_n+1X_nT_x have aroused considerable interest and shown remarkable potential applications in diverse fields. The unique ultrathin lamellar structure accompanied with charming electronic, optical, magnetic, mechanical and biological properties make MXenes as a kind of promising alternative biomaterials for versatile biomedical applications, as well as uncovering many new fundamental scientific discoveries. Herein, the current state-of-the-art advances of MXenes-related biomaterials are systematically summarized in this comprehensive review, especially focusing on the synthetic methodologies, design and surface engineering strategies, unique properties, biological effects, and particularly the property-activity-effect relationship of MXenes at the nano-bio interface. Furthermore, the elaborated MXenes for varied biomedical applications, such as biosensors and biodevices, antibacteria, bioimaging, therapeutics, theranostics, tissue engineering and regenerative medicine, are illustrated in detail. Finally, we discuss the current challenges and opportunities for future advancement of MXene-based biomaterials in-depth on the basis of the present situation, aiming to facilitate their early realization of practical biomedical applications.

MXenes: state-of-the-art synthesis, composites and bioapplications

MXenes have proven significant potential in a multitude of scientific domains as they provide substantial benefits over carbon graphene, such as ease of production and functionalization, large surface area, adjustable...

MXenes in photomedicine: Advances and prospects

MXenes and their related nanocomposites with superior physicochemical properties such as high surface area, ease of synthesis and functionalization, high drug loading capacity, collective therapy potentials, pH-triggered drug release behavior,...

Near-infrared light-triggered nano-prodrug for cancer gas therapy

Gas therapy (GT) has attracted increasing attention in recent years as a new cancer treatment method with favorable therapeutic efficacy and reduced side effects. Several gas molecules, such as nitric oxide (NO), carbon monoxide (CO), hydrogen (H2), hydrogen sulfide (H2S) and sulfur dioxide (SO2), have been employed to treat cancers by directly killing tumor cells, enhancing drug accumulation in tumors or sensitizing tumor cells to chemotherapy, photodynamic therapy or radiotherapy. Despite the great progress of gas therapy, most gas molecules are prone to nonspecific distribution when administered systemically, resulting in strong toxicity to normal tissues. Therefore, how to deliver and release gas molecules to targeted tissues on demand is the main issue to be considered before clinical applications of gas therapy. As a specific and noninvasive stimulus with deep penetration, near-infrared (NIR) light has been widely used to trigger the cleavage and release of gas from nano-prodrugs via photothermal or photodynamic effects, achieving the on-demand release of gas molecules with high controllability. In this review, we will summarize the recent progress in cancer gas therapy triggered by NIR light. Furthermore, the prospects and challenges in this field are presented, with the hope for ongoing development.

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.

Intelligent Pore Switch of Hollow Mesoporous Organosilica Nanoparticles for High Contrast Magnetic Resonance Imaging and Tumor-Specific Chemotherapy

Hollow mesoporous organosilica nanoparticles (HMONs) are widely considered as a promising drug nanocarrier, but the loaded drugs can easily leak from HMONs, resulting in the considerably decreased drug loading capacity and increased biosafety risk. This study reports the smart use of core/shell Fe₃O₄/Gd₂O₃ (FG) hybrid nanoparticles as a gatekeeper to block the pores of HMONs, which can yield an unreported large loading content (up to 20.4%) of DOX. The conjugation of RGD dimer (R2) onto the DOX-loaded HMON with FG capping (D@HMON@FG@R2) allowed for active tumor-targeted delivery. The aggregated FG in D@HMON@FG@R2 could darken the normal tissue surrounding the tumor due to the high r₂ value (253.7 mM^-1 s^-1) and high r₂/r₁ ratio (19.13), and the intratumorally released FG as a result of reducibility-triggered HMON degradation could brighten the tumor because of the high r₁ value (20.1 mM^-1 s^-1) and low r₂/r₁ ratio (7.01), which contributed to high contrast magnetic resonance imaging (MRI) for guiding highly efficient tumor-specific DOX release and chemotherapy.

