2D Nanomaterials for Cancer Theranostic Applications

Recent Progress in Carrier-Free Nanomedicine for Tumor Phototherapy

Safe and effective strategies are urgently needed to fight against the life-threatening diseases of various cancers. However, traditional therapeutic modalities, such as radiotherapy, chemotherapy and surgery, exhibit suboptimal efficacy for malignant tumors owing to the serious side effects, drug resistance and even relapse. Phototherapies, including photodynamic therapy (PDT) and photothermal therapy (PTT), are emerging therapeutic strategies for localized tumor inhibition, which can produce a large amount of reactive oxygen species (ROS) or elevate the temperature to initiate cell death by non-invasive irradiation. In consideration of the poor bioavailability of phototherapy agents (PTAs), lots of drug delivery systems have been developed to enhance the tumor targeted delivery. Nevertheless, the carriers of drug delivery systems inevitably bring biosafety concerns on account of their metabolism, degradation, and accumulation. Of note, carrier-free nanomedicine attracts great attention for clinical translation with synergistic antitumor effect, which is characterized by high drug loading, simplified synthetic method and good biocompatibility. In this review, the latest advances of phototherapy with various carrier-free nanomedicines are summarized, which may provide a new paradigm for the future development of nanomedicine and tumor precision therapy.

A MgFe-LDH Nanosheet-Incorporated Smart Thermo-Responsive Hydrogel with Controllable Growth Factor Releasing Capability for Bone Regeneration

Although growth factor (GF)-loaded hydrogels have been explored as promising materials in repairing bone defects, it still remains challenging to construct smart hydrogels with excellent gelation/mechanical properties as well as controllable GF releasing capability. Herein, the incorporation of bone morphogenetic protein 2 (BMP-2)-functionalized MgFe-layered double hydroxide (LDH) nanosheets into chitosan/silk fibroin (CS) hydrogels loaded with platelet-derived growth factor-BB (PDGF-BB) to construct a smart injectable thermo-responsive hydrogel (denoted as CSP-LB), which can achieve a burst release of PDGF-BB and a sustained release of BMP-2, for highly efficient bone regeneration is reported. The incorporation of MgFe-LDH in CS hydrogel not only shortens the gelation time and decreases sol-gel transition temperature, but also enhances the mechanical property of the hydrogel. Because of the sequential release of dual-GFs and sustained release of bioactive Mg²⁺ /Fe³⁺ ions, the in vitro experiments prove that the CSP-LB hydrogel exhibits excellent angiogenic and osteogenic properties compared with the CS hydrogel. In vivo experiments further prove that the CSP-LB hydrogel can significantly enhance bone regeneration with higher bone volume and mineral density than that of the CS hydrogel. This smart thermo-sensitive CSP-LB hydrogel possesses excellent gelation capability and angiogenic and osteogenic properties, thus providing a promising minimally invasive solution for bone defect treatment.

Advanced bioactive nanomaterials for diagnosis and treatment of major chronic diseases

With the rapid innovation of nanoscience and technology, nanomaterials have also been deeply applied in the medical and health industry and become one of the innovative methods to treat many diseases. In recent years, bioactive nanomaterials have attracted extensive attention and have made some progress in the treatment of some major chronic diseases, such as nervous system diseases and various malignant tumors. Bioactive nanomaterials depend on their physical and chemical properties (crystal structure, surface charge, surface functional groups, morphology, and size, etc.) and direct produce biological activity and play to the role of the treatment of diseases, compared with the traditional nanometer pharmaceutical preparations, biological active nano materials don't exert effects through drug release, way more directly, also is expected to be more effective for the treatment of diseases. However, further studies are needed in the evaluation of biological effects, fate in vivo, structure-activity relationship and clinical transformation of bionanomaterials. Based on the latest research reports, this paper reviews the application of bioactive nanomaterials in the diagnosis and treatment of major chronic diseases and analyzes the technical challenges and key scientific issues faced by bioactive nanomaterials in the diagnosis and treatment of diseases, to provide suggestions for the future development of this field.

Principle Superiority and Clinical Extensibility of 2D and 3D Charged Nanoprobe Detection Platform Based on Electrophysiological Characteristics of Circulating Tumor Cells

The electrical characteristic of cancer cells is neglected among tumor biomarkers. The development of nanoprobes with opposing charges for monitoring the unique electrophysiological characteristics of cancer cells. Micro-nano size adsorption binding necessitates consideration of the nanoprobe's specific surface area. On the basis of the electrophysiological characteristics of circulating tumor cells (CTCs), clinical application and performance assessment are determined. To demonstrate that cancer cells have a unique pattern of electrophysiological patterns compared to normal cells, fluorescent nanoprobes with opposing charges were developed and fabricated. Graphene oxide (GO) was used to transform three-dimensional (3D) nanoprobes into two-dimensional (2D) nanoprobes. Compare 2D and 3D electrophysiological magnetic nanoprobes (MNP) in clinical samples and evaluate the adaptability and development of CTCs detection based on cell electrophysiology. Positively charged nanoprobes rapidly bind to negatively charged cancer cells based on electrostatic interactions. Compared to MNPs(+) without GO, the GO/MNPs(+) nanoprobe is more efficient and uses less material to trap cancer cells. CTCs can be distinguished from normal cells that are fully unaffected by nanoprobes by microscopic cytomorphological inspection, enabling the tracking of the number and pathological abnormalities of CTCs in the same patient at various chemotherapy phases to determine the efficacy of treatment. The platform for recognizing CTCs on the basis of electrophysiological characteristics compensates for the absence of epithelial biomarker capture and size difference capture in clinical performance. Under the influence of electrostatic attraction, the binding surface area continues to influence the targeting of cancer cells by nanoprobes. The specific recognition and detection of nanoprobes based on cell electrophysiological patterns has enormous potential in the clinical diagnosis and therapeutic monitoring of cancer.

