A ROS-responsive and scavenging hydrogel for postoperative abdominal adhesion prevention.

Postoperative abdominal adhesion (PAA) widely occurs after abdominal surgery, which often produces severe complications. However, there were still no satisfactory anti-adhesive products including barriers and anti-adhesive agents. Herein, we developed a ROS-responsive and scavenging hydrogel barrier, termed AHBC/PSC, wherein the monomer AHBC was synthesized by phenylboronic acid (PBA)-modified hyaluronic acid (HA-PBA) further grafted with adipic dihydrazide (ADH) and PBA-based chlorogenic acid (CGA) via ROS-sensitive borate ester bond, and the other monomer PSC was constructed by polyvinyl alcohol (PVA) grafted with sulfated betaine (SB) and p-hydroxybenzaldehyde (-CHO). Further, the double crosslinked AHBC/PSC hydrogel was successfully fabricated between AHBC and PSC via forming dynamic covalent acylhydrazone bonds and borate ester bonds. Results showed that AHBC/PSC hydrogel had in situ gelation behavior, satisfactory mechanical properties (storage modulus of about 1 kPa and loss factor Tan δ of about 0.5), suitable wet tissue adhesion strength of about 2.3 kPa on rat abdominal wall, and good biocompatibility, achieving an ideal physical barrier. Particularly, CGA could be responsively released from the hydrogel by breakage of borate ester bonds between CGA and PBA based on high reactive oxygen species (ROS) levels of damaged tissue and exhibited great ROS scavenging capability to regulate inflammation and promote the polarization of macrophages from pro-inflammatory M1 phenotype to anti-inflammatory M2 phenotype. Moreover, the grafted SB as a zwitterionic group could reduce protein adsorption and fibroblast adhesion. Finally, the in vivo experiments revealed that AHBC/PSC hydrogel with good safety and in vivo retention behavior of about 2 weeks, effectively prevented PAA by regulating the inflammatory microenvironment and alleviating the fibrosis process. In brief, the versatile AHBC/PSC hydrogel would provide a more convenient and efficient approach for PAA prevention. STATEMENT OF SIGNIFICANCE: Postoperative abdominal adhesion (PAA) widely occurs after surgery and is often accompanied by severe complications. Excessive inflammation and oxidative stress are very crucial for PAA formation. This study provides a ROS-responsive and scavenging hydrogel with suitable mechanical properties, good biocompatibility and biodegradability, and resistance to protein and fibroblast. The antioxidant and anti-inflammatory active ingredient could be responsively released from the hydrogel via triggering by the high ROS levels in the postoperative microenvironment thereby regulating the inflammatory balance. Finally, the hydrogel would effectively regulate the development process of PAA thereby achieving non-adhesion wound healing.

Engineered low-pathogenic Helicobacter pylori as orally tumor immunomodulators for the stimulation of systemic immune response.

Gastric cancer constitutes a malignant neoplasm characterized by heightened invasiveness, posing significant global health threat. Inspired by the analysis that gastric cancer patients with Helicobacter pylori (H. pylori) infection have higher overall survival, whether H. pylori can be used as therapeutics agent and oral drug delivery system for gastric cancer. Hence, we constructed engineered H. pylori for gastric cancer treatment. A type Ⅱ H. pylori with low pathogenicity, were conjugated with photosensitizer to develop the engineered living bacteria NIR-triggered system (Hp-Ce6). Hp-Ce6 could maintain activity in stomach acid, quickly infiltrate through mucus layer and finally migrate to tumor region owing to the cell morphology and urease of H. pylori. H. pylori, accumulated in the tumor site, severed as vaccine to activate cGAS-STING pathway, and synergistically remodel the macrophages phenotype. Upon irradiation within stomach, Hp-Ce6 directly destroyed tumor cells via photodynamic effect inherited by Ce6, companied by inducing immunogenic tumor cell death. Additionally, Hp-Ce6 exhibited excellent biosafety with fecal elimination and minimal blood absorption. This work explores the feasibility and availability of H. pylori-based oral delivery platforms for gastric tumor and further provides enlightening strategy to utilize H. pylori invariably presented in the stomach as in-situ immunomodulator to enhance antitumor efficacy.

