Charge Reversion Simultaneously Enhances Tumor Accumulation and Cell Uptake of Layered Double Hydroxide Nanohybrids for Effective Imaging and Therapy

Ternary NiCoTi-layered double hydroxide nanosheets as a pH-responsive nanoagent for photodynamic/chemodynamic synergistic therapy

Combining photodynamic therapy (PDT) with chemodynamic therapy (CDT) has been proven to be a promising strategy to improve the treatment efficiency of cancer, because of the synergistic therapeutic effect arising between the two modalities. Herein, we report an inorganic nanoagent based on ternary NiCoTi-layered double hydroxide (NiCoTi-LDH) nanosheets to realize highly efficient photodynamic/chemodynamic synergistic therapy. The NiCoTi-LDH nanosheets exhibit oxygen vacancy-promoted electron-hole separation and photogenerated hole-induced O2-independent reactive oxygen species (ROS) generation under acidic circumstances, realizing in situ pH-responsive PDT. Moreover, due to the effective conversion between Co3+ and Co2+ caused by photogenerated electrons, the NiCoTi-LDH nanosheets catalyze the release of hydroxyl radicals (·OH) from H2O2 through Fenton reactions, resulting in CDT. Laser irradiation enhances the catalyzed ability of the NiCoTi-LDH nanosheets to promote the ROS generation, resulting in a better performance than TiO2 nanoparticles at pH 6.5. In vitro and in vivo experimental results show conclusively that NiCoTi-LDH nanosheets plus irradiation lead to efficient cell apoptosis and significant inhibition of tumor growth. This study reports a new pH-responsive inorganic nanoagent with oxygen vacancy-promoted photodynamic/chemodynamic synergistic performance, offering a potentially appealing clinical strategy for selective tumor elimination.

Layered Double Hydroxides: Recent Progress and Promising Perspectives Toward Biomedical Applications

Layered double hydroxides (LDHs) have been widely studied for biomedical applications due to their excellent properties, such as good biocompatibility, degradability, interlayer ion exchangeability, high loading capacity, pH-responsive release, and large specific surface area. Furthermore, the flexibility in the structural composition and ease of surface modification of LDHs makes it possible to develop specifically functionalized LDHs to meet the needs of different applications. In this review, the recent advances of LDHs for biomedical applications, which include LDH-based drug delivery systems, LDHs for cancer diagnosis and therapy, tissue engineering, coatings, functional membranes, and biosensors, are comprehensively discussed. From these various biomedical research fields, it can be seen that there is great potential and possibility for the use of LDHs in biomedical applications. However, at the same time, it must be recognized that the actual clinical translation of LDHs is still very limited. Therefore, the current limitations of related research on LDHs are discussed by combining limited examples of actual clinical translation with requirements for clinical translation of biomaterials. Finally, an outlook on future research related to LDHs is provided.

A near-infrared fluorescent probe for rapid and on-site detection of sulfur dioxide derivative in biological, food and environmental systems

Emission of toxic gaseous sulfur dioxide (SO2) and its derivative bisulfite (HSO3-) from various industrial applications, like food processing, transportation, and the coking process, has raised substantial concerns regarding environmental quality and public health. The probes for specific and sensitive detection of SO2 derivatives plays an essential role in their regulation, and ultimately mitigating their environmental and health implications, but the one that can detect SO2 derivatives onsite by end users remains limited. Herein, we report a new near-infrared fluorescence probe (SL) for rapid and onsite detection of SO2 derivative, HSO3- in industrial wastewater, food samples and for sensing its interaction with biological organisms. The SL is developed through coupling of quinolinium and coumarin moiety through an electron deficit CC bond that can specifically react with HSO3- via a Michael addition. By recording the blue shift of absorption and emission spectra, SL can sensitively detect HSO3- (limit of detection, 38 nM) in aqueous solution within 40 s SL is biocompatible, can be used for evaluating toxicity of SO2 derivatives in living organisms. The preparation of SL-stained test paper allows the colorimetric/fluorometric analysis for quantification of HSO3- onsite in food, river and coking wastewater samples using a smartphone. The successful development of SL not only provides a new tool to investigate HSO3- in biological, food and environmental systems, but also potentially promotes the application of fluorescence technique for rapid and onsite analysis of real-world samples by end users.

Chemical Modification of Cytochrome C for Acid-Responsive Intracellular Apoptotic Protein Delivery for Cancer Eradication

Delivering bioactive proteins into cells without carriers presents significant challenges in biomedical applications due to limited cell membrane permeability and the need for targeted delivery. Here, we introduce a novel carrier-free method that addresses these challenges by chemically modifying proteins with an acid-responsive cell-penetrating peptide (CPP) for selective intracellular delivery within tumours. Cytochrome C, a protein known for inducing apoptosis, served as a model for intracellular delivery of therapeutic proteins for cancer treatment. The CPP was protected with 2,3-dimethyl maleic anhydride (DMA) and chemically conjugated onto the protein surface, creating an acid-responsive protein delivery system. In the acidic tumour microenvironment, DMA deprotects and exposes the positively charged CPP, enabling membrane penetration. Both in vitro and in vivo assays validated the pH-dependent shielding mechanism, demonstrating the modified cytochrome C could induce apoptosis in cancer cells in a pH-selective manner. These findings provide a promising new approach for carrier-free and tumour-targeted intracellular delivery of therapeutic proteins for a wide range of potential applications.

