Biomineralized synthesis of a smart O2-regenerating nanoreactor for highly efficient starvation/gas therapy

Glucose oxidase and metal catalysts combined tumor synergistic therapy: mechanism, advance and nanodelivery system

Cancer has always posed a significant threat to human health, prompting extensive research into new treatment strategies due to the limitations of traditional therapies. Starvation therapy (ST) has garnered considerable attention by targeting the primary energy source, glucose, utilized by cancer cells for proliferation. Glucose oxidase (GOx), a catalyst facilitating glucose consumption, has emerged as a critical therapeutic agent for ST. However, mono ST alone struggles to completely suppress tumor growth, necessitating the development of synergistic therapy approaches. Metal catalysts possess enzyme-like functions and can serve as carriers, capable of combining with GOx to achieve diverse tumor treatments. However, ensuring enzyme activity preservation in normal tissue and activation specifically within tumors presents a crucial challenge. Nanodelivery systems offer the potential to enhance therapy effectiveness by improving the stability of therapeutic agents and enabling controlled release. This review primarily focuses on recent advances in the mechanism of GOx combined with metal catalysts for synergistic tumor therapy. Furthermore, it discusses various nanoparticles (NPs) constructs designed for synergistic therapy in different carrier categories. Finally, this review provides a summary of GOx-metal catalyst-based NPs (G-M) and offers insights into the challenges associated with G-M therapy, delivery design, and oxygen (O2) supply.

Recent Advances in Functional Nanomaterials for Catalytic Generation of Nitric Oxide: A Mini Review

As a gaseous second messenger, nitric oxide (NO) plays an important role in a series of signal pathways. Research on the NO regulation for various disease treatments has aroused wide concern. However, the lack of accurate, controllable, and persistent release of NO has significantly limited the application of NO therapy. Profiting from the booming development of advanced nanotechnology, a mass of nanomaterials with the properties of controllable release have been developed to seek new and effective NO nano-delivery approaches. Nano-delivery systems that generate NO through catalytic reactions exhibit unique superiority in terms of precise and persistent release of NO. Although certain achievements have been made in the catalytically active NO delivery nanomaterials, some basic but critical issues, such as the concept of design, are of low attention. Herein, an overview of the generation of NO through catalytic reactions and the design principles of related nanomaterials are summarized. Then, the nanomaterials that generate NO through catalytic reactions are classified. Finally, the bottlenecks and perspectives are also discussed in depth for the future development of catalytical NO generation nanomaterials.

A mesoporous MnO2-based nanoplatform with near infrared light-controlled nitric oxide delivery and tumor microenvironment modulation for enhanced antitumor therapy

A hollow mesoporous manganese dioxide-based (H-MnO₂) multifunctional nanoplatform, H-MnO₂ @AFIPB@PDA@Ru-NO@FA (MAPRF NPs), was prepared for synergistic cancer treatment, in which a histone deacetylase inhibitor AFIPB was loaded in its hollow cavity and a ruthenium nitrosyl donor (Ru-NO) and a folic acid (FA) targeting group were covalently decorated on its covered polydopamine (PDA) layer. The MAPRF NPs showed tumor microenvironment (TME)-responsive properties of depletion of glutathione (GSH) to disrupt the antioxidant defense system and on-demand drug delivery. And the released Mn²⁺ further catalyzed the decomposition of endogenous H₂O₂ to produce highly toxic hydroxyl radicals (·OH) for enhanced chemodynamic therapy (CDT). Furthermore, upon 808 nm light irradiation MAPRF NPs exhibited controlled nitric oxide (NO) delivery and simultaneously produced significant photothermal effect. Consequently, MAPRF NPs showed high mortality toward cancer cells in the presence of 808 nm light irradiation. This work provides a paradigm of multimodal synergistic therapy that combines NO-based gas therapy with TME modulation for efficient antitumor therapy.

