Photo-controlled liquid metal nanoparticle-enzyme for starvation/photothermal therapy of tumor by win-win cooperation

Rigid metal/liquid metal nanoparticles: Synthesis and application for locally ablative therapy

Locally ablative therapy, as the main therapy for advanced tumors, has fallen into a bottleneck in recent years. The breakthrough of metal nanoparticles provides a novel approach for ablative therapy. Previous studies have mostly focused on the combined field of rigid metal nanoparticles and ablation. However, with the maturity of the preparation process of liquid metal nanoparticles, liquid metal nanoparticles not only have metallic properties but also have fluid properties, showing the potential to be combined with ablation. At present, there is no review on the combination of liquid metal nanoparticles and ablation. In this article, we first review the preparation, characterization and application characteristics of rigid metal and liquid metal nanoparticles in ablation applications, and then summarize the advantages, disadvantages and possible future development trends of rigid and liquid metal nanoparticles.

Enhanced Cancer Starvation Therapy Enabled by an Autophagy Inhibitors-Encapsulated Biomimetic ZIF-8 Nanodrug: Disrupting and Harnessing Dual Pro-Survival Autophagic Responses

Autophagy is an important protective mechanism in maintaining or restoring cell homeostasis under physiological and pathological conditions. Nanoparticles (NPs) with certain components and morphologies can induce autophagic responses in cancer cells, providing a new perspective for establishing cancer therapy strategies. Herein, a novel nanodrug system, cell membranes-coated zeolitic imidazolate framework-8 (ZIF-8) NPs encapsulating chloroquine (CQ) and glucose oxidase (GOx) (defined as mCG@ZIF), is designed to achieve an enhanced anticancer effect with the combination of starvation therapy and an autophagy regulation strategy. It is found that ZIF-8 as a nanocarrier can induce autophagy to promote survival of cancer cells via the upstream Zn²⁺-stimulated mitochondrial reactive oxygen species (ROS) so that the anticancer effect is directly achieved by inhibiting this pro-survival autophagy using CQ released from mCG@ZIF under a tumor acidic microenvironment. Moreover, a cancer cell under starvation caused by GOx harnesses autophagy to maintain intracellular ATP levels and resist starvation therapy. The released CQ further inhibits the starvation-induced pro-survival autophagy and cuts off the protective pathway of cancer cells, enhancing the anticancer efficiency of GOx-based starvation therapy. Significantly, the cell membrane coating endows mCG@ZIF with excellent in vivo homotypic targeting ability. Both in vitro and in vivo results have confirmed the enhanced anticancer effect achieved by mCG@ZIF with a negligible side effect.

New anti-tumor strategy based on acid-triggered self-destructive and near-infrared laser light responses of nano-biocatalysts integrating starvation–chemo–photothermal therapies

Background

Inherent limitations of single cancer therapy are overcome by multi-therapy modality, which integrates characteristics of each therapeutic modality and material chemistry. The multi-modal method has the potential for becoming one of the next generation options for cancer treatments. Photothermal therapy (PTT) is an efficient, non-invasive treatment method that can be used on various cancer types. We propose an acid-triggered self-destructing nano-biocatalyst integrated starvation/chemical/photothermal triple therapy that is based on design principles and biomedical applications of GOx cancer treatment methods.

Methods

Scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), and zeta potentials were used to analyze the physical as well as chemical properties of MoS2@DOX/GOx@MnO2 (M@D/G@M). Further, Fourier transform infra-red (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) were used to assess the compositions of the nanocatalysts. The biological effects of M@D/G@M on cells were studied in vitro by inverted fluorescence microscopy, confocal laser scanning microscopy (CLSM), flow cytometry, CCK-8 test, and hemolysis test. Treatment effects of the nanocatalysts were evaluated in MHCC-97H tumor BALB/c mice, whose body weights, tumor local temperature, tumor volumes, and tumor histological changes were evaluated.

Results

There was a high DOX encapsulation efficiency of M@D/G@M (90.233%). The photothermal conversion efficiency (η) of M@D/G@M is 25.2%, and its oxygen production within 5 min reached 27.5 mg L−1. Cell internalization analysis showed that within 4 h, M@D/G@M was almost completely absorbed by HepG2 cells. Further, the highest red fluorescence and apoptosis effects of dead cells (59.07% apoptosis) as well as the lowest tumor volume index of mice (0.2862%) were observed in the M@D/G@M + pH6.0 + NIR treatment group.

Conclusions

Our findings inform the development and applications of multi-modal methods in tumor therapy.

Liposomal Glucose Oxidase for Enhanced Photothermal Therapy and Photodynamic Therapy against Breast Tumors

Organic near-infrared fluorescent dye mediated photothermal therapy (PTT) and photodynamic therapy (PDT) suffer from heat shock response, since, heat shock proteins (HSPs) are overexpressed and can repair the proteins damaged by PTT and PDT. Starvation therapy by glucose oxide (GOx) can inhibit the heat shock response by limiting the energy supply. However, the delivery of sufficient and active GOx remains a challenge. To solve this problem, we utilize liposomes as drug carriers and prepare GOx loaded liposome (GOx@Lipo) with a high drug loading content (12.0%) and high enzymatic activity. The successful delivery of GOx shows excellent inhibition of HSPs and enhances PTT and PDT. Additionally, we apply the same liposome formulation to load near-infrared dye 1,1'-dioctadecyl-3,3,3',3'-tetramethylindotricarbo cyanine iodide (DiR) and prepare DiR contained liposomes (DiR@Lipo) for PTT and PDT. The liposomal formulation substantially enhances the PTT and PDT properties of DiR as well as the cellular uptake and tumor accumulation. Finally, the combination therapy shows excellent tumor inhibition on 4T1 tumor-bearing mice. Interestingly, we also find that the starvation therapy can efficiently inhibit tumor metastasis, which is probably due to the immunogenic effect. Our work presents a biocompatible and effective carrier for the combination of starvation therapy and phototherapy, emphasizing the importance of auxiliary starvation therapy against tumor metastasis and offering important guidance for clinical PTT and PDT.

Responsive Liquid Metal Droplets: From Bulk to Nano

Droplets exist widely in nature and play an extremely important role in a broad variety of industrial processes. Typical droplets, including water and oil droplets, have received extensive attention and research, however their single properties still cannot meet diverse needs. Fortunately, liquid metal droplets emerging in recent years possess outstanding properties, including large surface tension, excellent electrical and thermal conductivity, convenient chemical processing, easy transition between liquid and solid phase state, and large-scale deformability, etc. More interestingly, liquid metal droplets with unique features can respond to external factors, including the electronic field, magnetic field, acoustic field, chemical field, temperature, and light, exhibiting extraordinary intelligent response characteristics. Their development over the past decade has brought substantial breakthroughs and progress. To better promote the advancement of this field, the present article is devoted to systematically summarizing and analyzing the recent fundamental progress of responsive liquid metal droplets, not only involving droplet characteristics and preparation methods, but also focusing on their diverse response behaviors and mechanisms. On this basis, the challenges and prospects related to the following development of liquid metal droplets are also proposed. In the future, responsive liquid metal droplets with a rapid development trend are expected to play a key role in soft robots, biomedicine, smart matter, and a variety of other fields.

