Fenton-like reaction, glutathione reduction, and photothermal ablation-built-in hydrogels crosslinked by cupric sulfate for loco-regional cancer therapy

Smart hydrogel: A new platform for cancer therapy

Cancer is a significant contributor to mortality worldwide, posing a significant threat to human life and health. The unique bioactivity, ability to precisely control drug release, and minimally invasive properties of hydrogels are indispensable attributes that facilitate optimal performance in cancer therapy. However, conventional hydrogels lack the ability to dynamically respond to changes in the surrounding environment, withstand drastic changes in the microenvironment, and trigger drug release on demand. Therefore, this review focuses on smart-responsive hydrogels that are capable of adapting and responding to external stimuli. We comprehensively summarize the raw materials, preparation, and cross-linking mechanisms of smart hydrogels derived from natural and synthetic materials, elucidate the response principles of various smart-responsive hydrogels according to different stimulation sources. Further, we systematically illustrate the important role played by hydrogels in modern cancer therapies within the context of therapeutic principles. Meanwhile, the smart hydrogel that uses machine learning to design precise drug delivery has shown great prospects in cancer therapy. Finally, we present the outlook on future developments and make suggestions for future related work. It is anticipated that this review will promote the practical application of smart hydrogels in cancer therapy and contribute to the advancement of medical treatment.

Biomimetic Copper Nanozyme Reprograms Cold Tumor via Cuproptosis-Pyroptosis Crosstalk for Potent Renal Carcinoma Immunotherapy

Immune checkpoint blockade (ICB) therapy is an emerging strategy for renal cell carcinoma (RCC). However, its clinical efficacy remains constrained by its inherently poor immunogenicity and insufficient cytotoxic T lymphocyte (CTL) infiltration. Herein, we engineer a biomimetic copper nanozyme (Cu2O-OMV) by integrating Cu2O nanoparticles with bacterial outer-membrane vesicles (OMVs) to activate the antitumor immune response and synergize with ICB therapy. The Cu2O-OMV nanozyme exhibits peroxidase (POD)-like catalytic activity and releases Cu+ to exert Fenton-like activity, generating cytotoxic hydroxyl radicals (·OH) for tumor inhibition. Furthermore, Cu+ accumulation promotes the occurrence of cuproptosis, leading to the mitochondrial aggregation of lipoylated dihydrolipoamide S-acetyltransferase and depletion of ferredoxin 1. Notably, Cu2O-OMV concurrently activates pyroptosis via the noncanonical inflammasome pathway through its intrinsic lipopolysaccharide cargo, directly inhibiting tumor growth and inducing inflammatory cytokine release. The coordinated induction of cuproptosis and pyroptosis synergistically amplifies immunogenic cell death to enhance tumor immunogenicity, thereby promoting dendritic cell maturation and CTL infiltration. After combining with αPD-L1, it effectively destroys tumor cells to activate the antitumor immune response, thereby inhibiting tumor metastasis. Our study demonstrates a biomimetic nanozyme-driven strategy that harnesses dual cuproptosis-pyroptosis pathways to enhance the tumor immunogenicity and amplify the ICB efficacy, offering a transformative approach for RCC immunotherapy.

Glucose oxidase/copper‑carbon dots/hyaluronic acid self-assembly for self-supply hydrogen peroxide in a double-enzyme cascade to enhance anti-tumor therapy

Although chemodynamic therapy (CDT) has proven to be a promising anti-tumor strategy, its efficacy is limited by the insufficient supply of H2O2 in tumor tissues. To solve the problem of insufficient H2O2, in this paper, a novel double-enzyme cascade nanoreactor hyaluronic-cinnamaldehyde Schiff base@glucose oxidase (GOx)/copper doped carbon dot (abbreviation HCFCTG), which constructed by co-assembly of copper doped carbon dot (CuFACDs-TPP), glucose oxidase (GOx) and hyaluronic-cinnamaldehyde Schiff base (HA-CA) was designed for the first time. The HCFCTG released GOx and CuFACDs-TPP under pH stimulation. GOx continues to supply H2O2 to CDT by consuming glucose, while cutting off the supply of nutrients to starve cancer cells to death (ST), ultimately amplifying the therapeutic effect of CDT. CuFACDs-TPP precisely anchors mitochondria to destroy mitochondria and induce apoptosis, while copper ions consume glutathione to amplify reactive oxygen species (ROS) levels. Self‑oxygenation of HCFCTG by Fenton-like reaction down-regulates hypoxia-inducible factor (HIF-1α) to consolidate CDT effect. The 808 nm laser activates the photothermal effect enhances CDT. In vitro and in vivo experiments proved that HCFCTG has good biocompatibility and excellent CDT effect. HCFCTG overcomes the problem of insufficient H2O2 in the CDT process.