Mesoporous Materials Make Hydrogels More Powerful in Biomedicine

Scientists have been attempting to improve the properties of mesoporous materials and expand their application since the 1990s, and the combination with hydrogels, macromolecular biological materials, is one of the research focuses currently. Uniform mesoporous structure, high specific surface area, good biocompatibility, and biodegradability make the combined use of mesoporous materials more suitable for the sustained release of loaded drugs than single hydrogels. As a joint result, they can achieve tumor targeting, tumor environment stimulation responsiveness, and multiple therapeutic platforms such as photothermal therapy and photodynamic therapy. Due to the photothermal conversion ability, mesoporous materials can significantly improve the antibacterial ability of hydrogels and offer a novel photocatalytic antibacterial mode. In bone repair systems, mesoporous materials remarkably strengthen the mineralization and mechanical properties of hydrogels, aside from being used as drug carriers to load and release various bioactivators to promote osteogenesis. In hemostasis, mesoporous materials greatly elevate the water absorption rate of hydrogels, enhance the mechanical strength of the blood clot, and dramatically shorten the bleeding time. As for wound healing and tissue regeneration, incorporating mesoporous materials can be promising for enhancing vessel formation and cell proliferation of hydrogels. In this paper, we introduce the classification and preparation methods of mesoporous material-loaded composite hydrogels and highlight the applications of composite hydrogels in drug delivery, tumor therapy, antibacterial treatment, osteogenesis, hemostasis, and wound healing. We also summarize the latest research progress and point out future research directions. After searching, no research reporting these contents was found.

Biodegradable nanomaterials for diagnosis and therapy of tumors

Although degradable nanomaterials have been widely designed and applied for cancer bioimaging and various cancer treatments, few reviews of biodegradable nanomaterials have been reported. Herein, we have summarized the representative research advances of biodegradable nanomaterials with respect to the mechanism of degradation and their application in tumor imaging and therapy. First, four kinds of tumor microenvironment (TME) responsive degradation are presented, including pH, glutathione (GSH), hypoxia and matrix metalloproteinase (MMP) responsive degradation. Second, external stimulation degradation is summarized briefly. Next, we have outlined the applications of nanomaterials in bioimaging. Finally, we have focused on some typical examples of biodegradable nanomaterials in radiotherapy (RT), photothermal therapy (PTT), starvation therapy, photodynamic therapy (PDT), chemotherapy, chemodynamic therapy (CDT), sonodynamic therapy (SDT), gene therapy, immunotherapy and combination therapy.

Fluorescent Self-Reporting Lipid Nanoparticles for Nitric Oxide/Gene Co-Delivery and Combination Therapy

The combination cancer therapy of nitric oxide (NO) with gene therapy is a promising method for tumor treatment. However, efficient co-delivery of gas and therapeutic genes to tumor cells remains a challenge. Herein, we designed a nano-sized ultraviolet (UV) light-responsive cationic lipid vector DPNO(Zn). Fluorescence spectroscopy and confocal imaging experiments revealed that DPNO(Zn) lipid nanoparticles (LNPs) could rapidly release NO under low-power UV light irradiation. Moreover, the fluorescence turn-on might take place along with the release of NO, indicating the self-reporting ability. Gene delivery experiments showed that DPNO(Zn) LNPs had good gene transfection ability, making such materials a good candidate for gas/gene combination therapy. In vitro antitumor assay demonstrated that the co-delivery system was more effective in inhibiting tumor cell proliferation than individual NO or pTrail treatment. Studies on the mechanism of tumor cell apoptosis induced by NO/pTrail co-delivery showed that NO could not only effectively increase the accumulation of p53 protein in tumor cells, thereby promoting the activation of caspase-3, but also induce mitochondrial damage. On the other hand, the Trail protein expressed by pTrail gene could enhance the degree of NO-induced caspase-3 activation, indicating the synergistic effect. These results proved that DPNO(Zn) LNP may serve as a multifunctional nanocarrier for potential tumor therapy.

Protein encapsulation of nanocatalysts: A feasible approach to facilitate catalytic theranostics

Enzyme-mimicking nanocatalysts, also termed nanozymes, have attracted much attention in recent years. They are considered potential alternatives to natural enzymes due to their multiple catalytic activities and high stability. However, concerns regarding the colloidal stability, catalytic specificity, efficiency and biosafety of nanomaterials in biomedical applications still need to be addressed. Proteins are biodegradable macromolecules that exhibit superior biocompatibility and inherent bioactivities; hence, the protein modification of nanocatalysts is expected to improve their bioavailability to match clinical needs. The diversity of amino acid residues in proteins provides abundant functional groups for the conjugation or encapsulation of nanocatalysts. Moreover, protein encapsulation can not only improve the overall performance of nanocatalysts in biological systems, but also bestow materials with new features, such as targeting and retention in pathological sites. This review aims to report the recent developments and perspectives of protein-encapsulated catalysts in their functional improvements, modification methods and applications in biomedicine.