Engineered Two-Dimensional Nanostructures as SERS Substrates for Biomolecule Sensing: A Review

Two-dimensional nanostructures (2DNS) attract tremendous interest and have emerged as potential materials for a variety of applications, including biomolecule sensing, due to their high surface-to-volume ratio, tuneable optical and electronic properties. Advancements in the engineering of 2DNS and associated technologies have opened up new opportunities. Surface-enhanced Raman scattering (SERS) is a rapid, highly sensitive, non-destructive analytical technique with exceptional signal amplification potential. Several structurally and chemically engineered 2DNS with added advantages (e.g., π-π* interaction), over plasmonic SERS substrates, have been developed specifically towards biomolecule sensing in a complex matrix, such as biological fluids. This review focuses on the recent developments of 2DNS-SERS substrates for biomolecule sensor applications. The recent advancements in engineered 2DNS, particularly for SERS substrates, have been systematically surveyed. In SERS substrates, 2DNS are used as either a standalone signal enhancer or as support for the dispersion of plasmonic nanostructures. The current challenges and future opportunities in this synergetic combination have also been discussed. Given the prospects in the design and preparation of newer 2DNS, this review can give a critical view on the current status, challenges and opportunities to extrapolate their applications in biomolecule detection.

Copperphosphotungstate Doped Polyanilines Nanorods for GSH-Depletion Enhanced Chemodynamic/NIR-II Photothermal Synergistic Therapy

Introduction

The high concentration of glutathione (GSH) and hydrogen peroxide (H₂O₂) levels within the tumor microenvironment (TME) are the major obstacle to induce the unsatisfactory anticancer treatment efficiency. The synergistic cancer therapy strategies of the combination the GSH depletion enhanced chemodynamic therapy (CDT) with photothermal therapy (PTT) have been proved to be the promising method to significantly improve the therapeutic efficacy.

Methods

The copperphosphotungstate was incorporated into polyanilines to design copperphosphotungstate doped polyaniline nanorods (CuPW@PANI Nanorods) via chemical oxidant polymerization of aniline. The low long-term toxicity and biocompatibility were evaluated. Both in vitro and in vivo experiments were carried out to confirm the GSH depletion enhanced CDT/NIR-II PTT synergistic therapy.

Results

CuPW@PANI Nanorods feature biosafety and biocompatibility, strong NIR-II absorbance, and high photothermal-conversion efficiency (45.14%) in NIR-II bio-window, making them highly applicable for photoacoustic imaging and NIR-II PTT. Moreover, CuPW@PANI Nanorods could consume endogenous GSH to disrupt redox homeostasis and perform a Fenton-like reaction with H₂O₂ to produce cytotoxic •OH for the enhanced CDT. Furthermore, NIR-II photothermal-induced local hyperthermia accelerates •OH generation to enhance CDT, which realizes high therapeutic efficacy in vivo.

Conclusion

This study provides a proof of concept of GSH-depletion augmented chemodynamic/NIR-II photothermal therapy.

Thickness-Tunable Growth of Composition-Controllable Two-Dimensional FexGeTe2

Two-dimensional (2D) magnetic materials provide an ideal platform for investigating novel magnetism and spin behavior in low-dimensional systems while being restricted by the deficiency of accurate bottom-up synthesis. To overcome this difficulty, a facile and universal flux-assisted growth (FAG) method is proposed to synthesize the multicomponent Fe_xGeTe₂ (x = 3-5) with different Fe contents and even alloyed with hetero metal atoms. This one-to-one method ensures the stoichiometry consistency from the Fe_xGeTe₂ and M_yFe_5-yGeTe₂ (M = Co, Ni) bulk crystal precursors to the 2D nanosheets, with controllable composition. Tuning the growth temperatures can provide thickness-tunable products. Changeable magnetic properties of Fe_xGeTe₂ and alloyed Co_yFe_5-yGeTe₂ are substantiated by the superconducting quantum interference device and reflective magnetic circular dichroism. This method generates thickness-tunable high-crystallinity Fe_xGeTe₂ samples without phase separation and exhibits a high tolerance to different substrates and a large temperature window, providing a new avenue to synthesize and explore such multicomponent 2D magnets and even the alloyed ones.

Advances in Stigmasterol on its anti-tumor effect and mechanism of action

Stigmasterol is a phytosterol derived from multiple herbaceous plants such as herbs, soybean and tobacco, and it has received much attention for its various pharmacological effects including anti-inflammation, anti-diabetes, anti-oxidization, and lowering blood cholesterol. Multiple studies have revealed that stigmasterol holds promise as a potentially beneficial therapeutic agent for malignant tumors because of its significant anti-tumor bioactivity. It is reported that stigmasterol has anti-tumor effect in a variety of malignancies (e.g., breast, lung, liver and ovarian cancers) by promoting apoptosis, inhibiting proliferation, metastasis and invasion, and inducing autophagy in tumor cells. Mechanistic study shows that stigmasterol triggers apoptosis in tumor cells by regulating the PI3K/Akt signaling pathway and the generation of mitochondrial reactive oxygen species, while its anti-proliferative activity is mainly dependent on its modulatory effect on cyclin proteins and cyclin-dependent kinase (CDK). There have been multiple mechanisms underlying the anti-tumor effect of stigmasterol, which make stigmasterol promising as a new anti-tumor agent and provide insights into research on its anti-tumor role. Presently, stigmasterol has been poorly understood, and there is a paucity of systemic review on the mechanism underlying its anti-tumor effect. The current study attempts to conduct a literature review on stigmasterol for its anti-tumor effect to provide reference for researchers and clinical workers.

Ligand Exchange on MoS2 Nanosheets: Applications in Array-Based Sensing and Drug Delivery

Two-dimensional MoS2 nanosheets (2D-MoS2) have been widely used in many biological applications due to their distinctive physicochemical properties. Further, the development of surface modification using thiolated ligands allows us to use them for many specific applications. But the effect of possible ligand exchange on 2D-MoS2 has never been explored, which can play an important role in diverse biological applications. In this study, we have observed the ligand-exchange phenomenon on 2D-MoS2 in the presence of different thiolated ligands. The initial study proceeded with boron-dipyrromethene (BODIPY) functionalized MoS2 with different concentrations of glutathione (GSH), which is the most abundant thiol species in the cytoplasm of various cancer cells. It was found that in the presence of GSH the fluorescence of BODIPY can be regenerated, which is time and concentration dependent. We have also examined this phenomenon with different thiol ligands and transition-metal dichalcogenides (TMDs). We observed a variable rate of ligand exchange in different solvents, surface functionality, and receptor environments that helped us to construct sensor arrays. Interestingly, a ligand-exchange process was not observed in the presence of dithiols. Further, this concept was applied to a cancerous cell line for in vitro delivery. We found that BODIPY-functionalized 2D-MoS2 undergoes thiol exchange by intracellular GSH and subsequently enhanced the fluorescence in the cytoplasm of cancer cells. This strategy can be applied to the development of 2D-TMD-based materials for various biological applications related to ligand exchange.

