Black phosphorus: Versatile two‐dimensional materials in cancer therapies

Bifunctional black phosphorus quantum dots platform: Delivery and remarkable immunotherapy enhancement of STING agonist

Cancer immunotherapy has been developed to improve therapeutic effects for patients by activating the innate immune stimulator of interferon gene (STING) pathway. However, most patients cannot benefit from this therapy, mainly due to the problems of excessively low immune responses and lack of tumor specificity. Herein, we report a solution to these two problems by developing a bifunctional platform of black phosphorus quantum dots (BPQDs) for STING agonists. Specifically, BPQDs could connect targeted functional groups and regulate surface zeta potential by coordinating metal ions to increase loading (over 5 times) while maintaining high universality (7 STING agonists). The controlled release of STING agonists enabled specific interactions with their proteins, activating the STING pathway and stimulating the secretion release of immunosuppressive factors by phosphorylating TBK1 and IFN-IRF3 and secreting high levels of immunostimulatory cytokines, including IL-6, IFN-α, and IFN-β. Moreover, the immunotherapy was enhanced was enhanced mild photothermal therapy (PTT) of BPQDs platform, producing enough T cells to eliminate tumors and prevent tumor recurrence. This work facilitates further research on targeted delivery of small-molecule immune drugs to enhance the development of clinical immunotherapy.

A Distinctive Insight into Inorganic Sonosensitizers: Design Principles and Application Domains

Sonodynamic therapy (SDT) as a promising non-invasive anti-tumor means features the preferable penetration depth, which nevertheless, usually can't work without sonosensitizers. Sonosensitizers produce reactive oxygen species (ROS) in the presence of ultrasound to directly kill tumor cells, and concurrently activate anti-tumor immunity especially after integration with tumor microenvironment (TME)-engineered nanobiotechnologies and combined therapy. Current sonosensitizers are classified into organic and inorganic ones, and current most reviews only cover organic sonosensitizers and highlighted their anti-tumor applications. However, there have few specific reviews that focus on inorganic sonosensitizers including their design principles, microenvironment regulation, etc. In this review, inorganic sonosensitizers are first classified according to their design rationales rather than composition, and the action rationales and underlying chemistry features are highlighted. Afterward, what and how TME is regulated based on the inorganic sonosensitizers-based SDT nanoplatform with an emphasis on the TME targets-engineered nanobiotechnologies are elucidated. Additionally, the combined therapy and their applications in non-cancer diseases are also outlined. Finally, the setbacks and challenges, and proposed the potential solutions and future directions is pointed out. This review provides a comprehensive and detailed horizon on inorganic sonosensitizers, and will arouse more attentions on SDT.

Self-Monitoring Theranostic Nanomaterials: Emerging Visual Agents for Real-Time Monitoring of Tumor Treatment Processes

Self-monitoring in tumor therapy is a concept that allows for real-time monitoring of the location and state of applied nanomaterials. This monitoring relies on dynamic signals, such as wave or magnetic signals, which vary in response to changes in the location and state of nanomaterials. Dynamic changes in nanomaterials can be monitored using dynamic signals, making it possible to determine and control the treatment process. Theranostic nanomaterials, which possess unique physical and chemical properties, have recently been explored as a viable option for self-monitoring. With the help of self-monitoring, theranostic nanomaterials can guide themselves to achieve region-selective treatment with higher controllability and safety. In this review, self-monitoring theranostic nanomaterials will be introduced in three parts according to their roles during therapy: tumor accumulation, tumor therapy, and metabolism. The limitations and future challenges of current self-monitoring theranostic nanomaterials will also be discussed.

ICG-based laser treatments for ophthalmic diseases: Toward their safe and rapid strategy

The eye is a very important organ, and keratitis, corneal neovascularization, floaters, age-related macular degeneration, and other vision problems have seriously affected people's quality of life. Among the ophthalmic treatments, laser photocoagulations have been proposed and have shown therapeutic effects in clinical settings. However, corneal thinning and bleeding lesions induced by laser damage have led to limit its applications. To treat the issues of traditional hyperthermia treatments, photosensitizers [e.g., indocyanine green (ICG)] have been investigated to increase the therapeutic effects of corneal neovascularization and choroidal neovascularization. In the recent study, with the help of ICG, laser-induced nanobubble was proposed to treat vitreous opacities. The developed strategies could enlarge the effect of laser irradiation and reduce the side effects, so as to expand the scope of laser treatments in clinical ophthalmic diseases.

Core-shell inorganic NP@MOF nanostructures for targeted drug delivery and multimodal imaging-guided combination tumor treatment

It is well known that metal-organic framework (MOF) nanostructures have unique characteristics such as high porosity, large surface areas and adjustable functionalities, so they are ideal candidates for developing drug delivery systems (DDSs) as well as theranostic platforms in cancer treatment. Despite the large number of MOF nanostructures that have been discovered, conventional MOF-derived nanosystems only have a single biofunctional MOF source with poor colloidal stability. Accordingly, developing core-shell MOF nanostructures with good colloidal stability is a useful method for generating efficient drug delivery, multimodal imaging and synergistic therapeutic systems. The preparation of core-shell MOF nanostructures has been done with a variety of materials, but inorganic nanoparticles (NPs) are highly effective for drug delivery and imaging-guided tumor treatment. Herein, we aimed to overview the synthesis of core-shell inorganic NP@MOF nanostructures followed by the application of core-shell MOFs derived from magnetic, quantum dots (QDs), gold (Au), and gadolinium (Gd) NPs in drug delivery and imaging-guided tumor treatment. Afterward, we surveyed different factors affecting prolonged drug delivery and cancer therapy, cellular uptake, biocompatibility, biodegradability, and enhanced permeation and retention (EPR) effect of core-shell MOFs. Last but not least, we discussed the challenges and the prospects of the field. We envision this article may hold great promise in providing valuable insights regarding the application of hybrid nanostructures as promising and potential candidates for multimodal imaging-guided combination cancer therapy.