Recent progress in nitric oxide-generating nanomedicine for cancer therapy

Nitric oxide (NO) is an endogenous, multipotent biological signaling molecule that participates in several physiological processes. Recently, exogenous supplementation of tumor tissues with NO has emerged as a potential anticancer therapy. In particular, it induces synergistic effects with other conventional therapies (such as chemo-, radio-, and photodynamic therapies) by regulating the activity of P-glycoprotein, acting as a vascular relaxant to relieve tumor hypoxia, and participating in the metabolism of reactive oxygen species. However, NO is highly reactive, and its half-life is relatively short after generation. Meanwhile, NO-induced anticancer activity is dose-dependent. Therefore, the targeted delivery of NO to the tumor is required for better therapeutic effects. In the past decade, NO-generating nanomedicines (NONs), which enable sustained and specific NO release in tumor tissues, have been developed for enhanced cancer therapy. This review describes the recent efforts and preclinical achievements in the development of NON-based cancer therapies. The chemical structures employed in the fabrication of NONs are summarized, and the strategies involved in NON-based cancer therapies are elaborated.

Fluorescent COFs with a Highly Conjugated Structure for Combined Starvation and Gas Therapy

Covalent organic frameworks (COFs) show great potential in biomedicine, but the synthesis of fluorescent ones with a highly conjugated structure in mild conditions remains a challenge. Herein, we reported a facile method to synthesize a nanosized, highly conjugated, and N-enriched COF material with bright fluorescence and further integrated it as a novel nanoplatform for efficient cancer starvation/gas therapy. High surface area and a porous structure endowed COFs with large loading capacity for both glucose oxidase and l-arginine, while conjugated monomer and N-doping guaranteed bright fluorescence and relatively strong interactions between loaded cargos. Well-designed size allowed easy cell uptake of drug-loaded COFs, which finally resulted in a highly efficient starvation therapy by consuming large amounts of glucose in cancer cells. H₂O₂, the byproduct during glucose consumption, was made full use of oxidizing l-arginine to generate toxic NO. This constructed combined starvation and gas therapy and exhibited emerging antimigration performance. Both in vitro and in vivo experiments confirmed an excellent cancer therapeutic effect than a single therapy, and the novel therapeutic platform showed good biocompatibility. Detailed mechanism study demonstrated that cell apoptosis and lysosomal damage contributed most to the synergistic treatment. Our study developed a new strategy to synthesize highly conjugated COFs with fluorescence and reported the potential applications in cancer therapy.

Glucose Metabolism Intervention-Facilitated Nanomedicine Therapy

Ordinarily, cancer cells possess features of abnormally increased nutrient intake and metabolic pathways. The disorder of glucose metabolism is the most important among them. Therefore, starvation therapy targeting glucose metabolism specifically, which results in metabolic disorders, restricted synthesis, and inhibition of tumor growth, has been developed for cancer therapy. However, issues such as inadequate targeting effectiveness and drug tolerance impede their clinical transformation. In recent years, nanomaterial-assisted starvation treatment has made significant progress in addressing these challenges, whether as a monotherapy or in combination with other medications. Herein, representative researches on the construction of nanosystems conducting starvation therapy are introduced. Elaborate designs and interactions between different treatment mechanisms are meticulously mentioned. Not only are traditional treatments based on glucose oxidase involved, but also newly sprung small molecule agents targeting glucose metabolism. The obstacles and potential for advancing these anticancer therapies were also highlighted in this review.