3D Printing Drug-Free Scaffold with Triple-Effect Combination Induced by Copper-Doped Layered Double Hydroxides for the Treatment of Bone Defects

Tissue-engineered poly(l-lactide) (PLLA) scaffolds have been widely used to treat bone defects; however, poor biological activities have always been key challenges for its further application. To address this issue, introducing bioactive drugs or factors is the most commonly used method, but there are often many problems such as high cost, uncontrollable and monotonous drug activity, and poor bioavailability. Here, a drug-free 3D printing PLLA scaffold with a triple-effect combination induced by surface-modified copper-doped layered double hydroxides (Cu-LDHs) is proposed. In the early stage of scaffold implantation, Cu-LDHs exert a photothermal therapy (PTT) effect to generate high temperature to effectively prevent bacterial infection. In the later stage, Cu-LDHs can further have a mild hyperthermia (MHT) effect to stimulate angiogenesis and osteogenic differentiation, demonstrating excellent vascularization and osteogenic activity. More importantly, with the degradation of Cu-LDHs, the released Cu2+ and Mg2+ provide an ion microenvironment effect and further synergize with the MHT effect to stimulate angiogenesis and osteogenic differentiation, thus more effectively promoting the healing of bone tissue. This triple-effect combined scaffold exhibits outstanding antibacterial, osteogenic, and angiogenic activities, as well as the advantages of low cost, convenient procedure, and long-term efficacy, and is expected to provide a promising strategy for clinical repair of bone defects.

Biguanide-anchored albumin-based nanoplatform inhibits epithelial-mesenchymal transition and reduces the stemness phenotype for metastatic cancer therapy

In clinical chemotherapy, albumin-bound paclitaxel (Abraxane) can improve the tumor targeting property and therapeutic efficacy of paclitaxel (PTX) against orthotopic malignancies. However, patients with metastatic cancer have a poor prognosis, probably due to the instability, chemoresistance, and inability of albumin-bound paclitaxel to alter the tumor microenvironment. Here we propose a new biguanide-modified albumin-based nanoplatform that encapsulates paclitaxel for the effective treatment of metastatic cancer. The PTX is encapsulated in poly (lactic-co-glycolic acid) cores coated with biguanide-modified albumin (HSA-NH). The functionalized nanoparticles (HSA-NH NPs) exhibit a remarkable stable profile with low drug release (P < 0.05 versus Abraxane), target tumor tissues, suppress epithelial-mesenchymal transition (EMT) events for anti-metastatic effects, and reduce the phenotype of cancer stem cells. As a result, HSA-NH NPs effectively prolong animal survival (55 days) by inhibiting not only primary tumor growth but also metastasis. This study provides proof of concept that the biguanide-anchored albumin-based nanoplatform encapsulating PTX is a powerful, safe, and clinically translational strategy for the treatment of metastatic cancer. STATEMENT OF SIGNIFICANCE: Albumin-bound paclitaxel (Abraxane) can increase paclitaxel's tumor targeting and therapeutic efficacy in clinical cancer treatments such as breast cancer. However, the instability, chemoresistance, and lack of tumor microenvironment modulation of albumin-bound paclitaxel may lead to poor therapeutic efficacy in metastatic cancer patients. Here we develop biguanide-anchored albumin-based nanoplatforms that encapsulate paclitaxel (HSA-NH NPs) for metastatic cancer treatment. Poly(lactic-co-glycolic acid) (PLGA) cores encapsulating paclitaxel improve the stability of HSA-NH NPs. Based on the activities of metformin, biguanide-anchored albumin adsorbed on PLGA cores improves paclitaxel efficacy, inhibits various aberrant changes during epithelial-mesenchymal transition, and reduces tumor cell stemness. The biguanide-anchored albumin-based nanoplatform encapsulating PTX can serve as a potent, safe, and clinically translational approach for metastatic cancer therapies.

Bioparameter-directed nanoformulations as MRI CAs enable the specific visualization of hypoxic tumour

A malignant tumour has hypoxic cells of varying degrees. The more severe the hypoxic degree, the more difficult the prognosis of the tumour and the higher the recurrence rate. Therefore, tumour hypoxia imaging is crucial. Magnetic resonance imaging (MRI) shows its strength in high resolution, depth of penetration and noninvasiveness. However, it needs more excellent contrast agents (CAs) to combat the complex tumour microenvironment (TME) and increased targeting of tumours to enhance clinical safety. Many research studies have focused on developing hypoxia-responsive MRI CAs that take advantage of the unique characteristics of hypoxic tumours. The low oxygen pressure, acidic TME, and up-regulated redox molecule levels found in hypoxic tumours serve as biological stimuli for nanoformulations that can accurately image the hypoxic region. This review highlights the importance of developing bioparameter-directed nanoformulations as MRI CAs for accurate tumour diagnosis. The design strategies and mechanisms of tumour-hypoxia imaging with nanoformulations are exemplified, with a focus on pH-responsiveness, redox-responsiveness, and p(O2)-responsiveness. The promising future of bioparameter-responsive nanoformulations for accurate tumour diagnosis and personalised cancer treatment is discussed.