Unexpected giant negative area compressibility in palladium diselenide

Negative area compressibility (NAC) is a counterintuitive 'squeeze-expand' behavior in solids that is very rare but attractive due to possible pressure-response applications and coupling with rich physicochemical properties. Herein, NAC behavior is reported in palladium diselenide with a large magnitude and wide pressure range. We discover that, apart from the rigid flattening of layers that has been generally recognized, the unexpected giant NAC effect in PdSe2 largely comes from anomalous elongation of intralayer chemical bonds. Both structural variations are driven by intralayer-to-interlayer charge transfer with enhanced interlayer interactions under pressure. Our work updates the mechanical understanding of this anomaly and establishes a new guideline to explore novel compression-induced properties.

Chirality-Dependent Tumor Phototherapy Using Amino Acid-Engineered Chiral Phosphorene

Phosphorene, also known as black phosphorus nanosheet (BPNS), has been investigated as a nanoagent for tumor therapy. However, promoting its intracellular accumulation while preventing the cytoplasmic decomposition remains challenging. Herein, for the first time, we propose a chiral BPNS designed through surface engineering based on amino acids with high biocompatibility and an abundant source for application in chirality-dependent tumor phototherapy based on its intracellular metabolism. The advantage of using cysteine (Cys) over other amino acids was that its d, l, or dl-form could efficiently work as the chirality inducer to modify the BPNS through electrostatic interaction and prevent alterations in the intrinsic properties of the BPNS. In particular, d-Cys-BPNS displayed an approximately threefold cytotoxic effect on tumor cells compared with l-Cys-BPNS, demonstrating a chirality-dependent therapy behavior. d-Cys-BPNS not only promoted high intracellular content but also showed resistance to cytoplasmic decomposition. Cys-engineered BPNS also demonstrated chirality-dependent phototherapy effects on tumor-bearing mice, in proximity to the results in vitro. Chiral engineering is expected to open new avenues that could promote the use of BPNS in tumor phototherapy and boost chiral nanomedicine.

Black phosphorous nanomaterials as a new paradigm for postoperative tumor treatment regimens

Surgery is currently a mainstream treatment modality for various solid tumor indications. However, aggressive resection of tumor tissues frequently causes postoperative complications, which severely undermine the well-being of patients. Moreover, the residue tumor cells may substantially increase the risk of local and distant tumor relapse. The recent development in black phosphorus (BP)-based nanomaterials offers a promising opportunity to address these clinical challenges. BP is an emerging nanomaterial with excellent biocompatibility and versatile functionality, which has already demonstrated great potential for a variety of biomedical applications including tumor therapy and tissue engineering. In this review, the recent advances in BP-based nanobiomaterials for the post-surgery treatment of solid tumor have been summarized, while specific emphasis was placed on their capability to continuously inhibit residue tumor growth at the surgery site as well as stimulating various healing mechanisms, aiming to preventing tumor relapse while promoting the healing of surgery-induced traumatic soft/hard tissue injuries. It is anticipated that the nanoengineered BP-based materials may open new avenues to tackle those clinical challenges in surgical treatment of solid tumors.

Charge reversal hairpin peptide modified synergy therapeutic nanoplatforms for tumor specific drug shuttling

Given the distinct pathological features of neoplasm tissues, multifunctional responsive nanocarriers have been recently considered as promising candidates to optimize the chemotherapy regime. As a result, we propose a graphene oxide-based pH-responsive drug delivery system via covalent assembly of "hairpin-like" cell penetrating peptides with acid sensitive and charge reversal properties to realize superior tumor specificity and lower toxicity. Graphene oxide here can serve as high doxorubicin-loading nanosheets and facilitate swift drug release in response to laser irradiation, which provides an efficient platform for the synergy of photo-chemotherapy. Structurally, polyglycol conjugation on the graphene oxide surface fulfils the function of nanocomposite stabilization. After administration, the elaborately acid sensitive cell penetrating peptides maintain the hairpin structure under physiological conditions, while after entering the tumor acidic microenvironment, they undergo charge reversal and structural conversion to promote the cellular uptake of nanoparticles. The evaluation of nanocomposites in vitro revealed their negligible systematic toxicity and remarkable antitumor effects. In vivo experiments also confirmed the impressive stability and tumor-specific targeting for alleviating breast cancer. In conclusion, hairpin peptide modified graphene oxide nanoparticles show multiple merits including high drug carrying capacity, selective tumor penetration, responsive drug release and effective combination oncotherapy.

Dynamic nano-assemblies based on two-dimensional inorganic nanoparticles: Construction and preclinical demonstration

Dynamic drug delivery systems (DDSs) have the ability of transforming their morphology and functionality in response to the biological microenvironments at the disease site and/or external stimuli, show spatio-temporally controllable drug delivery, and enhance the treatment efficacy. Due to the large surface area and modification flexibility, two-dimensional (2D) inorganic nanomaterials are being increasingly exploited for developing intelligent DDSs for biomedical applications. In this review, we summarize the engineering methodologies used to construct transformable 2D DDSs, including changing compositions, creating defects, and surface dot-coating with polymers, biomolecules, or nanodots. Then we present and discuss dynamic inorganic 2D DDSs whose transformation is driven by the diseased characteristics, such as pH gradient, redox, hypoxia, and enzyme in the tumor microenvironment as well as the external stimuli including light, magnetism, and ultrasound. Finally, the limitations and challenges of current transformable inorganic DDSs for clinical translation and their in vivo safety assessment are discussed.

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.