Three birds with one stone: oxygen self-supply engineering palladium nanocluster/titanium carbide hybrid for single-NIR laser-triggered synergistic photodynamic-photothermal therapy

As a key branch of the cross-discipline biophotonics, phototherapy, including photodynamic therapy (PDT), and photothermal therapy (PTT), is promising in biomedicine and visible light-driving PDT has been applied to clinical treatment. However, extensive applications of phototherapy are limited by the hypoxic microenvironment, laser penetration depth, and potential complexity for combined PDT/PTT. Thus, NIR-responsive oxygen self-supply nanocomposites functionalized with photosensitizers for achieving simultaneous in-depth PDT/PTT are urgently required. Herein, a multifunctional platform has been fabricated by co-immobilizing monodispersed ultrasmall Pd nanoclusters and a photosensitizer 5,10,15,20-Tetrakis (4-Aminophenyl)-21H,23H Porphyrin (Thp) on the surface of Ti3C2T x MXene nanosheets, generating the Pd-Thp-Ti3C2T x nanocomposite. Material characterization demonstrated that Pd nanoclusters and Thp were well-distributed on the MXene surface while MXene maintained its photothermal conversion efficiency and broad absorption. In this nanoplatform, irradiated by the single 808 nm laser, Pd selectively catalyzed the decomposition of H2O2 to O2, and O2 was continuously supplied to Thp for enhanced NIR-driving PDT. The in vivo fluorescence and photothermal imaging demonstrated the pronounced accumulation of nanocomposites in the tumor site. Both in vitro and in vivo results clearly demonstrated the nanocomposite had good biocompatibility, and that the synergistic PTT and enhanced PDT made apoptosis of the tumor cell achievable. This work not only proves this Pd-Thp-Ti3C2T x nanocomposite serves a promising solution for tumor hypoxia by inducing apoptosis of tumor cells with synergistic PTT and PDT, but also broadens the application of promising optical materials in biomedical field.

Organelle-targeted therapies: a comprehensive review on system design for enabling precision oncology

Cancer is a major threat to human health. Among various treatment methods, precision therapy has received significant attention since the inception, due to its ability to efficiently inhibit tumor growth, while curtailing common shortcomings from conventional cancer treatment, leading towards enhanced survival rates. Particularly, organelle-targeted strategies enable precise accumulation of therapeutic agents in organelles, locally triggering organelle-mediated cell death signals which can greatly reduce the therapeutic threshold dosage and minimize side-effects. In this review, we comprehensively discuss history and recent advances in targeted therapies on organelles, specifically including nucleus, mitochondria, lysosomes and endoplasmic reticulum, while focusing on organelle structures, organelle-mediated cell death signal pathways, and design guidelines of organelle-targeted nanomedicines based on intervention mechanisms. Furthermore, a perspective on future research and clinical opportunities and potential challenges in precision oncology is presented. Through demonstrating recent developments in organelle-targeted therapies, we believe this article can further stimulate broader interests in multidisciplinary research and technology development for enabling advanced organelle-targeted nanomedicines and their corresponding clinic translations.

The Surface Charge of Polymer-Coated Upconversion Nanoparticles Determines Protein Corona Properties and Cell Recognition in Serum Solutions

Applications of nanoparticles (NPs) in the life sciences require control over their properties in protein-rich biological fluids, as an NP quickly acquires a layer of proteins on the surface, forming the so-called "protein corona" (PC). Understanding the composition and kinetics of the PC at the molecular level is of considerable importance for controlling NP interaction with cells. Here, we present a systematic study of hard PC formation on the surface of upconversion nanoparticles (UCNPs) coated with positively-charged polyethyleneimine (PEI) and negatively-charged poly (acrylic acid) (PAA) polymers in serum-supplemented cell culture medium. The rationale behind the choice of UCNP is two-fold: UCNP represents a convenient model of NP with a size ranging from 5 nm to >200 nm, while the unique photoluminescent properties of UCNP enable direct observation of the PC formation, which may provide new insight into this complex process. The non-linear optical properties of UCNP were utilised for direct observation of PC formation by means of fluorescence correlation spectroscopy. Our findings indicated that the charge of the surface polymer coating was the key factor for the formation of PC on UCNPs, with an ensuing effect on the NP-cell interactions.

Surface Functionalization of Hydroxyapatite Scaffolds with MgAlEu-LDH Nanosheets for High-Performance Bone Regeneration

Although artificial bone repair scaffolds, such as titanium alloy, bioactive glass, and hydroxyapatite (HAp), have been widely used for treatment of large-size bone defects or serious bone destruction, they normally exhibit unsatisfied bone repair efficiency because of their weak osteogenic and angiogenesis performance as well as poor cell crawling and adhesion properties. Herein, the surface functionalization of MgAlEu-layered double hydroxide (MAE-LDH) nanosheets on porous HAp scaffolds is reported as a simple and effective strategy to prepare HAp/MAE-LDH scaffolds for enhanced bone regeneration. The surface functionalization of MAE-LDHs on the porous HAp scaffold can significantly improve its surface roughness, specific surface, and hydrophilicity, thus effectively boosting the cells adhesion and osteogenic differentiation. Importantly, the MAE-LDHs grown on HAp scaffolds enable the sustained release of Mg2+ and Eu3+ ions for efficient bone repair and vascular regeneration. In vitro experiments suggest that the HAp/MAE-LDH scaffold presents much enhanced osteogenesis and angiogenesis properties in comparison with the pristine HAp scaffold. In vivo assays further reveal that the new bone mass and mineral density of HAp/MAE-LDH scaffold increased by 3.18- and 2.21-fold, respectively, than that of pristine HAp scaffold. The transcriptome sequencing analysis reveals that the HAp/MAE-LDH scaffold can activate the Wnt/β-catenin signaling pathway to promote the osteogenic and angiogenic abilities.

Strategies for Solubility and Bioavailability Enhancement and Toxicity Reduction of Norcantharidin

Cantharidin (CTD) is the main active ingredient isolated from Mylabris, and norcantharidin (NCTD) is a demethylated derivative of CTD, which has similar antitumor activity to CTD and lower toxicity than CTD. However, the clinical use of NCTD is limited due to its poor solubility, low bioavailability, and toxic effects on normal cells. To overcome these shortcomings, researchers have explored a number of strategies, such as chemical structural modifications, microsphere dispersion systems, and nanodrug delivery systems. This review summarizes the structure-activity relationship of NCTD and novel strategies to improve the solubility and bioavailability of NCTD as well as reduce the toxicity. This review can provide evidence for further research of NCTD.

