Black Phosphorus Nanosheet-Based Drug Delivery System for Synergistic Photodynamic/Photothermal/Chemotherapy of Cancer

Anti-Parkinsonian Therapy: Strategies for Crossing the Blood-Brain Barrier and Nano-Biological Effects of Nanomaterials

Parkinson's disease (PD), a neurodegenerative disease that shows a high incidence in older individuals, is becoming increasingly prevalent. Unfortunately, there is no clinical cure for PD, and novel anti-PD drugs are therefore urgently required. However, the selective permeability of the blood-brain barrier (BBB) poses a huge challenge in the development of such drugs. Fortunately, through strategies based on the physiological characteristics of the BBB and other modifications, including enhancement of BBB permeability, nanotechnology can offer a solution to this problem and facilitate drug delivery across the BBB. Although nanomaterials are often used as carriers for PD treatment, their biological activity is ignored. Several studies in recent years have shown that nanomaterials can improve PD symptoms via their own nano-bio effects. In this review, we first summarize the physiological features of the BBB and then discuss the design of appropriate brain-targeted delivery nanoplatforms for PD treatment. Subsequently, we highlight the emerging strategies for crossing the BBB and the development of novel nanomaterials with anti-PD nano-biological effects. Finally, we discuss the current challenges in nanomaterial-based PD treatment and the future trends in this field. Our review emphasizes the clinical value of nanotechnology in PD treatment based on recent patents and could guide researchers working in this area in the future.

Reversing the Epithelial-Mesenchymal Transition in Metastatic Cancer Cells Using CD146-Targeted Black Phosphorus Nanosheets and a Mild Photothermal Treatment

Cancer metastasis leads to most deaths in cancer patients, and the epithelial-mesenchymal transition (EMT) is the key mechanism that endows the cancer cells with strong migratory and invasive abilities. Here, we present a nanomaterial-based approach to reverse the EMT in cancer cells by targeting an EMT inducer, CD146, using engineered black phosphorus nanosheets (BPNSs) and a mild photothermal treatment. We demonstrate this approach can convert highly metastatic, mesenchymal-type breast cancer cells to an epithelial phenotype (i.e., reversing EMT), leading to a complete stoppage of cancer cell migration. By using advanced nanomechanical and super-resolution imaging, complemented by immunoblotting, we validate the phenotypic switch in the cancer cells, as evidenced by the altered actin organization and cell morphology, downregulation of mesenchymal protein markers, and upregulation of epithelial protein markers. We also elucidate the molecular mechanism behind the reversal of EMT. Our results reveal that CD146-targeted BPNSs and a mild photothermal treatment synergistically contribute to EMT reversal by downregulating membrane CD146 and perturbing its downstream EMT-related signaling pathways. Considering CD146 overexpression has been confirmed on the surface of a variety of metastatic, mesenchymal-like cancer cells, this approach could be applicable for treating various cancer metastasis via modulating the phenotype switch in cancer cells.

Extended π-Conjugative Carbon Nitride for Single 1064 nm Laser-Activated Photodynamic/Photothermal Synergistic Therapy and Photoacoustic Imaging

The synergetic photodynamic/photothermal therapy, activated via a single-second near-infrared (NIR-II) laser and guided by photoacoustic imaging (PAI), receives significant attention for precise in vivo therapy. However, due to the lack of a corresponding theranostic agent, it faces a great challenge for practical clinical implementation. Here, we present a single diagnostic and therapeutic nanoplatform named carbon nitride nanoparticles (CN-NPs) for efficient NIR-II PAI-guided photodynamic therapy (PDT)/photothermal therapy (PTT). The CN-NPs were obtained by incorporating an aromatic compound (PTCDA) with a large π-structure into melem by high-temperature polymerization. The absorption of the obtained CN-NPs was significantly enhanced compared with pristine melem. Under 1064 nm laser illumination, sufficient reactive oxygen species (ROS) generated by CN-NPs could reduce the mitochondrial membrane potential. Moreover, the CN-NPs exhibited an efficient PTT effect through improved photothermal stability and high photo-to-heat conversion efficiency (47.6%). We were also able to monitor the accumulation and metabolism of CN-NPs in vivo of mice in real time using PAI. The in vivo experiments proved that the CN-NPs could inhibit tumor growth and recurrence completely under 1064 nm. Thus, the proposed innovative strategy would open a new avenue to explore and construct NIR-II responsive nanoplatforms with enhanced performance and safety for multimodal phototheranostics.

Photoactivated Release of Nitric Oxide and Antimicrobial Peptide Derivatives for Synergistic Therapy of Bacterial Skin Abscesses

It is of paramount importance to develop novel approaches for combating bacterial resistance and the integration of different antibacterial mechanisms is essential to achieve synergistic bactericidal efficiency while reducing the associated side effects. Herein, amphiphilic antimicrobial copolymers derived from poly-l-lysine (PLL), black phosphorus quantum dots (BPQDs) as near-infrared (NIR) sensitizer, and S-nitrosocysteamine (SNO) as nitric oxide (NO) donor, are assembled into PELI@BPQD-SNO nanoparticles through electrostatic interactions. Amphiphilic copolymers with isopentanyl grafts on PLL at a ratio of 50% achieve an optimal balance between antibacterial activity and hemolysis rate. Photothermal effect of BPQDs leads to NIR-responsive release of NO and the combination with amphiphilic copolymers mutually enhances long-term inhibition of bacterial growth. In an S. aureus-infected subcutaneous abscess model, the bactericidal rate of PELI@BPQD-SNO/NIR treatment reaches nearly 99.6%, which is significantly higher than those without NO release (38%) or amphiphilic copolymers (24%) or NIR irradiation (17%). PELI@BPQD-SNO/NIR treatment shows full recovery of infected wounds, efficient retardation of inflammatory cells, and reconstruction of blood vessels similar to those of healthy skin. Therefore, the electrostatic assembly demonstrates a promising strategy to deliver charged therapeutic agents and the photoactivated release of NO and amphiphilic copolymers achieves synergistic antibacterial efficacy without using any antibiotics.