Nanoparticles with transformable physicochemical properties for overcoming biological barriers

In recent years, tremendous progress has been made in the development of nanomedicines for advanced therapeutics, yet their unsatisfactory targeting ability hinders the further application of nanomedicines. Nanomaterials undergo a series of processes, from intravenous injection to precise delivery at target sites. Each process faces different or even contradictory requirements for nanoparticles to pass through biological barriers. To overcome biological barriers, researchers have been developing nanomedicines with transformable physicochemical properties in recent years. Physicochemical transformability enables nanomedicines to responsively switch their physicochemical properties, including size, shape, surface charge, etc., thus enabling them to cross a series of biological barriers and achieve maximum delivery efficiency. In this review, we summarize recent developments in nanomedicines with transformable physicochemical properties. First, the biological dilemmas faced by nanomedicines are analyzed. Furthermore, the design and synthesis of nanomaterials with transformable physicochemical properties in terms of size, charge, and shape are summarized. Other switchable physicochemical parameters such as mobility, roughness and mechanical properties, which have been sought after most recently, are also discussed. Finally, the prospects and challenges for nanomedicines with transformable physicochemical properties are highlighted.

Functionalized nanozyme with drug loading for enhanced tumour combination treatment of catalytic therapy and chemotherapy

Nanozyme-based tumour catalytic therapy has attracted widespread attention in recent years, but the therapeutic efficacy is limited due to the trapping of hydroxyl radicals (˙OH) by endogenous glutathione (GSH) in the tumour microenvironment (TME). Zr/Ce-MOFs/DOX/MnO2 is constructed in this work to serve as a new kind of nanozyme for combination chemotherapy and catalytic treatment. Zr/Ce-MOFs can produce ˙OH in a mimic TME, and the MnO2 on the surface could deplete the GSH, further promoting the ˙OH generation. The pH/GSH dual stimulation accelerates the release of anticancer drug doxorubicin (DOX) in tumour tissue for enhanced tumour chemotherapy. Moreover, Mn2+ produced by the reaction of Zr/Ce-MOFs/DOX/MnO2 and GSH can be used as the contrast agent for T1-MRI. The potential antitumour effect of Zr/Ce-MOFs/DOX/MnO2 is demonstrated by in vitro and in vivo cancer treatment tests. This work thus provides a new nanozyme-based platform for enhanced combination chemotherapy and catalytic treatment for tumours.

Multifunctional Layered Double Hydroxides for Drug Delivery and Imaging

Two-dimensional nanomaterials, particularly layered double hydroxides (LDHs), have been widely applied in the biomedical field owing to their biocompatibility, biodegradability, controllable drug release/loading ability, and enhanced cellular permeability. Since the first study analyzing intercalative LDHs in 1999, numerous studies have investigated their biomedical applications, including drug delivery and imaging; recent research has focused on the design and development of multifunctional LDHs. This review summarizes the synthetic strategies and in-vivo and in-vitro therapeutic actions and targeting properties of single-function LDH-based nanohybrids and recently reported (from 2019 to 2023) multifunctional systems developed for drug delivery and/or bio-imaging.

"Trojan horse" nanoparticle-delivered cancer cell membrane vaccines to enhance cancer immunotherapy by overcoming immune-escape

Cancer cell membranes (CCMs) have emerged as advanced cancer treatment vaccines to boost the immune response against cancer and have shown great potential in cancer immunotherapy. However, the CCM vaccine confronts the challenges of a weak and short immune response, ascribed to the immune escape and low accumulation of the CCM in antigen presentation cells (APCs). To overcome these shortcomings, we devised a "Trojan horse" CCM nano-vaccine delivered by layered double hydroxide (LDH) nanoparticles with mannose targeting and bovine serum albumin (BSA) coating to overcome the immune escape challenge, efficiently boosting the immune response to cancer cells. This "Trojan horse" CCM nano-vaccine, named LGCMB, is constructed by assembling the CCM antigen on CpG-LDH (LG), followed by mannose-BSA coating for the APC target and BSA coating to mask immune-escape protein on the CCM. The in vitro cellular uptake and maturation data have clearly shown that the BSA coating strategy with mannose as a "Trojan horse" efficiently targeted APCs (macrophages and DCs) and effectively inhibited the immune escape of the CCM, competently stimulating the APC maturation. Moreover, LGCMB can migrate to the draining lymph nodes (LNs) and trigger tumor-specific CD8⁺ T cell responses in vivo. As expected, the LGCMB nano-vaccine significantly suppressed tumor growth in vivo, showing great potential as a precision cancer vaccine.