Multifunctional Bioactive Dual-Layered Nanofibrous Matrix for Effective Breast Cancer Therapy and Enhanced Wound Healing

Surgical resection is the primary treatment for triple-negative breast cancer (TNBC). Post-operative complications, including tumor recurrence and bacterial infections, hinder complete remission and long-term recovery. To address these challenges, a multifunctional bioactive dual-layered nanofibrous matrix (MBDL-NanoMat) featuring adaptive shape control, excellent wound adherence, tunable drug release profiles, and superior biocompatibility for post-surgical applications is developed. The MBDL-NanoMat comprises a hydrophilic (HyPhil) layer and a hydrophobic (HyPhob) layer, offering distinct functionalities. The HyPhil layer, electrospun with gelatin and copper peroxide nanoparticles (Cu NPs), rapidly releases Cu NPs to induce anticancer effects through chemodynamic therapy (CDT), ferroptosis, and cuproptosis along with antibacterial action. Near-infrared laser irradiation enhances therapeutic efficacy through photothermal therapy (PTT). The HyPhob layer ensures prolonged therapeutic effects by releasing therapeutic molecules, such as rapamycin, enabling sustained chemotherapy (CT) and antibacterial activity. This synergistic therapeutic system integrates multiple mechanisms-CT, CDT, PTT, ferroptosis, and cuproptosis-suppressing tumor recurrence and accelerating wound healing. Preclinical results demonstrated enhanced angiogenesis, collagen deposition, and dermal regeneration without systemic safety. In short, the MBDL-NanoMat platform offers a unique advantage in post-surgical TNBC care by simultaneously targeting tumor recurrence and facilitating wound healing. Further investigation of this platform can significantly improve oncological and regenerative medicine strategies.

An encounter between metal ions and natural products: natural products-coordinated metal ions for the diagnosis and treatment of tumors

Natural products-coordinated metal ions to form the nanomedicines are in the spotlight for cancer therapy. Some natural products could be coordinated with metal ions forming nanomedicines via simple and green environmental self-assembly, which not only improved the bioavailability of natural products, but also conferred multiple therapeutic modalities and multimodal imaging. On the one hand, in the weak acidity, glutathione (GSH) and hydrogen peroxide (H2O2) overexpression of tumor microenvironment (TME), such carrier-free nanomedicines could be further enhanced the therapeutic effect via optimizing the species of metal ions. On the other hand, nanomedicines could exert the precise treatment of tumor under the guidance of multiple imaging. Hence, this review summarized the research progress in recent years on the application of natural product-coordinated metal ions in cancer therapy. In addition, the prospects and challenges for the application of natural product-coordinated metal ions were discussed, especially how to improve targeting ability and stability and assess the safety of metal ions, so as to facilitate the clinical translation and application of natural product-coordinated metal ions nanomedicines.

Intravascular Casting Radiopaque Hydrogel Systems for Transarterial Chemo/Cascade Catalytic/Embolization Therapy of Hepatocellular Carcinoma

This paper introduces catheter-directed intravascular casting hydrogels for transarterial chemo/starvation/chemodynamic embolization (TACSCE) therapy of hepatocellular carcinoma (HCC). Comprising Mn ion-crosslinked hyaluronic acid-dopamine (HD) with glucose oxidase (for glucose decomposition to H2O2 in starvation therapy), doxorubicin (for chemotherapy), and iopamidol (for X-ray imaging), these hydrogels are fabricated for transarterial embolization therapy guided by X-ray fluoroscopy. Mn4+ (from MnO2) demonstrates strong coordination with the catechol group of HD, providing hypoxia relief through O2 generation and cellular glutathione (GSH) consumption, compared to the OH radical generation potential of Mn2+. The gelation time-controlled, catheter-injectable, and rheologically tuned multitherapeutic/embolic gel system effectively reaches distal arterioles, ensuring complete intravascular casting with fewer complications related to organic solvents. Glucose deprivation, cascade reactive oxygen species (ROS) generation, GSH depletion, and sustained release profiles of multiple drug cargos from the hydrogel system are also achieved. The combined chemo/starvation/chemodynamic efficacies of these designed hydrogel systems are confirmed in HCC cell cultures and HCC-bearing animal models. The developed radiopaque/injectable/embolic/sol-to-gel transformable systems for TACSCE therapy may offer enhanced therapeutic efficacies compared to typical transarterial embolization and transarterial chemoembolization procedures for HCC.

Anti-Colon Cancer Activity of Copper-Doped Folate Carbon Dots/MnO2 Complexes Based on Oxygenation and Immune-Enhancing Effects

In clinical practice, the treatment of colon cancer is faced with the dilemma of metastasis and recurrence, which is related to immunosuppression and hypoxia. Immune checkpoint blockade (ICB) is a negative regulatory pathway of immunity. Immune checkpoint blockade (ICB) is an important immunotherapy method. However, inadequate immunogenicity reduces the overall response rate of ICB. In this study, a tumor microenvironment-responsive nanomedicine (Cu-FACD@MnO2@FA) was prepared to increase host immune response and increase intracellular oxygen levels. Cu-FACD@MnO2@FA preferentially enriched at the tumor site, combined with the immune checkpoint inhibitor alpha PD-L1, induced sufficient immunogenicity to treat colon cancer. Immunofluorescence detection of tumor cells and tissues showed that the expression of hypoxa-inducing factor 1α was significantly down-regulated after treatment and the expression of immunoactivity-related proteins was significantly changed. In vivo treatment in a bilateral tumor mouse model showed complete ablation of the primary tumor and efficient inhibition of the distal tumor. In this study, for the first time, the oxygenation effects of MnO2-coated Cu-doped carbon dots and chemodynamic therapy and a strategy of combining with immuno-blocking therapy were used for treating colon cancer.