Bioenzyme-based nanomedicines for enhanced cancer therapy

Bioenzymes that catalyze reactions within living systems show a great promise for cancer therapy, particularly when they are integrated with nanoparticles to improve their accumulation into tumor sites. Nanomedicines can deliver toxic bioenzymes into cancer cells to directly cause their death for cancer treatment. By modulating the tumor microenvironment, such as pH, glucose concentration, hypoxia, redox levels and heat shock protein expression, bioenzyme-based nanomedicines play crucial roles in improving the therapeutic efficacy of treatments. Moreover, bioenzyme-mediated degradation of the major components in tumor extracellular matrix greatly increases the penetration and retention of nanoparticles in deep tumors and infiltration of immune cells into tumor tissues, thus enhancing the efficacies of chemotherapy, phototherapy and immunotherapy. In this review, we summarize the recent progresses of bioenzyme-based nanomedicines for enhanced cancer therapy. The design and working mechanisms of the bioenzyme-based nanomedicines to achieve enhanced chemotherapy, photothermal therapy, photodynamic therapy, chemodynamic therapy, radiotherapy and immunotherapy are introduced in detail. At the end of this review, a conclusion and current challenges and perspectives in this field are given.

Applications of liquid metals in nanotechnology

Post-transition liquid metals (LMs) offer new opportunities for accessing exciting dynamics for nanomaterials. As entities with free electrons and ions as well as fluidity, LM-based nanomaterials are fundamentally different from their solid counterparts. The low melting points of most post-transition metals (less than 330 °C) allow for the formation of nanodroplets from bulk metal melts under mild mechanical and chemical conditions. At the nanoscale, these liquid state nanodroplets simultaneously offer high electrical and thermal conductivities, tunable reactivities and useful physicochemical properties. They also offer specific alloying and dealloying conditions for the formation of multi-elemental liquid based nanoalloys or the synthesis of engineered solid nanomaterials. To date, while only a few nanosized LM materials have been investigated, extraordinary properties have been observed for such systems. Multi-elemental nanoalloys have shown controllable homogeneous or heterogeneous core and surface compositions with interfacial ordering at the nanoscale. The interactions and synergies of nanosized LMs with polymeric, inorganic and bio-materials have also resulted in new compounds. This review highlights recent progress and future directions for the synthesis and applications of post-transition LMs and their alloys. The review presents the unique properties of these LM nanodroplets for developing functional materials for electronics, sensors, catalysts, energy systems, and nanomedicine and biomedical applications, as well as other functional systems engineered at the nanoscale.

Engineering the Surface of Ti3C2 MXene Nanosheets for High Stability and Multimodal Anticancer Therapy

The surface of Ti₃C₂ MXene nanosheets (TC NSs) was first modified with the antioxidants sodium ascorbate (SA) and dopamine (DA) (DSTC NS) to improve their stability in oxidative and hydration environments and thereby improve their bioapplications. This novel approach not only improved MXene stability by arresting oxidation but also increased the available functional groups for further functionalization with various biomolecules. The DSTC NSs were then sequentially conjugated with enzyme glucose oxidase (GOx) and photosensitizer Ce6 to render the obtained CGDSTC NSs with glucose starvation and photodynamic therapeutic properties and thus attain high efficiency in killing cancer cells through the cooperative effect. The as-synthesized CGDSTC NSs demonstrated tremendous photothermal effect with conversion efficiency of 45.1% and photodynamic (ROS generation) properties upon irradiation with 808 and 671 nm lasers. Furthermore, it was observed that the enzymatic activity of CGDSTC NSs increased upon laser irradiation due to enhanced solution temperature. During in vitro studies, the CGDSTC NSs exhibited cytocompatability to HePG2 and HeLa cells under nonstimulus conditions. However, they elicited more than 90% cell-killing efficiency in the presence of glucose and laser irradiation via the cooperative effect between starvation therapy and phototherapy. These results indicate that CGDSTC NSs could be used as potential therapeutic agents to eradicate cancers with no or few adverse effects. This surface modification approach is also simple and facile to adopt in MXene-based research.

Recent advances in in situ oxygen-generating and oxygen-replenishing strategies for hypoxic-enhanced photodynamic therapy

Cancer is a leading cause of death worldwide, accounting for an estimated 10 million deaths by 2020. Over the decades, various strategies for tumor therapy have been developed and evaluated. Photodynamic therapy (PDT) has attracted increasing attention due to its unique characteristics, including low systemic toxicity and minimally invasive nature. Despite the excellent clinical promise of PDT, hypoxia is still the Achilles' heel associated with its oxygen-dependent nature related to increased tumor proliferation, angiogenesis, and distant metastases. Moreover, PDT-mediated oxygen consumption further exacerbates the hypoxia condition, which will eventually lead to the poor effect of drug treatment and resistance and irreversible tumor metastasis, even limiting its effective application in the treatment of hypoxic tumors. Hypoxia, with increased oxygen consumption, may occur in acute and chronic hypoxia conditions in developing tumors. Tumor cells farther away from the capillaries have much lower oxygen levels than cells in adjacent areas. However, it is difficult to change the tumor's deep hypoxia state through different ways to reduce the tumor tissue's oxygen consumption. Therefore, it will become more difficult to cure malignant tumors completely. In recent years, numerous investigations have focused on improving PDT therapy's efficacy by providing molecular oxygen directly or indirectly to tumor tissues. In this review, different molecular oxygen supplementation methods are summarized to alleviate tumor hypoxia from the innovative perspective of using supplemental oxygen. Besides, the existing problems, future prospects and potential challenges of this strategy are also discussed.

2D antimonene-integrated composite nanomedicine for augmented low-temperature photonic tumor hyperthermia by reversing cell thermoresistance

The overexpression of heat shock proteins (HSPs) in tumor cells can activate inherent defense mechanisms during hyperthermia-based treatments, inducing thermoresistance and thus diminishing the treatment efficacy. Here, we report a distinct "non-inhibitor involvement" strategy to address this issue through engineering a calcium-based nanocatalyst (G/A@CaCO₃-PEG). The constructed nanocatalyst consists of calcium carbonate (CaCO₃)-supported glucose oxidase (GOD) and 2D antimonene quantum dots (AQDs), with further surface modification by lipid bilayers and polyethylene glycol (PEG). The engineered G/A@CaCO₃-PEG nanocatalyst features prolonged blood circulation, which is stable at neutral pH but rapidly degrades under mildly acidic tumor microenvironment, resulting in rapid release of drug cargo in the tumor microenvironment. The integrated GOD effectively catalyzes the depletion of glucose for reducing the supplies of adenosine triphosphate (ATP) and subsequent down-regulation of HSP expression. This effect then augments the therapeutic efficacy of photothermal hyperthermia induced by 2D AQDs upon irradiation with near-infrared light as assisted by reversing the cancer cells' thermoresistance. Consequently, synergistic antineoplastic effects can be achieved via low-temperature photothermal therapy. Systematic in vitro and in vivo evaluations have demonstrated that G/A@CaCO₃-PEG nanocatalysts feature potent antitumor activity with a high tumor-inhibition rate (83.92%). This work thus paves an effective way for augmenting the hyperthermia-based tumor treatments via restriction of the ATP supply.

