Enhanced Antitumor Efficacy by a Cascade of Reactive Oxygen Species Generation and Drug Release

NIR-II D-A-D-Type Small-Molecule Coordination with Carboxylatopillar[5]Arene: a Multifunctional Phototheranostic for Low-Temperature NIR-II Photothermal/Platinum-Based/Chemodynamic Combination Cancer Immunotherapy

Low-temperature second near-infrared region (NIR-II) photothermal therapy (PTT) has shown significant potential in minimizing damage to normal tissues and reducing inflammation. However, it still faces challenge of insufficient immune response. Thus, a multifunctional phototheranostic nanoparticle (BDPB/Pt/Fe@P[5]) is developed by co-loading BDPB, CDHPt, and Fe2⁺ with a pH-sensitive lipid DSPE-PEOz2K. The carboxylatopillar[5]arene (CP[5]) used to construct this nanoparticle exhibits strong host-guest recognition with pyridine salts, alleviating aggregation caused quench (ACQ) effect and enhancing the NIR-II emission of the donor-acceptor-donor (D-A-D)-type organic small molecule (BDPB). CP[5] provides suitable vehicles for encapsulating platinum (IV) prodrugs (CDHPt) and Fe2⁺ ions via metal coordination for controllable reactive oxygen species (ROS) release. Under low-intensity NIR-II laser irradiation and an acidic tumor microenvironment, the nanoparticles degrade, releasing CDHPt and Fe2⁺ ions for platinum-based therapy and chemodynamic therapy (CDT). CDHPt facilitates the direct production of superoxide anions (O₂·⁻) from O₂ and partially converts it into the highly cytotoxic hydroxyl radicals, thereby promoting the Fenton reaction process. The therapeutic efficacy is further synergized by immunogenic cell death (ICD) effect.

Self-Accelerated Nanoregulators for Positive Feedback Ferroptosis-Immunotherapy

Activating specific immunity through intelligent delivery of chemotherapeutic drugs shows great potential for effective tumor therapy. However, conventional tumor microenvironment-responsive nanomedicines are often difficult to achieve both specificity and sensitivity, leading to severe adverse effects or limited drug release efficiency. Furthermore, the immunosuppressive microenvironment of tumor will also seriously restrict the treatment efficacy. In this work, a cascade-responsive multi-polyprodrug nanoregulator is developed. Under the tumor microenvironment with high hydrogen peroxide level, the nanoregulators can simultaneously release chemotherapeutic drugs (doxorubicin), indoleamine 2,3-dioxygenase 1 inhibitor (1-methyl-tryptophan) and cinnamaldehyde in a self-accelerating manner. The combination of reactive oxygen species-induced ferroptosis and doxorubicin-induced apoptosis can synergistically enhance immunogenic cell death and activate the immune response. The released1-methyl-tryptophan can promote cytotoxic T lymphocyte activation and reduce immune escape by inhibiting the tryptophan conversion. Meanwhile, it also enhances ferroptosis by inhibiting reactive oxygen species scavenging and cystine/glutamate antiporter expression, achieving the positive feedback ferroptosis-immunotherapy. This work provides a self-accelerated drug delivery strategy and a potential cooperation mode for tumor synergistic immunotherapy based on ferroptosis-apoptosis.

Evolution of nMOFs in photodynamic therapy: from porphyrins to chlorins and bacteriochlorins for better efficacy

Photodynamic therapy (PDT) has gained significant attention due to its non-invasive nature, low cost, and ease of operation. Nanoscale metal-organic frameworks (nMOFs) incorporating porphyrins, chlorins, and bacteriochlorins have emerged as one of the most prominent photoactive materials for tumor PDT. These nMOFs could enhance the water solubility, stability and loading efficiency of photosensitizers (PSs). Their highly ordered porous structure facilitates O2 diffusion and enhances the generation of 1O2 from hydrophobic porphyrins, chlorins, and bacteriochlorins, thereby improving their efficacy of phototherapy. This review provides insights into the PDT effects of nMOFs derived from porphyrins, chlorins, and bacteriochlorins. It overviews the design strategies, types of reactive oxygen species (ROS), ROS generation efficiency, and the unique biological processes involved in inhibiting tumor cell proliferation, focusing on the mechanism by which molecular structure leads to enhanced photochemical properties. Finally, the review highlights the new possibilities offered by porphyrins, chlorins, and bacteriochlorins-based nMOFs for tumor PDT, emphasizing how optimized design can further improve the bioapplication of porphyrin derivatives represented PSs. With ongoing research and technological advancements, we anticipate that this review will garner increased attention from scientific researchers toward porphyrin-based nMOFs, thereby elevating their potential as a prominent approach in the treatment of malignant tumors.

Dual Cascade-Responsive Multifunctional Nanoparticles to Overcome Bacterium-Induced Drug Inactivation and Enhanced Photodynamic and Chemo-Immunotherapy of Pancreatic Cancer

The harsh biological barriers and bacteria within tumor microenvironment not only hinder drug penetration and induce drug inactivation, but also inhibit antitumor immune responses. Here a tumor microenvironment dual cascade-responsive multifunctional nanoparticle, Gem/Emo@NP@GHA is reported, which is engineered from a hyaluronidase (HAase)-responsive guanidine group functionalized hyaluronic acid (GHA) shell and a glutathione (GSH)-responsive biopolymer core (Gem/Emo@NP), that encapsulates anticancer drug gemcitabine (Gem) and two-photon-excited photosensitizer emodin (Emo). The constructed Gem/Emo@NP@GHA can specifically target the tumor and subsequently be degraded by HAase-abundant in the extracellular matrix. Thus, the resulting Gem/Emo@NP achieved size reduction and charge reversal, strengthening deep tumor penetration. Upon internalization, the positively charged Gem/Emo@NP effectively kills intratumor bacteria by inducing membrane depolarization. Furthermore, the high levels of GSH within tumor cells disrupt the disulfide bonds of Gem/Emo@NP, triggering drug release. Thereby, the undecomposed Gem successfully induces tumor cell apoptosis and necrosis. Under laser irradiation, photosensitizer Emo generates high singlet oxygen (1O2), further eliminating tumors and intracellular bacteria. More importantly, Gem/Emo@NP@GHA can activate T cell-mediated immune response, further enhancing antitumor activity. These findings provide a promising approach to treating bacterially infected tumors through the synergistic application of chem-immunotherapy and two-photon-excited photodynamic therapy.

Tumor-Targeted Catalytic Immunotherapy

Cancer immunotherapy holds significant promise for improving cancer treatment efficacy; however, the low response rate remains a considerable challenge. To overcome this limitation, advanced catalytic materials offer potential in augmenting catalytic immunotherapy by modulating the immunosuppressive tumor microenvironment (TME) through precise biochemical reactions. Achieving optimal targeting precision and therapeutic efficacy necessitates a thorough understanding of the properties and underlying mechanisms of tumor-targeted catalytic materials. This review provides a comprehensive and systematic overview of recent advancements in tumor-targeted catalytic materials and their critical role in enhancing catalytic immunotherapy. It highlights the types of catalytic reactions, the construction strategies of catalytic materials, and their fundamental mechanisms for tumor targeting, including passive, bioactive, stimuli-responsive, and biomimetic targeting approaches. Furthermore, this review outlines various tumor-specific targeting strategies, encompassing tumor tissue, tumor cell, exogenous stimuli-responsive, TME-responsive, and cellular TME targeting strategies. Finally, the discussion addresses the challenges and future perspectives for transitioning catalytic materials into clinical applications, offering insights that pave the way for next-generation cancer therapies and provide substantial benefits to patients in clinical settings.

Triggering multiple modalities of cell death via dual-responsive nanomedicines to address the narrow therapeutic window of β-lapachone

The clinical translation of the anticancer drug β-lapachone (LAP) has been limited by the narrow therapeutic window. Stimuli-responsive anticancer drug delivery systems have gained tremendous attention in recent years to alleviate adverse effects and enhance therapeutic efficacy. Here, we report a dual pH- and enzyme-responsive nanocarrier to address the above issue of LAP. In detail, the epigallocatechin gallate (EGCG) and ferric ions were employed to engineer nanoscale ferric ion-polyphenol complexes where LAP was physically encapsulated therein. The coordination bond between Fe3+ and the catechol moiety of EGCG was sensitive to the low pH, enabling the triggered cargo release in the acidic endosomes/lysosomes. Afterward, the released LAP was activated by the overexpressed NAD(P)H: quinone oxidoreductase 1 (NQO1) and ferroptosis suppressor protein 1 (FSP1) in the tumor cells, followed by the generation of reactive oxygen species (ROS), and the induction of oxidative stress and apoptotic cell death. Meanwhile, EGCG could upregulate gasdermin E (GSDME), and ferric ions were involved in the Fenton reaction. Hence, EGCG and ferric ions could sensitize the toxicity of LAP through the induction of multiple cell death pathways (e.g., pyroptosis, ferroptosis, apoptosis, and necroptosis). The current work enlarged the LAP's therapeutic window via controlled cargo release and vehicle sensitization.