Simulating and Predicting Adsorption of Organic Pollutants onto Black Phosphorus Nanomaterials

Layered black phosphorus (BP) has exhibited exciting application prospects in diverse fields. Adsorption of organics onto BP may influence environmental behavior and toxicities of both organic pollutants and BP nanomaterials. However, contributions of various intermolecular interactions to the adsorption remain unclear, and values of adsorption parameters such as adsorption energies (E_ad) and adsorption equilibrium constants (K) are lacking. Herein, molecular dynamic (MD) and density functional theory (DFT) was adopted to calculate E_ad and K values. The calculated E_ad and K values for organics adsorbed onto graphene were compared with experimental ones, so as to confirm the reliability of the calculation methods. Polyparameter linear free energy relationship (pp-LFER) models on E_ad and logK were developed to estimate contributions of different intermolecular interactions to the adsorption. The adsorption in the gaseous phase was found to be more favorable than in the aqueous phase, as the adsorbates need to overcome cohesive energies of water molecules onto BP. The affinity of the aromatics to BP was comparable to that of graphene. The pp-LFER models performed well for predicting the E_ad and K values, with external explained variance ranging from 0.90 to 0.97, and can serve as effective tools to rank adsorption capacities of organics onto BP.

Combining nanotechnology with the multifunctional roles of neutrophils against cancer and inflammatory disease

Neutrophils, the most abundant leukocytes in humans, play a crucial role in acute inflammation during infection and tumorigenesis. Neutrophils are the major types of cells recruited to the inflammation sites induced by pathogens, exhibiting great homing ability towards inflammatory disorders and tumor sites. Therefore, a neutrophil-based drug delivery system (NDDS) has become a promising platform for anti-cancer and anti-inflammatory treatment. Recent decades have witnessed the huge progress of applying nanomaterials in drug delivery. Nanomaterials are regarded as innovative components to enrich the field of neutrophil-based therapies due to their unique physiochemical characteristics. In this review, the latest advancement of combining diverse nanomaterials with an NDDS for cancer and inflammatory disease treatment will be summarized. It is discussed how nanomaterials empower the therapeutic area of an NDDS and how an NDDS circumvents the limitations of nanomaterials. Moreover, based on the finding that neutrophils are closely involved in the progression of cancer and inflammatory diseases, emerging therapeutic strategies that target neutrophils will be outlined. Finally, as neutrophils were demonstrated to play a central role in the immunopathology of COVID-19, which causes necroinflammation that is responsible for the cytokine storm and sepsis during coronavirus infections, novel therapeutic approaches that anchor neutrophils against the pathological consequences related to COVID-19 will be highlighted as well.

Injectable Black Phosphorus Nanosheets for Wireless Nongenetic Neural Stimulation

Neurons can be modified to express light-sensitive proteins for enabling stimulation with a high spatial and temporal resolution, but such techniques require gene transfection and systematical implantation. Here, a black phosphorus nanosheet-based injectable strategy is described for wireless neural stimulation both in vitro and in vivo without cell modifications. These nanosheets, with minimal invasiveness, high biocompatibility, and biodegradability, are anchored on cell membranes as miniature near-infrared (NIR) light transducers to create local heating for neural activity excitation. Based on cultured multielectrode-array recording, in vivo electrophysiology analysis, and open field behavioral tests, it is demonstrated that remotely applied NIR illumination can reliably trigger spiking activity in cultured neurons and rat brains. Excitingly, reliable regulation of brain function to control animal behaviors is also described. Moreover, this approach has shown its potential for future clinical use by successful high-frequency stimulation in cells and animals in this proof-of-concept study. It is believed that this new method will offer a powerful alternative to other neural stimulation solutions and potentially be of independent value to the healthcare system.

Neodymium (3+)-Coordinated Black Phosphorus Quantum Dots with Retrievable NIR/X-Ray Optoelectronic Switching Effect for Anti-Glioblastoma

Heteroatom interaction of atomically thin nanomaterials enables the improvement of electronic transfer, band structure, and optical properties. Black phosphorus quantum dots (BP QDs) are considered to be candidate diagnostic and/or therapeutic agents due to their innate biocompatibility and exceptional photochemical effects. However, BP QDs are not competitive regarding second near-infrared (NIR-II) window medical diagnosis and X-ray induced phototherapy. Here, an Nd³⁺ ion coordinated BP QD (BPNd) is synthesized with the aim to sufficiently improve its performances in NIR-II fluorescence imaging and X-ray induced photodynamic therapy, benefitting from the retrievable NIR/X-ray optoelectronic switching effects between BP QD and Nd³⁺ ion. Given its ultrasmall size and efficient cargo loading capacity, BPNd can easily cross the blood-brain barrier to precisely monitor the growth of glioblastoma through intracranial NIR-II fluorescence imaging and impede its progression by specific X-ray induced, synergistic photodynamic chemotherapy.