Hybrid theranostic microbubbles for ultrasound/photoacoustic imaging guided starvation/low-temperature photothermal/hypoxia-activated synergistic cancer therapy

Constructing a theranostic agent for high-contrast multimodality imaging-guided synergistic therapy with long-term tumor retention and minimum systemic side effects still remains a major challenge. Herein, a hybrid microbubble-based theranostic platform was developed for dual-modality ultrasound (US) and enhanced photoacoustic (PA) imaging-guided synergistic tumor therapy by combining starvation therapy, low-temperature photothermal therapy (PTT), and hypoxia-activated therapy, based on polydopamine (PDA) doped poly(vinyl alcohol) microbubbles loaded with glucose oxidase (GOx) (PDA-PVAMBs@GOx) and hypoxia-activated prodrug (HAP) tirapazamine (TPZ). For dual-modality US/enhanced PA imaging, PDA-PVAMBs provided 6.5-fold amplified PA signals relative to freely dispersed PDA nanoparticles (PDA NPs). For synergistic cancer therapy, oxygen (O₂) carried by PDA-PVAMBs@GOx was first released to promote starvation therapy by loaded GOx. Then, moderate near-infrared (NIR) laser irradiation triggered PTT and improved enzymatic activity of GOx with its optimal activity around 47 °C. Subsequently, GOx-mediated tumor starvation depleted O₂ and exacerbated the hypoxia environment, thereby activating the toxicity of TPZ in the tumor site. Through dual-modality US/PA imaging monitoring, PDA-PVAMBs@GOx with long-term retention (∼7 days) combined with PTT and TPZ significantly inhibited the growth of solid tumors with minimum systemic side effects, which might be a powerful tool for effective tumor treatment.

A multifunctional nanoamplifier with self-enhanced acidity and hypoxia relief for combined photothermal/photodynamic/starvation therapy

Phototherapies, including photothermal therapy (PTT) and photodynamic therapy (PDT) have been potential noninvasive therapeutic modality with high efficiency, however, there still exist some intrinsic limitations that impede their clinical applications. Herein, taking the advantages of the synergistic effect and high reactivity of manganese dioxide (MnO₂) nanosheets and glucose oxidase (GOx), multifunctional MPDA@MnO₂-MB-GOx nanoamplifier was constructed for enhanced PTT, PDT, and starvation therapy. In tumor microenvironment (TME), MnO₂ nanosheets on the surface of mesoporous polydopamine (MPDA) could react with endogenous hydrogen peroxide (H₂O₂) and generate oxygen (O₂) to relieve tumor hypoxia, thus enhancing the efficacy of PDT and GOx catalysis. Glucose consumption under the catalysis of GOx will enhance the acidity of TME and increase intracellular H₂O₂ concentration, which in turn promotes the production of O₂ by MnO₂ nanosheets, thus forming efficient cascade reaction and maximizing the efficacy of the functional agents. Furthermore, the heat generated by MPDA under the irradiation of 808 nm laser can accelerate chemical reactions, thus further enhancing synergistic therapeutic efficacy. In vitro/vivo results emphasize that enhanced cancer cell death and tumor inhibition are gained by modulating unfavorable TME with the functional nanosystem, which highlights the promise of the synthesized MPDA@MnO₂-MB-GOx nanomaterial to overcome the limitations of phototherapy.

Multifunctional nanoreactors-integrated microneedles for cascade reaction-enhanced cancer therapy

Starvation therapy based on glucose oxidase (GOx) has attracted considerable attention in tumor treatment. However, several shortcomings severely hinder its further applications, including limited therapeutic efficacy, poor enzyme stability, and potential side effects. Herein, a strategy of cascade reaction-enhanced combined therapy based on the oxygen-evolving multifunctional nanoreactors is proposed for tumor therapy. The GOx and catalase (CAT) are immobilized in metal-organic frameworks by biomimetic mineralization to improve their stability via spatial confinement. The GOx can consume glucose, reduce ATP levels, and down-regulate the expression of heat shock proteins, which consequently sensitize tumor cells to indocyanine green-based photothermal therapy. Furthermore, the hydrogen peroxide generated by GOx as well as overexpressed in tumor can be decomposed by CAT and continuously generate oxygen, which further enhance the efficacy of oxygen-dependent starvation therapy and photodynamic therapy. The nanoreactors are directly delivered to the superficial tumor by microneedles, achieving efficient tumor accumulation and dramatically strengthened antitumor efficacy without obvious side effects, which provides a valuable paradigm for the application of cascade reaction-based combined therapy.

Biomimetic synthesis of a novel O2-regeneration nanosystem for enhanced starvation/chemo-therapy

Glucose oxidase-mediated starvation therapy that effectively cuts off energy supply holds great promise in cancer treatment. However, high glutathione (GSH) contents and anoxic conditions severely reduce therapy efficiency and cannot fully kill cancer cells. Herein, to resolve the above problem, this study constructed a biomimetic nanosystem based on nanreproo-MnO₂with porous craspedia globose-like structure and high specific surface area, and it was further modified with dopamine and folic acid to guarantee good biocompatibility and selectivity toward cancer cells. This nanosystem responsively degraded and reacted with GSH and acid to regenerate O₂, which significantly increased intracellular O₂levels, accelerated glucose consumption, and improved starvation therapy efficiency. Moreover, anticancer drug of camptothecin was further loaded, and notably enhanced cancer growth inhibition was obtained at very low drug concentrations. Most importantly, this novel therapy could unprecedentedly inhibit cancer cell migration to a very low ratio of 19%, and detailed cell apoptosis analyses revealed late stage apoptosis contributed most to the good therapeutic effect. This work reported a new train of thought to improve starvation therapy in biomedicine, and provided a new strategy to design targeted nanocarrier to delivery mixed drugs to overcome the restriction of starvation therapy and develop new therapy patterns.

pH-Sensitive Polymeric Vesicles for GOx/BSO Delivery and Synergetic Starvation-Ferroptosis Therapy of Tumor

Typical glucose oxidase (GOx)-based starvation therapy is a promising strategy for tumor treatment; however, it is still difficult to achieve an effective therapeutic effect via a single starvation therapy. Herein, we designed a pH-sensitive polymeric vesicle (PV) self-assembled by histamine-modified chondroitin sulfate (CS-his) for codelivery of GOx and l-buthionine sulfoximine (BSO). GOx can consume glucose to induce the starvation therapy after the PVs reach cancer cell. Moreover, the product H₂O₂ will be reduced by a high concentration of glutathione (GSH) in the tumor cell, resulting in a reduction of the GSH content. The released BSO finally further reduced the GSH level. As a result, the signaling pathway of the ferroptosis will be activated. The in vivo results demonstrated that GOx/BSO@CS PVs exhibit a good inhibitory effect on the growth of 4T1 tumors in mice. Thus, this work provides a facile strategy to prepare pH-sensitive nanomedicine for synergistic starvation-ferroptosis therapy of tumor.