ROS-responsive sprayable hydrogel as ROS scavenger and GATA6+ macrophages trap for the prevention of postoperative abdominal adhesions.

Postoperative abdominal adhesions are a common clinical problem after surgery and can cause many serious complications. Current most commonly used antiadhesion products are less effective due to their short residence time and focus primary on barrier function. Herein, we developed a sprayable hydrogel barrier (sHA-ADH/OHA-E) with self-regulated drug release based on ROS levels at the trauma site, to serve as a smart inflammatory microenvironment modulator and GATA6+ macrophages trap for non-adherent recovery from abdominal surgery. Sulfonated hyaluronic acid (HA) conjugates modified with adipic dihydrazide (sHA-ADH), and oxidized HA conjugates grafted with epigallocatechin-3-gallate (EGCG) via ROS-cleavable boronate bonds (OHA-E) were synthesized. sHA-ADH/OHA-E hydrogel was facilely fabricated within 5 s after simply mixing sHA-ADH and OHA-E through forming dynamic covalent acylhydrazones. With good biocompatibility, appropriate mechanical strength, tunable shear-thinning, self-healing, asymmetric adhesion, and reasonable in vivo retention time, sHA-ADH/OHA-E hydrogel meets the requirements of a perfect physical barrier. Intriguingly, sulfonic acid groups endowed the hydrogel with satisfactory anti-fibroblast and macrophage attachment capability, and were demonstrated for the first time to act as polyanion traps to prevent GATA6+ macrophages aggregation. Importantly, EGCG could be intelligently released by ROS triggering to alleviate oxidative stress and promote proinflammatory M1 macrophage polarize to antiinflammatory M2 phenotype. Further, the fibrinolytic system balance was restored to reduce fibrosis. Thanks to the above advantages, the sHA-ADH/OHA-E hydrogel exhibited excellent anti-adhesion effects in a rat sidewall defect-cecum abrasion model and is expected to be a promising and clinically translatable antiadhesion barrier.

A mitochondria-targeting ROS-activated nanoprodrug for self-augmented antitumor oxidation therapy.

Mitochondrion is an ideal target for amplifying ROS attack in antitumor treatment. Benefiting from distinctive properties of mitochondria, the precise delivery of ROS generator to mitochondria could maximumly utilize ROS for oxidation therapy. Herein, we prepared an innovative ROS-activatable nanoprodrug (HTCF) which dually targets tumor cells and mitochondria for antitumor therapy. Cinnamaldehyde (CA) was conjugated to ferrocene (Fc) and triphenylphosphine by thioacetal linker, to synthesize mitochondria-targeting ROS-activated prodrug (TPP-CA-Fc), which subsequently self-assembled into nanoprodrug via host-guest interactions between TPP-CA-Fc and cyclodextrin-decorated hyaluronic acid conjugate. Under mitochondrial high ROS condition, especially in tumor cells, HTCF selectively initiate in-situ Fenton reaction to catalyze H2O2 into highly cytotoxic •OH, ensuring maximum generation and utilization of •OH for precision CDT. Meanwhile, the mitochondrial high ROS trigger thioacetal bond cleavage and CA release. The released CA stimulate mitochondrial oxidative stress aggravation and H2O2 regeneration, which in turn react with Fc for more •OH generation, forming self-amplifying positive feedback cycle of CA release and ROS burst. With self-augmented Fenton reaction and mitochondria-specific destruction, HTCF ultimately induce intracellular ROS burst and severe mitochondrial dysfunction for amplified ROS-mediated antitumor therapy. Such an ingenious organelles-specialized nanomedicine exhibited prominent antitumor effect both in vitro and in vivo, revealing underlying perspectives to amplify tumor-specific oxidation therapy.

Harnessing Engineered Immune Cells and Bacteria as Drug Carriers for Cancer Immunotherapy.