Towards a switchable nanoparticle behavior using inverse electron-demand Diels-Alder chemistry and ectoenzyme-based ligand activation

Nanoparticles (NPs) as drug delivery platforms encounter numerous obstacles on their journey from administration to the target site. Often, diametrically opposing particle properties are desirable to overcome biological and physical barriers. Therefore, stimuli-responsive NPs have been developed to allow for specific particle adaptation. In this work, it was demonstrated that NPs can be rendered switchable with respect to their interaction with a receptor through an external chemical stimulus. A combination of the inverse electron-demand Diels-Alder (iEDDA) reaction for subsequent NP functionalization and ectoenzyme-based ligand activation allowed for specific particle tailoring. Building on this, a two-step process for target cell recognition was developed. First, NPs were functionalized with Angiotensin-I (Ang-I) as inactive ligand using iEDDA chemistry. At the target site, the ligand was enzymatically processed to Angiotensin-ll (Ang-II) by cellular ectoenzymes. Ang-ll binds as active ligand to the angiotensin ll type 1 (AT1) receptor on the target cell surface. This enzymatic activation aims to minimize the biological effect of the ligand prior to particle binding, while the NP target cell specificity is increased by a two-step recognition with enzymatic processing and receptor binding.

Tumor Microenvironment Cascade Activated Biodegradable Nano-Enzymes for Glutathione-Depletion and Ultrasound-Enhanced Chemodynamic Therapy

Chemodynamic therapy (CDT) is emerged as a novel and promising tumor therapy by using the powerful reactive oxygen species (ROS) to kill cancer cells. However, the current CDT is remarkably inhibited due to insufficient H2O2 supply and over-expression of glutathione (GSH) in the tumor microenvironment (TME). Herein, a biodegradable self-supplying H2O2 nano-enzyme of CuO2@CaP with a GSH-consumption effect is designed for cascade enhanced CDT to overcome the problem of H2O2 deficiency and GSH overexpression. In this design, CuO2@CaP is gradually degraded to Ca2+, Cu2+, and H2O2 in acidic TME, resulting in synergistically enhanced CDT owing to the efficient self-supplied H2O2 and GSH-depletion and Ca2+ overload therapy. Interestingly, the faster degradation of CuO2@CaP and promoted production rate of •OH are further achieved after triggering with ultrasound (US). And, the US-enhanced CDT and Ca2+ overload synergistic antitumor therapy is successfully achieved in vivo. These findings provide a promising strategy for designing biodegradable nano-enzymes with self-supplying H2O2 and GSH consumption for US-mediated CDT.

Nanomaterial-based regulation of redox metabolism for enhancing cancer therapy

Altered redox metabolism is one of the hallmarks of tumor cells, which not only contributes to tumor proliferation, metastasis, and immune evasion, but also has great relevance to therapeutic resistance. Therefore, regulation of redox metabolism of tumor cells has been proposed as an attractive therapeutic strategy to inhibit tumor growth and reverse therapeutic resistance. In this respect, nanomedicines have exhibited significant therapeutic advantages as intensively reported in recent studies. In this review, we would like to summarize the latest advances in nanomaterial-assisted strategies for redox metabolic regulation therapy, with a focus on the regulation of redox metabolism-related metabolite levels, enzyme activity, and signaling pathways. In the end, future expectations and challenges of such emerging strategies have been discussed, hoping to enlighten and promote their further development for meeting the various demands of advanced cancer therapies. It is highly expected that these therapeutic strategies based on redox metabolism regulation will play a more important role in the field of nanomedicine.

Dual-enzyme inhibiting nanomedicines for enhanced cancer chemodynamic therapy by inducing intratumoral acidosis

Deficiency of endogenous hydrogen peroxide and insufficient intracellular acidity are usually two important factors limiting chemodynamic therapy (CDT). Here we report a glutathione-responsive nanomedicine that can provide a suitable environment for CDT by inhibiting dual-enzymes simultaneously. The nanomedicine is constructed by encapsulation of a novel hydrogen sulfide donor in nanomicelle assembled by glutathione-responsive amphiphilic polymer. In response to intracellular glutathione, the nanomedicine can efficiently release the active ingredients hydrogen sulfide, carbonic anhydrase inhibitor and ferrocene. The hydrogen sulfide can increase the concentrations of hydrogen peroxide and lactic acid by inhibiting catalase and enhancing glycolysis. The carbonic anhydrase inhibitor can further induce intratumoral acidosis by inhibiting the function of carbonic anhydrase IX. Therefore, the nanomedicine can provide more efficient reaction conditions for the ferrocene-mediated Fenton reaction to generate abundant toxic hydroxyl radicals. In vivo results show that the combination of enhanced CDT and acidosis can effectively inhibit tumor growth. This design of nanomedicine provides a promising dual-enzyme inhibiting strategy to enhance antitumor efficacy of CDT.

Glutathione-depleting polyprodrug nanoparticle for enhanced photodynamic therapy and cascaded locoregional chemotherapy

Nanomedicines that combine reactive oxygen species (ROS)-responsive polyprodrug and photodynamic therapy have shown great potential for improving treatment efficacy. However, the consumption of ROS by overexpressed glutathione in tumor cells is a major obstacle for achieving effective ROS amplification and prodrug activation. Herein, we report a polyprodrug-based nanoparticle that can realize ROS amplification and cascaded drug release. The nanoparticle can respond to the high level of hydrogen peroxide in tumor microenvironment, achieving self-destruction and release of quinone methide. The quinone methide depletes intracellular glutathione and thus decreases the antioxidant capacity of cancer cells. Under laser irradiation, a large amount of ROS will be generated to induce cell damage and prodrug activation. Therefore, the glutathione-depleting polyprodrug nanoparticles can efficiently inhibit tumor growth by enhanced photodynamic therapy and cascaded locoregional chemotherapy.

ROS-Responsive Nanoprobes for Bimodal Imaging-Guided Cancer Targeted Combinatorial Therapy

Purpose

Chemotherapy mediated by Reactive oxygen species (ROS)-responsive drug delivery systems can potentially mitigate the toxic side effects of chemotherapeutic drugs and significantly enhance their therapeutic efficacy. However, achieving precise targeted drug delivery and real-time control of ROS-responsive drug release at tumor sites remains a formidable challenge. Therefore, this study aimed to describe a ROS-responsive drug delivery system with specific tumor targeting capabilities for mitigating chemotherapy-induced toxicity while enhancing therapeutic efficacy under guidance of Fluorescence (FL) and Magnetic resonance (MR) bimodal imaging.

Methods

Indocyanine green (ICG), Doxorubicin (DOX) prodrug pB-DOX and Superparamagnetic iron oxide (SPIO, Fe3O4) were encapsulated in poly(lactic-co-glycolic acid) (PLGA) by double emulsification method to prepare ICG/ pB-DOX/ Fe3O4/ PLGA nanoparticles (IBFP NPs). The surface of IBFP NPs was functionalized with mammaglobin antibodies (mAbs) by carbodiimide method to construct the breast cancer-targeting mAbs/ IBFP NPs (MIBFP NPs). Thereafter, FL and MR bimodal imaging ability of MIBFP NPs was evaluated in vitro and in vivo. Finally, the combined photodynamic therapy (PDT) and chemotherapy efficacy evaluation based on MIBFP NPs was studied.

Results

The multifunctional MIBFP NPs exhibited significant targeting efficacy for breast cancer. FL and MR bimodal imaging clearly displayed the distribution of the targeting MIBFP NPs in vivo. Upon near-infrared laser irradiation, the MIBFP NPs loaded with ICG effectively generated ROS for PDT, enabling precise tumor ablation. Simultaneously, it triggered activation of the pB-DOX by cleaving its sensitive moiety, thereby restoring DOX activity and achieving ROS-responsive targeted chemotherapy. Furthermore, the MIBFP NPs combined PDT and chemotherapy to enhance the efficiency of tumor ablation under guidance of bimodal imaging.

Conclusion

MIBFP NPs constitute a novel dual-modality imaging-guided drug delivery system for targeted breast cancer therapy and offer precise and controlled combined treatment options.

Mitochondria-mediated self-cycling nanoreactor enabling uninterrupted oxidative damage for enhanced chemodynamic therapy

Chemodynamic therapy (CDT), which employs intracellular H2O2 to produce toxic hydroxyl radicals to kill cancer cells, has received great attention due to its specificity to tumors. However, the relatively insufficient endogenous H2O2 and the short-lifetime and limited diffusion distance of •OH compromise the therapeutic efficacy of CDT. Mitochondria, which play crucial roles in oncogenesis, are highly vulnerable to elevated oxidative stress. Herein, we constructed a mitochondria-mediated self-cycling system to achieve high dose of •OH production through continuous H2O2 supply. Cinnamaldehyde (CA), which can elevate H2O2 level in the mitochondria, was loaded in Cu(II)-containing metal organic framework (MOF), termed as HKUST-1. After actively targeting mitochondria, the intrinsic H2O2 in mitochondria of cancer cells could induce degradation of MOF, releasing the initial free CA. The released CA further triggered the upregulation of endogenous H2O2, resulting in the subsequent adequate release of CA and the final burst growth of H2O2. The cycle process greatly promoted the Fenton-like reaction between Cu2+ and H2O2 and induced long-term high oxidative stress, achieving enhanced chemodynamic therapy. In a word, we put forward an efficient strategy for enhanced chemodynamic therapy.