A New Sono-Chemo Sensitizer Overcoming Tumor Hypoxia for Augmented Sono/Chemo-Dynamic Therapy and Robust Immune-Activating Response

Novel sonosensitizers with intrinsic characteristics for tumor diagnosis, efficient therapy, and tumor microenvironment regulation are appealing in current sonodynamic therapy. Herein, a manganese (Mn)-layered double hydroxide-based defect-rich nanoplatform is presented as a new type of sono-chemo sensitizer, which allows ultrasound to efficiently trigger reactive oxygen species generation for enhanced sono/chemo-dynamic therapy. Moreover, such a nanoplatform is able to relieve tumor hypoxia and achieve augmented singlet oxygen production via catalyzing endogenous H2 O2 into O2 . On top of these actions, the released Mn2+ ions and immune-modulating agent significantly intensify immune activation and reverse the immunosuppressive tumor microenvironment to the immunocompetent one. Consequently, this nanoplatform exhibits excellent anti-tumor efficacy and effectively suppresses both primary and distant tumor growth, demonstrating a new strategy to functionalize nanoparticles as sono-chemo sensitizers for synergistic combination cancer therapy.

The adjacent effect between Gd(III) and Cu(II) in layered double hydroxide nanoparticles synergistically enhances T1-weighted magnetic resonance imaging contrast

Magnetic resonance imaging (MRI) is one key technology in modern diagnostic medicine. However, the development of high-relaxivity contrast agents with favorable properties for imaging applications remains a challenging task. In this work, dual Gd(III) and Cu(II) doped-layered double hydroxide (GdCu-LDH) nanoparticles show significantly higher longitudinal relaxivity compared with sole-metal-based LDH (Gd-LDH and Cu-LDH) nanoparticles. This relaxation enhancement in GdCu-LDH is also much greater than the simple addition of the relaxivity rate of the two paramagnetic ions in Gd-LDH and Cu-LDH, presumably attributed to synergistic T₁ shortening between adjacent Gd(III) and Cu(II) in the LDH host layers (adjacent effect). Moreover, our GdCu-LDH nanoparticles exhibit a pH-ultrasensitive property in MRI performance and show much clearer MR imaging for tumor tissues in mice than Gd-LDH and Cu-LDH at the equivalent doses. Thus, these novel Gd/Cu-co-doped LDH nanoparticles provide higher potential for accurate cancer diagnosis in clinic application. To the best of our knowledge, this is the first report that two paramagnetic metal ions in one nanoparticle synergistically improve the T₁-MRI contrast.

Surface modification of two-dimensional layered double hydroxide nanoparticles with biopolymers for biomedical applications

Layered double hydroxides (LDHs) are appealing nanomaterials for (bio)medical applications and their potential is threefold. One can gain advantage of the structure of LDH frame (i.e., layered morphology), anion exchanging property towards drugs with acidic character and tendency for facile surface modification with biopolymers. This review focuses on the third aspect, as it is necessary to evaluate the advantages of polymer adsorption on LDH surfaces. Beside the short discussion on fundamental and structural features of LDHs, LDH-biopolymer interactions will be classified in terms of the effect on the colloidal stability of the dispersions. Thereafter, an overview on the biocompatibility and biomedical applications of LDH-biopolymer composite materials will be given. Finally, the advances made in the field will be summarized and future research directions will be suggested.

Biofunctional Layered Double Hydroxide Nanohybrids for Cancer Therapy

Layered double hydroxides (LDHs) with two-dimensional nanostructure are inorganic materials that have attractive advantages such as biocompatibility, facile preparation, and high drug loading capacity for therapeutic bioapplications. Since the intercalation chemistry of DNA molecules into the LDH materials were reported, various LDH nanohybrids have been developed for biomedical drug delivery system. For these reasons, LDHs hybridized with numerous therapeutic agents have a significant role in cancer imaging and therapy with targeting functions. In this review, we summarized the recent advances in the preparation of LDH nanohybrids for cancer therapeutic strategies including gene therapy, chemotherapy, immunotherapy, and combination therapy.

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.

Two-dimensional nanomaterials for tumor microenvironment modulation and anticancer therapy

The development of two-dimensional (2D) nanomaterials for cancer therapy has attracted increasing attention due to their high specific surface area, unique ultrathin structure, electronic and photonic properties. For biomedical applications, investigations into the family of 2D materials have been sparked by graphene and its derivatives. Many 2D nanomaterials, including layered double hydroxides, transition metal dichalcogenides, nitrides and carbonitrides, black phosphorus nanosheets, and metal-organic framework nanosheets, are extensively explored as cancer theranostic platforms. In addition to the high drug loading, 2D nanomaterials are featured with improved physiological properties of drugs, prolonged blood circulation, and increased tumor accumulation and bioavailability. As a consequence, 2D nanomaterials have been widely examined in pre-clinical tumor therapy, particularly through the tumor microenvironment (TME) modulation. This review summarizes recent progresses in developing 2D nanomaterials for TME modulating-based cancer diagnosis and therapy. It is anticipated that this review will benefit researchers to obtain a deeper understanding of interactions between 2D nanomaterials and TME components and develop rational and reliable 2D nanomedicines for pre/clinical cancer theranostics.