Immunotherapy continues to be in the spotlight of oncology therapy research in the past few years and has been proven to be a promising option to modulate one's innate and adaptive immune systems for cancer treatment. However, the poor delivery efficiency of immune agents, potential off-target toxicity, and nonimmunogenic tumors significantly limit its effectiveness and extensive application. Recently, emerging biomaterial-based drug carriers, including but not limited to immune cells and bacteria, are expected to be potential candidates to break the dilemma of immunotherapy, with their excellent natures of intrinsic tumor tropism and immunomodulatory activity. More than that, the tiny vesicles and physiological components derived from them have similar functions with their source cells due to the inheritance of various surface signal molecules and proteins. Herein, we presented representative examples about the latest advances of biomaterial-based delivery systems employed in cancer immunotherapy, including immune cells, bacteria, and their derivatives. Simultaneously, opportunities and challenges of immune cells and bacteria-based carriers are discussed to provide reference for their future application in cancer immunotherapy.

pH-activatable oxidative stress amplifying dissolving microneedles for combined chemo-photodynamic therapy of melanoma.

Photodynamic therapy (PDT)-mediated oxidation treatment is extremely attractive for skin melanoma ablation, but the strong hydrophobicity and poor tumor selectivity of photosensitizers, as well as the oxygen-consuming properties of PDT, leading to unsatisfactory therapeutic outcomes. Herein, a tumor acidic microenvironment activatable dissolving microneedle (DHA@HPFe-MN) was developed to realize controlled drug release and excellent chemo-photodynamic therapy of melanoma via oxidative stress amplification. The versatile DHA@HPFe-MN was fabricated by crosslinking a self-synthesized protoporphyrin (PpIX)-ADH-hyaluronic acid (HA) conjugate HA-ADH-PpIX with "iron reservoir" PA-Fe3+ complex in the needle tip via acylhydrazone bond formation, and dihydroartemisinin (DHA) was concurrently loaded in the hydrogel network. HA-ADH-PpIX with improved water solubility averted undesired aggregation of PpIX to ensure enhanced PDT effect. DHA@HPFe-MN with sharp needle tip, efficient drug loading and excellent mechanical strength could efficiently inserted into skin and reach the melanoma sites, where the acidic pH triggered the degradation of microneedles, enabling Fe-activated and DHA-mediated oxidation treatment, as evidenced by abundant reactive oxygen species (ROS) generation. Moreover, under light irradiation, a combined chemo-photodynamic therapeutic effect was achieved with amplified ROS generation. Importantly, the Fe-catalyzed ROS production of DHA was oxygen-independent, which work in synergy with the oxygen-dependent PDT to effectively destroy tumor cells. This versatile microneedles with excellent biosafety and biodegradability can be customized as a promising localized drug delivery system for combined chemo-photodynamic therapy of melanoma.

ROS-triggered cycle amplification effect: A prodrug activation nanoamplifier for tumor-specific therapy.

Selective in situ activation of prodrugs or generation of bioactive drugs is an important approach to reducing the side effects of chemotherapy. Herein, a tailored ROS-activable prodrug nanomedicine (Cu-SK@DTC-PPB) was developed as the prodrug activation nanoamplifier for highly selective antitumor therapy. Cu-SK@DTC-PPB was rationally constructed by the diethyldithiocarbamate (DTC) prodrug DTC-PPB and the nanoscale coordinated framework Cu-SK based on copper and the ROS generator shikonin (SK). Cu2+, SK and DTC were kept in the inactive state in the fabricated Cu-SK@DTC-PPB. In the presence of ROS within tumors, DTC-PPB can be activated to release less cytotoxic DTC, which can rapidly chelate Cu2+ from the Cu-SK framework to synthesize highly cytotoxic Cu(DTC)2 and induce SK to release in a cascade. The released SK can generate ROS to increase the intracellular ROS level, further activating DTC-PPB to release more DTC. That is, Cu-SK@DTC-PPB can undergo a self-amplifying positive feedback loop to induce numerous bioactive Cu(DTC)2 formation and SK release triggered by a small amount of ROS within the tumor microenvironment, which endows the transformation of "less toxic-to-high toxic" and thus significantly improve its selectivity towards tumors. Therefore, this study provides a new strategy of prodrug activation for tumor therapy with high efficiency and low toxicity. STATEMENT OF SIGNIFICANCE: Owing to the striking difference in ROS level between cancer cells and normal cells, ROS-responsive prodrugs are regarded as a promising approach for tumor-specific therapy. However, the stability and responsiveness of prodrugs are hard to balance. Preferable sensitivity may cause premature activation while favorable stability may lead to incomplete prodrug activation and insufficient active drug release. This study provides a tailored ROS-responsive prodrug activation nanoamplifier with favorable stability and effective prodrug activation capacity. The nanoamplifier can undergo a self-amplifying positive feedback loop to achieve numerous bioactive drugs generation in situ under ROS triggers within the tumor microenvironment, showing the enhanced antitumor therapeutic effect. Thus, this study provides a new strategy for prodrug activation and tumor-specific therapy.