A multifunctional nanoplatform for chemotherapy and nanocatalytic synergistic cancer therapy achieved by amplified lipid peroxidation

Traditional cancer chemotherapy suffers from low efficacy and severe side effects, limiting its use as a first-line treatment. To address this issue, we investigated a novel way to induce lipid peroxidation (LPO), which plays an essential role in ferroptosis and may be useful against cancer cells and tumors. In this study, a pH-responsive synergistic cancer therapy nanoplatform was prepared using CaCO3 co-loaded with oleanolic acid (OA) and lipoxygenase (LOX), resulting in the formation OLCaP NP. This nanoplatform exhibited good drug release properties in an acidic tumor environment owing to the presence of CaCO3. As a result of acidic stimulation at tumor sites, the OLCaP NP released OA and LOX. OA, a chemotherapeutic drug with anticancer activity, is already known to promote the apoptosis of cancer cells, and LOX is a natural enzyme that catalyzes the oxidation of polyunsaturated fatty acids, leading to the accumulation of lipid peroxides and promoting the apoptosis of cancer cells. More importantly, OA upregulated the expression of acyl-coenzyme A synthetase long-chain family member 4 (ACSL4), which promoted enzyme-mediated LPO. Based on our combined chemotherapy and nanocatalytic therapy, the OLCaP NP not only had remarkable antitumor ability but also upregulated ACSL4 expression, allowing further amplification of LPO to inhibit tumor growth. These findings demonstrate the potential of this nanoplatform to enhance the therapeutic efficacy against tumors by inducing oxidative stress and disrupting lipid metabolism, highlighting its clinical potential for improved cancer treatment. STATEMENT OF SIGNIFICANCE: This study presents a novel nanoplatform that combines oleanolic acid (OA), a chemotherapeutic drug, and lipoxygenase (LOX), which oxidizes polyunsaturated fatty acids to trigger apoptosis, for targeted cancer therapy. Unlike traditional treatments, our nanoplatform exhibits pH-responsive drug release, specifically in acidic tumor environments. This innovation enhances the therapeutic effects of OA and LOX, upregulating acyl-CoA synthetase long-chain family member 4 expression and amplifying lipid peroxidation to promote tumor cell apoptosis. Our findings significantly advance the existing literature by demonstrating a synergistic approach that combines chemotherapy and nanocatalytic therapy. The scientific impact of this work lies in its potential to improve cancer treatment efficacy and specificity, offering a promising strategy for clinical applications and future research in cancer therapy.

Current progress in the regulation of endogenous molecules for enhanced chemodynamic therapy

Chemodynamic therapy (CDT) is a potential cancer treatment strategy, which relies on Fenton chemistry to transform hydrogen peroxide (H2O2) into highly cytotoxic reactive oxygen species (ROS) for tumor growth suppression. Although overproduced H2O2 in cancerous tissues makes CDT a feasible and specific tumor therapeutic modality, the treatment outcomes of traditional chemodynamic agents still fall short of expectations. Reprogramming cellular metabolism is one of the hallmarks of tumors, which not only supports unrestricted proliferative demands in cancer cells, but also mediates the resistance of tumor cells against many antitumor modalities. Recent discoveries have revealed that various cellular metabolites including H2O2, iron, lactate, glutathione, and lipids have distinct effects on CDT efficiency. In this perspective, we intend to provide a comprehensive summary of how different endogenous molecules impact Fenton chemistry for a deep understanding of mechanisms underlying endogenous regulation-enhanced CDT. Moreover, we point out the current challenges and offer our outlook on the future research directions in this field. We anticipate that exploring CDT through manipulating metabolism will yield significant advancements in tumor treatment.

Phase and Defect Engineering of MoSe2 Nanosheets for Enhanced NIR-II Photothermal Immunotherapy

Inducing immunogenic cell death (ICD) during photothermal therapy (PTT) has the potential to effectively trigger photothermal immunotherapy (PTI). However, ICD induced by PTT alone is often limited by inefficient PTT, low immunogenicity of tumor cells, and a dysregulated redox microenvironment. Herein, we develop MoSe2 nanosheets with high-percentage metallic 1T phase and rich exposed active Mo centers through phase and defect engineering of MoSe2 as an effective nanoagent for PTI. The metallic 1T phase in MoSe2 nanosheets endows them with strong PTT performance, and the abundant exposed active Mo centers endow them with high activity for glutathione (GSH) depletion. The MoSe2-mediated high-performance PTT synergizing with efficient GSH depletion facilitates the release of tumor-associated antigens to induce robust ICD, thus significantly enhancing checkpoint blockade immunotherapy and activating systemic immune response in mouse models of colorectal cancer and triple-negative metastatic breast cancer.

Engineering a pH-responsive polymeric micelle co-loaded with paclitaxel and triptolide for breast cancer therapy

Breast cancer has overtaken lung cancer as the number one cancer worldwide. Paclitaxel (PTX) is a widely used first-line anti-cancer drug, but it is not very effective in clinical breast cancer therapy. It has been reported that triptolide (TPL) can enhance the anticancer effect of paclitaxel, and better synergistic therapeutic effects are seen with concomitant administration of PTX and TPL. In this study, we developed pH-responsive polymeric micelles for co-delivery of PTX and TPL, which disassembling in acidic tumour microenvironments to target drug release and effectively kill breast cancer cells. Firstly, we synthesized amphiphilic copolymer mPEG2000-PBAE through Michael addition reaction, confirmed by various characterizations. Polymer micelles loaded with TPL and PTX (TPL/PTX-PMs) were prepared by the thin film dispersion method. The average particle size of TPL/PTX-PMs was 97.29 ± 1.63 nm, with PDI of 0.237 ± 0.003 and Zeta potential of 9.57 ± 0.80 mV, LC% was 6.19 ± 0.21%, EE% was 88.67 ± 3.06%. Carrier material biocompatibility and loaded micelle cytotoxicity were assessed using the CCK-8 method, demonstrating excellent biocompatibility. Under the same drug concentration, TPL/PTX-PMs were the most toxic to tumour cells and had the strongest proliferation inhibitory effect. Cellular uptake assays revealed that TPL/PTX-PMs significantly increased intracellular drug concentration and enhanced antitumor activity. Overall, pH-responsive micellar co-delivery of TPL and PTX is a promising approach for breast cancer therapy.

Integrated anti-vascular and immune-chemotherapy for colorectal carcinoma using a pH-responsive polymeric delivery system

Colorectal carcinoma (CRC) has become one of the most prevalent malignant tumors and exploring a potential therapeutic strategy with diminished drug-associated adverse effects to combat CRC is urgent. Herein, we designed a pH-responsive polymer to efficiently encapsulate a stimulator of interferon genes (STING) agonist (5,6- dimethylxanthenone-4-acetic acid, termed ASA404) and a common clinically used chemotherapeutic agent (1-hexylcarbamoyl-5-fluorouracil, termed HCFU). Investigations in vitro demonstrated that polymer encapsulation endowed the system with a pH-dependent disassembly behavior (pHt 6.37), which preferentially selected cancerous cells with a favorable dose reduction (dose reduction index (DRI) of HCFU was 4.09). Moreover, the growth of CRC in tumor-bearing mice was effectively suppressed, with tumor suppression rates up to 94.74%, and a combination index (CI) value of less than one (CI = 0.41 for CT26 cell lines), indicating a significant synergistic therapeutic effect. Histological analysis of the tumor micro-vessel density and enzyme-linked immunosorbent assay (ELISA) tests indicated that the system increased TNF-α and IFN-β levels in serum. Therefore, this research introduces a pH-responsive polymer-based theranostic platform with great potential for immune-chemotherapeutic and anti-vascular combination therapy of CRC.

Reversal of Chemoresistance via Staged Liberation of Chemodrug and siRNA in Hierarchical Response to ROS Gradient

P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) often leads to the failure of antitumor chemotherapy, and codelivery of chemodrug with P-gp siRNA (siP-gp) represents a promising approach for treating chemoresistant tumors. To maximize the antitumor efficacy, it is desired that the chemodrug be latently released upon completion of siP-gp-mediated gene silencing, which however, largely remains an unmet demand. Herein, core-shell nanocomplexes (NCs) are developed to overcome MDR via staged liberation of siP-gp and chemodrug (doxorubicin, Dox) in hierarchical response to reactive oxygen species (ROS) concentration gradients. The NCs are constructed from mesoporous silica nanoparticles (MSNs) surface-decorated with cRGD-modified, PEGylated, ditellurium-crosslinked polyethylenimine (RPPT), wherein thioketal-linked dimeric doxorubicin (TK-Dox2) and photosensitizer are coencapsulated inside MSNs while siP-gp is embedded in the RPPT polymeric layer. RPPT with ultrahigh ROS-sensitivity can be efficiently degraded by the low-concentration ROS inside cancer cells to trigger siP-gp release. Upon siP-gp-mediated gene silencing and MDR reversal, light irradiation is performed to generate high-concentration, lethal amount of ROS, which cleaves thioketal with low ROS-sensitivity to liberate the monomeric Dox. Such a latent release profile greatly enhances Dox accumulation in Dox-resistant cancer cells (MCF-7/ADR) in vitro and in vivo, which cooperates with the generated ROS to efficiently eradicate MCF-7/ADR xenograft tumors.