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

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

Dual-Loaded Liposomes Tagged with Hyaluronic Acid Have Synergistic Effects in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most lethal subtypes of breast cancer. Although chemotherapy is considered the most effective strategy for TNBC, most chemotherapeutics in current use are cytotoxic, meaning they target antiproliferative activity but do not inhibit tumor cell metastasis. Here, a TNBC-specific targeted liposomal formulation of epalrestat (EPS) and doxorubicin (DOX) with synergistic effects on both tumor cell proliferation and metastasis is described. These liposomes are biocompatible and effectively target tumor cells owing to hyaluronic acid (HA) modification on their surface. This active targeting, mediated by CD44-HA interaction, allows DOX and EPS to be delivered simultaneously to tumor cells in vivo, where they suppress not only TNBC tumor growth and the epithelial-mesenchymal transition, but also cancer stem cells, which collectively suppress tumor growth and metastasis of TNBC and may also act to prevent relapse of TNBC.

Mitochondrial Glutathione Depletion Nanoshuttles for Oxygen-Irrelevant Free Radicals Generation: A Cascaded Hierarchical Targeting and Theranostic Strategy Against Hypoxic Tumor

An oxygen-irrelevant free radicals generation strategy has shown great potential in hypoxic tumor therapy. However, insufficient tumor accumulation, nonspecific intracellular localization, and the presence of highly reductive mitochondrial glutathione (GSH) dramatically hamper the free radicals therapeutic efficacy. Herein, a hierarchical targeting system was constructed by Fe-doped polydiaminopyridine nanoshuttles, indocyanine green (ICG), and an oxygen-irrelevant radicals generator (AIPH) to possess a negative charge. An acid-specific charge-reverse capability of the shuttles was achieved to enhance cell uptake in the tumor microenvironment (TME). In addition, the iron release occurs only in the acidic TME, which can be used as acidity enhancers to strengthen the charge-reverse process, thereby leading to more efficient tumor internalization and deep penetration. Moreover, such a nanosystem has significantly improved the delivery efficiency of nanoshuttles (16.06%) in the tumor tissues at 24 h postinjection, much higher than that of naked Fe-doped polydiaminopyridine (6.59%). More importantly, the nanoshuttles enable simultaneously mitochondria targeting and corresponding GSH depleting capability to show advantages in free radicals-based therapy after charge reversion, leading to a powerful tumor inhibition rate (>95%). The prescence of iron could allow for magnetic resonance imaging, while ICG allowed for photoacoustic imaging and fluorescence imaging to guide the therapeutic process. The remarkable features of the nanoshuttles may open a new avenue to explore an oxygen-irrelevant free radicals generating system for accurate cancer theranostics.

A dual-responsive nanoplatform with feedback amplification improves antitumor efficacy of photodynamic therapy

A good photosensitizer (PS) delivery system could enhance the efficiency and reduce the side effects of anti-tumor photodynamic therapy (PDT) by improving accumulation in the tumor, uptake by tumor cells, and intracellular release of the PS. Thus, we rationally developed a multi-stimulus-responsive PS nanocarrier with a double-layered core-shell structure: mPEG-azo-hyaluronic acid-sulfide-Ce6 (PaHAsC). In PaHAsC, the mPEG coat provides protection before entering the hypoxic tumor microenvironment, where mPEG leaves to expose the HA layer. HA then targets overexpressed CD44 on tumor cells for enhanced internalization. Finally, GSH-mediated intracellular release of Ce6 augments ROS generation and O₂ consumption under light stimulation. This also aggravates hypoxia in tumor sites to accelerate mPEG removal, forming a positive feedback loop. Data show that PaHAsC dramatically improved the PDT efficacy of Ce6, eliminating most tumors and 80% of tumor-bearing mice survived. With a safe profile, PaHAsC has potential for further development and is a useful example of a PS delivery system.

Stimuli-Responsive Nanoparticles for Controlled Drug Delivery in Synergistic Cancer Immunotherapy

Cancer immunotherapy has achieved promising clinical progress over the recent years for its potential to treat metastatic tumors and inhibit their recurrences effectively. However, low patient response rates and dose-limiting toxicity remain as major dilemmas for immunotherapy. Stimuli-responsive nanoparticles (srNPs) combined with immunotherapy offer the possibility to amplify anti-tumor immune responses, where the weak acidity, high concentration of glutathione, overexpressions of enzymes, and reactive oxygen species, and external stimuli in tumors act as triggers for controlled drug release. This review highlights the design of srNPs based on tumor microenvironment and/or external stimuli to combine with different anti-tumor drugs, especially the immunoregulatory agents, which eventually realize synergistic immunotherapy of malignant primary or metastatic tumors and acquire a long-term immune memory to prevent tumor recurrence. The authors hope that this review can provide theoretical guidance for the construction and clinical transformation of smart srNPs for controlled drug delivery in synergistic cancer immunotherapy.