Dual targeting nanoparticles for epilepsy therapy

For epilepsy therapy, one-third of the patients worldwide are resistant to antiepileptic drugs mainly due to the existence of the blood-brain barrier (BBB) that prevents the drugs from reaching the epileptic lesions. Here, we design a double targeting nanoparticle carrying lamotrigine (LTG) to cross the BBB and further concentrate at the neurons. We prepare the nanoparticles on a microfluidic chip by encapsulating LTG in poly(lactic-co-glycolic acid) (PLGA) to form a core (PL) and capping the core with a shell of lipids conjugated with the D-T7 peptide (targeting the BBB) and Tet1 peptide (targeting the neuron) to form D-T7/Tet1-lipids@PL nanoparticles (NPs). In vitro and in vivo experiments show that D-T7/Tet1-lipids@PL NPs have excellent neuron targeting, antiepileptic, and protecting effects. Our approach provides a new strategy for improving the therapeutic efficacy of existing antiepileptic drugs.

Recent advances in near-infrared-II hollow nanoplatforms for photothermal-based cancer treatment

Near-infrared-II (NIR-II, 1000–1700 nm) light-triggered photothermal therapy (PTT) has been regarded as a promising candidate for cancer treatment, but PTT alone often fails to achieve satisfactory curative outcomes. Hollow nanoplatforms prove to be attractive in the biomedical field owing to the merits including good biocompatibility, intrinsic physical-chemical nature and unique hollow structures, etc. On one hand, hollow nanoplatforms themselves can be NIR-II photothermal agents (PTAs), the cavities of which are able to carry diverse therapeutic units to realize multi-modal therapies. On the other hand, NIR-II PTAs are capable of decorating on the surface to combine with the functions of components encapsulated inside the hollow nanoplatforms for synergistic cancer treatment. Notably, PTAs generally can serve as good photoacoustic imaging (PAI) contrast agents (CAs), which means such kind of hollow nanoplatforms are also expected to be multifunctional all-in-one nanotheranostics. In this review, the recent advances of NIR-II hollow nanoplatforms for single-modal PTT, dual-modal PTT/photodynamic therapy (PDT), PTT/chemotherapy, PTT/catalytic therapy and PTT/gas therapy as well as multi-modal PTT/chemodynamic therapy (CDT)/chemotherapy, PTT/chemo/gene therapy and PTT/PDT/CDT/starvation therapy (ST)/immunotherapy are summarized for the first time. Before these, the typical synthetic strategies for hollow structures are presented, and lastly, potential challenges and perspectives related to these novel paradigms for future research and clinical translation are discussed.

Design Strategies of Tumor-Targeted Delivery Systems Based on 2D Nanomaterials

Conventional chemotherapy and radiotherapy are nonselective and nonspecific for cell killing, causing serious side effects and threatening the lives of patients. It is of great significance to develop more accurate tumor-targeting therapeutic strategies. Nanotechnology is in a leading position to provide new treatment options for cancer, and it has great potential for selective targeted therapy and controlled drug release. 2D nanomaterials (2D NMs) have broad application prospects in the field of tumor-targeted delivery systems due to their special structure-based functions and excellent optical, electrical, and thermal properties. This review emphasizes the design strategies of tumor-targeted delivery systems based on 2D NMs from three aspects: passive targeting, active targeting, and tumor-microenvironment targeting, in order to promote the rational application of 2D NMs in clinical practice.

Multifunctional nanotheranostics for near infrared optical imaging-guided treatment of brain tumors

Malignant brain tumors, a heterogeneous group of primary and metastatic neoplasms in the central nervous system (CNS), are notorious for their highly invasive and devastating characteristics, dismal prognosis and low survival rate. Recently, near-infrared (NIR) optical imaging modalities including fluorescence imaging (FLI) and photoacoustic imaging (PAI) have displayed bright prospect in innovation of brain tumor diagnoses, due to their merits, like noninvasiveness, high spatiotemporal resolution, good sensitivity and large penetration depth. Importantly, these imaging techniques have been widely used to vividly guide diverse brain tumor therapies in a real-time manner with high accuracy and efficiency. Herein, we provide a systematic summary of the state-of-the-art NIR contrast agents (CAs) for brain tumors single-modal imaging (e.g., FLI and PAI), dual-modal imaging (e.g., FLI/PAI, FLI/magnetic resonance imaging (MRI) and PAI/MRI) and triple-modal imaging (e.g., MRI/FLI/PAI and MRI/PAI/computed tomography (CT) imaging). In addition, we update the most recent progress on the NIR optical imaging-guided therapies, like single-modal (e.g., photothermal therapy (PTT), chemotherapy, surgery, photodynamic therapy (PDT), gene therapy and gas therapy), dual-modal (e.g., PTT/chemotherapy, PTT/surgery, PTT/PDT, PDT/chemotherapy, PTT/chemodynamic therapy (CDT) and PTT/gene therapy) and triple-modal (e.g., PTT/PDT/chemotherapy, PTT/PDT/surgery, PTT/PDT/gene therapy and PTT/gene/chemotherapy). Finally, we discuss the opportunities and challenges of the CAs and nanotheranostics for future clinic translation.

Boron Neutron Capture Therapy: Clinical Application and Research Progress

Boron neutron capture therapy (BNCT) is a binary modality that is used to treat a variety of malignancies, using neutrons to irradiate boron-10 (¹⁰B) nuclei that have entered tumor cells to produce highly linear energy transfer (LET) alpha particles and recoil ⁷Li nuclei (¹⁰B [n, α] ⁷Li). Therefore, the most important part in BNCT is to selectively deliver a large number of ¹⁰B to tumor cells and only a small amount to normal tissue. So far, BNCT has been used in more than 2000 cases worldwide, and the efficacy of BNCT in the treatment of head and neck cancer, malignant meningioma, melanoma and hepatocellular carcinoma has been confirmed. We collected and collated clinical studies of second-generation boron delivery agents. The combination of different drugs, the mode of administration, and the combination of multiple treatments have an important impact on patient survival. We summarized the critical issues that must be addressed, with the hope that the next generation of boron delivery agents will overcome these challenges.