Ozone Therapy in the Integrated Treatment of Female Dogs with Mammary Cancer: Oxidative Profile and Quality of Life

Considering the high frequency of malignant breast tumors, there is a growing search for new therapeutic strategies that control neoplastic growth and dissemination, combined with fewer adverse reactions. Therefore, this study evaluated the effects of ozone therapy in female dogs with mammary cancer undergoing chemotherapy treatment. Twenty-five canines diagnosed with malignant mammary neoplasia were divided into two groups: one treated with carboplatin alone (n = 11) and the other with carboplatin associated with ozone therapy (n = 14). Clinical and laboratory evaluations, mastectomy, analysis of the oxidative profile based on total antioxidant capacity (TAC) and serum concentrations of malondialdehyde (MDA), survival rate, and quality of life were performed. Animals in the ozone therapy group had higher concentrations of red blood cells and platelets, significantly improving the survival rate and quality of life. Furthermore, adverse reactions were less intense and frequent in this group, which was associated with an increase in TAC and a reduction in MDA. These results indicate that the combination of carboplatin and ozone therapy represents a promising complementary treatment for female dogs with mammary cancer, as it was associated with fewer adverse reactions and a better oxidative profile.

An Eco-friendly Approach to ZnO NP Synthesis Using Citrus reticulata Blanco Peel/Extract: Characterization and Antibacterial and Photocatalytic Activity

Emission of greenhouse gases and infectious diseases caused by improper agro-waste disposal has gained significant attention in recent years. To overcome these hurdles, agro-waste can be valorized into valuable bioactive compounds that act as reducing or stabilizing agents in the synthesis of nanomaterials. Herein, we report a simple circular approach using Citrus reticulata Blanco (C. reticulata) waste (peel powder/aqueous extract) as green reducing and capping/stabilizing agents and Zn nitrate/acetate precursors to synthesize ZnO nanoparticles (NPs) with efficient antimicrobial and photocatalytic activities. The obtained NPs crystallized in a hexagonal wurtzite structure and differed clearly in their morphology. UV-vis analysis of the nanoparticles showed a characteristic broad absorption band between 330 and 414 nm belonging to ZnO NPs. Fourier transform infrared (FTIR) spectroscopy of ZnO NPs exhibited a Zn-O band close to 450 cm-1. The band gap values were in the range of 2.84-3.14 eV depending on the precursor and agent used. The crystallite size obtained from size-strain plots from measured XRD patterns was between 7 and 26 nm, with strain between 16 and 4%. The highly crystalline nature of obtained ZnO NPs was confirmed by clear ring diffraction patterns and d-spacing values of the observed lattice fringes. ZnNPeelMan_400 and ZnNExtrMan showed good stability, as the zeta potential was found to be around -20 mV, and reduced particle aggregation. Photoluminescence analysis revealed different defects belonging to oxygen vacancies (VO+ and VO+2) and zinc interstitial (Zni) sites. The presence of oxygen vacancies on the surface of ZnAcExtrMan_400 and ZnAcPeelMan_400 increased antimicrobial activity, specifically against Gram-negative bacteria Escherichia coli (E. coli) and Salmonella enteritidis (S. enteritidis). ZnNExtrMan with a minimal inhibitory concentration of 0.156 mg/mL was more effective against Gram-positive bacteria Staphylococcus aureus (S. aureus), revealing a high influence of particle size and shape on antimicrobial activity. In addition, the photocatalytic activity of the ZnO NPs was examined by assessing the degradation of acid green dye in an aqueous solution under UV light irradiation. ZnAcPeelMan_400 exhibited excellent photocatalytic activity (94%) within 90 min after irradiation compared to other obtained ZnO NPs.

Nano-Engineering Strategies for Tumor-Specific Therapy

Nanodelivery systems (NDSs) provide promising prospects for decreasing drug doses, reducing side effects, and improving therapeutic effects. However, the bioapplications of NDSs are still compromised by their fast clearance, indiscriminate biodistribution, and limited tumor accumulation. Hence, engineering modification of NDSs aiming at promoting tumor-specific therapy and avoiding systemic toxicity is usually needed. An NDS integrating various functionalities, including flexible camouflage, specific biorecognition, and sensitive stimuli-responsiveness, into one sequence would be "smart" and highly effective. Herein, we systematically summarize the related principles, methods, and progress. At the end of the review, we predict the obstacles to precise nanoengineering and prospects for the future application of NDSs.

A pH-sensitive imidazole grafted polymeric micelles nanoplatform based on ROS amplification for ferroptosis-enhanced chemodynamic therapy

Highly toxic reactive oxygen species (ROS), crucial in inducing apoptosis and ferroptosis, are pivotal for cell death pathways in cancer therapy. However, the effectiveness of ROS-related tumor therapy is impeded by the limited intracellular ROS and substrates, coupled with the presence of abundant ROS scavengers like glutathione (GSH). In this research, we developed acid-responsive, iron-coordinated polymer nanoparticles (PPA/TF) encapsulating a mitochondrial-targeting drug alpha-tocopheryl succinate (α-TOS) for enhanced synergistic tumor treatment. The imidazole grafted micelles exhibit prolonged blood circulation and improve the delivery efficiency of the hydrophobic drug α-TOS. Additionally, PPA's design aids in delivering Fe3+, supplying ample iron ions for chemodynamic therapy (CDT) and ferroptosis through the attachment of imidazole groups to Fe3+. In the tumor's weakly acidic intracellular environment, PPA/TF facilitates pH-responsive drug release. α-TOS specifically targets mitochondria, generating ROS and replenishing those depleted by the Fenton reaction. Moreover, the presence of Fe3+ in PPA/TF amplifies ROS upregulation, promotes GSH depletion, and induces oxidative damage and ferroptosis, effectively inhibiting tumor growth. This research presents an innovative ROS-triggered amplification platform that optimizes CDT and ferroptosis for effective cancer treatment.

A Novel Polyamino Acid Sulfur Dioxide Prodrug Synergistically Elevates ROS with β-Lapachone in Cancer Treatment

Due to the distorted redox balance, cancer cells are considered more vulnerable to excessive reactive oxygen species (ROS). In a variety of oxidative stress-related therapies, gas therapy has emerged as a new therapeutic strategy owing to its efficacy and biosafety. Herein, a newly-discovered gasotransmitter sulfur dioxide (SO2) and a tumor specific ROS generation agent β-lapachone (Lapa) were firstly combined for anticancer therapy. Firstly, amphiphilic glutathione (GSH) responsive polypeptide SO2 prodrug PEG-b-poly(Lys-DNs) was synthesized by ring opening polymerization of SO2-containing N-carboxyanhydride. Then, Lapa was encapsulated into the polymeric micelles with loading content of 8.6 % and loading efficiency of 51.6 %. The obtained drug-loaded nanoparticles (NPs(Lapa)) exhibited a fast release of Lapa and SO2 in the stimuli of 10 mM GSH in PBS. Subsequently, in vitro experiment showed that NPs(Lapa) exhibited obvious cytotoxicity towards 4 T1 cancer cells at a concentration of 2.0 μg/mL, which may be attributed to the depletion of intracellular GSH and upregulation of ROS level both by SO2 release and by the ROS generation from lapachone transformation. In vivo fluorescence imaging showed that the NPs were gradually enriched in tumor tissues in 24 h, probably due to the enhanced permeability and retention effect of NPs. Finally, NPs(Lapa) showed the best anticancer effect in 4 T1 tumor bearing mice with a tumor inhibiting rate (IRT) of 61 %, whereas IRT for free Lapa group was only 23.6 %. This work may be a new attempt to combine SO2 gas therapy with ROS inducer for anticancer therapy through oxidative stress.

Dual-Responsive Supramolecular Polymeric Nanomedicine for Self-Cascade Amplified Cancer Immunotherapy

Insufficient tumor immunogenicity and immune escape from tumors remain common problems in all tumor immunotherapies. Recent studies have shown that pyroptosis, a form of programmed cell death that is accompanied by immune checkpoint inhibitors, can induce effective immunogenic cell death and long-term immune activation. Therapeutic strategies to jointly induce pyroptosis and reverse immunosuppressive tumor microenvironments are promising for cancer immunotherapy. In this regard, a dual-responsive supramolecular polymeric nanomedicine (NCSNPs) to self-cascade amplify the benefits of cancer immunotherapy is designed. The NCSNPs are formulated by β-cyclodextrin coupling nitric oxide (NO) donor, a pyroptosis activator, and NLG919, an indoleamine 2,3-dioxygenase (IDO) inhibitor, and self-assembled through host-guest molecular recognition and hydrophobic interaction to obtain nanoparticles. NCSNPs possess excellent tumor accumulation and bioavailability attributed to ingenious supramolecular engineering. The study not only confirms the occurrence of NO-triggered pyroptosis in tumors for the first time but also reverses the immunosuppressive microenvironment in tumor sites via an IDO inhibitor by enhancing the infiltration of cytotoxic T lymphocytes, to achieve remarkable inhibition of tumor proliferation. Thus, this study provides a novel strategy for cancer immunotherapy.