Hydrogel design to overcome thermal resistance and ROS detoxification in photothermal and photodynamic therapy of cancer

Responsive heat resistance (by heat shock protein upregulation) and spontaneous reactive oxygen species (ROS) detoxification have been regarded as the major obstacles for photothermal/photodynamic therapy of cancer. To overcome the thermal resistance and improve ROS susceptibility in breast cancer therapy, Au ion-crosslinked hydrogels including indocyanine green (ICG) and polyphenol are devised. Au ion has been introduced for gel crosslinking (by catechol-Au3+ coordination), cellular glutathione depletion, and O2 production from cellular H2O2. ICG can generate singlet oxygen from O2 (for photodynamic therapy) and induce hyperthermia (for photothermal therapy) under the near-infrared laser exposure. (-)-Epigallocatechin gallate downregulates heat shock protein to overcome heat resistance during hyperthermia and exerts multiple anticancer functions in spite of its ironical antioxidant features. Those molecules are concinnously engaged in the hydrogel structure to offer fast gel transformation, syringe injection, self-restoration, and rheological tuning for augmented photo/chemotherapy of cancer. Intratumoral injection of multifunctional hydrogel efficiently suppressed the growth of primary breast cancer and completely eliminated the residual tumor mass. Proposed hydrogel system can be applied to tumor size reduction prior to surgery of breast cancer and the complete remission after its surgery.

Tailoring Hyaluronic Acid Hydrogels for Biomedical Applications

Hyaluronic acid (HA) is an attractive anionic polysaccharide polymer with inherent pharmacological properties and versatile chemical groups for modification. Due to their water retention ability, biocompatibility, biodegradation, cluster of differentiation‐44 targeting, and highly designable capacity, HA hydrogels have been an emerging biomaterial, showing tailoring performance in terms of chemical modifications and hydrogel forms. Various preparation technologies have been developed for the fabrication of the tailoring HA hydrogels with unique structures and functions. They have been utilized in diverse biomedical applications like drug delivery and tissue engineering scaffolds. Herein, this review comprehensively summarizes the HA derivatives with different molecule weights and functional modifications. Then the various fabrication methods to obtain tailoring hydrogels in the forms of nanogel, nanofiber, microparticle, microneedle patch, injectable hydrogel, and scaffold are reviewed as well. The emphasis is focused on the shining biomedical applications of these tailoring HA hydrogels in anti‐bacteria, anti‐inflammation, wound healing, cancer treatment, regenerative medicine, psoriasis treatment, diagnosis, etc. The potentials and prospects are subsequently given to inspire further investigation, aiming at accelerating product translation from research to clinic.

A Detailed Insight into the Effects of Morphologies of Cerium Oxide on Fenton-like Reactions for Different Applications

As an exceptional Fenton-like reagent, cerium oxide (CeO2 ) finds applications in biomedical science and organic pollutants treatment. The Fenton-like reaction catalyzed by CeO2 typically encompasses two distinct processes: one resembling the classical Fenton reaction, wherein cerium (Ce3+ ) triggers the decomposition of hydrogen peroxide (H2 O2 ) to yield reactive oxygen species (ROS), and the other involves the complexation of H2 O2 on the Ce3+ surface, leading to the formation of peroxides. However, the influence of diverse CeO2 morphologies on these two reaction pathways has not been comprehensively explored. In this study, CeO2 exhibiting three typical morphologies, rods, cubes, and spheres, were prepared. The generation of ROS and peroxides was evaluated using the 3,3,5,5-tetramethylbenzidine (TMB) oxidation reaction and the reduction current of H2 O2 , respectively. Moreover, the impacts of pH variations and CeO2 /H2 O2 concentrations on the production and conversion of these two reaction products were investigated. To corroborate the distinctions between the resultant products and their applicability, apoptosis assays and acid orange 7 (AO7) degradation analyses were performed. Notably, CeO2 rods exhibited the highest proportion of Ce3+ , predominantly engaging in complexation with H2 O2 to foster peroxide formation, thereby facilitating the robust degradation of AO7. However, the generated peroxides appeared to occupy Ce3+ sites, thereby impeding the H2 O2 decomposition process. Conversely, Ce3+ species on the surface of CeO2 cubes were primarily involved in H2 O2 decomposition, leading to heightened ROS production, and thus showcasing substantial potential for damaging A549 tumor cells. It is worth noting that the ability of these Ce3+ species to form peroxides through complexation with H2 O2 was comparatively reduced. In summation, this study sheds light on the intricate interplay between distinct CeO2 morphologies and their divergent impacts on Fenton-like reactions. These findings expand our comprehension of the influences on its reactivity of CeO2 morphologies and open new insights for applications in diverse domains, from organic dye degradation to tumor therapy.