Titanium Sulfide Nanosheets Serve as Cascade Bioreactors for H2 S-Mediated Programmed Gas-Sonodynamic Cancer Therapy

Gas-mediated sonodynamic therapy (SDT) has the potential to become an effective strategy to improve the therapeutic outcome and survival rate of cancer patients. Herein, titanium sulfide nanosheets (TiSX NSs) are prepared as cascade bioreactors for sequential gas-sonodynamic cancer therapy. TiSX NSs themselves as hydrogen sulfide (H2 S) donors can burst release H2 S gas. Following H2 S generation, TiSX NSs are gradually degraded to become S-defective and partly oxidized into TiOX on their surface, which endows TiSX NSs with high sonodynamic properties under ultrasound (US) irradiation. In vitro and in vivo experiments show the excellent therapeutic effects of TiSX NSs. In detail, large amounts of H2 S gas and reactive oxygen species (ROS) can simultaneously inhibit mitochondrial respiration and ATP synthesis, leading to cancer cell apoptosis. Of note, H2 S gas also plays important roles in modulating and activating the immune system to effectively inhibit pulmonary metastasis. Finally, the metabolizable TiSX NSs are excreted out of the body without inducing any significant long-term toxicity. Collectively, this work establishes a cascade bioreactor of TiSX NSs with satisfactory H2 S release ability and excellent ROS generation properties under US irradiation for programmed gas-sonodynamic cancer therapy.

A Codispersed Nanosystem of Silver-anchored MoS2 Enhances Antibacterial and Antitumor Properties of Selective Laser Sintered Scaffolds

Tumor recurrence and bacterial infection are common problems during bone repair and reconstruction after bone tumor surgery. In this study, silver-anchored MoS₂ nanosheets (Ag@PMoS₂) were synthesized by in situ reduction, then a composite polymer scaffold (Ag@PMoS₂/PGA) with sustained antitumor and antibacterial activity was successfully constructed by selective laser sintering technique. In the Ag@PMoS₂ nanostructures, silver nanoparticles (Ag NPs) were sandwiched between adjacent MoS₂ nanosheets (MoS₂ NSs), which restrained the restacking of the MoS₂ NSs. In addition, the MoS₂ NSs acted as steric hindrance layers, which prevented the aggregation of Ag NPs. More importantly, MoS₂ NSs can provide a barrier layer for Ag NPs, hindering Ag NPs from reacting with the external solution to prevent its quick release. The results showed that Ag@PMoS₂/PGA scaffolds have stronger photothermal effect and antitumor function. Meanwhile, the Ag@PMoS₂/PGA scaffolds also demonstrated slow control of silver ion (Ag⁺) release and more efficient long-term antibacterial ability. Besides, composite scaffolds have been proved to kill the MG-63 cells by inducing apoptosis and inhibit bacterial proliferation by upregulating the level of bacterial reactive oxygen species. This kind of novel bifunctional implants with antitumor and antibacterial properties provides better choice for the artificial bone transplantation after primary bone tumor resection.

Biomimetic synthesis of protein-DNA-CaHPO4 hybrid nanosheets for biosensing: Detection of thrombin as an example

Traditional strategies for coupling of proteins with DNA involve the additional modifications on protein or DNA to construct protein-DNA conjugates, resulting in complex or time-consuming coupling process. This study presented a biomimetic synthesis strategy to elaborately synthesize a new type of biomolecule-inorganic hybrid nanosheets. Horseradish peroxidase (HRP) and DNA aptamer can be easily combined with CaHPO₄ via coprecipitation simultaneously to form all-inclusive HRP-aptamer-CaHPO₄ hybrid (HAC) nanosheets integrating bifunction of biorecognition and signal amplification, which was proceeded in the green environment at room temperature and required no additional modifications on CaHPO₄, protein and DNA. Therefore, it avoided tedious linking and purification procedures. The HAC nanosheets were then employed as the signal labels and showed excellent performance for detecting thrombin. This bioinspired approach provides great possibilities to facile and efficient immobilization of protein, DNA or even other types of biomolecules (e.g., RNA and peptide) on inorganic nanomaterials and endows great potential in the preparation of a variety of multifunctional biomolecule-CaHPO₄ two-dimensional (2D) nanobiohybrids for various applications extending from biosensing to energy, biomedicine, environmental science and catalysis.

Multimodal molecular imaging in the second near-infrared window

Near-infrared-II (NIR-II) fluorescence imaging has rapidly developed for the noninvasive investigation of physiological and pathological activities in living organisms with high spatiotemporal resolution. However, the penetration depth of fluorescence restricts its ability to provide deep anatomical information. Scientists integrate NIR-II fluorescence imaging with other imaging modes (such as photoacoustic and magnetic resonance imaging) to create multimodal imaging that can acquire detailed anatomical and quantitative information with deeper penetration by using multifunctional probes. This review offers a comprehensive picture of NIR-II-based dual/multimodal imaging probes and highlights advances in bioimaging and therapy. In addition, seminal studies and trends in multimodal imaging probes activated by NIR-II laser are summarized and several key points regarding future clinical translation are elucidated.

How to Treat Melanoma? The Current Status of Innovative Nanotechnological Strategies and the Role of Minimally Invasive Approaches like PTT and PDT

Melanoma is the most aggressive type of skin cancer, the incidence and mortality of which are increasing worldwide. Its extensive degree of heterogeneity has limited its response to existing therapies. For many years the therapeutic strategies were limited to surgery, radiotherapy, and chemotherapy. Fortunately, advances in knowledge have allowed the development of new therapeutic strategies. Despite the undoubted progress, alternative therapies are still under research. In this context, nanotechnology is also positioned as a strong and promising tool to develop nanosystems that act as drug carriers and/or light absorbents to potentially improve photothermal and photodynamic therapies outcomes. This review describes the latest advances in nanotechnology field in the treatment of melanoma from 2011 to 2022. The challenges in the translation of nanotechnology-based therapies to clinical applications are also discussed. To sum up, great progress has been made in the field of nanotechnology-based therapies, and our understanding in this field has greatly improved. Although few therapies based on nanoparticulate systems have advanced to clinical trials, it is expected that a large number will come into clinical use in the near future. With its high sensitivity, specificity, and multiplexed measurement capacity, it provides great opportunities to improve melanoma treatment, which will ultimately lead to enhanced patient survival rates.