Nanomedomics

Nanomaterials have attractive physicochemical properties. A variety of nanomaterials such as inorganic, lipid, polymers, and protein nanoparticles have been widely developed for nanomedicine via chemical conjugation or physical encapsulation of bioactive molecules. Superior to traditional drugs, nanomedicines offer high biocompatibility, good water solubility, long blood circulation times, and tumor-targeting properties. Capitalizing on this, several nanoformulations have already been clinically approved and many others are currently being studied in clinical trials. Despite their undoubtful success, the molecular mechanism of action of the vast majority of nanomedicines remains poorly understood. To tackle this limitation, herein, this review critically discusses the strategy of applying multiomics analysis to study the mechanism of action of nanomedicines, named nanomedomics, including advantages, applications, and future directions. A comprehensive understanding of the molecular mechanism could provide valuable insight and therefore foster the development and clinical translation of nanomedicines.

Targeting lncRNA16 by GalNAc-siRNA conjugates facilitates chemotherapeutic sensibilization via the HBB/NDUFAF5/ROS pathway

Chemoresistance is a significant barrier to effective cancer treatment. Potential mechanisms for chemoresistance include reactive oxygen species (ROS) accumulation and expression of chemoresistance-promoting genes. Here, we report a novel function of lncRNA16 in the inhibition of ROS generation and the progression of chemoresistance. By analyzing the serum levels of lncRNA16 in a cohort of 35 patients with non-small cell lung cancer (NSCLC) and paired serum samples pre- and post-treatment from 10 NSCLC patients receiving neoadjuvant platinum-based chemotherapy, performing immunohistochemistry (IHC) assays on 188 NSCLC tumor samples, using comprehensive identification of RNA-binding proteins by mass spectrometry (ChIRP-MS) assays, as well as RNA immunoprecipitation (RIP) and RNA pull-down analyses, we discovered that patients with increased serum levels of lncRNA16 exhibited a poor response to platinum-based chemotherapy. The expression of hemoglobin subunit beta (HBB) and NDUFAF5 significantly increases with the development of chemoresistance. LncRNA16 binds to HBB and promotes HBB accumulation by inhibiting autophagy. LncRNA16 can also inhibit ROS generation via the HBB/NDUFAF5 axis and function as a scaffold to facilitate the colocalization of HBB and NDUFAF5 in the mitochondria. Importantly, preclinical studies in mouse models of chemo-resistant NSCLC have suggested that lncRNA16 targeting by trivalent N-acetylgalactosamine (GalNAc)-conjugated siRNA restores chemosensitivity and results in tumor growth inhibition with no detectable toxicity in vivo. Overall, lncRNA16 is a promising therapeutic target for overcoming chemoresistance, and the combination of first-line platinum-based chemotherapy with lncRNA16 intervention can substantially enhance anti-tumor efficacy.

Tumor Microenvironment Activatable Nanoprodrug System for In Situ Fluorescence Imaging and Therapy of Liver Cancer

The development of new imaging and treatment nanoprodrug systems is highly demanded for diagnosis and therapy of liver cancer, a severe disease characterized by a high recurrence rate. Currently, available small molecule drugs are not possible for cancer diagnosis because of the fast diffusion of imaging agents and low efficacy in treatment due to poor water solubility and significant toxic side effects. In this study, we report the development of a tumor microenvironment activatable nanoprodrug system for the diagnosis and treatment of liver cancer. This nanoprodrug system can accumulate in the tumor site and be selectively activated by an excess of hydrogen peroxide (H2O2) in the tumor microenvironment, releasing near-infrared solid-state organic fluorescent probe (HPQCY-1) and phenylboronic acid-modified camptothecin (CPT) prodrug. Both HPQCY-1 and CPT prodrugs can be further activated in tumor sites for achieving more precise in situ near-infrared (NIR) fluorescence imaging and treatment while reducing the toxic effects of drugs on normal tissues. Additionally, the incorporation of hydrophilic multivalent chitosan as a carrier effectively improved the water solubility of the system. This research thus provides a practical new approach for the diagnosis and treatment of liver cancer.

Accelerated cascade melanoma therapy using enzyme-nanozyme-integrated dissolvable polymeric microneedles

Dissolvable polymeric microneedles (DPMNs) have emerged as a powerful technology for the localized treatment of diseases, such as melanoma. Herein, we fabricated a DPMN patch containing a potent enzyme-nanozyme composite that transforms the upregulated glucose consumption of cancerous cells into lethal reactive oxygen species via a cascade reaction accelerated by endogenous chloride ions and external near-infrared (NIR) irradiation. This was accomplished by combining glucose oxidase (Gox) with a NIR-responsive chloroperoxidase-like copper sulfide (CuS) nanozyme. In contrast with subcutaneous injection, the microneedle system highly localizes the treatment, enhancing nanomedicine uptake by the tumor and reducing its systemic exposure to the kidneys and spleen. NIR irradiation further controls the potency and toxicity of the formulation by thermally disabling Gox. In a mouse melanoma model, this unique combination of photothermal, starvation, and chemodynamic therapies resulted in complete tumor eradication (99.2 ± 0.8 % reduction in tumor volume within 10 d) without producing signs of systemic toxicity. By comparison, other treatment combinations only resulted in a 42-76.5 % reduction in tumor growth. The microneedle patch design is therefore not only highly potent but also with regulated toxicity and improved safety.

A Sequential Dual Functional Supramolecular Hydrogel with Promoted Drug Release to Scavenge ROS and Stabilize HIF-1α for Myocardial Infarction Treatment

Myocardial infarction (MI) has a characteristic inflammatory microenvironment due to the overproduction of reactive oxygen species (ROS) and causes the extraordinary deposition of collagen and thereby fibrosis. An on-demand adaptive drug releasing hydrogel is designed to modulate the inflammatory microenvironment and inhibit cardiac fibroblasts (CFs) proliferation post MI by scavenging the overproduced ROS and releasing 1,4-dihydrophenonthrolin-4-one-3-carboxylic acid (DPCA) to maintain the expression of hypoxia-inducible factor 1α (HIF-1α). DPCA is prefabricated to a prodrug linked with disulfide bond (DPCA-S-S-OH). The DPCA-S-S-OH and carboxylated calixarene (CSAC4A) are grafted onto the backbone of methacrylated hyaluronic acid (HAMA) to obtain HAMA-S-S-DPCA and HAMA-CA, respectively, which are further reacted to form a dual network hydrogel (R+ /DPCA(CA)) with covalent linking and host-guest interaction between DPCA and CSAC4A. The ROS-triggered hydrolysis of ester bond and subsequently sustaining release of DPCA from the cavity of CSAC4A jointly cause the constant expression of HIF-1α, which significantly restricts the CFs proliferation, leading to suppressed fibrosis and promoted heart repair.

Dual-Programmable Semiconducting Polymer NanoPROTACs for Deep-Tissue Sonodynamic-Ferroptosis Activatable Immunotherapy

Proteolysis-targeting chimeras (PROTACs) can provide promising opportunities for cancer treatment, while precise regulation of their activities remains challenging to achieve effective and safe therapeutic outcomes. A semiconducting polymer nanoPROTAC (SPNFeP ) is reported that can achieve ultrasound (US) and tumor microenvironment dual-programmable PROTAC activity for deep-tissue sonodynamic-ferroptosis activatable immunotherapy. SPNFeP is formed through a nano-precipitation of a sonodynamic semiconducting polymer, a ferroptosis inducer, and a newly synthesized PROTAC molecule. The semiconducting polymers work as sonosensitizers to produce singlet oxygen (1 O2 ) via sonodynamic effect under US irradiation, and ferroptosis inducers react with intratumoral hydrogen peroxide (H2 O2 ) to generate hydroxyl radical (·OH). Such a dual-programmable reactive oxygen species (ROS) generation not only triggers ferroptosis and immunogenic cell death (ICD), but also induces on-demand activatable delivery of PROTAC molecules into tumor sites. The effectively activated nanoPROTACs degrade nicotinamide phosphoribosyl transferase (NAMPT) to suppress tumor infiltration of myeloid-derived suppressive cells (MDSCs), thus promoting antitumor immunity. In such a way, SPNFeP mediates sonodynamic-ferroptosis activatable immunotherapy for entirely inhibiting tumor growths in both subcutaneous and 2-cm tissue-covered deep tumor mouse models. This study presents a dual-programmable activatable strategy based on PROTACs for effective and precise cancer combinational therapy.

Cleavage and Noncleavage Chemistry in Reactive Oxygen Species (ROS)-Responsive Materials for Smart Drug Delivery

The design and development of advanced drug delivery systems targeting reactive oxygen species (ROS) have gained significant interest in recent years for treating various diseases, including cancer, psychiatric diseases, cardiovascular diseases, neurological diseases, metabolic diseases, and chronic inflammations. Integrating specific chemical bonds capable of effectively responding to ROS and triggering drug release into the delivery system is crucial. In this Review, we discuss commonly used conjugation linkers (chemical bonds) and categorize them into two groups: cleavable linkers and noncleavable linkers. Our goal is to clarify their unique drug release mechanisms from a chemical perspective and provide practical organic synthesis approaches for their efficient production. We showcase numerous significant examples to demonstrate their synthesis routes and diverse applications. Ultimately, we strive to present a comprehensive overview of cleavage and noncleavage chemistry, offering insights into the development of smart drug delivery systems that respond to ROS.