The bright future of nanotechnology in lymphatic system imaging and imaging-guided surgery

Lymphatic system is identified the second vascular system after the blood circulation in mammalian species, however the research on lymphatic system has long been hampered by the lack of comprehensive imaging modality. Nanomaterials have shown the potential to enhance the quality of lymphatic imaging due to the unparalleled advantages such as the specific passive targeting and efficient co-delivery of cocktail to peripheral lymphatic system, ease molecular engineering for precise active targeting and prolonged retention in the lymphatic system of interest. Multimodal lymphatic imaging based on nanotechnology provides a complementary means to understand the kinetics of lymphoid tissues and quantify its function. In this review, we introduce the established approaches of lymphatic imaging used in clinic and summarize their strengths and weaknesses, and list the critical influence factors on lymphatic imaging. Meanwhile, the recent developments in the field of pre-clinical lymphatic imaging are discussed to shed new lights on the design of new imaging agents, the improvement of delivery methods and imaging-guided surgery strategies.

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.

Trifunctional Graphene Quantum Dot@LDH Integrated Nanoprobes for Visualization Therapy of Gastric Cancer

Visualization technology has become a trend in tumor therapy in recent years. The superior optical properties of graphene quantum dots (GQDs) make them suitable candidates for tumor diagnosis, but their tumor targeting and drug-carrying capacities are still not ideal for treatment. Sulfur-doped graphene quantum dots (SGQDs) with stable fluorescence are prepared in a previous study. A reliable strategy by associating layered double hydroxides (LDHs) and etoposide (VP16) is designed for precise visualization therapy. Trifunctional LDH@SGQD-VP16 integrated nanoprobes can simultaneously achieve targeted aggregation, fluorescence visualization, and chemotherapy. LDH@SGQD-VP16 can accumulate in the tumor microenvironment, owing to pH-sensitive properties and long-term photostability in vivo, which can provide a basis for cancer targeting, real-time imaging, and effect tracking. The enhanced therapeutic and attenuated side effects of VP16 are demonstrated, and the apoptosis caused by LDH@SGQD-VP16 is ≈2.7 times higher than that of VP16 alone, in HGC-27 cells. This work provides a theoretical and experimental basis for LDH@SGQD-VP16 as a potential multifunctional agent for visualization therapy of gastric cancer.

Ferrous ions doped layered double hydroxide: smart 2D nanotheranostic platform with imaging-guided synergistic chemo/photothermal therapy for breast cancer

Developing simple and efficient nanotheranostic platforms with behavior responsive to the acid microenvironment of a tumor is of great significance for accurate tumor diagnosis and therapy. In this study, a smart 2D nanotheranostic platform has been successfully fabricated by doping functional ferrous ions into as-synthesized MgAl-layered double hydroxide (LDH) with doxurubicin (DOX) loading to form Fe-LDH/DOX NPs, which achieved magnetic resonance imaging (MRI)-guided synergistic chemo/photothermal therapy for breast cancer. The doping of ferrous ions into Fe-LDH/DOX enabled a strong photo-induced heating ability with a high photothermal conversion efficiency of 45.67%, which could be combined with the antitumor drug DOX to achieve the synergistic effect of photothermal therapy (PTT) and chemotherapy for killing tumor cells. Additionally, its in vitro pH-dependent degradation behavior and T₂-weighted MRI effect revealed that the as-prepared Fe-LDH/DOX is sensitive to the tumor acid microenvironment. Most importantly, the growth rate of tumors in 4T1 bearing mice could be effectively inhibited after the synergistic treatment of PTT and chemotherapy by Fe-LDH/DOX. These results show that doping functional metal ions into LDH NPs may open a novel approach to fabricating an LDH NP-based nanotheranostics platform with advanced diagnostic and therapeutic performances.

Carbon-Defect-Driven Boron Carbide for Dual-Modal NIR-II/Photoacoustic Imaging and Photothermal Therapy

Recently, tremendous attention has been evoked in the discovery of defect-engineered nanomaterials for near-infrared second window (NIR-II)-driven cancer therapy. Herein, we have constructed a novel type of carbon defects enriched in boron carbide nanomaterial (denoted as B₄C@C) through reacting B₄C and glucose by a hydrothermal method. The carbon defect concentration in B₄C@C has been significantly increased after coating with glucose; thus, B₄C@C exhibited a distinct photothermal response under the NIR-II window and the efficiency of photothermal conversion is determined to reach 45.4%, which is higher than the carbon-based nanomaterials in the NIR-II region. Both Raman spectra and X-ray photoelectron spectroscopy (XPS) spectra reveal that B₄C@C has rich sp²-hybridized carbon defects and effectively increases the NIR-II window light absorption capacity, thus enhancing the nonradiative recombination rate and improving the NIR-II photothermal effect. Furthermore, the B₄C@C nanosheets allows for tumor phototherapy and simultaneous photoacoustic imaging. This work indicates the huge potential of B₄C@C as a novel photothermal agent, which might arise much attention in exploring boron-based nanomaterials for the advantage of cancer therapy.