Activatable photothermal agents with target-initiated large spectral separation for highly effective reduction of side effects

Photothermal agents (PTAs) with minimized side effects are critical for transforming cancer photothermal therapy (PTT) into clinical applications. However, most currently available PTAs lack true selective activation to reduce side effects because of heavy spectral overlap between photothermal agents and their corresponding products. This study reports the construction of activatable PTAs with target-initiated large spectral separation for highly effective reduction of side effects. Such designed probes involve two H2O2-activatable PTAs, aza-BOD-B1 (single activatable site) and aza-BOD-B2 (multiple activatable site). After interacting with H2O2, aza-BOD-B1 only displays a mild absorption redshift (60 nm) from 750 nm to 810 nm with serious spectral overlap, resulting in a mild photothermal effect on normal tissues upon 808 nm light irradiation. In contrast, aza-BOD-B2 displays a large absorption spectral separation (150 nm) from 660 nm to 810 nm, achieving true selective activation to minimize side effects during PTT of cancer. Besides, in vitro and in vivo investigations demonstrated that aza-BOD-B2 can specifically induce photothermal ablation of cancer cells and tumors while leaving normal sites undamaged, whereas aza-BOD-B1 exhibits undesirable side effects on normal cells. Our study provides a practical solution to the problem of undesired side effects of phototherapy, an advance in precision medicine.

Atomic Layer Deposition of Large-Area Polycrystalline Transition Metal Dichalcogenides from 100 °C through Control of Plasma Chemistry

Two-dimensional transition metal dichalcogenides, such as MoS2, are intensely studied for applications in electronics. However, the difficulty of depositing large-area films of sufficient quality under application-relevant conditions remains a major challenge. Herein, we demonstrate deposition of polycrystalline, wafer-scale MoS2, TiS2, and WS2 films of controlled thickness at record-low temperatures down to 100 °C using plasma-enhanced atomic layer deposition. We show that preventing excess sulfur incorporation from H2S-based plasma is the key to deposition of crystalline films, which can be achieved by adding H2 to the plasma feed gas. Film composition, crystallinity, growth, morphology, and electrical properties of MoS x films prepared within a broad range of deposition conditions have been systematically characterized. Film characteristics are correlated with results of field-effect transistors based on MoS2 films deposited at 100 °C. The capability to deposit MoS2 on poly(ethylene terephthalate) substrates showcases the potential of our process for flexible devices. Furthermore, the composition control achieved by tailoring plasma chemistry is relevant for all low-temperature plasma-enhanced deposition processes of metal chalcogenides.

MXenes Thin Films: From Fabrication to Their Applications

Two-dimensional MXenes possessed exceptional physiochemical properties such as high electrical conductivity (20,000 Scm-1), flexibility, mechanical strength (570 MPa), and hydrophilic surface functionalities that have been widely explored for energy storage, sensing, and catalysis applications. Recently, the fabrication of MXenes thin films has attracted significant attention toward electronic devices and sensor applications. This review summarizes the exciting features of MXene thin film fabrication methods such as vacuum-assisted filtration (VAF), electrodeposition techniques, spin coating, spray coating, dip-coating methods, and other physical/chemical vapor deposition methods. Furthermore, a comparison between different methods available for synthesizing a variety of MXenes films was discussed in detail. This review further summarizes fundamental aspects and advances of MXenes thin films in solar cells, batteries, electromagnetic interference shielding, sensing, etc., to date. Finally, the challenges and opportunities in terms of future research, development, and applications of MXenes-based films are discussed. A comprehensive understanding of these competitive features and challenges shall provide guidelines and inspiration for further growth in MXenes-based functional thin films and contribute to the advances in MXenes technology.

Biofunctionalized graphene oxide nanosheet for amplifying antitumor therapy: Multimodal high drug encapsulation, prolonged hyperthermal window, and deep-site burst drug release

Biofunctional surface-modification surpassed critical limitation of graphene oxide (GO) in biocompatibility and drug delivery efficiency, contributing to versatile biomedical applications. Here, a protein corona-bridged GO nanoplatform with high drug loading, longstanding hyperthermia, and controllable drug release, was engineered for amplified tumor therapeutic benefits. Structurally, GO surface was installed with phenylboronic acid (PBA) layer, on which iRGD conjugated apolipoprotein A-I (iRGD-apoA-I) was coordinated via boron electron-deficiency, to form the sandwich-like GO nanosheet (iAPG). The GO camouflaging by iRGD-apoA-I corona provided multimodal high doxorubicin (DOX) loading by π-π stacking and coordination, and generated a higher photothermal transformation efficiency simultaneously. In vitro studies demonstrated that iAPG significantly improved drug penetration and internalization, then achieved tumor-targeted DOX release through near-infrared (NIR) controlled endo/lysosome disruption. Moreover, iAPG mediated site-specific drug shuttling to produce a 3.53-fold enhancement of tumor drug-accumulation compared to the free DOX in vivo, and induced deep tumor penetration dramatically. Primary tumor ablation and spontaneous metastasis inhibition were further demonstrated with negligible side effects under optimal NIR. Taken together, our work provided multifunctional protein corona strategy to inorganic nanomaterials toward advantageous biomedical applications.

Azadirachta indica Seed Derived Carbon Nanocapsules: Cell Imaging, Depolarization of Mitochondrial Membrane Potential, and Dose-Dependent Control Death of Breast Cancer

In this work, a series of mesoporous carbon nanocapsules (mCNS) of size below 10 nm have been prepared from Azadirachta indica seeds with a very easy and cost-effective approach. These nanocapsules can emit red and green light and are effective for cell imaging. Further, these carbon nanocapsules are biocompatible toward the normal healthy cells, however, they possess modest cytotoxicity against the MCF-7 (human breast cancer) and triple-negative breast cancer (TNBC) (MDA- MB-231 breast cancer cells), and the rate of killing cancer cells strongly depends on the dose of mCNCs. Further, the mitochondrial membrane potential and apoptosis assay were performed to analyze the therapeutic significance of these nanocapsules to kill breast cancer. Results showed that these carbon nanocapsules can depolarize the mitochondrial membrane potential alone (without using conventional drugs) and can change the physiological parameters and cellular metabolic energy of the cancer cells and kill them. The apoptosis results confirmed the death of breast cancer cells in the form of apoptosis and necrosis. Moreover, the results suggested that the porous carbon nanocapsules (mCNCs) reported herein can be used as a potential candidate and useful for the theranostic applications such as for cancer cell detection and therapy without using any conventional drugs.