A metal ions-mediated natural small molecules carrier-free injectable hydrogel achieving laser-mediated photo-Fenton-like anticancer therapy by synergy apoptosis/cuproptosis/anti-inflammation

Tumor microenvironment (TME) plays an important role in the tumorigenesis, proliferation, invasion and metastasis. Thereby developing synergistic anticancer strategies with multiple mechanisms are urgent. Copper is widely used in the treatment of tumor chemodynamic therapy (CDT) due to its excellent laser-mediated photo-Fenton-like reaction. Additionally, copper can induce cell death through cuproptosis, which is a new modality different from the known death mechanisms and has great promise in tumor treatment. Herein, we report a natural small molecules carrier-free injectable hydrogel (NCTD Gel) consisted of Cu²⁺-mediated self-assembled glycyrrhizic acid (GA) and norcantharidin (NCTD), which are mainly governed by coordination and hydrogen bonds. Under 808 nm laser irradiation, NCTD Gel can produce reactive oxygen species (ROS), consume glutathione (GSH) and overcome hypoxia in TME, leading to synergistically regulate TME via apoptosis, cuproptosis and anti-inflammation. In addition, NCTD Gel's CDT display high selectivity and good biocompatibility as it relies on the weak acidity and H₂O₂ overexpression of TME. Notably, NCTD Gel's components are originated from clinical agents and its preparation process is easy, green and economical, without any excipients. This study provides a new carrier-free hydrogel synergistic antitumor strategy, which has a good prospect in industrial production and clinical transformation.

Alum-tuned hyaluronic acid-based hydrogel with immune checkpoint inhibition for immunophoto therapy of cancer

Alum-crosslinked hyaluronic acid-dopamine (HD) hydrogel containing indocyanine green (ICG) with anti-programmed cell death-1 (PD-1) antibody (Ab) administration was developed for immunophoto therapy of cancer. Alum modulates the rheological characteristics of hydrogel for enabling syringe injection, shear-thinning feature, and slower biodegradation. In addition, alum in HD-based hydrogel provided CD8+ T cell-mediated immune responses for cancer therapy. ICG in the hydrogel under near-infrared (NIR) light exposure may induce hyperthermia and generate singlet oxygen for selective cancer cell killing. HD/alum/ICG hydrogel injection with NIR laser irradiation elevated PD-1 level in CD8+ T cells. Administration of PD-1 Ab aiming at highly expressed PD-1 in T cells may amplify the anticancer efficacies of HD/alum/ICG hydrogel along with NIR laser. HD/alum/ICG hydrogel with NIR light may have both CD8+ T cell-linked immune responses and ICG-related photodynamic/photothermal effects. Additional injection of immune checkpoint inhibitor can ultimately suppress primary and distant tumor growth by combination with those therapeutic actions.

Nanorod/nanodisk-integrated liquid crystalline systems for starvation, chemodynamic, and photothermal therapy of cancer

Indocyanine green (ICG), glucose oxidase (GOx), and copper(II) sulfate (Cu)-installed hybrid gel based on organic nanorod (cellulose nanocrystal [CNC]) and inorganic nanodisk (Laponite [LAP]) was developed to perform a combination of starvation therapy (ST), chemodynamic therapy (CDT), and photothermal therapy (PTT) for localized cancers. A hybrid CNC/LAP network with a nematic phase was designed to enable instant gelation, controlled viscoelasticity, syringe injectability, and longer in vivo retention. Moreover, ICG was introduced into the CNC/LAP gel system to induce hyperthermia of tumor tissue, amplifying the CDT effect; GOx was used for glucose deprivation (related to the Warburg effect); and Cu was introduced for hydroxyl radical generation (based on Fenton-like chemistry) and cellular glutathione (GSH) degradation in cancer cells. The ICG/GOx/Cu-installed CNC/LAP gel in combination with near-infrared (NIR) laser realized improved antiproliferation, cellular reactive oxygen species (ROS) generation, cellular GSH degradation, and apoptosis induction in colorectal cancer (CT-26) cells. In addition, local injection of the CNC/ICG/GOx/Cu/LAP gel into the implanted CT-26 tumor while irradiating it with NIR laser provided strong tumor growth suppression effects. In conclusion, the designed hybrid nanorod/nanodisk gel network can be efficiently applied to the local PTT/ST/CDT of cancer cells.

Cuproptosis-Inducible Chemotherapeutic/Cascade Catalytic Reactor System for Combating with Breast Cancer

Cascade hydroxyl radical generating hydrogel reactor structures including a chemotherapeutic agent are invented for multiple treatment of breast cancer. Glucose oxidase (GOx) and cupric sulfate (Cu) are introduced for transforming accumulated glucose (in cancer cells) to hydroxyl radicals for starvation/chemodynamic therapy. Cu may also suppress cancer cell growth via cuproptosis-mediated cell death. Berberine hydrochloride (BER) is engaged as a chemotherapeutic agent in the hydrogel reactor for combining with starvation/chemodynamic/cuproptosis therapeutic modalities. Moreover, Cu is participated as a gel crosslinker by coordinating with catechol groups in hyaluronic acid-dopamine (HD) polymer. Controlling viscoelasticity of hydrogel reactor can extend the retention time following local injection and provide sustained drug release patterns. Low biodegradation rate of designed HD/BER/GOx/Cu hydrogel can reduce dosing frequency in local cancer therapy and avoid invasiveness-related inconveniences. Especially, it is anticipated that HD/BER/GOx/Cu hydrogel system can be applied for reducing size of breast cancer prior to surgery as well as tumor growth suppression in clinical application.