Thermosensitive hydrogel-functionalized gold nanorod/mesoporous MnO2 nanoparticles for tumor cell-triggered drug delivery

MnO₂ owns distinct redox, imaging, and degradable properties corresponding to the tumor microenvironment. However, the onefold structure and non-modifiable property cause many obstacles to anticancer applications. In this report, we first prepared a typical core-shell gold nanorod (GNR)/manganese dioxide (MnO₂) nanoparticles (GNR/MnO₂ NPs). Interestingly, the MnO₂ had a mesoporous channel and modifiable hydroxyl group (OH). Here, the unique 'OH' groups were modified and further grafted with poly(N-isopropylacrylamide-co-acrylic acid) (PNA). As a dual-sensitive hydrogel, it was selected as the thermal/pH-sensitive component in the hybrid nanoparticles (GNR/MnO₂/PNA NPs). The anticancer drug doxorubicin hydrochloride (DOX) was selected and loaded into the hybrid nanoparticles (GNR/MnO₂/PNA-DOX NPs). The GNR/MnO₂/PNA NPs achieved satisfying drug-loading efficiency and glutathione (GSH)/pH/thermal-responsive drug-controlled release. As a side benefit, the GNR/MnO₂/PNA NPs showed potential as excellent near-infrared (NIR)-excited nanoplatforms for photothermal therapy (PTT). Delightedly, the studies demonstrated that the GNR/MnO₂/PNA-DOX NPs showed a noticeable killing effect on tumor cells, whether it is tumor cell-triggered drug release or photothermal effect. Besides, it not only could enhance mitochondrial damage but also could inhibit the migration and invasion of tumor cells. Quite the reverse, it had little negative impact on normal cells. The feature can prevent anticancer drugs and nanoparticles from killing normal cells. Consequently, GNR/MnO₂/PNA NPs have potential applications in drug delivery and synergistic therapy due to these advantageous features.

A Versatile Calcium Phosphate Nanogenerator for Tumor Microenvironment-activated Cancer Synergistic Therapy

Gas therapy is an emerging "green" cancer treatment strategy; however, its outcome often restricted by the complexity, diversity, and heterogeneity of tumor. Herein, a tumor targeting and tumor microenvironment-activated calcium phosphate nanotheranostic system (denoted as GCAH) is constructed for effective synergistic cancer starvation/gas therapy. GCAH is obtained by a facile biomineralization strategy using glucose oxidase (GOx) as a biotemplate, followed by loading of l-Arginine (L-Arg) and modification of hyaluronic acid (HA) to allow special selectivity for glycoprotien CD44 overexpressed cancer cells. This nanotheranostic system not only exhausts the glucose nutrients in tumor region by the GOx-triggered glucose oxidation, the generated H₂ O₂ can oxidize L-Arg into NO under acidic tumor microenvironment for enhanced gas therapy. As such, there are significant enhancement effects of starvation therapy and gas therapy through the cascade reactions of GOx and L-Arg, which yields a remarkable synergistic therapeutic effect for 4T1 tumor-bearing mice without discernible toxic side effects.

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.

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.

Bio-inspired zwitterionic polymeric chelating assembly for treatment of copper-induced cytotoxicity and hemolysis

We developed a hemocompatible, bio-inspired, multivalent, polymeric-chelating assembly based on the poly(2-methacryloyloxyethyl phosphorylcholine)-b-poly(serinyl acrylate) (PMPC-b-PserA) zwitterionic diblock copolymer. Functional PMPC-b-PserA was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization to catch and encapsulate free copper ions (Cu²⁺) in a solution. PMPC with an identical polar group to phospholipids exhibits high hydrophilicity and fouling resistance against non-specific adsorption, and inertness to the metal ions. On the other hand, PserA with pendant groups of amino acids possesses a strong capability to react with Cu²⁺ by coordination interaction. Therefore, when PMPC-b-PserA was brought into contact with Cu²⁺, a hydrophobic core with multiple coordination "bridges" between polymers and Cu²⁺ was formed, leading to self-assembly of core-shell polymer-metal nanoparticles. As a result, free Cu²⁺ ions can be removed from the solution to prevent damage to cells and tissues. The synthesis and chemical structure of PMPC-b-PserA were characterized, and the formation of self-assembled polymer-Cu²⁺ nanoparticles and colloidal stability were analyzed. More importantly, the detoxification of PMPC-b-PserA in presence of Cu²⁺ with fibroblast cells was demonstrated by increased cell viability >80%. In addition, the hemolysis, which occurred due to disruption of RBC membranes by free Cu²⁺, was effectively suppressed by adding PMPC-b-PserA. The bio-inspired and biocompatible chelating agent of PMPC-b-PserA provides a new treatment approach to encapsulate and detoxify heavy metals in complex media for chelation therapy.