A Review of pH-Responsive Organic-Inorganic Hybrid Nanoparticles for RNAi-Based Therapeutics

RNA interference (RNAi) shows great potential in the treatment of varying cancer and genetic disorders. The lack of safe and effective delivery methods is an ongoing challenge to realize the full potential of RNAi-based therapeutics. pH-responsive hybrid nanoparticle is a promising non-virus platform for small interfering RNA (siRNA) delivery with unique properties including the robust response to the acidic microenvironment and the capability of theranostic and combined therapeutics. The mechanism of RNAi and the delivery barriers for RNAi-based therapeutics are first discussed. Then, the general patterns of pH-response and the typical construction of hybrid nanoparticles are demonstrated. The recent advances in pH-responsive organic-inorganic hybrid nanoparticles for siRNA delivery are highlighted, in particular, how pH-response of ionizable groups, acid-labile bonds, and decomposition of inorganic components affect the physicochemical properties of hybrid nanoparticles and benefit the cellular uptake and intracellular trafficking of siRNA payloads are discussed. At last, the remaining problems and the prospects for pH-responsive hybrid nanoparticles for siRNA delivery are analyzed.

Biomimetic nanotherapy: core-shell structured nanocomplexes based on the neutrophil membrane for targeted therapy of lymphoma

Background

Non-Hodgkin’s lymphoma (NHL) is a malignant disease of lymphoid tissue. At present, chemotherapy is still the main method for the treatment of NHL. R-CHOP can significantly improve the survival rate of patients. Unfortunately, DOX is the main cytotoxic drug in R-CHOP and it can lead to adverse reactions. Therefore, it is particularly important to uncover new treatment options for NHL.

Results

In this study, a novel anti-tumor nanoparticle complex Nm@MSNs-DOX/SM was designed and constructed in this study. Mesoporous silica nanoparticles (MSNs) loaded with Doxorubicin (DOX) and anti-inflammatory drugs Shanzhiside methylester (SM) were used as the core of nanoparticles. Neutrophil membrane (Nm) can be coated with multiple nanonuclei as a shell. DOX combined with SM can enhance the anti-tumor effect, and induce apoptosis of lymphoma cells and inhibit the expression of inflammatory factors related to tumorigenesis depending on the regulation of Bcl-2 family-mediated mitochondrial pathways, such as TNF-α and IL-1β. Consequently, the tumor microenvironment (TME) was reshaped, and the anti-tumor effect of DOX was amplified. Besides, Nm has good biocompatibility and can enhance the EPR effect of Nm@MSNs-DOX/SM and increase the effect of active targeting tumors.

Conclusions

This suggests that the Nm-modified drug delivery system Nm@MSNs-DOX/SM is a promising targeted chemotherapy and anti-inflammatory therapy nanocomplex, and may be employed as a specific and efficient anti-Lymphoma therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-00922-4.

A tumor-activatable peptide supramolecular nanoplatform for the delivery of dual-gene targeted siRNAs for drug-resistant cancer treatment

Combinatorial short interference RNA (siRNA) technology for the silencing of multiple genes is expected to provide an effective therapeutic approach for cancer with complex genetic mutation and dysregulation. Herein we present a tumor-activatable supramolecular nanoplatform for the delivery of siRNAs to target telomerase and telomeres for paclitaxel-resistant non-small-cell lung cancer (A549/PTX) treatment. Two different sequences of siRNA are incorporated in a single nanoparticle, which is obtained by self-assembly from a peptide dendrimer. The siRNA stability is improved by the nanoparticle in the presence of serum compared to free siRNA, and these siRNAs are protected from RNA enzyme degradation. In the tumor extracellular acid environment, the PEG corona of the nanoparticle is removed to promote the internalization of siRNAs into tumor cells. The disulfide linkages between the nanoparticle and siRNAs are cleared in the reductive environment of the tumor cells, and the siRNAs are released in the cytoplasm. In vitro experiments show that the gene expression of hTERT and TRF2 at the mRNA and protein levels of A549/PTX tumor cells is down-regulated, which results in cooperative restraining proliferation and invasion of A549/PTX tumor cells. For the tumor cell-targeting function of the MUC1 aptamer and the EPR effect, sufficient tumor accumulation of nanoparticles was observed. Meanwhile, a shift of negative surface charge of nanoparticles to positive charge in the tumor extracellular microenvironment enhances deep penetration of siRNA-incorporating nanoparticles into tumor tissues. In vivo animal studies support that successful down-regulation of hTERT and TRF2 gene expression achieves effective inhibition of the growth and neovascularization of drug-resistant tumor cells. This work has provided a new avenue for drug-resistant cancer treatment by designing and synthesizing a tumor-activatable nanoplatform to achieve the delivery of dual-gene targeted combinatorial siRNAs.