Cu2+-pyropheophorbide-a-cystine conjugate-mediated multifunctional mesoporous silica nanoparticles for photo-chemodynamic therapy/GSH depletion combined with immunotherapy cancer

Photodynamic therapy (PDT) and chemodynamic therapy (CDT) can activate immunogenicity, so PDT and CDT combined immunotherapy is a promising treatment strategy. However, insufficient hydrogen peroxide activity, hypoxia, and overexpressed glutathione in the tumor microenvironment (TME) significantly impaired the ability to activate immunogenicity. Thus, in this paper, self-reinforcing conjugates Cu²⁺-Pyropheophorbide-a-Cysteine (CuPPaCC), combined synergetic NIR and pH triggered PDT/CDT with glutathione depletion ability was constructed. CuPPaCC was encapsulated in mesoporous silica, and spherical HSCuPPaCC nanoparticles were prepared by Hyaluronic acid (HA) on the silica surface by Schiff base modification. HSCuPPaCC has tumor-specific targeting via HA mediated. In acidic solution, the Schiff base of HSCuPPaCC is destroyed and CuPPaCC is released (>70%), with excellent pH response release function. The results of the MTT analysis showed that the PDT/CDT synergistic anti-tumor effect was significant. HSCuPPaCC was activated in TME, catalyzing the decomposition of hydrogen peroxide to generate hydroxyl radicals and oxygen, alleviating TME hypoxia, replenishing oxygen to PDT, and significantly down regulating hypoxia factor HIF-1α expression. HSCuPPaCC has an excellent dual ROS mechanism and a dual depleting GSH mechanism resulting in a surge in intracellular ROS levels to efficiently kill cancer cells, enhance the ability to induce immunogenicity, and make tumors more sensitive to checkpoint PD-L1 blockade therapy. With the CT26 mouse model, not only the primary tumor was eradicated, but also the distal tumor at the end of treatment was completely suppressed by HSCuPPaCC combined with anti-PD-L1 immune checkpoint blockade therapy.

Local delivery of artesunate dimer liposomes incorporated injectable hydrogel for H2O2 and pH-independent chemodynamic therapy

Chemodynamic therapy (CDT) has emerged as a powerful tumor treatment option by inducing the imbalance of redox homeostasis in cancer cells. Nevertheless, the therapeutic outcomes were greatly limited because of insufficient endogenous H₂O₂ and upregulated cellular antioxidant defense in the tumor microenvironment (TME). Herein, a liposome-incorporated in-situ alginate hydrogel locoregional treatment strategy was developed, which involves using hemin-loaded artesunate dimer liposomes (HAD-LP) as redox-triggered self-amplified C-center free radical nanogenerator to enhance CDT. First, HAD-LP based on artesunate dimer glycerophosphocholine (ART-GPC) was prepared by a thin film method. Their spherical structure was manifested by dynamic light scattering (DLS) and transmission electron microscope (TEM). The generation of C-center free radicals from HAD-LP was carefully evaluated by using methylene blue (MB) degradation method. The results suggested that the hemin was reduced to heme under the action of glutathione (GSH), which could catalyze the breakage of endoperoxide of ART-GPC derived dihydroartemisinin (DHA) to generate toxic C-centered free radicals in a H₂O₂ and pH-independent manner. Moreover, the change of intracellular GSH and free radical level was monitored through ultraviolet spectroscopy and confocal laser scanning microscope (CLSM). It was revealed that the hemin reduction induced GSH depletion and elevated free radical level, disrupting cellular redox homeostasis. After co-incubation with MDA-MB-231 or 4 T1 cells, HAD-LP was found to be highly cytotoxic. In order to prolong retention and improve antitumor efficacy, HAD-LP was mixed with alginate and injected intratumorally into 4 T1 tumor bearing mice. The injected HAD-LP and alginate mixture formed in-situ hydrogel and achieved best antitumor effect with the growth inhibition rate of 72.6%. Together, the hemin-loaded artesunate dimer liposome-incorporated alginate hydrogel possessed effective antitumor activity through redox-triggered C-center free radical generation induced apoptosis in a H₂O₂ and pH-independent manner, which might be a promising candidate in the application of chemodynamic anti-tumor therapy.