Black Phosphorus nanoparticles for dual therapy of non-small cell lung cancer

Lung cancer remains one of the leading causes of death in humans. Gefitinib is an inhibitor of epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) commonly used to suppress tumor growth. However, constantly use of gefitinib results in drug-resistance, reduced efficacy, and undesired side effects. To circumvent these drawbacks, targeted and photothermal therapies have emerged as effective strategies. Herein, we are first to adopt a black phosphorus nanoparticle-based novel delivering strategy by combining gefitinib and cancer cytomembrane to treat non-small cell lung cancer (NSCLC). In these gefitinib-containing nano-carrier, cyanine5 (Cy5) biotin-labeled black phosphorus was incorporated with cancer membrane and then consist of a nanomaterial (BPGM), which enabled to deliver gefitinib to the tumors effectively. The combination of BPGM showed reinforcing effects to suppress NSCLC cells and xenograft tumors without apparent adverse effects both in vitro and in vivo. BPGM facilitated the delivery of gefitinib to tumor tissue and extended its retention time within tumors. These studies thus suggest that black phosphorus may serve as novel delivery strategy for lung cancer.

Synthesis of red/black phosphorus-based composite nanosheets with a Z-scheme heterostructure for high-performance cancer phototherapy

Two dimensional black phosphorus nanosheets (BP NSs) have attracted plenty of attention in the research field of cancer photonic therapy. However, the poor stability and relatively low efficiency of reactive oxygen species (ROS) generation of BP NSs limit their practical application. To address these drawbacks, herein we report a red/black phosphorus (RP/BP) composite nanosheet, M-RP/BP@ZnFe₂O₄, which was synthesized by (1) partially converting red phosphorus (RP) to black phosphorus (BP) followed by liquid-phase ultrasonic exfoliation to form RP/BP NSs, (2) in situ synthesis of ZnFe₂O₄ nanoparticles on the surface of RP/BP NSs, (3) and wrapping with the MCF-7 cell membrane. Due to the presence of RP, BP, ZnFe₂O₄ and the cell membrane, the M-RP/BP@ZnFe₂O₄ NSs exhibited high performance in cancer phototherapy with the following features: (i) a Z-scheme heterojunction structure was formed between RP/BP NSs thus enabling high separation efficiency of the photogenerated electrons and holes; (ii) the photoexcitation holes in the valence band of RP can break the tumor microenvironment by oxidizing glutathione; (iii) the NSs could decompose water to produce H₂O₂ and O₂, which can be further converted to toxic ˙OH through the ZnFe₂O₄ catalyzed Fenton reaction and ¹O₂ through energy transfer, respectively; and (iv) the cell membrane wrapping improved the targeting of the composite NSs at the tumor site and photonic therapy can be finally triggered by a 660 nm laser to convert O₂ to ˙O₂^- and ¹O₂. The in vitro cytotoxicity experiments showed that more than 90% cells were killed after photodynamic therapy (PDT) at 0.3 mg mL^-1 M-RP/BP@ZnFe₂O₄ NSs, and the animal experiments with xenograft tumor model mice indicated that tumor growth was completely inhibited and the highest survival rate of 83.3% at 60 days post PDT was obtained.

Reactive oxygen species / photothermal therapy dual-triggered biomimetic gold nanocages nanoplatform for combination cancer therapy via ferroptosis and tumor-associated macrophage repolarization mechanism

With the continuous development of cancer nanotechnology, an important trend in the research is to combine the broad application prospects of functional nanomaterials with recent biological discoveries and technological advances. Herein, a cancer cell membrane-camouflaged gold nanocage loading doxorubicin (DOX) and l-buthionine sulfoximine (BSO) (denoted as m@Au-D/B NCs) was constructed as an innovative nanoplatform to confer promising cancer combination therapy by evoking effective ferroptosis and immune responses. Briefly, the loading of BSO and DOX could induce ferroptosis through simultaneous effective glutathione (GSH) consumption and reactive oxygen species (ROS) accumulation. Gold nanocages (AuNCs) with distinct anti-tumor application performance was utilized as ideal nanocarrier for drug loading, evoking photothermal effects and photochemical catalysis to generate more ROS under near-infrared (NIR) irradiation. Moreover, m@Au-D/B NCs-mediated photothermal therapy (PTT) combined with ROS production could repolarize the tumor-associated macrophages (TAMs) from pro-tumor (M2) phenotype to anti-tumor (M1) phenotype, thus improving tumor-suppressive immune environment and then promoting the activation of effector cells and release of pro-inflammatory cytokines, in which the antitumor responses were evoked robustly in a methodical approach. The anti-tumor effects in vivo implied that m@Au-D/B NCs could significantly inhibit tumor growth without severe toxicity. Hence, this homotypic targeting nanosystem could offer an auspicious anticancer access by triggering combination cancer therapy via ferroptosis and tumor-associated macrophage repolarization mechanism.

Zinc-Loaded Black Phosphorus Multifunctional Nanodelivery System Combined With Photothermal Therapy Have the Potential to Treat Prostate Cancer Patients Infected With COVID-19

Since 2019, coronavirus disease 2019 (COVID-19) has swept the world and become a new virus threatening the health of all mankind. The survey found that prostate cancer accounts for one in three male cancer patients infected with COVID-19. This undoubtedly makes prostate cancer patients face a more difficult situation. Prostate cancer is the second most harmful malignant tumor in men because of its insidious onset, easy metastasis, and easy development into castration-resistant prostate cancer even after treatment. Due to its high immunogenicity and a small number of specific infiltrating T cells with tumor-associated antigens in the tissue, it is difficult to obtain a good therapeutic effect with immune checkpoint blocking therapy alone. Therefore, in the current study, we developed a platform carrying Doxorubicin (DOX)-loaded black phosphate nanometer combined with photothermal therapy (PTT) and found this drug combination stimulated the immungentic cell death (ICD) process in PC-3 cells and DC maturation. More importantly, zinc ions have a good immunomodulatory function against infectious diseases, and can improve the killing ability of the nanosystem against prostate cancer cells. The introduction of Aptamer (Apt) enhances the targeting of the entire nanomedicine. We hope that this excellent combination will lead to effective treatment strategies for prostate cancer patients infected with COVID-19.