Electrospun Silk Fibroin/Polylactic-co-glycolic Acid/Black Phosphorus Nanosheets Nanofibrous Membrane with Photothermal Therapy Potential for Cancer

Photothermal therapy is a promising treating method for cancers since it is safe and easily controllable. Black phosphorus (BP) nanosheets have drawn tremendous attention as a novel biodegradable thermotherapy material, owing to their excellent biocompatibility and photothermal properties. In this study, silk fibroin (SF) was used to exfoliate BP with long-term stability and good solution-processability. Then, the prepared BP@SF was introduced into fibrous membranes by electrospinning, together with SF and polylactic-co-glycolic acid (PLGA). The SF/PLGA/BP@SF membranes had relatively smooth and even fibers and the maximum stress was 2.92 MPa. Most importantly, the SF/PLGA/BP@SF membranes exhibited excellent photothermal properties, which could be controlled by the BP@SF content and near infrared (NIR) light power. The temperature of SF/PLGA/BP@SF composite membrane was increased by 15.26 °C under NIR (808 nm, 2.5 W/cm2) irradiation for 10 min. The photothermal property of SF/PLGA/BP@SF membranes significantly killed the HepG2 cancer cells in vitro, indicating its good potential for application in local treatment of cancer.

Layered double hydroxide-based nanomaterials for biomedical applications

Against the backdrop of increased public health awareness, inorganic nanomaterials have been widely explored as promising nanoagents for various kinds of biomedical applications. Layered double hydroxides (LDHs), with versatile physicochemical advantages including excellent biocompatibility, pH-sensitive biodegradability, highly tunable chemical composition and structure, and ease of composite formation with other materials, have shown great promise in biomedical applications. In this review, we comprehensively summarize the recent advances in LDH-based nanomaterials for biomedical applications. Firstly, the material categories and advantages of LDH-based nanomaterials are discussed. The preparation and surface modification of LDH-based nanomaterials, including pristine LDHs, LDH-based nanocomposites and LDH-derived nanomaterials, are then described. Thereafter, we systematically describe the great potential of LDHs in biomedical applications including drug/gene delivery, bioimaging diagnosis, cancer therapy, biosensing, tissue engineering, and anti-bacteria. Finally, on the basis of the current state of the art, we conclude with insights on the remaining challenges and future prospects in this rapidly emerging field.

Mitochondrial adaptation in cancer drug resistance: prevalence, mechanisms, and management

Drug resistance represents a major obstacle in cancer management, and the mechanisms underlying stress adaptation of cancer cells in response to therapy-induced hostile environment are largely unknown. As the central organelle for cellular energy supply, mitochondria can rapidly undergo dynamic changes and integrate cellular signaling pathways to provide bioenergetic and biosynthetic flexibility for cancer cells, which contributes to multiple aspects of tumor characteristics, including drug resistance. Therefore, targeting mitochondria for cancer therapy and overcoming drug resistance has attracted increasing attention for various types of cancer. Multiple mitochondrial adaptation processes, including mitochondrial dynamics, mitochondrial metabolism, and mitochondrial apoptotic regulatory machinery, have been demonstrated to be potential targets. However, recent increasing insights into mitochondria have revealed the complexity of mitochondrial structure and functions, the elusive functions of mitochondria in tumor biology, and the targeting inaccessibility of mitochondria, which have posed challenges for the clinical application of mitochondrial-based cancer therapeutic strategies. Therefore, discovery of both novel mitochondria-targeting agents and innovative mitochondria-targeting approaches is urgently required. Here, we review the most recent literature to summarize the molecular mechanisms underlying mitochondrial stress adaptation and their intricate connection with cancer drug resistance. In addition, an overview of the emerging strategies to target mitochondria for effectively overcoming chemoresistance is highlighted, with an emphasis on drug repositioning and mitochondrial drug delivery approaches, which may accelerate the application of mitochondria-targeting compounds for cancer therapy.

Facile fabrication of screen-printed MoS2 electrodes for electrochemical sensing of dopamine

Molybdenum disulfide (MoS₂) screen-printed working electrodes were developed for dopamine (DA) electrochemical sensing. MoS₂ working electrodes were prepared from high viscosity screen-printable inks containing various concentrations and sizes of MoS₂ particles and ethylcellulose binder. Rheological properties of MoS₂ inks and their suitability for screen-printing were analyzed by viscosity curve, screen-printing simulation and oscillatory modulus. MoS₂ inks were screen-printed onto conductive FTO (Fluorine-doped Tin Oxide) substrates. Optical microscopy and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX) analysis were used to characterize the homogeneity, topography and thickness of the screen-printed MoS₂ electrodes. The electrochemical performance was assessed through differential pulse voltammetry. Results showed an extensive linear detection of dopamine from 1 µM to 300 µM (R² = 0.996, sensitivity of 5.00 × 10^-8 A μM^-1), with the best limit of detection being 246 nM. This work demonstrated the possibility of simple, low-cost and rapid preparation of high viscosity MoS₂ ink and their use to produce screen-printed FTO/MoS₂ electrodes for dopamine detection.

Research trends in biomedical applications of two-dimensional nanomaterials over the last decade - A bibliometric analysis

Two-dimensional (2D) nanomaterials with versatile properties have been widely applied in the field of biomedicine. Despite various studies having reviewed the development of biomedical 2D nanomaterials, there is a lack of a study that objectively summarizes and analyzes the research trend of this important field. Here, we employ a series of bibliometric methods to identify the development of the 2D nanomaterial-related biomedical field during the past 10 years from a holistic point of view. First, the annual publication/citation growth, country/institute/author distribution, referenced sources, and research hotspots are identified. Thereafter, based on the objectively identified research hotspots, the contributions of 2D nanomaterials to the various biomedical subfields, including those of biosensing, imaging/therapy, antibacterial treatment, and tissue engineering are carefully explored, by considering the intrinsic properties of the nanomaterials. Finally, prospects and challenges have been discussed to shed light on the future development and clinical translation of 2D nanomaterials. This review provides a novel perspective to identify and further promote the development of 2D nanomaterials in biomedical research.

Nonmetal Graphdiyne Nanozyme-Based Ferroptosis-Apoptosis Strategy for Colon Cancer Therapy

Ferroptosis-apoptosis, a new modality of induced cell death dependent on reactive oxygen species, has drawn tremendous attention in the field of nanomedicine. A metal-free ferroptosis-apoptosis inducer was reported based on boron and nitrogen codoped graphdiyne (BN-GDY) that possesses efficient glutathione (GSH) depletion capability and concurrently induces ferroptosis by deactivation of GSH-dependent peroxidases 4 (GPX4) and apoptosis by downregulation of Bcl2. The high catalytic activity of BN-GDY is explicated by both kinetic experiments and density functional theory (DFT) calculations of Gibbs free energy change during hydrogen peroxide (H₂O₂) decomposition. In addition, a unique sequence Bi-Bi mechanism is discovered, which is distinct from the commonly reported ping-pong Bi-Bi mechanism of most peroxidase mimics and natural enzymes. We anticipate that this nonmetal ferroptosis-apoptosis therapeutic concept by carbon-based nanomaterials would provide proof-of-concept evidence for nanocatalytic medicines in cancer therapy.