Copper nanocrystalline-doped folic acid-based super carbon dots for an enhanced antitumor effect in response to tumor microenvironment stimuli

Chemodynamic therapy (CDT) is a promising cancer treatment strategy to induce tumor cell apoptosis with harmful reactive oxygen species (ROS), yet over-expression of glutathione (GSH) in the tumor microenvironment (TME) severely depletes the ROS and limits the CDT efficacy. Copper-containing materials could efficiently decrease the level of GSH in the TME. In this study, copper nanocrystalline-doped folic acid-based super carbon dots (FA-CDs@Cu^x) were prepared to realize an enhanced antitumor effect in response to tumor microenvironment stimuli. Folic acid (FA) was used as a source of carbon dots to improve the targetability of nanomaterials to tumor cells with over-expressed FA receptors. Copper existed mainly in the form of copper nanocrystals, which were embedded on the carbon core by in situ reduction of Cu²⁺ by gluconic acid. The prepared composites were found to reduce the intracellular H₂O₂ into hydroxyl radicals (˙OH) and consume GSH efficiently in tumor cells. Copper-doping enabled the CDs to absorb near-infrared light and to give a high photothermal transformation efficiency (54.3%) and high singlet oxygen atom yield (56.83%), endowing the super carbon dots with synergetic CDT/PTT/PDT functions in response to the TME and NIR stimuli, which have been investigated systematically by in vitro and in vivo biological experiments.

Application of Hydrogels as Carrier in Tumor Therapy: A Review

Cancer is one of the most intractable diseases in the world because of its high recurrence rate, high metastasis rate and high lethality rate. Traditional chemotherapy, radiotherapy and surgery have unsatisfactory therapeutic effects and cause many severe side effects at the same time. Hydrogel is a new type of biomaterial with the advantages of good biocompatibility and easy degradation, which can be used as a carrier of functional nanomaterials for tumor therapy. Herein, we represent the progress of hydrogels with different skeletons and their application as carrier in tumor treatment. The hydrogels are listed as polyethylene glycol-based hydrogels, chitosan-based hydrogels, peptide-based hydrogels, hyaluronic acid-based hydrogels, steroid-based hydrogels and other hydrogels by skeletons, and their properties, modifications and toxicities were introduced. Some representative applications of combined hydrogels with nanomaterial for chemotherapy, photodynamic therapy, photothermal therapy, sonodynamic therapy, chemodynamic therapy and synergistic therapy are highlighted.

Rapid In Situ Deposition of Iron-Chelated Polydopamine Coating on the Polyacrylamide Hydrogel Dressings for Combined Photothermal and Chemodynamic Therapy of Skin Wound Infection

Pathogenic bacterial infections of skin wounds have caused a significant threat to clinical treatment and human life safety. Here, we develop a bactericidal hydrogel dressing consisting of a polyacrylamide (PAM) hydrogel framework with in situ surface-deposition of iron-dopped polydopamine (FePDA). The prepared hydrogel dressing (FePDA-PAM) has a compact surface, good tensile strength, and excellent elastic recovery ability. The introduction of Fe3+ ions improve the photothermal therapy (PTT) efficiency of the PDA and endow the hydrogel dressing with chemodynamic therapy (CDT) properties. In vitro experiments show that the antibacterial effect of FePDA-PAM hydrogel on Staphylococcus aureus reach nearly 100% under the combined action of H2O2 and 808 nm near-infrared (NIR) laser, indicating an excellent combined antibacterial property of PTT and CDT. Furthermore, the FePDA-PAM + H2O2 + NIR treatment group in the in vivo antibacterial experiments displays lowest relative wound area and optimal wound healing within 5 days of treatment, thereby indicating the intensive skin wound disinfection. To summarize, the FePDA-PAM hydrogel has simple preparation and good biosafety. It may serve as a potential wound dressing for the combined PTT/CDT dual-mode antibacterial therapy.

Ferrocene and glucose oxidase-installed multifunctional hydrogel reactors for local cancer therapy

A hyaluronic acid (HA)-based one-pot hydrogel reactor with single syringe injection and immediate gelation was developed for starvation therapy (ST), chemodynamic therapy (CDT), ferroptosis, and photothermal therapy (PTT) against breast cancer. A rheologically tuned hydrogel network, composed of HA-phenylboronic acid (HP) and HA-dopamine (HD), was designed by introducing a boronate ester linkage (phenylboronic acid-dopamine interaction) and polydopamine bond (pH control). Ferrocene (Fc)-conjugated HP (Fc-HP) was synthesized to achieve ferroptosis, Fenton reaction-involved toxic hydroxyl radical (^•OH) generation, and photothermal ablation in cancer therapy. Glucose oxidase (GOx) was entrapped in the pH-modulated Fc-HP (Fc-HP°)/HD hydrogel network for converting intracellular glucose to H₂O₂ to enable its own supply. The GOx/Fc combination-installed hydrogel reactor system can provide sustained ST/CDT/PTT functions along with ferroptosis. Injection of Fc-HP°/HD/GOx hydrogel with single-syringe injectability, shear-thinning feature, and self-healing capability offered a slow biodegradation rate and high safety profiles. Peritumorally injected Fc-HP°/HD/GOx hydrogel also efficiently suppressed the growth of breast cancer based on multifunctional therapeutic approaches with reduced dosing frequency. Hyperthermia induced by near-infrared (NIR) laser absorption may amplify the therapeutic effects of free radicals. It is expected that this Fc-HP°/HD/GOx hydrogel system can be applied to local cancer therapy with high efficacy and safety profiles.