Photothermal Therapy may be a Double-edge Sword by Inducing the Formation of Bacterial Antibiotic Tolerance

Photothermal nanoparticles are thought to be the most potential candidates against infectious disease, by disrupting cell membrane and inhibiting metabolism. However, subpopulation survived with this low-activity state may be endowed...

Shape-Controllable Tellurium-Driven Heterostructures with Activated Robust Immunomodulatory Potential for Highly Efficient Radiophotothermal Therapy of Colon Cancer

Tellurium (Te)-based semiconductor easily leads to the recombination of photogenerated electron-hole pairs (h⁺-e^-) that severely limits the efficiency of reactive oxygen species (ROS) generation and further hinders its clinical application in biomedicine. With regard to these problems, herein we designed and synthesized a Te heterostructure (BTe-Pd-Au) by incorporating palladium (Pd) and gold (Au) elements to promote its radiosensitivity and photothermal performance, thus realizing highly efficient radiophotothermal tumor elimination by activating robust immunomodulatory potential. This shape-controllable heterostructure that coated by Pd on the surface of Te nanorods and Au in the center of Te nanorods was simply synthesized by using in situ synthesis method, which could promote the generation and separation of h⁺-e^- pairs, thereby exhibiting superior ROS producing ability and photothermal conversion efficiency. Using a mouse model of colon cancer, we proved that BTe-Pd-Au-R-combined radiophotothermal therapy not only eradicated tumor but also elicited to a series of antitumor immune responses by enhancing the cytotoxic T lymphocytes, triggering dendritic cells maturation, and decreasing the percentage of M2 tumor-associated macrophages. In summary, our study highlights a facile strategy to design Te-driven heterostructure with versatile performance in radiosensitization, photothermal therapy, and immunomodulation and offers great promise for clinical translational treatment of colon cancer.

Interface-Engineered Paclitaxel-Based Hollow Mesoporous Organosilica Nanoplatforms for Photothermal-Enhanced Chemotherapy of Tumor

Having benefited from the combination of different therapeutic modalities, functionalized nanoplatforms with synergistic strategies have aroused great interest in anticancer treatment. Herein, an engineered, a biodegradable hollow mesoporous organosilica nanoparticle (HMON)-based nanoplatform was fabricated for photothermal-enhanced chemotherapy of tumor. For the first time, we demonstrated that HMONs could serve as nanocarriers for co-delivering of both the paclitaxel and photothermal agent new indocyanine green (IR820), denoted as Paclitaxel/IR820@ HMONs-PEG. The as-prepared nanosystem exhibited a high paclitaxel-loading capacity of 28.4%, much higher than most paclitaxel-loaded nanoformulations. Furthermore, incorporating thioether bonds (S-S) into the HMONs' framework endowed them with GSH-responsive biodegradation behavior, leading to the controllable release of drugs under a tumor reducing microenvironment, and hindered the premature release of paclitaxel. Upon being irradiated with an NIR laser, the obtained co-delivery nanosystem exhibited great photothermal properties generated from IR820. The fabricated nanocomposites could significantly suppress tumor growth under NIR laser irradiation, as validated by in vitro and in vivo assessments. Combined with outstanding biocompatibility, the constructed nanosystem holds great potential in combinational antitumor therapy.

Electron Matters: Recent Advances in Passivation and Applications of Black Phosphorus

2D materials have experienced rapid and explosive development in the past decades. Among them, black phosphorus (BP) is one of the most promising materials on account of its thickness-dependent bandgap, high charge-carrier mobility, in-plane anisotropic structure, and excellent biocompatibility, as well as the broad applications brought by the properties. In view of the electron configuration, the most unique feature of BP is the lone-pair electrons on each P atom. The lone-pair electrons inevitably cause high reactivity of BP, particularly toward water/oxygen, which greatly limits the practical application of BP under ambient conditions. The other side of the coin is that BP can serve as an electron donor to promote the construction of BP-based hybrid materials and/or to boost the performance of BP or BP-based hybrid materials in applications. Here, recent advances in passivation and application of BP by addressing the interaction between the lone-pair electrons of BP and the other materials are discussed, and prospects for future research on BP are also proposed.

Strong Penetration-Induced Effective Photothermal Therapy by Exosome-Mediated Black Phosphorus Quantum Dots

Nanocancer medicine, such as photothermal therapy (PTT), as a promising way to solve cancer without side effects, faces a huge biological barrier during the circulation of nanoparticles in the body, including nanobiological interactions in the blood, isolation of nanoparticles in the macrophage system, tumor spillover effect, and especially uneven intratumoral distribution of nanoparticles, which cast a shadow over the hope. To address the problem of intratumoral distribution, an effective photothermal agent is introduced by packaging the black phosphorus quantum dots (BPQDs) into exosome vector (EXO) through electroporation method. With the improving and proper stability for better therapy, the resulting BPQDs@EXO nanospheres (BEs) exhibit good biocompatibility, long circulation time, and excellent tumor targeting ability, hence impressive PTT efficiency evidenced by highly efficient tumor ablation in vivo. Importantly, great permeability on organoids contributed by EXO appears with BEs, which strongly promotes the efficient killing ability. These BP-based nanospheres must promise high clinical potential due to the high PTT efficiency and minimal side effects.