Cell Membrane Camouflaged Metal Oxide-Black Phosphorus Biomimetic Nanocomplex Enhances Photo-chemo-dynamic Ferroptosis

Despite the availability of various treatment options, the inherent complexity of tumors significantly impairs therapeutic efficacy. Recently, combination treatments exhibited great anticancer potential due to low cross-resistance and good therapeutic additivity. Herein, a photoactive metal oxide-black phosphorus biomimetic nanocomplex (photophage) is developed for improving the antitumor combination of ferroptosis and photodynamic therapy (PDT). The photophage is composed of M1 macrophage membrane camouflaged MnO2 and Fe3O4 nanoparticles anchored black phosphorus nanosheets (BPNs), which together trigger a synergistic antitumor action. Fe3O4 acts as an iron source to activate Fenton-reaction-dependent ferroptosis, which can be further strengthened by BPN-mediated PDT. Besides the original antitumor effects, PDT also generates reactive oxygen species to enhance lipid peroxidation and glutathione depletion, which in turn reinforce ferroptosis and PDT efficacy. Importantly, MnO2 can in situ generate oxygen to relieve tumor hypoxia and consequently leverage cell behaviors to improve therapeutic responses. Particularly, M1 macrophage membrane modification endows the photophage with good tumor targeting capability and tumor penetration, which promote synergistic ferroptosis and PDT to destroy tumors while reducing systemic side effects, resulting in the prolonged survival of tumor-bearing mice. Therefore, we present a biomimetic nanoplatform for overcoming tumor barriers and advancing tumor-targeted treatment.

2D materials-based nanomedicine: From discovery to applications

Due to their unique physicochemical characteristics, 2D materials have attracted more and more attention in the biomedicine field. Currently, 2D materials-based nanomedicines have been extensively applied in various diseases including cancer, bacterial infection, tissue engineering, biological protection, neurodegenerative diseases, and cardiovascular disease. Depending on their various characteristics, these 2D nanomedicines exert their therapeutic effect in different ways, showing great clinical application prospects. Herein, we focus on the various biomedical applications of 2D materials-based nanomedicine. The structures and characteristics of several typical 2D nanomaterials with different configurations and their corresponding biomedical applications are first introduced. Then, the potential of 2D nanomedicines on therapeutic and imaging and their biological functionalization are discussed. Furthermore, the therapeutic potentials of 2D nanomedicines in various diseases are also comprehensively summarized. At last, the challenges and perspectives for the advancement of 2D nanomedicines in clinical transformation are outlooks.

Engineering of 2D nanomaterials to trap and kill SARS-CoV-2: a new insight from multi-microsecond atomistic simulations

In late 2019, coronavirus disease 2019 (COVID-19) was caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Spike protein is one of the surface proteins of SARS-CoV-2 that is essential for its infectious function. Therefore, it received lots of attention for the preparation of antiviral drugs, vaccines, and diagnostic tools. In the current study, we use computational methods of chemistry and biology to study the interaction between spike protein and its receptor in the body, angiotensin-I-converting enzyme-2 (ACE2). Additionally, the possible interaction of two-dimensional (2D) nanomaterials, including graphene, bismuthene, phosphorene, p-doped graphene, and functionalized p-doped graphene, with spike protein is investigated. The functionalized p-doped graphene nanomaterials were found to interfere with spike protein better than the other tested nanomaterials. In addition, the interaction of the proposed nanomaterials with the main protease (Mpro) of SARS-CoV-2 was studied. Functionalized p-doped graphene nanomaterials showed more capacity to prevent the activity of Mpro. These 2D nanomaterials efficiently reduce the transmissibility and infectivity of SARS-CoV-2 by both the deformation of the spike protein and inhibiting the Mpro. The results suggest the potential use of 2D nanomaterials in a variety of prophylactic approaches, such as masks or surface coatings, and would deserve further studies in the coming years.

Mixed-Ligand Metal-Organic Frameworks for All-in-One Theranostics with Controlled Drug Delivery and Enhanced Photodynamic Therapy

Mixed-ligand metal-organic frameworks (MOFs) multiply the properties and improve the versatility of conventional MOFs for theranostic applications. A tumor targeting and tumoral microenvironment-responsive system is significant for specific and efficient cancer theranostics. Herein, we report a kind of versatile mixed-porphyrin ligand MOF as a multifunctional matrix for multimodality-imaging-guided synergistic therapy. Tetrakis(4-carboxyphenyl)porphyrin (TCPP) shows the properties of fluorescence (FL) and photodynamic therapy (PDT), while Mn-TCPP owns magically the properties of T1-weighted magnetic resonance (MR) imaging and photothermal conversion for photothermal imaging and photothermal therapy (PTT). Because of the same coordination capacity and mode of TCPP and Mn-TCPP to Zr4+ ions, MOFs with adjustable ligand ratios were easily prepared. The mixed-ligand MOFs exhibited a high drug loading capacity for 10-hydroxycamptothecin (HCPT, 65%). After modification with hyaluronic acid (HA) through a disulfide bond (-S-S-), the MOF-S-S-HA composites possess enhanced PDT and tumor-targeted redox-responsive drug release properties due to the -S-S- bond. Thus, excellent fluorescence, MR, and photothermal trimodality imaging, redox-responsive drug release, and enhanced PDT/PTT are integrated together in the mixed-ligand MOFs as "all-in-one" theranostic agents.

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.

Hydrogels for Antitumor and Antibacterial Therapy

As a highly absorbent and hydrophobic material with a three-dimensional network structure, hydrogels are widely used in biomedical fields for their excellent biocompatibility, low immunogenicity, adjustable physicochemical properties, ability to encapsulate a variety of drugs, controllability, and degradability. Hydrogels can be used not only for wound dressings and tissue repair, but also as drug carriers for the treatment of tumors. As multifunctional hydrogels are the focus for many researchers, this review focuses on hydrogels for antitumor therapy, hydrogels for antibacterial therapy, and hydrogels for co-use in tumor therapy and bacterial infection. We highlighted the advantages and representative applications of hydrogels in these fields and also outlined the shortages and future orientations of this useful tool, which might give inspirations for future studies.