NIR-II-responsive AuNRs@SiO2-RB@MnO2 nanotheranostic for multimodal imaging-guided CDT/PTT synergistic cancer therapy

Specific tumor-responsive capabilities and efficient synergistic therapeutic performance are the keys to effective tumor treatment. Herein, AuNRs@SiO₂-RB@MnO₂ was developed as a new type of tumor-responsive nanotheranostic for multimodal imaging and synergistic chemodynamic/photothermal therapy. In AuNRs@SiO₂-RB@MnO₂, the SiO₂ layer wraps the AuNRs, providing light absorption in the second near-infrared (NIR-II) region. The SiO₂ layer also adsorbs the MnO₂ nanosheets, which have Fenton-like activity, resulting in a fluorescent sensing platform based on the fluorescence quenching properties of MnO₂ for rhodamine B dye. The fluorescence can be recovered by the consumption of MnO₂ by glutathione, which simultaneously produces Mn²⁺ in the tumor region. The recovery of fluorescence reflects the consumption of glutathione and the increase in Mn²⁺, which produces hydroxyl radicals via Fenton-like reaction in the tumor microenvironment to realize chemodynamic therapy. Meanwhile, the AuNRs are a good photothermal reagent that can effectively absorb NIR-II light and convert it into heat energy to kill tumor cells via photothermal therapy. The NIR-II absorption performance of the AuNRs provides good photoacoustic imaging and deep photothermal performance, which is favorable for efficient NIR-II photoacoustic imaging-guided photothermal therapy. As a result, the AuNRs@SiO₂-RB@MnO₂ nanotheranostic exhibits outstanding imaging and synergistic chemodynamic/photothermal therapeutic performance for tumor imaging and treatment.

Chemodynamic Therapy via Fenton and Fenton-Like Nanomaterials: Strategies and Recent Advances

Chemodynamic therapy (CDT), a novel cancer therapeutic strategy defined as the treatment using Fenton or Fenton-like reaction to produce •OH in the tumor region, was first proposed by Bu, Shi, and co-workers in 2016. Recently, with the rapid development of Fenton and Fenton-like nanomaterials, CDT has attracted tremendous attention because of its unique advantages: 1) It is tumor-selective with low side effects; 2) the CDT process does not depend on external field stimulation; 3) it can modulate the hypoxic and immunosuppressive tumor microenvironment; 4) the treatment cost of CDT is low. In addition to the Fe-involved CDT strategies, the Fenton-like reaction-mediated CDT strategies have also been proposed, which are based on many other metal elements including copper, manganese, cobalt, titanium, vanadium, palladium, silver, molybdenum, ruthenium, tungsten, cerium, and zinc. Moreover, CDT has been combined with other therapies like chemotherapy, radiotherapy, phototherapy, sonodynamic therapy, and immunotherapy for achieving enhanced anticancer effects. Besides, there have also been studies that extend the application of CDT to the antibacterial field. This review introduces the latest advancements in the nanomaterials-involved CDT from 2018 to the present and proposes the current limitations as well as future research directions in the related field.

A binuclear Fe(iii)/quinizarin complex as a structural model for anthracycline drugs binding to iron

Quinizarin, an anthracyclin-like compound, was used to prepare a binuclear complex, [(Fe(cyclam))2Qz]Cl(PF6)3, which showed damage to DNA with glutathione. This mimic of anthracyclin drugs might explain undesired side effects of these compounds.

Autocatalytic oncotherapy nanosystem with glucose depletion for cascade amplification of hypoxia-activated chemotherapy and H2O2-dependent chemodynamic therapy

Hypoxia-activated prodrug is an appealing oncotherapy strategy, but limited by insufficient tumor hypoxia. Moreover, standalone prodrug fails to treat tumor satisfactorily due to tumor complexity. Herein, a nanosystem (TPZ@FeMSN-GOX) was...

Ferroptosis-Inducing Nanomedicine for Cancer Therapy

Ferroptosis, a new iron- and reactive oxygen species-dependent form of regulated cell death, has attracted much attention in the therapy of various types of tumors. With the development of nanomaterials, more and more evidence shows the potential of ferroptosis combined with nanomaterials for cancer therapy. Recently, there has been much effort to develop ferroptosis-inducing nanomedicine, specially combined with the conventional or emerging therapy. Therefore, it is necessary to outline the previous work on ferroptosis-inducing nanomedicine and clarify directions for improvement and application to cancer therapy in the future. In this review, we will comprehensively focus on the strategies of cancer therapy based on ferroptosis-inducing nanomedicine currently, elaborate on the design ideas of synthesis, analyze the advantages and limitations, and finally look forward to the future perspective on the emerging field.

Fast dissolving nanofiber mat for the local antimicrobial application of roxithromycin in oral cavity

Fast disintegrating and dissolving nanofiber (NF) mat was devised to deliver roxithromycin for the treatment of the respiratory tract infection. NF membrane was made by an electrospinning process with poly(vinyl alcohol) (PVA), hydroxypropyl-β-cyclodextrin (HP-β-CD), and d-α-tocopheryl polyethylene glycol succinate (TPGS) for local application of roxithromycin. Roxithromycin has a poor water solubility thus HP-β-CD is introduced for enhancing drug solubility by forming an inclusion complex in this study. The addition of TPGS provided multiple roles such as accelerating wetting, disintegration, and dissolution speed and overcoming bacterial resistance. Roxithromycin was successfully entrapped in NF structure and drug amorphization occurred during the electrospinning process. PVA/HP-β-CD/TPGS/roxithromycin (PHTR) NF exhibited faster wetting, disintegration, and dissolution speed rather than the other NF mats. PHTR NF displayed higher antibacterial potentials in Gram-negative bacteria (E. coli) and Gram-positive bacteria (S. aureus) compared to other NF mat formulations. The administration of PHTR NF to oral cavity in pneumococcal disease mouse model provided the most efficient therapeutic potentials in lung tissue. Designed multiple phase-based NF mat may be one of powerful local drug delivery systems for the therapy of respiratory tract infection.