All-in-One Nanomedicine: Multifunctional Single-Component Nanoparticles for Cancer Theranostics

The development of cancer diagnostic imaging and treatment is a major concern worldwide. By integrating imaging and therapy into one theranostic nanoplatform for simultaneously detecting tumors, evaluating the targeting ability and timely monitoring therapeutic responses provide more opportunities for precision medicine. Among various theranostic nanosystems, a series of single-component nanoparticles (NPs) have been developed for "all-in-one" theranostics, which presents the unique properties of facile preparation, simple composition, defined structure, high reproducibility, and excellent biocompatibility. Specifically, utilizing single-component NPs for both diagnostics and therapeutics can reduce the possible numerous untoward side effects and risks to the living body. In this review, the recent progress of multifunctional single-component NPs in the applications of cancer theranostics is systematically summarized. Notably, the structure design, categories of NPs, targeted strategies, biomedical applications, potential barriers, challenges, and prospects for the future clinical practice of this rapidly growing field are discussed.

A biodegradable multifunctional nanoplatform based on antimonene nanosheets for synergistic cancer phototherapy and dual imaging

Recently, nanomaterials have been well-studied in cancer therapy, but some of them often experience difficulties with degradation in vivo, which could cause severe damage to the human body. Among numerous biodegradable nanomaterials, antimonene nanosheets (AMNSs) are versatile, and possess photothermal and photodynamic properties and photoacoustic imaging (PAI) and drug loading ability. Herein, we employed a clearable multifunctional system. The small molecule photosensitizer IR820 and the gold nanoparticles (AuNPs) at small sizes of approximately 5 nm were loaded onto AMNSs coated with biodegradable chitosan (CS). This nanoplatform showed excellent photothermal and photodynamic properties, satisfactory degradability and photoacoustic imaging ability, good biocompatibility and effective NIR light triggered intracellular synergistic treatment. It also displayed good fluorescence imaging ability in the experiment of cell uptake. These suggested that this versatile nanoplatform was able to significantly enhance the therapeutic efficiency based on synergistic phototherapy, and could also be applied in fluorescence and photoacoustic dual imaging for integrating diagnosis and treatment.

A Ti2N MXene-based nanosystem with ultrahigh drug loading for dual-strategy synergistic oncotherapy

The exploration of MXenes, especially nitride MXenes, in the field of theranostic nanomedicine is still in its infancy. Here, towards synergistic chemo-photothermal oncotherapy, we demonstrate the first kind of 2D titanium nitride (Ti₂N) MXene-based nanosystem (Ti₂N@oSi) for dual-strategy synergistic oncotherapy. The unique structure of Ti₂N nanosheets endows the drug carriers with an ultrahigh loading capacity of 796.3% and an excellent NIR photothermal conversion efficiency of 41.6% for chemo-photothermal therapy. After being coated with a biodegradable organosilica shell, the Ti₂N@oSi nanocarriers show excellent characteristics of tumor targeting, pH/glutathione/photothermal-responsive drug release and dual-drug combination chemotherapy. Both in vitro and in vivo therapeutic evaluations demonstrate the pronounced tumor growth inhibition effect and superior biocompatibility of Ti₂N@oSi nanocarriers. The excellent drug loading ability, photothermal conversion ability and surface modifiability of Ti₂N open up new opportunities for tumor microenvironment-targeted synergistic oncotherapy. This work is supposed to broaden the application of MXenes in nanomedicine and, particularly, provide the first sight to the biomedical application of nitride MXenes.

A Tumor Microenvironment-Responsive Theranostic Agent for Synergetic Therapy of Disulfiram-Based Chemotherapy and Chemodynamic Therapy

Despite the fact that chemotherapy has been widely used in the clinical treatment of breast cancer, the toxicity of chemotherapeutics to normal tissues cannot be ignored due to the low specificity. Therefore, due to the non-negligible toxicity of chemotherapeutic agents to normal tissues, tumor microenvironment (TME)-responsive cancer therapy has attracted a great deal of attention. Here, we report a TME-responsive theranostic nanoagent MnOx@PAA@HKUST-1-DSF@BSA fabricated via a layer-by-layer synthesis method. Once endocytosed by tumor cells, the nanoagent can be degraded into Mn²⁺ for magnetic resonance imaging and Cu²⁺ for Fenton-like reaction and chelating with released disulfiram in situ, achieving enhanced chemotherapy. Both in vitro and in vivo experiments demonstrate that the TME-targeted nanoagent can efficiently kill tumor cells. This work provides an alternative option for effective imaging and treatment of breast cancer without collateral damage to normal tissues.

NIR-triggered drug delivery system for chemo-photothermal therapy of posterior capsule opacification

Posterior capsule opacification (PCO) is the most common complication after cataract surgery and is likely to cause the second loss of vision. Pharmacological PCO prophylaxis has been proved to be effective, yet no clinical option is available due to the lack of a suitable mode of administration. In this work, we propose a unique concept of NIR dual-triggered drug release from black phosphorus (BP)-based implantable intraocular lens (IOL) for controlled drug release and chemo-photothermal combination therapy of PCO. Here, IOL is used as a "reservoir" of doxorubicin-loaded black phosphorus (BP-DOX), and BP is used as NIR activation agent for controlled drug release and photothermal therapy. This BP-DOX integrated IOL, namely BP-DOX@IOL, shows the characteristics of good transmittance, good mechanical property, NIR dual-triggered drug release behaviors, and excellent photothermal efficacy. In vivo studies reveal that there is no PCO occurrence in rabbits' model by using BP-DOX@IOL combined NIR irradiation, which exhibits distinct superiority on inhibiting PCO than the control group (100% PCO occurrence) 28 days post-surgery. This novel IOL drug delivery system would be a promising strategy for the future clinical application for PCO prophylaxis and treatment.