A multivalent polyphenol-metal-nanoplatform for cascade amplified chemo-chemodynamic therapy

Chemodynamic therapy (CDT), as an emerging therapeutic strategy, kills cancer cells by converting intracellular hydrogen peroxide (H2O2) into cytotoxic oxidizing hydroxyl radicals (⋅OH). However, the therapeutic efficiency of CDT is compromised due to the insufficient endogenous H2O2 and metal catalysts in tumor cells. The use of multivalent polyphenols with multiple hydroxyl functions provides a facile yet robust means for efficient CDT augmentation. For this purpose, we reported herein the construction of polyphenol-metal nanoparticles (NPs) via a phenol-metal coordination strategy. The uniqueness of this study is the preparation of only one polymer construct with multivalency that can afford various supramolecular interactions for simultaneous "one-pot" loading of different therapeutic species, i.e., doxorubicin (DOX), glucose oxidases (GOD), and Fe3+ and further co-self-assembly into a stabilized nanomedicine for cascade amplified chemo-chemodynamic therapy. Specifically, the tumor intracellular acidic pH-triggered DOX release could serve for chemotherapy as well as enhance the intracellular H2O2 level. Together with the extra H2O2 and gluconic acid produced by the GOD-triggered glucose consumption, DOX@POAD-Fe@GOD NPs promoted Fe3+participation in the Fe-mediated Fenton reaction for cascade amplified chemo-chemodynamic therapy. Notably, this formulation displayed a greater anti-tumor effect with a tumor inhibition ratio 1.6-fold higher than that of free DOX in a BALB/c mice model bearing 4T1 tumors. Overall, the multivalent polyphenol-metal nanoplatform developed herein integrates chemotherapy, starvation therapy, and CDT for synergistic enhanced anticancer efficiency, which shows great potential for clinical translations. STATEMENT OF SIGNIFICANCE: Chemodynamic therapy (CDT) generally suffers from compromised therapeutic efficiency due to insufficient endogenous H2O2 and metal catalysts in tumor cells. To develop a facile yet robust strategy for efficient CDT augmentation, we reported herein construction of a multivalent polyphenol-metal nanoplatform, DOX@POAD-Fe@GOD nanoparticles (NPs) via a phenol-metal coordination strategy. This nanoplatform integrates multiple supramolecular dynamic interactions not only for simultaneously safe encapsulation of doxorubicin (DOX), Fe3+, and glucose oxidases (GOD), but also for cascade amplified chemo-chemodynamic therapy. Specifically, the intracellular acidic pH-triggered dissociation of DOX@POAD-Fe@GOD NPs promoted the release of Fe3+, DOX, and GOD for significantly increased ROS levels that can accelerate Fenton reactions for cascaded chemotherapy, starvation therapy, and CDT with amplified antitumor efficiency in vivo.

Formulation of DOX-dimer with bi-functionalized chitooligosaccharide for tumor-specific self-boosted drug release and synergistic chemo/chemodynamic therapy

The toxic side effects and possible drug resistance of the chemotherapeutics hinder their antitumor efficacy. Here, a pH/reactive oxygen species (ROS) dual-triggered nanodrug was developed for the tumor-specific self-boosted drug release and synergistic chemo/chemodynamic therapy, by formulating ROS-cleavable doxorubicin (DOX)-based dimer (DOX-TK-DOX) with bi-functionalized chitooligosaccharide (COS-Fc-TK) with ferrocenecarboxylic acid (Fc) and thioketal (TK). The resultant DOX-TK-DOX/COS-Fc-TK nanoparticles with a high DOX content of 39.70 % showed tumor-specific self-boosted drug release, which was triggered by highly toxic OH generated via Fc-catalyzed Fenton reaction of the endogenous H2O2 in tumor intracellular microenvironment. As a result, a synergistic chemo/chemodynamic therapy with combination index (CI) of 0.94 was achieved for selective treatment of tumors.

A Photo-Activated Continuous Reactive Oxygen Species Nanoamplifier for Dual-Dynamic Cascade Cancer Therapy

The special redox homeostasis of tumor cells makes reactive oxygen species (ROS)-based approaches a promising cancer therapeutic strategy. Among these approaches, photodynamic therapy is the most widely studied ROS-based treatment due to its ability to achieve targeted therapy by local light irradiation. However, achieving efficient and continuous ROS generation without prolonged laser exposure is still challenging. In this work, a photo-activated continuous ROS nanoamplifier is proposed for photodynamic-chemodynamic cascade therapy. Upon local laser irradiation, the nanoamplifier can continuously amplify cellular oxidative stress through a positive feedback loop of "light-triggered ROS generation, ROS-responsive prodrug activation, and Fenton reaction-mediated ROS cyclic regenerative amplification", avoiding tissue damage caused by excessive laser exposure. This strategy provides a potential pathway to overcome the limitations of ROS-based therapeutic approaches.

Catalytic MnWO4 Nanorods for Chemodynamic Therapy Synergized Radiotherapy of Triple Negative Breast Cancer

Nanomedicine‐based synergy of chemodynamic therapy (CDT) and radiotherapy (RT) modulated by tumor microenvironment enables rapid tumor ablation, which holds great hope for the refractory and recurrent cancers, such as triple negative breast cancer (TNBC). The clinical translation of hafnium oxide (HfO2), commercially named as NBTXR3, has aroused new research focus on single‐component inorganic nanomedicines as clinical candidates. Herein, the single‐component MnWO4 is first reported as a new kind of Fenton‐like agent yet radiosensitizer for TNBC treatment undergoing the synergistic CDT/RT mechanism. MnWO4 nanorods are synthesized via a simple one‐pot hydrothermal method and then undergo a layer‐by‐layer PEGylation to obtain bioavailable MnWO4‐PEG (MWP). MWP‐based Fenton‐like reaction efficacy depends on reaction time, temperatures, pH values, and MWP concentrations. Mn‐triggered chemodynamic effect delays RT‐induced DNA damage repair and sorts cell cycles distribution toward radiosensitive phases, while W‐mediated radiosensitization improves the tumoral H2O2 overexpression to enhance CDT, remarkably amplifying of the intracellular oxidative stress to boost 4T1 cell apoptosis. In vitro and in vivo evaluations further demonstrate the effectiveness and biosafety of MWP‐based synergistic therapy. Considering the potential magnetic resonance and computed tomography imaging capabilities, MWP can be expected as an intelligent cancer theranostics for imaging‐guided cancer therapy in clinic in the future.

Reactive X (where X = O, N, S, C, Cl, Br, and I) species nanomedicine

Reactive oxygen, nitrogen, sulfur, carbonyl, chlorine, bromine, and iodine species (RXS, where X = O, N, S, C, Cl, Br, and I) have important roles in various normal physiological processes and act as essential regulators of cell metabolism; their inherent biological activities govern cell signaling, immune balance, and tissue homeostasis. However, an imbalance between RXS production and consumption will induce the occurrence and development of various diseases. Due to the considerable progress of nanomedicine, a variety of nanosystems that can regulate RXS has been rationally designed and engineered for restoring RXS balance to halt the pathological processes of different diseases. The invention of radical-regulating nanomaterials creates the possibility of intriguing projects for disease treatment and promotes advances in nanomedicine. In this comprehensive review, we summarize, discuss, and highlight very-recent advances in RXS-based nanomedicine for versatile disease treatments. This review particularly focuses on the types and pathological effects of these reactive species and explores the biological effects of RXS-based nanomaterials, accompanied by a discussion and the outlook of the challenges faced and future clinical translations of RXS nanomedicines.

Exploring novel strategies to improve anti-tumour efficiency: The potential for targeting reactive oxygen species

The cellular milieu in which malignant growths or cancer stem cells reside is known as the tumour microenvironment (TME). It is the consequence of the interactivity amongst malignant and non-malignant cells and directly affects cancer development and progression. Reactive oxygen species (ROS) are chemically reactive molecules that contain oxygen, they are generated because of numerous endogenous and external factors. Endogenous ROS produced from mitochondria is known to significantly increase intracellular oxidative stress. In addition to playing a key role in several biological processes both in healthy and malignant cells, ROS function as secondary messengers in cell signalling. At low to moderate concentrations, ROS serves as signalling transducers to promote cancer cell motility, invasion, angiogenesis, and treatment resistance. At high concentrations, ROS can induce oxidative stress, leading to DNA damage, lipid peroxidation and protein oxidation. These effects can result in cell death or trigger signalling pathways that lead to apoptosis. The creation of innovative therapies and cancer management techniques has been aided by a thorough understanding of the TME. At present, surgery, chemotherapy, and radiotherapy, occasionally in combination, are the most often used methods for tumour treatment. The current challenge that these therapies face is the lack of spatiotemporal application specifically at the lesion which results in toxic effects on healthy cells associated with off-target drug delivery and undesirably high doses. Nanotechnology can be used to specifically deliver various chemicals via nanocarriers to target tumour cells, thereby increasing the accumulation of ROS-inducing agents at the site of the tumour. Nanoparticles can be engineered to release ROS-inducing agents in a controlled manner to the TME that will in turn react with the ROS to either increase or decrease it, thereby improving antitumour efficiency. Nano-delivery systems such as liposomes, nanocapsules, solid lipid nanoparticles and nanostructured lipid carriers were explored for the up/down-regulation of ROS. This review will discuss the use of nanotechnology in targeting and altering the ROS in the TME.