Self-assembled FeS-based cascade bioreactor with enhanced tumor penetration and synergistic treatments to trigger robust cancer immunotherapy

Major challenges for cancer treatment are how to effectively eliminate primary tumor and sufficiently induce immunogenic cell death (ICD) to provoke a robust immune response for metastasis control. Here, a self-assembled cascade bioreactor was developed to improve cancer treatment with enhanced tumor penetration and synergistic therapy of starvation, chemodynamic (CDT) and photothermal therapy. Ultrasmall FeS-GOx nanodots were synthesized with glucose oxidase (GOx) as template and induced by paclitaxel (PTX) to form self-assembling FeS-GOx@PTX (FGP) via hydrophobic interaction. After accumulated at tumor sites, FGP disassembles to smaller FeS-GOx for enhanced deep tumor penetration. GOx maintains high enzymatic activity to catalyze glucose with assistant of oxygen to generate hydrogen peroxide (H₂O₂) as starvation therapy. Fenton reaction involving the regenerated H₂O₂ in turn produced more hydroxyl radicals for enhanced CDT. Following near-infrared laser at 808 nm, FGPs displayed pronounced tumor inhibition in vitro and in vivo by the combination therapy. The consequent increased exposure to calreticulin amplified ICD and promoted dendritic cells maturation. In combination with anti-CTLA4 checkpoint blockade, FGP can absolutely eliminate primary tumor and avidly inhibit distant tumors due to the enhanced intratumoral infiltration of cytotoxic T lymphocytes. Our work presents a promising strategy for primary tumor and metastasis inhibition.

In situ hydrogen nanogenerator for bimodal imaging guided synergistic photothermal/hydrogen therapies

Multifunctional nanoagents integrating multiple therapeutic and imaging functions hold promise in the field of non-invasive and precise tumor therapies. However, the complex preparation process and uncertain drug metabolism of nanoagents loaded with various therapeutic agents or imaging agents greatly hinder its clinical applications. Developing simple and effective nanoagents that integrate multiple therapeutic and imaging functions remain a huge challenge. Therefore, a novel strategy based on in situ hydrogen release is proposed in this work: aminoborane (AB) was loaded onto mesoporous polydopamine nanoparticles (MPDA NPs) as a prodrug for hydrogen production, and then, PEG was modified on the surface of nanoparticles (represented as AB@MPDA-PEG). MPDA NPs not only act as photothermal agents (PTA) with high photothermal conversion efficiency (808 nm, η = 38.72%) but also as the carriers of AB accumulated in the tumor through enhanced permeability and retention (EPR) effect. H₂ gas generated by AB in the weak acid conditions of the tumor microenvironment (TME) not only was used to treat tumors via a combination of hydrogen and photothermal therapies but also serves as a US and CT contrast agent, providing accurate guidance for tumor treatment. Finally, in vivo and in vitro investigation suggest that the designed multifunctional nanosystem not only showed excellent properties such as high hydrogen-loading capacity, long-lasting sustained hydrogen release ability and excellent biocompatibility but also achieve selective PTT/hydrogen therapies and US/CT bimodal imaging functions, which can effectively guide antitumor therapies. The proposed hydrogen gas-based strategy for combination therapies and bimodal imaging integration holds promise as an efficient and safe tumor treatment for future clinical translation.

Applications of Aptamer-Bound Nanomaterials in Cancer Therapy

Cancer is still a major disease that threatens human life. Although traditional cancer treatment methods are widely used, they still have many disadvantages. Aptamers, owing to their small size, low toxicity, good specificity, and excellent biocompatibility, have been widely applied in biomedical areas. Therefore, the combination of nanomaterials with aptamers offers a new method for cancer treatment. First, we briefly introduce the situation of cancer treatment and aptamers. Then, we discuss the application of aptamers in breast cancer treatment, lung cancer treatment, and other cancer treatment methods. Finally, perspectives on challenges and future applications of aptamers in cancer therapy are discussed.

A general in-situ reduction method to prepare core-shell liquid-metal / metal nanoparticles for photothermally enhanced catalytic cancer therapy

Gallium indium (GaIn) alloy as a kind of liquid metal (LM) with unique chemical and physical properties has attracted increasing attention for its potential biomedical applications. Herein, a series of core-shell GaIn@Metal (Metal: Pt, Au, Ag, and Cu) heterogeneous nanoparticles (NPs) are obtained by a simple in-situ reduction method. Take core-shell GaIn@Pt NPs for example, the synthesized GaIn@Pt NPs after Pt growth on their surface showed significantly improved photothermal conversion efficiency (PCE) and thermal stability under near-infrared (NIR) II light irradiation. Moreover, the core-shell GaIn@Pt NPs also exhibited good Fenton-like catalytic effect due to the presence of Pt on their surface, and could convert tumor endogenous H₂O₂ to generate reactive oxygen species (ROS) for cancer cell killing. With biocompatible polyethylene glycol (PEG) modification, such GaIn@Pt-PEG NPs showed efficient tumor homing after intravenous injection, and could lead to effective NIR II triggered photothermal-chemodynamic synergistic therapy of tumors as evidenced in a mouse tumor model. Our work highlights the ingenious use of the chemical properties of metals, providing a rather simple route for the surface engineering of LM-based multifunctional nanoplatforms to achieve a variety of functionalities.

Dual targeting smart drug delivery system for multimodal synergistic combination cancer therapy with reduced cardiotoxicity

This study first reports the development of a smart drug delivery system (DDS) for multimodal synergistic cancer therapy combining chemo-photothermal-starvation approaches. A magnetic photothermal agent was synthesized by preparing iron oxide (IO) nanoparticles (NPs) with covalently attached indocyanine green (ICG) and glucose oxidase (GOx) (ICGOx@IO). Synthesized ICGOx@IO NPs were co-encapsulated with doxorubicin (Dox) and EGCG ((-)-epigallocatechin-3-gallate) inside PLGA (poly(lactic-co-glycolic acid)) NPs using multiple emulsion solvent evaporation method. Such formulation gave the advantage of triggered drug release by near-infrared (NIR) laser irradiation (808 nm at 1 W/cm²). RGD peptide was attached to the surface of PLGA NPs and the final hydrodynamic size was around 210 nm. Dual targeting by peptide and 240 mT external magnet significantly improved cellular uptake. Cellular uptake was observed using FACS, electron and optical microscopy. Dual targeting along with laser irradiation could reduce in vitro cell viability by 90 ± 2% (Dox-equivalent dose: 10 µg/ml) and complete tumor ablation was achieved in vivo due to synergetic therapeutic effect. Another attractive feature of the DDS was the significant reduction of cardiotoxicity of doxorubicin by EGCG. This new platform is thus expected to hold strong promise for future multimodal combination therapy of cancers. STATEMENT OF SIGNIFICANCE: Doxorubicin is one of the most studied and effective chemotherapeutic agents whose application is hindered due to its cardiotoxicity. In this study, we used (-)-Epigallocatechin-3-gallate (EGCG) to overcome that limitation. However, drug delivery to tumor sites with no/minimum accumulation in healthy organs is always challenging. Although peptide-based targeting is very popular, the effectiveness of receptor/ligand binding active targeting is sometimes questioned which motivated us to apply dual targeting approach. Multimodal therapies can exhibit synergistic effects and subsequently reduce the required dose of drug over monotherapy. We aimed to achieve chemo-photothermal-starvation combination therapy in this study and such achievement is yet to be reported. Our developed system also has the advantage of triggered drug release by near-infrared (NIR) laser irradiation.