NIR-activated self-sensitized polymeric micelles for enhanced cancer chemo-photothermal therapy

NIR-activated therapies based on light-responsive drug delivery systems are emerging as a remote-controlled method for cancer precise therapy. In this work, fluorescent dye indocyanine green (ICG)-conjugated and bioactive compound gambogic acid (GA)-loaded polymeric micelles (GA@PEG-TK-ICG PMs) were smoothly fabricated via the self-assembly of the reactive oxygen species (ROS)-responsive thioketal (TK)-linked amphiphilic polymer poly(ethyleneglycol)-thioketal-(indocyanine green) (PEG-TK-ICG). The resultant micelles demonstrated increased resistance to photobleaching, enhanced photothermal conversion efficiency, NIR-controlled drug release behavior, preferable biocompatibility, and excellent tumor accumulation performance. Moreover, upon an 808 nm laser irradiation, the micellar photoactive chromophore ICG converted the absorbed optical energy to both hyperthermia for photothermal therapy (PTT) and ROS as the feedback trigger to the micelles for the tumor-specific release of GA, which could serve as not only a chemotherapeutic drug to directly kill tumor cells but also a heat shock protein 90 (HSP90) inhibitor to realize the photothermal sensitization. As a result, an extremely high tumor inhibition rate (97.9%) of mouse 4 T1 breast cancer models was achieved with negligible side effects after the chemo-photothermal synergistic therapy. This NIR-activated nanosystem with photothermal self-sensitization function may provide a feasible option for the effective treatment of aggressive breast cancers.

Inorganic Nanomaterials with Intrinsic Singlet Oxygen Generation for Photodynamic Therapy

Inorganic nanomaterials with intrinsic singlet oxygen (1 O2 ) generation capacity, are emerged yet dynamically developing materials as nano-photosensitizers (NPSs) for photodynamic therapy (PDT). Compared to previously reported nanomaterials that have been used as either carriers to load organic PSs or energy donors to excite the attached organic PSs through a Foster resonance energy transfer process, these NPSs possess intrinsic 1 O2 generation capacity with extremely high 1 O2 quantum yield (e.g., 1.56, 1.3, 1.26, and 1.09) than any classical organic PS reported to date, and thus are facilitating to make a revolution in PDT. In this review, the recent advances in the development of various inorganic nanomaterials as NPSs, including metal-based (gold, silver, and tungsten), metal oxide-based (titanium dioxide, tungsten oxide, and bismuth oxyhalide), metal sulfide-based (copper and molybdenum sulfide), carbon-based (graphene, fullerene, and graphitic carbon nitride), phosphorus-based, and others (hybrids and MXenes-based NPSs) are summarized, with an emphasis on the design principle and 1 O2 generation mechanism, and the photodynamic therapeutic performance against different types of cancers. Finally, the current challenges and an outlook of future research are also discussed. This review may provide a comprehensive account capable of explaining recent progress as well as future research of this emerging paradigm.

NIR-II Responsive Hydrogel as an Angiogenesis Inhibition Agent for Tumor Microenvironment Reprogramming

Regulation of angiogenesis is a great challenge for effective anticancer therapy. Generally, anti-angiogenic therapies are focused on inhibition of inducers involved in pro-angiogenic communication pathways. Despite the great potential of anti-angiogenic therapy, engineering efficient angiogenesis inhibition agents (AIAs) is still a formidable challenge, since most anti-angiogenic therapies are limited due to the cancer recurrence via compensatory expression of different angiogenic mediators. Herein, we present a new strategy of near-infrared-II (NIR-II) responsive hydrogel AIAs, constructed by incorporation of nitric oxide (NO) precursor (BNN6) and 2D WO_2.9 nanosheets within hydrogel (WB@hydrogel). Because of the defect/2D engineering, the bandgap of the WO_2.9 nanosheets narrows, which extends the absorption to the NIR-II region. It offers a favorable NIR-II controlled manner for NO generation through irradiation time and light intensity. The continuous supply of NO can activate the expression of wild-type p53 protein and further reverse the transcriptional expression of pro- and anti-angiogenic factors of the tumor microenvironment (TME), subsequently alternating pro-angiogenic TME to anti-angiogenic TME. In the murine tumor model, this method achieved high tumor growth inhibition (TGI) rate and excellent anti-recurrence efficiency.