NIR-II-driven and glutathione depletion-enhanced hypoxia-irrelevant free radical nanogenerator for combined cancer therapy

BACKGROUND

Though the combination of photodynamic therapy (PDT) and chemodynamic therapy (CDT) appears to be very attractive in cancer treatment, hypoxia and overproduced glutathione (GSH) in the tumor microenvironment (TME) limit their efficacy for further application.

RESULTS

In this work, a smart hypoxia-irrelevant free radical nanogenerator (AIPH/PDA@CuS/ZIF-8, denoted as APCZ) was synthesized in situ via coating copper sulphide (CuS)-embedded zeolitic imidazolate framework-8 (ZIF-8) on the free radical initiator 2,2'-azobis[2-(2-imidazolin-2-yl)propane]-dihydrochloride (AIPH)-loaded polydopamine (PDA). APCZ showed promising GSH-depleting ability and near-infrared (NIR)-II photothermal performance for combined cancer therapy. Once internalized by 4T1 cells, the outer ZIF-8 was rapidly degraded to trigger the release of CuS nanoparticles (NPs), which could react with local GSH and sequentially hydrogen peroxide (H₂O₂) to form hydroxyl radical (·OH) for CDT. More importantly, the hyperthermia generated by APCZ upon 1064 nm laser excitation not only permitted NIR-II photothermal therapy (PTT) and promoted CDT, but also triggered the decomposition of AIPH to give toxic alkyl radical (·R) for oxygen-independent PDT. Besides, the PDA together with CuS greatly decreased the GSH level and resulted in significantly enhanced PDT/CDT in both normoxic and hypoxic conditions. The tumors could be completely eradicated after 14 days of treatment due to the prominent therapeutic effects of PTT/PDT/CDT. Additionally, the feasibility of APCZ as a photoacoustic (PA) imaging contrast agent was also demonstrated.

CONCLUSIONS

The novel APCZ could realize the cooperative amplification effect of free radicals-based therapies by NIR-II light excitation and GSH consumption, and act as a contrast agent to improve PA imaging, holding tremendous potential for efficient diagnosis and treatment of deep-seated and hypoxic tumors.

Polypseudorotaxane and polydopamine linkage-based hyaluronic acid hydrogel network with a single syringe injection for sustained drug delivery

Polypseudorotaxane structure and polydopamine bond-based crosslinked hyaluronic acid (HA) hydrogels including donepezil-loaded microspheres were developed for subcutaneous injection. Both dopamine and polyethylene glycol (PEG) were covalently bonded to the HA polymer for catechol polymerization and inclusion complexation with alpha-cyclodextrin (α-CD), respectively. A PEG chain of HA-dopamine-PEG (HD-PEG) conjugate was threaded with α-CD to make a polypseudorotaxane structure and its pH was adjusted to 8.5 for dopamine polymerization. Poly(lactic-co-glycolic acid) (PLGA)/donepezil microsphere (PDM) was embedded into the HD-PEG network for its sustained release. The HD-PEG/α-CD/PDM 8.5 hydrogel system exhibited an immediate gelation pattern, injectability through single syringe, self-healing ability, and shear-thinning behavior. Donepezil was released from the HD-PEG/α-CD/PDM 8.5 hydrogel in a sustained pattern. Following subcutaneous injection, the weight of excised HD-PEG/α-CD/PDM 8.5 hydrogel was higher than the other groups on day 14. These findings support the clinical feasibility of the HD-PEG/α-CD/PDM 8.5 hydrogel for subcutaneous injection.

A Review on Hydrogels with Photothermal Effect in Wound Healing and Bone Tissue Engineering

Photothermal treatment (PTT) is a promising strategy to deal with multidrug-resistant bacteria infection and promote tissue regeneration. Previous studies demonstrated that hyperthermia can effectively inhibit the growth of bacteria, whereas mild heat can promote cell proliferation, further accelerating wound healing and bone regeneration. Especially, hydrogels with photothermal properties could achieve remotely controlled drug release. In this review, we introduce a photothermal agent hybrid in hydrogels for a photothermal effect. We also summarize the potential mechanisms of photothermal hydrogels regarding antibacterial action, angiogenesis, and osteogenesis. Furthermore, recent developments in photothermal hydrogels in wound healing and bone regeneration applications are introduced. Finally, future application of photothermal hydrogels is discussed. Hydrogels with photothermal effects provide a new direction for wound healing and bone regeneration, and this review will give a reference for the tissue engineering.