Stimuli Responsive Nitric Oxide-Based Nanomedicine for Synergistic Therapy

Gas therapy has received widespread attention from the medical community as an emerging and promising therapeutic approach to cancer treatment. Among all gas molecules, nitric oxide (NO) was the first one to be applied in the biomedical field for its intriguing properties and unique anti-tumor mechanisms which have become a research hotspot in recent years. Despite the great progress of NO in cancer therapy, the non-specific distribution of NO in vivo and its side effects on normal tissue at high concentrations have impaired its clinical application. Therefore, it is important to develop facile NO-based nanomedicines to achieve the on-demand release of NO in tumor tissue while avoiding the leakage of NO in normal tissue, which could enhance therapeutic efficacy and reduce side effects at the same time. In recent years, numerous studies have reported the design and development of NO-based nanomedicines which were triggered by exogenous stimulus (light, ultrasound, X-ray) or tumor endogenous signals (glutathione, weak acid, glucose). In this review, we summarized the design principles and release behaviors of NO-based nanomedicines upon various stimuli and their applications in synergistic cancer therapy. We also discuss the anti-tumor mechanisms of NO-based nanomedicines in vivo for enhanced cancer therapy. Moreover, we discuss the existing challenges and further perspectives in this field in the aim of furthering its development.

Functionalized 2D Nb2C nanosheets for primary and recurrent cancer photothermal/immune-therapy in the NIR-II biowindow

Near-infrared-II (NIR-II) cancer photothermal therapy (PTT) has become more and more attractive as the NIR-II light shows a higher tissue penetrating depth, which leads to better anti-cancer effects. Recently, the members of the MXene family have been reported as NIR-II photothermal agents, possessing a high specific surface area and a fascinating light-to-heat conversion rate at the same time. Herein, we reported a combination of NIR-II photothermal therapy and immune therapy based on the MXene family member niobium carbide (Nb₂C). First, Nb₂C nanosheets (NSs) under 50 nm were prepared. They showed a high photothermal conversion efficiency under a 1064-nm laser, and the NIR-II light showed a deeper tissue penetration depth. Then, a nanoplatform with high R837 stability and a high loading rate was obtained after modification with a polydopamine (PDA) layer on the surface of Nb₂C. With the R837 modification, the percentage of mature dendritic cells (DCs) increased and the immune response enhanced, compared with the immune response caused by PTT only. Finally, a red blood cell (RBC) membrane was applied as a coat over the nanoplatform in order to avoid excessive blood clearance. During in vivo experiments, blood circulation of Nb₂C@PDA-R837@RBC nanoparticles (NPs) was prolonged, and all primary tumors were eliminated. Secondary tumors were also inhibited effectively due to the strengthened immune response, proving that Nb₂C@PDA-R837@RBC NPs could inhibit tumor recurrence. All the results above indicated Nb₂C@PDA-R837@RBC NPs as a potential RBC camouflaged nanoplatform for the combination of effective PTT and immune therapy towards tumor treatment.

Gas and gas-generating nanoplatforms in cancer therapy

Gas therapy is the usage of certain gases with special therapeutic effects for the treatment of diseases. Hydrogen (H₂), nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H₂S) acting as gas signalling molecules are representative gases in cancer therapy. They act directly on mitochondria or nuclei to lead to cell apoptosis. They can also alleviate immuno-suppression in the tumour microenvironment and promote phenotype conversion of tumour-associated macrophages. Moreover, the combination of gas therapy and other traditional therapy methods can reduce side effects and improve therapeutic efficacy. Here, we discuss the roles of NO, CO, H₂S and H₂ in cancer biology. Considering the rapidly developing nanotechnology, gas-generating nanoplatforms which can achieve targeted delivery and controlled release were also discussed. Finally, we highlight the current challenges and future opportunities of gas-based cancer therapy.