Inorganic nanoparticle agents for enhanced chemodynamic therapy of tumours

With the recent interest in the role of oxidative species/radicals in diseases, inorganic nanomaterials with redox activities have been extensively investigated for their potential use in nanomedicine. While many studies focusing on relieving oxidative stress to prevent pathogenesis and to suppress the progression of diseases have shown considerable success, another approach for increasing oxidative stress using nanomaterials to kill malignant cells has suffered from low efficiency despite its wide applicability to various targets. Chemodynamic therapy (CDT) is an emerging technique that can resolve such a problem by exploiting the characteristic tumour microenvironment to achieve high selectivity. In this review, we summarize the recent strategies and underlying mechanisms that have been used to improve the CDT performance using inorganic nanoparticles. In addition to the design of CDT agents, the effects of contributing factors, such as the acidity and the levels of hydrogen peroxide and antioxidants in the tumour microenvironment, together with their modulation and application in combination therapy, are presented. The challenges lying ahead of future clinical translation of this rapidly advancing technology are also discussed.

Precisely Amplifying Intracellular Oxidative Storm by Metal-Organic Coordination Polymers to Augment Anticancer Immunity

Oxidative stress accompanying the reactive oxygen species (ROS) burst governs immunocyte infiltration, activation, and differentiation in tumor microenvironments and thus can elicit robust antitumor immunity. Here, we identify a photoactive metal-organic coordination polymer (MOCP), composed of an organometallic core formed by cytotoxic mitoxantrone (MTX) acylates and photosensitive Ru(BIQ)-HDBB [BIQ = 2,2'-biquinoline, HDBB = 4,4'-di(4-benzoato)-2,2'-bipyridine] linked by Fe(II) ions via coordinate covalent bonds and an amphipathic shell encapsulating cholesterol-modified siRNA against GPX4 (siGPX4) via hydrophobic force, to precisely amplify intracellular oxidative storm. MOCPs simultaneously encapsulated MTX, Ru, and siGPX4 with efficiencies >98% and loaded Fe with efficiencies of ∼0.49%. With longer blood circulation and higher tumor accumulation, MOCPs with a 670 nm LED irradiation generate abundant ROS to induce biomembrane dysfunction and subsequently contribute to ferroptotic and immunogenic cell death, which drive tumor-associated antigen-specific immunity. MTX analogs contributed to Type I immunogenic cell death (ICD), while oxidative storm served as a damager for endo/lysosomal escape, an initiator for ferroptosis, and an inducer for type II ICD. Moreover, the blockade of CD73 that reduces extoATP catabolism unleashes immunosuppression, finally enhancing antitumor immune stimulation of MOCPs to promote orthotopic mammary cancer regression and prevent postoperative advanced cancer from recurrence and metastasis. MOCPs by exposing sufficient antigenicity thus provide a platform to synergize immune checkpoint inhibitors for the treatment of immunologically cold tumors.

Effects of N-acetylcysteine on CG8005 gene-mediated proliferation and apoptosis of Drosophila S2 embryonic cells

To investigate the effect of the antioxidant N-acetylcysteine (NAC) on the proliferation and apoptosis in CG8005 gene-interfering Drosophila S2 embryonic cells by scavenging intracellular reactive oxygen species (ROS). The interfering efficiency of CG8005 gene in Drosophila S2 embryonic cells was verified by real-time quantitative PCR (qRT-PCR). Different concentrations of NAC and phosphate buffered saline (PBS) were used to affect the Drosophila S2 embryonic cells. The growth state of Drosophila S2 embryonic cells was observed by light microscope. Two probes dihydroethidium (DHE) and 2,7-dichlorodihydrofluorescein-acetoacetate (DCFH-DA) were used to observe the ROS production in each group after immunofluorescence staining. TUNEL staining and flow cytometry were used to investigate the apoptosis level of Drosophila S2 embryos, and CCK-8 (Cell Counting Kit-8) was used to detect the cell viability of Drosophila S2 embryos. The knockdown efficiency of siCG8005-2 fragment was high and stable, which was verified by interference efficiency (P < 0.05). There was no significant change in the growth of Drosophila S2 embryonic cells after the treatment of NAC as compared to PBS group. Moreover, knockdowning CG8005 gene resulted in an increase in ROS and apoptosis in Drosophila S2 embryonic cells (P < 0.05) and a decrease in proliferation activity (P < 0.05). In addition, the pretreatment of antioxidant NAC could inhibit ROS production in Drosophila S2 embryonic cells (P < 0.05), reduce cell apoptosis (P < 0.05), and improve cell survival (P < 0.05). The CG8005 gene in Drosophila S2 embryonic cells could regulate the proliferation and apoptosis of S2 embryonic cells by disrupting the redox homeostasis, and antioxidant NAC could inhibit cell apoptosis and promotes cell proliferation by scavenging ROS in Drosophila S2 embryonic cells, which is expected to provide novel insights for the pathogenesis of male infertility and spermatogenesis.

Tailored Beta-Lapachone Nanomedicines for Cancer-Specific Therapy

Nanotechnology shows the power to improve efficacy and reduce the adverse effects of anticancer agents. As a quinone-containing compound, beta-lapachone (LAP) is widely employed for targeted anticancer therapy under hypoxia. The principal mechanism of LAP-mediated cytotoxicity is believed due to the continuous generation of reactive oxygen species with the aid of NAD(P)H: quinone oxidoreductase 1 (NQO1). The cancer selectivity of LAP relies on the difference between NQO1 expression in tumors and that in healthy organs. Despite this, the clinical translation of LAP faces the problem of narrow therapeutic window that is challenging for dose regimen design. Herein, the multifaceted anticancer mechanism of LAP is briefly introduced, the advance of nanocarriers for LAP delivery is reviewed, and the combinational delivery approaches to enhance LAP potency in recent years are summarized. The mechanisms by which nanosystems boost LAP efficacy, including tumor targeting, cellular uptake enhancement, controlled cargo release, enhanced Fenton or Fenton-like reaction, and multidrug synergism, are also presented. The problems of LAP anticancer nanomedicines and the prospective solutions are discussed. The current review may help to unlock the potential of cancer-specific LAP therapy and speed up its clinical translation.

Self-driven nanoprodrug platform with enhanced ferroptosis for synergistic photothermal-IDO immunotherapy

Insufficient immune stimulation and stubborn immune resistance are the critical factors limiting tumor immunotherapy. Here, we report a multifunctional nanoprodrug platform with self-driven indoximod (IND) release and oxidative stress amplification. The aim is to awaken immune responses and block the indoleamine 2,3-dioxygenase (IDO) pathway through a combination of ferroptosis, photothermal therapy, and immunotherapy. This nanosystem improved the delivery efficiency of IND due to click chemistry linked ROS responsive prodrug and self-driven drug release. Meanwhile, the tactic of simultaneously increasing ROS and eliminating GSH amplified oxidative stress and strengthened ferroptosis, which further enhanced immunogenicity along with polydopamine-based photothermal therapy. IDO immunization combined with ferroptosis as well as photothermal therapy not only stimulated immune response, but also reversed immune suppression with enhanced immune memory. Therefore, primary tumor, distant tumor, and cancer metastasis were inhibited. This study provides a perspective on immunotherapeutics for cancer treatment.

A Strategy of Fenton Reaction Cycloacceleration for High-Performance Ferroptosis Therapy Initiated by Tumor Microenvironment Remodeling

The emerging tumor ferroptosis therapy confronts impediments of the tumor microenvironment (TME) with weak intrinsic acidity, inadequate endogenous H2 O2 , and a powerful intracellular redox balance system that eliminates toxic reactive oxygen species (ROS). Herein, a strategy of Fenton reaction cycloacceleration initiated by remodeling the TME for magnetic resonance imaging (MRI)-guided high-performance ferroptosis therapy of tumors is proposed. The synthesized nanocomplex exhibits enhanced accumulation at carbonic anhydrase IX (CAIX)-positive tumors based on the CAIX-mediated active targeting, and increased acidification via the inhibition of CAIX by 4-(2-aminoethyl) benzene sulfonamide (ABS) (remodeling TME). This accumulated H+ and abundant glutathione in TME synergistically trigger biodegradation of the nanocomplex to release the loaded cuprous oxide nanodots (CON), β-lapachon (LAP), Fe3+ , and gallic acid-ferric ions coordination networks (GF). The Fenton and Fenton-like reactions are cycloaccelerated via the catalytic loop of Fe-Cu, and the LAP-triggered and nicotinamide adenine dinucleotide phosphate quinone oxidoreductase1-mediated redox cycle, generating robust ROS and plenitudinous lipid peroxides accumulation for ferroptosis of tumor cells. The detached GF network has improved relaxivities in response to the TME. Therefore, the strategy of Fenton reaction cycloacceleration initiated by remodeling the TME is promising for MRI-guided high-performance ferroptosis therapy of tumors.