Enzyme-Loaded pH-Sensitive Photothermal Hydrogels for Mild-temperature-mediated Combinational Cancer Therapy

Photothermal therapy (PTT) that utilizes hyperthermia to ablate cancer cells is a promising approach for cancer therapy, while the generated high temperature may lead to damage of surrounding normal tissues and inflammation. We herein report the construction of glucose oxidase (GOx)-loaded hydrogels with a pH-sensitive photothermal conversion property for combinational cancer therapy at mild-temperature. The hydrogels (defined as CAG) were formed via coordination of alginate solution containing pH-sensitive charge-transfer nanoparticles (CTNs) as the second near-infrared (NIR-II) photothermal agents and GOx. In the tumor sites, GOx was gradually released from CAG to consume glucose for tumor starvation and aggravate acidity in tumor microenvironment that could turn on the NIR-II photothermal conversion property of CTNs. Meanwhile, the released GOx could suppress the expression of heat shock proteins to enable mild NIR-II PTT under 1,064 nm laser irradiation. As such, CAG mediated a combinational action of mild NIR-II PTT and starvation therapy, not only greatly inhibiting the growth of subcutaneously implanted tumors in a breast cancer murine model, but also completely preventing lung metastasis. This study thus provides an enzyme loaded hydrogel platform with a pH-sensitive photothermal effect for mild-temperature-mediated combinational cancer therapy.

Biomimetic Nanoreactor for Cancer Eradication via Win-Win Cooperation between Starvation/Photo/Chemodynamic Therapies

Combining phototherapy with the cancer cell metabolic pathway altering strategies, that is, glucose starvation, would be a promising approach to accomplish high curative efficiency of cancer treatment. Accordingly, herein, we sought to construct a multifunctional biomimetic hybrid nanoreactor by fastening nanozyme AuNPs (glucose oxidase activity) and PtNPs (catalase and peroxidase activity) and photosensitizer Indocyanine green (ICG) onto the polydopamine (PDA) surface (ICG/Au/Pt@PDA-PEG) to attain superior cancer cell killing efficiency though win-win cooperation between starvation therapy, phototherapy, and chemodynamic therapy. The as-synthesized ICG/Au/Pt@PDA-PEG has shown excellent light-to-heat conversion (photothermal therapy) and reactive oxygen species generation (photodynamic therapy) properties upon laser irradiation and also red-shifted ICG absorption (from 780 to 800 nm) and enhanced its photostability. Further, the ICG/Au/Pt@PDA-PEG NRs have reduced the solution glucose concentration and slightly increased solution oxygen levels and also enhanced 3,3',5,5'-tetramethylbenzidine oxidation in the presence of glucose through a cascade of enzymatic activities. The in vitro results demonstrated that the ICG/Au/Pt@PDA-PEG NRs have superior therapeutic efficacy against cancer cells via the cooperative effect between starvation/photo/chemodynamic therapies and not much toxicity to normal cells.

Conjugated Polymer-Ferrocence Nanoparticle as an NIR-II Light Powered Nanoamplifier to Enhance Chemodynamic Therapy

Chemodynamic therapy (CDT) is a promising therapeutic modality with transition metal ions and endogenous H₂O₂ as reagents, but its efficiency is impaired by low endogenous H₂O₂ levels and nonregeneration of metal ions. Most intracellular H₂O₂ supplement strategies use oxidases and are intensively dependent on oxygen participation. The hypoxia microenvironments of solid tumors weaken their performance. Here, we develop a near-infrared II light powered nanoamplifier to improve the local oxygen level and to enhance CDT. The nanoamplifier CPNP-Fc/Pt consists of ferrocene (Fc)- and cisplatin prodrug (Pt(IV))-modified conjugated polymer nanoparticles (CPNPs). CPNP has a donor-acceptor structure and demonstrates a good photothermal effect under 1064 nm light irradiation, which accelerates blood flow and efficiently elevates the local oxygen content. In response to intracellular glutathione, Pt(II) is released from CPNP-Fc/Pt and triggers enzymatic cascade reactions with nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) and superoxide dismutase to convert oxygen into H₂O₂. The enhanced oxygen level results in efficient intracellular H₂O₂ supply. Fc is reacted with H₂O₂ and converted to Fc⁺ via the Fenton reaction, with the generation of hydroxyl radicals for CDT. Unlike free metal ions, the Fe(III) in Fc⁺ is reduced to Fe(II) by intracellular NAD(P)H, which achieves the regeneration of Fc. The sufficient intracellular H₂O₂ supply and efficient Fc regeneration effectively enhance the Fenton reaction and demonstrate good in vivo CDT results with tumor growth suppression. This design offers a promising strategy to enhance CDT efficiency in the hypoxia microenvironment of solid tumors.

Transformable Spinose Nanodrums with Self-Supplied H2 O2 for Photothermal and Cascade Catalytic Therapy of Tumor

Advances in enzymes involve an efficient biocatalytic process, which has demonstrated great potential in biomedical applications. However, designing a functional carrier for enzymes equipped with satisfactory degradability and loading efficiency, remains a challenge. Here, based on transformable liquid metal (LM), a spinose nanodrum is designed as protein carrier to deliver enzyme for tumor treatment. With the assistance of spines and a special drum-like shape, it is found that the spiny LM can carry much more enzymes than spherical LM under the same condition. Benefiting from the satisfactory enzyme loading efficiency of spiny LM, a plasma amine oxidase immobilized spinose LM nanosystem enveloped with epigallocatechin gallate (EGCG)-Fe³⁺ (LMPE) is fabricated for photothermal and cascade catalytic tumor therapy. Activated by the acidic condition in the tumor microenvironment, the LMPE can oxidize spermine (Spm) and spermidine (Spd) to generate hydrogen peroxide (H₂ O₂ ) for Fenton catalytic reaction to produce the lethal hydroxyl radical (•OH) for tumor cell killing. Combined with remarkable photothermal performance of LM, LMPE exhibits significant inhibition of tumor in vivo.

NIR-II reinforced intracellular cyclic reaction to enhance chemodynamic therapy with abundant H2O2 supply

Chemodynamic therapy (CDT) is an ideal therapeutic modality with endogenous H₂O₂ as stimulus. Most intracellular H₂O₂ supplement strategies for improving CDT efficiency are strongly rely on oxygen participation, and the hypoxia tumor microenvironment impairs their performance. Here we develop a self-assembled metal-organic coordinated nanoparticle Cu-OCNP/Lap with NIR-II reinforced intracellular cyclic reaction to enhance CDT efficiency. Cu-OCNP/Lap is synthesized using Cu²⁺ as nodes and 1,4,5,8-tetrahydroxyanthraquinone (THQ) and banoxantrone dihydrochloride (AQ4N) as ligands, with β-lapachone (β-Lap) loading to conduct intracellular cyclic reaction. Cu-OCNP/Lap has good photothermal effect at NIR-II window, and the corresponding local temperature increase speeds blood flow and supplies sufficient oxygen at tumor site to reinforce β-Lap cyclic reaction with abundant H₂O₂ generation. Cu⁺ is released from Cu-OCNP/Lap in response to glutathione (GSH) and triggers CDT. Sufficient intracellular H₂O₂ supply enhances CDT effect and demonstrates good suppressions for tumor growth. This design offers a promising strategy to enhance CDT efficiency.