Two-dimensional biomaterials: material science, biological effect and biomedical engineering applications

To date, nanotechnology has increasingly been identified as a promising and efficient means to address a number of challenges associated with public health. In the past decade, two-dimensional (2D) biomaterials, as a unique nanoplatform with planar topology, have attracted explosive interest in various fields such as biomedicine due to their unique morphology, physicochemical properties and biological effect. Motivated by the progress of graphene in biomedicine, dozens of types of ultrathin 2D biomaterials have found versatile bio-applications, including biosensing, biomedical imaging, delivery of therapeutic agents, cancer theranostics, tissue engineering, as well as others. The effective utilization of 2D biomaterials stems from the in-depth knowledge of structure-property-bioactivity-biosafety-application-performance relationships. A comprehensive summary of 2D biomaterials for biomedicine is still lacking. In this comprehensive review, we aim to concentrate on the state-of-the-art 2D biomaterials with a particular focus on their versatile biomedical applications. In particular, we discuss the design, fabrication and functionalization of 2D biomaterials used for diverse biomedical applications based on the up-to-date progress. Furthermore, the interactions between 2D biomaterials and biological systems on the spatial-temporal scale are highlighted, which will deepen the understanding of the underlying action mechanism of 2D biomaterials aiding their design with improved functionalities. Finally, taking the bench-to-bedside as a focus, we conclude this review by proposing the current crucial issues/challenges and presenting the future development directions to advance the clinical translation of these emerging 2D biomaterials.

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.

MXenes for Cancer Therapy and Diagnosis: Recent Advances and Current Challenges

MXenes endowed with several attractive physicochemical attributes, namely, specific large surface area, significant electrical conductivity, magnetism, low toxicity, luminescence, and high biocompatibility, have been considered as promising candidates for cancer therapy and theranostics. These two-dimensional (2D) nanostructures endowed with photothermal, chemotherapeutic synergistic, and photodynamic effects have shown promising potential for decidedly effectual and noninvasive anticancer treatments. They have been explored for photothermal/chemo-photothermal therapy (PTT) and for targeted anticancer drug delivery. Remarkably, MXenes with their unique optical properties have been employed for bioimaging and biosensing, and their excellent light-to-heat transition competence renders them an ideal biocompatible and decidedly proficient nanoscaled agent for PTT appliances. However, several important challenging issues still linger regarding their stability in physiological environments, sustained/controlled release of drugs, and biodegradability that need to be addressed. This Perspective emphasizes the latest advancements of MXenes and MXene-based materials in the domain of targeted cancer therapy/diagnosis, with a focus on the current trends, important challenges, and future perspectives.

Photoacoustic Cavitation-Ignited Reactive Oxygen Species to Amplify Peroxynitrite Burst by Photosensitization-Free Polymeric Nanocapsules

Photoacoustic (PA) technology can transform light energy into acoustic wave, which can be used for either imaging or therapy that depends on the power density of pulsed laser. Here, we report photosensitizer-free polymeric nanocapsules loaded with nitric oxide (NO) donors, namely NO-NCPs, formulated from NIR light-absorbable amphiphilic polymers and a NO-releasing donor, DETA NONOate. Controlled NO release and nanocapsule dissociation are achieved in acidic lysosomes of cancer cells. More importantly, upon pulsed laser irradiation, the PA cavitation can excite water to generate significant reactive oxygen species (ROS) such as superoxide radical (O₂ ^.- ), which further spontaneously reacts with the in situ released NO to burst highly cytotoxic peroxynitrite (ONOO^- ) in cancer cells. The resultant ONOO^- generation greatly promotes mitochondrial damage and DNA fragmentation to initiate programmed cancer cell death. Apart from PA imaging, PA cavitation can intrinsically amplify reactive species via photosensitization-free materials for promising disease theranostics.