Ca2+-supplying black phosphorus-based scaffolds fabricated with microfluidic technology for osteogenesis

Effective osteogenesis remains a challenge in the treatment of bone defects. The emergence of artificial bone scaffolds provides an attractive solution. In this work, a new biomineralization strategy is proposed to facilitate osteogenesis through sustaining supply of nutrients including phosphorus (P), calcium (Ca), and silicon (Si). We developed black phosphorus (BP)-based, three-dimensional nanocomposite fibrous scaffolds via microfluidic technology to provide a wealth of essential ions for bone defect treatment. The fibrous scaffolds were fabricated from 3D poly (l-lactic acid) (PLLA) nanofibers (3D NFs), BP nanosheets, and hydroxyapatite (HA)-porous SiO2 nanoparticles. The 3D BP@HA NFs possess three advantages: i) stably connected pores allow the easy entrance of bone marrow-derived mesenchymal stem cells (BMSCs) into the interior of the 3D fibrous scaffolds for bone repair and osteogenesis; ii) plentiful nutrients in the NFs strongly improve osteogenic differentiation in the bone repair area; iii) the photothermal effect of fibrous scaffolds promotes the release of elements necessary for bone formation, thus achieving accelerated osteogenesis. Both in vitro and in vivo results demonstrated that the 3D BP@HA NFs, with the assistance of NIR laser, exhibited good performance in promoting bone regeneration. Furthermore, microfluidic technology makes it possible to obtain high-quality 3D BP@HA NFs with low costs, rapid processing, high throughput and mass production, greatly improving the prospects for clinical application. This is also the first BP-based bone scaffold platform that can self-supply Ca2+, which may be the blessedness for older patients with bone defects or patients with damaged bones as a result of calcium loss.

2D Nanosheets-A New Class of Therapeutic Formulations against Cancer

Researchers in cancer nanomedicine are exploring a revolutionary multifaceted carrier for treatment and diagnosis, resulting in the proposal of various drug cargos or "magic bullets" in this past decade. Even though different nano-based complexes are registered for clinical trials, very few products enter the final stages each year because of various issues. This prevents the formulations from entering the market and being accessible to patients. In the search for novel materials, the exploitation of 2D nanosheets, including but not limited to the highly acclaimed graphene, has created extensive interest for biomedical applications. A unique set of properties often characterize 2D materials, including semiconductivity, high surface area, and their chemical nature, which allow simple decoration and functionalization procedures, structures with high stability and targeting properties, vectors for controlled and sustained release of drugs, and materials for thermal-based therapies. This review discusses the challenges and opportunities of recently discovered 2D nanosheets for cancer therapeutics, with special attention paid to the most promising design technologies and their potential for clinical translation in the future.

Nano-photosensitizers for enhanced photodynamic therapy

Photodynamic therapy (PDT) utilizes photosensitizers (PSs) together with irradiation light of specific wavelength interacting with oxygen to generate cytotoxic reactive oxygen species (ROS), which could trigger apoptosis and/or necrosis-induced cell death in target tissues. During the past two decades, multifunctional nano-PSs employing nanotechnology and nanomedicine developed, which present not only photosensitizing properties but additionally accurate drug release abilities, efficient response to optical stimuli and hypoxia resistance. Further, nano-PSs have been developed to enhance PDT efficacy by improving the ROS yield. In addition, nano-PSs with additive or synergistic therapies are significant for both currently preclinical study and future clinical practice, given their capability of considerable higher therapeutic efficacy under safer systemic drug dosage. In this review, nano-PSs that allow precise drug delivery for efficient absorption by target cells are introduced. Nano-PSs boosting sensitivity and conversion efficiency to PDT-activating stimuli are highlighted. Nano-PSs developed to address the challenging hypoxia conditions during PDT of deep-sited tumors are summarized. Specifically, PSs capable of synergistic therapy and the emerging novel types with higher ROS yield that further enhance PDT efficacy are presented. Finally, future demands for ideal nano-PSs, emphasizing clinical translation and application are discussed.

Synthesis and stabilization of black phosphorus and phosphorene: recent progress and perspectives

Two-dimensional black phosphorus (BP) has triggered tremendous research interest owing to its unique crystal structure, high carrier mobility, and tunable direct bandgap. Preparation of few-layer BP with high quality and stability is very important for its related research and applications in biomedicine, electronics, and optoelectronics. In this review, the synthesis methods of BP, including the preparation of bulk BP crystal which is an important raw material for preparing few-layer BP, the popular top-down methods, and some direct growth strategies of few-layer BP are comprehensively overviewed. Then chemical ways to enhance the stability of few-layer BP are concretely introduced. Finally, we propose a selection rule of preparation methods of few-layer BP according to the requirement of specific BP properties for different applications. We hope this review would bring some insight for future researches on BP and contributes to the acceleration of BP's commercial progress.

Dual-responsive ultrathin 1T-phase niobium telluride nanosheet-based delivery systems for enhanced chemo-photothermal therapy

1T-phase niobium telluride (NbTe₂) nanosheets are becoming increasingly important in emerging fields, such as spintronics, sensors and magneto-optoelectronics, due to their excellent physical and chemical properties. However, exploration on their biomedical applications are limited. Herein, ultrathin 1T-phase NbTe₂ single-crystalline nanosheets with excellent photothermal performance, high drug-loading rate, near-infrared (NIR) light/acidic pH-triggered drug release, and low toxicity were developed for potentiated photothermal therapy. Importantly, they showed excellent biocompatibility in vivo and in vitro. NbTe₂ nanosheets loaded with integrated stress response inhibitors (ISRIB) could achieve chemo-photothermal therapy of tumors through the ATF4-ASNS signaling axis. Ultrathin 1T-phase NbTe₂ single-crystalline nanosheets with unique photothermal properties, drug loading rate and safety provide dramatic possibilities in biomedical applications, such as tissue imaging, photothermal therapeutics and pharmaceutics.