Biomimetic nanoreactor for targeted cancer starvation therapy and cascade amplificated chemotherapy

Consuming glucose by glucose oxidase (GOx) has attracted great interest in cancer starvation therapy, but the therapeutic effect is severely limited by the tumor hypoxia environment. Herein, to overcome such limitation, cancer cell membranes disguised biomimetic nanoreactors were elaborately established for synergetic cancer starvation therapy and cascade amplificated hypoxia activated chemotherapy. Via a metallothionein-like self-assembly and infiltration approach, GOx and hypoxia activated prodrug banoxantrone (AQ4N) were efficiently loaded into metal-organic framework ZIF-8 nanocarriers to yield nanoreactor AQ4N/GOx@ZIF-8. Subsequently, the biomimetic nanoreactor (AQ4N/GOx@ZIF-8@CM) was obtained by camouflaging the nanoreactor with cancer cell membrane, which endowed the biomimetic nanoreactor homotypic targeting, immune escape and prolonged blood circulation features. Once targeted accumulating into tumor sites, the acid environment triggered the decomposition of ZIF-8, then encapsulated GOx and AQ4N were released. GOx would rapidly exhaust endogenous glucose and O₂ to shut off the energy supply of tumor cells for starvation treatment. Furthermore, the aggravated tumor intracellular hypoxia environment would activate the cytotoxicity of AQ4N for chemotherapy. In vitro and in vivo results demonstrated that the designed biomimetic nanoreactor exhibited negligible systemic toxicity, besides, the combination of starvation therapy and cascade amplified hypoxia activated chemotherapy significantly inhibited the tumor growth and improved the therapeutic efficacy.

Galvanic replacement reaction for in situ fabrication of litchi-shaped heterogeneous liquid metal-Au nano-composite for radio-photothermal cancer therapy

With tremendous research advances in biomedical application, liquid metals (LM) also offer fantastic chemistry for synthesis of novel nano-composites. Herein, as a pioneering trial, litchi-shaped heterogeneous eutectic gallium indium-Au nanoparticles (EGaIn-Au NPs), served as effective radiosensitizer and photothermal agent for radio-photothermal cancer therapy, have been successfully prepared using in situ interfacial galvanic replacement reaction. The enhanced photothermal conversion efficiency and boosted radio-sensitization effect could be achieved with the reduction of Au nanodots onto the eutectic gallium indium (EGaIn) NPs surface. Most importantly, the growth of tumor could be effectively inhibited under the combined radio-photothermal therapy mediated by EGaIn-Au NPs. Inspired by this approach, in situ interfacial galvanic replacement reaction may open a novel strategy to fabricate LM-based nano-composite with advanced multi-functionalities.

Synergy of hypoxia relief and heat shock protein inhibition for phototherapy enhancement

BACKGROUND

Phototherapy is a promising strategy for cancer therapy by reactive oxygen species (ROS) of photodynamic therapy (PDT) and hyperthermia of photothermal therapy (PTT). However, the therapeutic efficacy was restricted by tumor hypoxia and thermal resistance of increased expression of heat shock protein (Hsp). In this study, we developed albumin nanoparticles to combine hypoxia relief and heat shock protein inhibition to overcome these limitations for phototherapy enhancement.

RESULTS

Near-infrared photosensitizer (IR780) and gambogic acid (GA, Hsp90 inhibitor) were encapsulated into albumin nanoparticles via hydrophobic interaction, which was further deposited MnO2 on the surface to form IGM nanoparticles. Both in vitro and in vivo studies demonstrated that IGM could catalyze overexpress of hydrogen peroxide to relive hypoxic tumor microenvironment. With near infrared irradiation, the ROS generation was significantly increase for PDT enhancement. In addition, the release of GA was promoted by irradiation to bind with Hsp90, which could reduce cell tolerance to heat for PTT enhancement. As a result, IGM could achieve better antitumor efficacy with enhanced PDT and PTT.

CONCLUSION

This study develops a facile approach to co-deliver IR780 and GA with self-assembled albumin nanoparticles, which could relive hypoxia and suppress Hsp for clinical application of cancer phototherapy.

Regulating glucose metabolism using nanomedicines for cancer therapy

The regulation of glucose metabolism is a research focus in cancer treatment. Glucose metabolism is essential for maintaining the growth and proliferation of tumor cells, thus offering us great opportunities for tumor treatment. Recently, much progress has been made in efficient cancer treatment by regulating the pathway of glucose metabolism with nanomedicines due to the rapid development of nanotechnology and promising drug targets. In this review, we first introduced the pathway of cell energy supply from the perspective of aerobic and anaerobic processes. Then, we discussed the recent research progress in regulating glucose metabolism for various tumor resistance strategies including heat resistance, multiple drug resistance, and hypoxia. Finally, we presented the prospects and challenges of developing multifunctional nanoagents for efficient chemotherapy, hyperthermia, dynamic therapy and so on by regulating glucose metabolism.

Dual-light triggered metabolizable nano-micelles for selective tumor-targeted photodynamic/hyperthermia therapy

Phototherapy, including photodynamic and photothermal therapies, is a non-invasive photo-triggered tumor treatment. Combination therapy and new synergistic therapeutic reagents may hold promise for improving these treatments. Herein, we report an amphiphilic iridium-based photosensitizer (C14-IP2000) loaded with a hydrophobic photo-thermal drug (ZnPc) to form nano-micelles (ZNPs) for dual-light triggered tumor phototherapy. The C14-IP2000 was contained within ZNPs consisting of an iridium complex core decorated with hydrophilic polyethylene glycol chains to extend the time in blood circulation, and two hydrophobic carbon chains to enhance the loading capacity and the hydrophobic interaction with the loaded reagent. The designed ZNPs showed effective blood circulation, passive tumor targeting ability, remarkable photodynamic conversion ability, and good photothermal conversion capability, and therefore may be used for combined tumor ablation. Our results demonstrated that the amphipathic bionic structure of ZNPs not only enables self-assembled reagent fabrication with prolonged circulation time and favorable metabolic characteristics for tumor combination therapy, but also provides a nanostructure strategy for the modification of functionalized reagents.

Synthesis and application of core-shell liquid metal particles: a perspective of surface engineering

Liquid metal micro/nano particles (LMPs) from gallium and its alloys have attracted tremendous attention in the last decade due to the unique combination of their metallic and fluidic properties at relatively low temperatures. Unfortunately, there is limited success so far in realizing the highly controllable fabrication and functionalization of this emerging material, posing great obstacles to further promoting its fundamental and applied studies. This review aims to explore solutions for the on-demand design and manipulation of LMPs through physicochemically engineering their surface microenvironment, including compositions, structures, and properties, which are featured by the encapsulation of LMPs inside a variety of synthetic shell architectures. These heterophase, core-shell liquid metal composites display adjustable size and structure-property relationships, rendering improved performances in several attractive scenarios including but not limited to soft electronics, nano/biomedicine, catalysis, and energy storage/conversion. Challenges and opportunities regarding this burgeoning field are also disclosed at the end of this review.

Biomedical Applications of Liquid Metal Nanoparticles: A Critical Review

This review is focused on the basic properties, production, functionalization, cytotoxicity, and biomedical applications of liquid metal nanoparticles (LMNPs), with a focus on particles of the size ranging from tens to hundreds of nanometers. Applications, including cancer therapy, medical imaging, and pathogen treatment are discussed. LMNPs share similar properties to other metals, such as photothermal conversion ability and a propensity to form surface oxides. Compared to many other metals, especially mercury, the cytotoxicity of gallium is low and is considered by many reports to be safe when applied in vivo. Recent advances in exploring different grafting molecules are reported herein, as surface functionalization is essential to enhance photothermal therapeutic effects of LMNPs or to facilitate drug delivery. This review also outlines properties of LMNPs that can be exploited in making medical imaging contrast agents, ion channel regulators, and anti-pathogenic agents. Finally, a foresight is offered, exemplifying underexplored knowledge and highlighting the research challenges faced by LMNP science and technology in expanding into applications potentially yielding clinical advances.