Heat/pH-boosted release of 5-fluorouracil and albumin-bound paclitaxel from Cu-doped layered double hydroxide nanomedicine for synergistical chemo-photo-therapy of breast cancer

Considerable attention has been devoted to nanomedicine development for breast cancer therapy, while the therapeutic efficiency is far from satisfactory owing to non-specific biodistribution-caused side effects and limitation of single modal treatment. In this study, we have developed a novel nanomedicine for efficient combination breast cancer therapy. This nanomedicine was based on copper-doped layered double hydroxide (Cu-LDH) nanoparticles loaded with two FDA-approved anticancer drugs, i.e. 5-fluorouracil (5-FU) and albumin-bound paclitaxel (nAb-PTX) with complementary chemotherapeutic actions. The 5-FU/Cu-LDH@nAb-PTX nanomedicine showed pH-sensitive heat-facilitated therapeutic on-demand release and demonstrated the moderate-to-strong synergy of photothermal therapy and chemotherapy in inducing apoptosis of breast cancer cells (4 T1). This nanomedicine had a high colloidal stability in saline and serum, and efficiently accumulated in the tumor tissue. Remarkably, this nanomedicine nearly eliminated 4 T1 tumors in vivo after a two-course treatment under mild 808 nm laser irradiation (0.75 W/cm², 3 min) at very low doses of 5-FU and nAb-PTX (0.25 and 0.50 mg/kg, 8-50 times less than that used in other nanoformulations), without observable side effects. Therefore, this research provides a novel approach to designing multifunctional nanomedicines for on-demand release of chemotherapeutics to cost-effectively treat breast cancer with minimal side effects in future clinic applications.

Matrix Metalloproteinase-9-Responsive Surface Charge-Reversible Nanocarrier to Enhance Endocytosis as Efficient Targeted Delivery System for Cancer Diagnosis and Therapy

Nanoparticles, that can be enriched in the tumor microenvironment and deliver the payloads into cancer cells, are desirable carriers for theranostic agents in cancer diagnosis and treatment. However, efficient targeted delivery and enhanced endocytosis for probes and drugs in theranostics are still major challenges. Here, a nanoparticle, which is capable of charge reversal from negative to positive in response to matrix metalloproteinase 9 (MMP9) in tumor microenvironment is reported. This nanoparticle is based on a novel charge reversible amphiphilic molecule consisting of hydrophobic oleic acid, MMP9-cleavable peptide, and glutamate-rich segment (named as OMPE). The OMPE-modified cationic liposome forms an intelligent anionic nanohybrid (O-NP) with enhanced endocytosis through surface charge reversal in response to MMP9 in vitro. Successfully, O-NP nanohybrid performs preferential accumulation and enhances the endocytosis in MMP9-expressing xenografted tumors in mouse models, which improve the sensitivity of diagnosis agents and the antitumor effects of drugs in vivo by overcoming their low solubility and/or nonspecific enrichment. These results indicate that O-NP can be a promising delivery platform for cancer diagnosis and therapy.

Synergistic Cancer Photochemotherapy via Layered Double Hydroxide-Based Trimodal Nanomedicine at Very Low Therapeutic Doses

The success of cancer therapy is always accompanied by severe side effects due to the high amount of toxic antitumor drugs that off-target normal organs/tissues. Herein, we report the development of a trifunctional layered double hydroxide (LDH) nanosystem for combined photochemotherapy of skin cancer at very low therapeutic doses. This nanosystem (ICG/Cu-LDH@BSA-DOX) is composed of acid-responsive bovine serum albumin-doxorubicin prodrug (BSA-DOX) and indocyanine green (ICG)-intercalated Cu-doped LDH nanoparticle. ICG/Cu-LDH@BSA-DOX is able to release DOX in an acid-triggered manner, efficiently and simultaneously generates heating and reactive oxygen species (ROS) upon 808 nm laser irradiation, and synergistically induces apoptosis of skin cancer cells. In vivo therapeutic evaluations demonstrate that ICG/Cu-LDH@BSA-DOX nearly eradicated the tumor tissues upon one-course treatment using very low doses of therapeutic agents (0.175 mg/kg DOX, 0.5 mg/kg Cu, and 0.25 mg/kg ICG) upon very mild 808 nm laser irradiation (0.3 W/cm² for 2 min). This work thus provides a novel strategy to design anticancer nanomedicine for efficient combination cancer treatment with minimal side effects in clinical applications.

Enhancing Tumor Accumulation and Cellular Uptake of Layered Double Hydroxide Nanoparticles by Coating/Detaching pH-Triggered Charge-Convertible Polymers

Layered double hydroxide (LDH) nanoparticles are extensively explored as multifunctional nanocarriers due to their versatility in both the host layer and the interlayer anion. In this study, we report modification of positively charged Cu-containing LDH nanoparticles with a pH-responsive charge-changeable polymer to improve the particle colloidal stability in blood circulation, reduce the nonspecific uptake by normal cells in organs, and subsequently facilitate tumor accumulation and uptake by tumor cells in the acidic tumor microenvironment. In vitro experimental results demonstrate that this promising charge-convertible polymer-LDH nanocarrier well reduces the capture by macrophages in the physiologic medium (pH 7.4) but facilitates the uptake by tumor cells due to detaching of the coated polymer layer in the weakly acidic condition (pH 6.8). Cu-containing LDH nanoparticles also show pH-responsive magnetic resonance imaging (MRI) contrast capacity (i.e., r ₁ relaxivity). In vivo MRI further confirms effective tumor accumulation of the charge-convertible nanohybrids, with ∼4.8% of the injected dose accumulated at 24 h postintravenous injection, proving the potential as a versatile delivery nanocarrier to enhance the antitumor treatment.