Fabrication of a composite 3D-printed titanium alloy combined with controlled in situ drug release to prevent osteosarcoma recurrence

Osteosarcoma is a malignant bone tumor occurring in adolescents. Surgery combined with adjuvant or neoadjuvant chemotherapy is the standard treatment. However, systemic chemotherapy is associated with serious side effects and a high risk of postoperative tumor recurrence, leading to a high amputation rate and mortality in cancer patients. Implant materials that can simultaneously repair large bone defects and prevent osteosarcoma recurrence are in urgent need. Herein, an intelligent system comprising 3D-printed titanium scaffold (TS) and pH-responsive PEGylated paclitaxel prodrugs was fabricated for bone defect reconstruction and recurrence prevention following osteosarcoma surgery. The drug-loaded implants exhibited excellent stability and biocompatibility for supporting the activity of bone stem cells under normal body fluid conditions and the rapid release of drugs in response to faintly acidic environments. An in vitro study demonstrated that five human osteosarcoma cell lines could be efficiently eradicated by paclitaxel released in an acidic microenvironment. Using mice models, we demonstrated that the drug-loaded TS can enable a pH-responsive treatment of postoperative tumors and effectively prevent osteosarcoma recurrence. Therefore, local implantation of this composite scaffold may be a promising topical therapeutic method to prevent osteosarcoma recurrence.

Injectable thermo-sensitive hydrogel loaded hollow copper sulfide nanoparticles for ROS burst in TME and effective tumor treatment

Introduction: Lung cancer the most prevalent cause of cancer-related deaths, and current therapies lack sufficient specificity and efficacy. This study developed an injectable thermosensitive hydrogel harboring hollow copper sulfide nanoparticles and β-lapachone (Lap) (CLH) for lung tumor treatment. Methods: The hydrogel-encapsulated CLH system can remotely control the release of copper ions (Cu2+) and drugs using photothermal effects for non-invasive controlled-release drug delivery in tumor therapy. The released Cu2+ consumes the overexpressed GSH in TME and the generated Cu+ further exploits the TME characteristics to initiate nanocatalytic reactions for generating highly toxic hydroxyl radicals. In addition, in cancer cells overexpressing Nicotinamide adenine dinucleotide (phosphate): quinone oxidoreductase 1 (NQO1), Lap can catalyze the generation of hydrogen peroxide (H2O2) through futile redox cycles. H2O2 is further converted into highly toxic hydroxyl radicals via the Fenton-like reaction, leading to a burst of reactive oxygen species in TME, which further enhances the therapeutic effect of chemokines. Results: Analysis of the antitumor efficacy in a subcutaneous A549 lung tumor model mice showed a significant delay in tumor growth and no systemic toxicity was detected. Discussion: In conclusion, we have established a CLH nanodrug platform that enables efficient lung tumor therapy through combined photothermal/chemodynamic therapy (CDT) treatment and self-supplying H2O2 to achieve cascade catalysis, leading to explosive amplification of oxidative stress.

A Smart Benzothiazole-Based Conjugated Polymer Nanoplatform with Multistimuli Response for Enhanced Synergistic Chemo-Photothermal Cancer Therapy

The combination of chemotherapy and phototherapy has received tremendous attention in multimodal cancer therapy. However, satisfactory therapeutic outcomes of chemo-photothermal therapy (chemo-PTT) still remain challenging. Herein, a biocompatible smart nanoplatform based on benzothiazole-linked conjugated polymer nanoparticles (CPNs) is rationally designed, for effectively loading doxorubicin (DOX) and Mo-based polyoxometalate (POM) through both dynamic chemical bond and intermolecular interactions, with an expectation to obtain new anticancer drugs with multiple stimulated responses to the tumor microenvironment (TME) and external laser irradiation. Controlled drug release of DOX from the obtained nanoformulation (CPNs-DOX-PEG-cRGD-BSA@POM) triggered by both endogenous stimulations (GSH and low pH) and exogenous laser irradiation has been well demonstrated by pharmacodynamics investigations. More intriguingly, incorporating POM into the nanoplatform not only enables the nanomedicine to achieve mild hyperthermia but also makes it exhibit self-assembly behavior in acidic TME, producing enhanced tumor retention. Benefiting from the versatile functions, the prepared CPNs-DOX-PEG-cRGD-BSA@POM exhibited excellent tumor targeting and therapeutic effects in murine xenografted models, showing great potential in practical cancer therapy.

Inspired by bis-β-carboline alkaloids: Construction and antitumor evaluation of a novel bis-β-carboline scaffold as potent antitumor agents

Bis-β-carboline alkaloids are widely distributed in natural products and represent a promising drug-like scaffold for discovering drugs and bioactive molecules. In this study, we utilized the structural simplification strategy to construct a novel bis-β-carboline scaffold via "one-pot" condensation-Mannich reaction. The simplified bis-β-carboline derivatives were obtained in good yield. Antitumor evaluation revealed most compounds, especially 3m, displayed potent antitumor activity (IC₅₀ values for 3m: 0.96 μM ∼ 1.52 μM). More importantly, 3m displayed valuable antitumor properties including anti-migration and anti-invasion activity against cancer cells, antiangiogenic and vascular-disrupting properties. Mechanistic studies revealed 3m potently inhibited both Top1 and Top2 activity, thus interfering with DNA synthesis in cancer cells. Taken together, this study developed a new synthetic methodology to construct a novel bis-β-carboline scaffold, which represents a promising lead structure for antitumor drug discovery.

Iron-doped cross-linked lipoic acid nano-aggregates for ferroptosis-mediated cancer treatment

Recently, Fenton reaction-mediated ferroptosis has attracted great attention in cancer treatment while the metabolism loss of iron and the limited endogenous H₂O₂ level imped its clinical application. Here, a new ferroptosis inducer (Fe@cLANAs) constructed only by Fe(II) and (R)-(+)-lipoic acid (LA) was developed for tumor ablation. After entering the tumor cells, the Fe@cLANAs dissociated into disdihydrolipoic acid (DHLA) and released iron, which would regenerate each other to continuously provide iron and H₂O₂ to enhance ferroptosis. The Fe@cLANAs demonstrated the IC₅₀^Fe below 10 μM against various tumor cells, an anti-tumor effect comparable to many chemotherapy drugs. In vivo antitumor evaluation based on the tumor cell-derived xenograft model showed a tumor inhibitory rate (TIR) of 97.4% at the iron usage of 1.53 mg/kg, the lowest iron usage reported so far in ferrotherapy using iron as the main agent to treat tumors. Notably, the good anti-tumor effect of Fe@cLANAs was further achieved in the glioma patient-derived xenograft (PDX) model. This strategy utilizing the reciprocal circulation of metal iron and LA to delay the metabolism loss of iron and increase the H₂O₂ level in the tumor cells holds a great potential for ferroptosis-mediated cancer treatment. STATEMENT OF SIGNIFICANCE: The metabolism loss of iron and the limited endogenous H₂O₂ level are key factors to impede the clinical application of ferroptosis-mediated cancer treatment. Herein, a new ferroptosis inducer constructed only by lipoic acid and iron is developed to delay the metabolism loss of iron and increase the level of endogenous H₂O₂ by causing a cyclic regeneration of Fe(II)/Fe(III) and LA/DHLA in the tumor cells. According to the previous reports, at least 75 mg/kg of iron dosage was needed to achieve effective antitumor efficacy, here, the use of only 1.53 mg/kg iron in Fe@cLANAs achieved the TIR of 97.4% and 62.8% in the U251 CDX and glioma PDX models, showing the good prospect of Fe@cLANAs in clinic.

Amplification of Lipid Peroxidation by Regulating Cell Membrane Unsaturation To Enhance Chemodynamic Therapy

Lipid peroxidation (LPO) is one of the most damaging processes in chemodynamic therapy (CDT). Although it is well known that polyunsaturated fatty acids (PUFAs) are much more susceptible than saturated or monounsaturated ones to LPO, there is no study exploring the effect of cell membrane unsaturation degree on CDT. Here, we report a self-reinforcing CDT agent (denoted as OA@Fe-SAC@EM NPs), consisting of oleanolic acid (OA)-loaded iron single-atom catalyst (Fe-SAC)-embedded hollow carbon nanospheres encapsulated by an erythrocyte membrane (EM), which promotes LPO to improve chemodynamic efficacy via modulating the degree of membrane unsaturation. Upon uptake of OA@Fe-SAC@EM NPs by cancer cells, Fe-SAC-catalyzed conversion of endogenous hydrogen peroxide into hydroxyl radicals, in addition to initiating the chemodynamic therapeutic process, causes the dissociation of the EM shell and the ensuing release of OA that can enrich cellular membranes with PUFAs, enabling LPO amplification-enhanced CDT.