A robust hybrid nanozyme@hydrogel platform as a biomimetic cascade bioreactor for combination antitumor therapy

The development of highly effective and minimally invasive approaches for cancer treatment is the ultimate goal. Herein, an injectable hybrid hydrogel as a biomimetic cascade bioreactor is designed for combination antitumor therapy by providing spatiotemporally-controlled and long-term delivery of therapeutic agents. This hybrid nanozyme@hydrogel (hPB@gellan) is doped with Prussian blue (PB) nanoparticles via the in situ nanoprecipitation method in the polysaccharide gellan matrix. The obtained PB nanoparticles have a small size of 10 nm and play dual roles as a photothermal agent with a photothermal conversion efficiency of 59.6% and as a nanozyme to decompose hydrogen peroxide into oxygen. By incorporating glucose oxidase (GOD) into the hybrid hydrogel, a cascade bioreactor is formed for PB-promoted glucose consumption. Owing to its shear-thinning and self-recovery properties, the hybrid hydrogel is locally administered into tumors, and shows long-term resistance against body clearance and metabolism. The in vivo antitumor results demonstrate that the tumors in the group of combined photothermal and starvation therapy (GOD/hPB@gellan + NIR) are greatly eliminated with a tumor suppression rate of 99.7% 22 days after the treatment. The outstanding antitumor performance is attributed to the main attack by NIR-triggered hyperthermia and the holding attack by GOD-mediated starvation from the catalytic bioreactor of the hybrid hydrogel. Taking into consideration the advantages of biosafety, simple synthetic approaches and facile manipulation in treatment, the hybrid hydrogel has great potential for clinical translation.

Gallium-Based Liquid Metal Particles for Therapeutics

Gallium (Ga) and Ga-based liquid metal (LM) alloys offer low toxicity, excellent electrical and thermal conductivities, and fluidity at or near room temperature. Ga-based LM particles (LMPs) synthesized from these LMs exhibit both fluidic and metallic properties and are suitable for versatile functionalization in therapeutics. Functionalized Ga-based LMPs can be actuated using physical or chemical stimuli for drug delivery, cancer treatment, bioimaging, and biosensing. However, many of the fundamentals of their unique characteristics for therapeutics remain underexplored. We present the most recent advances in Ga-based LMPs in therapeutics based on the underlying mechanisms of their design and implementation. We also highlight some future biotechnological opportunities for Ga-based LMPs based on their extraordinary advantages.

Engineering of a Core-Shell Nanoplatform to Overcome Multidrug Resistance via ATP Deprivation

Inhibiting the function of P-glycoprotein (P-gp) transporter, which causes drug efflux through adenosine triphosphate (ATP)-dependent manner, has become an effective strategy to conquer multidrug resistance (MDR) of cancer cells. However, there remains challenges for effective co-delivery, sequential release of P-gp modulator and chemotherapeutic agent. In this work, a novel type of core-shell nanoparticle is reported. It can independently encapsulate a high amount (about 683 µg mg^-1 ) of chemotherapeutic agent doxorubicin (DOX) in the mesoporous polydopamine (MPDA) core and glucose oxidase (GOx) in the zeolite imidazolate frameworks-8 (ZIF-8) shell, namely MPDA@ZIF-8/DOX+GOx. The fast release of GOx triggered by acid-sensitive degradation of the ZIF-8 shell consumes glucose to starve cancer cells for ATP deprivation and effective suppress ATP-dependent drug efflux in advance, and then effectively facilitates the accumulation of DOX in MCF-7/ADR cancer cells. Experiments in vitro and in vivo demonstrate that the fabricated nanosystem can dramatically improve anticancer effects for MDR through sequential release property and exhibit excellent biocompatibility. Overall, this work reveals new insights in the use of GOx for MDR treatment.

Bortezomib-Encapsulated CuS/Carbon Dot Nanocomposites for Enhanced Photothermal Therapy via Stabilization of Polyubiquitinated Substrates in the Proteasomal Degradation Pathway

Photothermal therapy (PTT) is an emerging therapeutic strategy in the treatment of cancer; however, a critical challenge remains in the rational design of synergistic nanoparticles as a potential photothermal transduction agent that can effectively enhance the therapeutic outcome of PTT for tumor ablation. Herein, we rationally designed, developed, and characterized hollow-structured CuS nanoparticles composited with carbon dots (CuSCDs), which demonstrated excellent photothermal conversion efficiency under a 808 nm laser irradiation with enhanced biocompatibility and reduced toxicity. Following coating with a macrophage membrane hybridized with T7 peptide on the surface of the proteasome inhibitor loaded CuSCD, CuSCDB@MMT7 exhibited targeted specificity to cancer cells with the characteristics of immunity escaping and enhanced transferrin receptor-mediated endocytosis. Predominantly, CuSCDB@MMT7-triggered PTT exhibited the accumulation of the polyubiquitinated tumor suppressor protein that is heat stabilized under NIR induced hyperthermia, facilitating augmented tumor cell apoptosis and the attenuated metastasis. This study provides a proof-of-concept for the proteasome inhibitor-loaded CuS/carbon dot nanocomposite-PTT strategy and highlights a promising therapeutic strategy for realizing enhanced therapeutic outcomes for effective clinical cancer therapy.

A Glucose/Oxygen-Exhausting Nanoreactor for Starvation- and Hypoxia-Activated Sustainable and Cascade Chemo-Chemodynamic Therapy

Fenton reaction-mediated chemodynamic therapy (CDT) can kill cancer cells via the conversion of H₂ O₂ to highly toxic HO•. However, problems such as insufficient H₂ O₂ levels in the tumor tissue and low Fenton reaction efficiency severely limit the performance of CDT. Here, the prodrug tirapazamine (TPZ)-loaded human serum albumin (HSA)-glucose oxidase (GOx) mixture is prepared and modified with a metal-polyphenol network composed of ferric ions (Fe³⁺ ) and tannic acid (TA), to obtain a self-amplified nanoreactor termed HSA-GOx-TPZ-Fe³⁺ -TA (HGTFT) for sustainable and cascade cancer therapy with exogenous H₂ O₂ production and TA-accelerated Fe³⁺ /Fe²⁺ conversion. The HGTFT nanoreactor can efficiently convert oxygen into HO• for CDT, consume glucose for starvation therapy, and provide a hypoxic environment for TPZ radical-mediated chemotherapy. Besides, it is revealed that the nanoreactor can significantly elevate the intracellular reactive oxygen species content and hypoxia level, decrease the intracellular glutathione content, and release metal ions in the tumors for metal ion interference therapy (also termed "ion-interference therapy" or "metal ion therapy"). Further, the nanoreactor can also increase the tumor's hypoxia level and efficiently inhibit tumor growth. It is believed that this tumor microenvironment-regulable nanoreactor with sustainable and cascade anticancer performance and excellent biosafety represents an advance in nanomedicine.