Mito-Bomb: Targeting Mitochondria for Cancer Therapy

Cancer has been one of the most common life-threatening diseases for a long time. Traditional cancer therapies such as surgery, chemotherapy (CT), and radiotherapy (RT) have limited effects due to drug resistance, unsatisfactory treatment efficiency, and side effects. In recent years, photodynamic therapy (PDT), photothermal therapy (PTT), and chemodynamic therapy (CDT) have been utilized for cancer treatment owing to their high selectivity, minor resistance, and minimal toxicity. Accumulating evidence has demonstrated that selective delivery of drugs to specific subcellular organelles can significantly enhance the efficiency of cancer therapy. Mitochondria-targeting therapeutic strategies are promising for cancer therapy, which is attributed to the essential role of mitochondria in the regulation of cancer cell apoptosis, metabolism, and more vulnerable to hyperthermia and oxidative damage. Herein, the rational design, functionalization, and applications of diverse mitochondria-targeting units, involving organic phosphine/sulfur salts, quaternary ammonium (QA) salts, peptides, transition-metal complexes, guanidinium or bisguanidinium, as well as mitochondria-targeting cancer therapies including PDT, PTT, CDT, and others are summarized. This review aims to furnish researchers with deep insights and hints in the design and applications of novel mitochondria-targeting agents for cancer therapy.

Rapid bacterial elimination achieved by sonodynamic Au@Cu2O hybrid nanocubes

Although efforts have been devoted to develop new antibacterial agents and techniques, the challenge of bacterial infection remains unresolved and is even increasing. Sonodynamic therapy (SDT) driven by ultrasound (US) has demonstrated effectiveness in terms of penetration and it can help to clinically address the problem of deep tissue bacterial infection. In recent years, a variety of sonosensitizers, which were originally designed for photodynamic therapy, have been adopted for SDT. Yet, their unstable chemical stability and ineffective electron-hole separation are not favorable for clinical applications. Hence, we designed a new type of antibacterial sonosensitizer-namely, Au@Cu₂O hybrid nanocubes-in which an interfacial Schottky junction was built between a p-type semiconductor Cu₂O and a noble metal Au. When US stimulation was applied, the electrons from Cu₂O could be excited at the junction and transferred to Au. Since the formed Schottky barrier could block the backflow of US-excited electrons, a prolonged electron-hole separation can be successfully established. Additionally, because of the boosted sonocatalytic activity, the Au@Cu₂O hybrid nanocubes could produce a large amount of reactive oxygen species (ROS), which are subject to US stimulation. Furthermore, we found that the sonocatalytic activity of the Au@Cu₂O hybrid nanocubes could be reinforced by increasing the amount of Au, enabling 99.67% of Staphylococcus aureus (S. aureus) to be killed by US stimulation for 15 minutes. The cytocompatibility of Au@Cu₂O hybrid nanocubes was improved by a red blood cell membrane (RBC) coating over the surface, and the membrane did not sacrifice its superior antibacterial properties.

Photosynthetic Cyanobacteria-Hybridized Black Phosphorus Nanosheets for Enhanced Tumor Photodynamic Therapy

Photodynamic therapy (PDT) has attracted tremendous attention due to its advantages such as high safety and effectiveness compared to traditional radiotherapy and chemotherapy. However, the intratumoral hypoxic microenvironment will inevitably compromise the PDT effect of the highly oxygen-dependent type II photosensitizers, implicating the urgent demand for continuous intratumoral oxygenation. Herein, biocompatible photosynthetic cyanobacteria have been modified with inorganic two-dimensional black phosphorus nanosheets (BPNSs) to be a novel bioreactor termed as Cyan@BPNSs. Upon 660 nm laser irradiation, the photosynthetic cyanobacteria generate oxygen continuously in situ through photosynthesis, followed by the photosensitization of BPNSs for activating oxygen into singlet oxygen (¹ O₂ ), resulting in a large amount of ¹ O₂ accumulation at the tumor site and the consequent strong tumor cell killing effect both in vitro and in vivo. This work provides an attractive strategy for efficient and biocompatible PDT, meanwhile extends the scope of microbiotic nanomedicine by hybridizing microorganisms with inorganic nanophotosensitizer.

Tuning the Toxicity of Reactive Oxygen Species into Advanced Tumor Therapy

The biological functions and toxic effects of reactive oxygen species (ROS) are generally entangled. A large amount of ROS may cause oxidative damage to cell biomolecules, leading to cell death. Tumor treatment can be carried out by using the toxicity of ROS, and various nanosystems related to ROS have been designed. In fact, the level of active oxygen in the biological microenvironment can be regulated in advanced therapeutics via designed nanoscale engineering, which can open up a new direction of treatment with specific simplicity. In this progress report, the authors first introduced how ROS causes cell death. Then, recent studies on converting the inherent toxicity from ROS into advanced treatment tools are highlighted.

Black Phosphorus/Polymers: Status and Challenges

As a newly emerged mono-elemental nanomaterial, black phosphorus (BP) has been widely investigated for its fascinating physical properties, including layer-dependent tunable band gap (0.3-1.5 eV), high ON/OFF ratio (10⁴ ), high carrier mobility (10³ cm² V^-1 s^-1 ), excellent mechanical resistance, as well as special in-plane anisotropic optical, thermal, and vibrational characteristics. However, the instability caused by chemical degradation of its surface has posed a severe challenge for its further applications. A focused BP/polymer strategy has more recently been developed and implemented to hurdle this issue, so at present BP/polymers have been developed that exhibit enhanced stability, as well as outstanding optical, thermal, mechanical, and electrical properties. This has promoted researchers to further explore the potential applications of black phosphorous. In this review, the preparation processes and the key properties of BP/polymers are reviewed, followed by a detailed account of their diversified applications, including areas like optoelectronics, bio-medicine, and energy storage. Finally, in accordance with the current progress, the prospective challenges and future directions are highlighted and discussed.