Tumor Metabolism‐Engineered Composite Nanoplatforms Potentiate Sonodynamic Therapy via Reshaping Tumor Microenvironment and Facilitating Electron–Hole Pairs’ Separation

Reactive oxygen species (ROS) depletion and low ROS production that result from the intratumoral redox metabolism equilibrium and low energy conversion efficiency from ultrasound mechanical energy to ROS‐represented chemical energy, respectively, are two vital inhibitory factors of sonodynamic therapy (SDT). To address the two concerns, a tumor metabolism‐engineered composite nanoplatform capable of intervening intratumoral ROS metabolism, breaking the redox equilibrium, and reshaping the tumor microenvironment is constructed to reinforce SDT against tumors. In this metabolism‐engineered nanoplatform, Nb2C nanosheets serve as the scaffold to accommodate TiO2 sonosensitizers and l‐buthionine‐sulfoximine. Systematic experiments show that such nanoplatforms can reduce ROS depletion via suppressing glutathione synthesis and simultaneously improving ROS production via the Nb2C‐enhanced production and separation of electron–hole pairs. Contributed by the combined effect, net ROS content can be significantly elevated, which results in the highly efficient anti‐tumor outcomes in vivo and in vitro. Moreover, the combined design principles, that is, tumor metabolism modulation for reducing ROS depletion and electron–hole pair separation for facilitating ROS production, can be extended to other ROS‐dependent therapeutic systems.

Complementary autophagy inhibition and glucose metabolism with rattle-structured polydopamine@mesoporous silica nanoparticles for augmented low-temperature photothermal therapy and in vivo photoacoustic imaging

Rattle-structured nanoparticles with movable cores, porous shells and hollow interiors have shown great effectiveness in drug delivery and cancer theranostics. Targeting autophagy and glucose have provided alternative strategies for cancer intervention therapy. Herein, rattle-structured polydopamine@mesoporous silica nanoparticles were prepared for in vivo photoacoustic (PA) imaging and augmented low-temperature photothermal therapy (PTT) via complementary autophagy inhibition and glucose metabolism.

Methods: The multifunctional rattle-structured nanoparticles were designed with the nanocore of PDA and the nanoshell of hollow mesoporous silica (PDA@hm) via a four-step process. PDA@hm was then loaded with autophagy inhibitor chloroquine (CQ) and conjugated with glucose consumer glucose oxidase (GOx) (PDA@hm@CQ@GOx), forming a corona-like structure nanoparticle.

Results: The CQ and GOx were loaded into the cavity and decorated onto the surface of PDA@hm, respectively. The GOx-mediated tumor starvation strategy would directly suppress the expression of HSP70 and HSP90, resulting in an enhanced low-temperature PTT induced by PDA nanocore. In addition, autophagy inhibition by the released CQ made up for the loss of low-temperature PTT and starvation efficiencies by PTT- and starvation-activated autophagy, realizing augmented therapy efficacy. Furthermore, the PDA nanocore in the PDA@hm@CQ@GOx could be also used for PA imaging.

Conclusion: Such a “drugs” loaded rattle-structured nanoparticle could be used for augmented low-temperature PTT through complementarily regulating glucose metabolism and inhibiting autophagy and in vivo photoacoustic imaging.

Width-Consistent Mesoporous Silica Nanorods with a Precisely Controlled Aspect Ratio for Lysosome Dysfunctional Synergistic Chemotherapy/Photothermal Therapy/Starvation Therapy/Oxidative Therapy

Although differently shaped mesoporous silica is widely studied, the formation of width-consistent mesoporous silica nanorods (MSNRs) with a precisely controlled aspect ratio (AR: length/width) is challenging and has not been reported. Herein, width-consistent (100 nm) MSNRs with ARs of 2, 3, 4, 6, 8, and 10 were obtained by increasing the concentrations while maintaining the molar ratio of cetyltrimethylammonium bromide (CTAB) and tetraethyl orthosilicate (TEOS). The results demonstrated that the as-prepared MSNR with an AR of 6 (AR6) possesses high cellular-uptake efficiency and drug-loading capacity. Thus, AR6-based cancer-cell-targeting nanosystems were designed. These nanosystems encapsulated doxorubicin (DOX) into the porous channel of AR6, adsorbed glucose oxidase (GOx), and then formed a polydopamine (PDA) layer for Siramesine (Siram, a lysosome dysfunctional drug) adsorption and folic acid modification. In this design, the PDA shell could prevent the leakage of loading components and keep the activity of GOx during delivery while achieving an on-demand drug release in the targeted location and photothermal therapy under near-infrared irradiation. The increase in temperature was highly beneficial for elevating the catalytic efficiency of GOx, accelerating the consumption of intracellular glucose, and generating a relatively high level of cytotoxic H₂O₂, all of which enhanced starvation and oxidative therapies. Siram was employed to inhibit lysosomal metabolism and accompany GOx to reach a dual-enhanced starvation therapy effect. In addition, DOX entered the nucleus and altered DNA for chemotherapy. The results showed that the nanosystems have superior therapeutic efficacy against cancer cells and not much toxicity to normal cells. Therefore, this study provides a novel strategy for lysosome dysfunctional synergistic chemotherapy/photothermal therapy/starvation therapy/oxidative therapy based on MSNR.

Attributes, Fabrication, and Applications of Gallium-Based Liquid Metal Particles

This work discusses the attributes, fabrication methods, and applications of gallium-based liquid metal particles. Gallium-based liquid metals combine metallic and fluidic properties at room temperature. Unlike mercury, which is toxic and has a finite vapor pressure, gallium possesses low toxicity and effectively zero vapor pressure at room temperature, which makes it amenable to many applications. A variety of fabrication methods produce liquid metal particles with variable sizes, ranging from nm to mm (which is the upper limit set by the capillary length). The liquid nature of gallium enables fabrication methods-such as microfluidics and sonication-that are not possible with solid materials. Gallium-based liquid metal particles possess several notable attributes, including a metal-metal oxide (liquid-solid) core-shell structure as well as the ability to self-heal, merge, and change shape. They also have unusual phase behavior that depends on the size of the particles. The particles have no known commercial applications, but they show promise for drug delivery, soft electronics, microfluidics, catalysis, batteries, energy harvesting, and composites. Existing challenges and future opportunities are discussed herein.

Protein-Based Artificial Nanosystems in Cancer Therapy

Proteins, like actors, play different roles in specific applications. In the past decade, significant achievements have been made in protein-engineered biomedicine for cancer therapy. Certain proteins such as human serum albumin, working as carriers for drug/photosensitizer delivery, have entered clinical use due to their long half-life, biocompatibility, biodegradability, and inherent nonimmunogenicity. Proteins with catalytic abilities are promising as adjuvant agents for other therapeutic modalities or as anticancer drugs themselves. These catalytic proteins are usually defined as enzymes with high biological activity and substrate specificity. However, clinical applications of these kinds of proteins remain rare due to protease-induced denaturation and weak cellular permeability. Based on the characteristics of different proteins, tailor-made protein-based nanosystems could make up for their individual deficiencies. Therefore, elaborately designed protein-based nanosystems, where proteins serve as drug carriers, adjuvant agents, or therapeutic drugs to make full use of their intrinsic advantages in cancer therapy, are reviewed. Up-to-date progress on research in the field of protein-based nanomedicine is provided.