Bortezomib prodrug catalytic nanoreactor for chemo/chemodynamic therapy and macrophage re-education.

Chemodynamic therapy (CDT), an emerging tumor-specific therapeutic modality, is frequently restrained by insufficient intratumoral Fenton catalysts and increasingly inefficient catalysis caused by the continuous consumption of limited H2O2 within tumors. Herein, we engineered a pH-responsive bortezomib (BTZ) polymer prodrug catalytic nanoreactor (HeZn@HA-BTZ) capable of self-supplying Fenton catalyst and H2O2. It is aimed for tumor-specific chemo/chemodynamic therapy via oxidative stress and endoplasmic reticulum (ER) stress dual-amplification and macrophage repolarization. A catechol­boronate bond-based hyaluronic acid-BTZ prodrug HA-DA-BTZ was modified on Hemin and Zn2+ coordination nanoscale framework (HeZn), an innovative CDT inducer, to construct He-Zn@HA-BTZ. He-Zn@HA-BTZ with good stability and superior peroxidase-like activity preferentially accumulated at tumor sites and be actively internalized by tumor cells. Under the cleavage of catechol­boronate bond in acidic endo/lysosomes, pre-masked BTZ was rapidly released to induce ubiquitinated protein aggregation, robust ER stress and elevated H2O2 levels. The amplified H2O2 was further catalyzed by HeZn via Fenton-catalytic reactions to produce hypertoxic •OH, enabling cascaded oxidative stress amplification and long-lasting effective CDT, which in turn aggravated BTZ-induced ER stress. Eventually, a dual-amplification of oxidative stress and ER stress was achieved to initiate cell apoptosis/necrosis with reduced BTZ toxicity. Intriguingly, He-Zn@HA-BTZ could repolarize macrophages from M2 to antitumor M1 phenotype for potential tumor therapy. This "all in one" prodrug nanocatalytic reactor not only enriches the CDT inducer library, but provides inspirational strategy for simultaneous oxidative stress and ER stress based excellent cancer therapy.

Fibroblast activation protein α activatable theranostic pro-photosensitizer for accurate tumor imaging and highly-specific photodynamic therapy.

The development of activatable photosensitizers (aPSs) responding to tumor-specific biomarkers for precision photodynamic therapy (PDT) is urgently required. Due to the unique proteolytic activity and highly restricted distribution of tumor-specific enzymes, enzyme activatable photosensitizers display superior selectivity. Methods: Herein, a series of novel Fibroblast Activation Protein α (FAPα) activatable theranostic pro-photosensitizers were designed by conjugating the different N-terminal blocked FAPα-sensitive dipeptide substrates with a clinical PS, methylene blue (MB), through a self-immolative linker, which resulting in the annihilation of the photoactivity (fluorescence and phototoxicity). The best FAPα-responsive pro-photosensitizer was screened out through hydrolytic efficiency and blood stability. Subsequently, a series of in vitro and in vivo experiments were carried out to investigate the FAPα responsiveness and enhanced PDT efficacy. Results: The pro-photosensitizers could be effectively activated by tumor-specific FAPα in the tumor sites. After response to FAPα, the "uncaged" MB can recover its fluorescence and phototoxicity for tumor imaging and cytotoxic singlet oxygen (1O2) generation, eventually achieving accurate imaging-guided PDT. Simultaneously, the generated azaquinone methide (AQM) could serve as a glutathione (GSH) scavenger to rapidly and irreversibly weaken intracellular antioxidant capacity, realizing synergistic oxidative stress amplification and enhanced PDT effect. Conclusion: This novel FAPα activatable theranostic pro-photosensitizers allow for accurate tumor imaging and admirable PDT efficacy with minimal systemic side effects, offering great potential in clinical precision antitumor application.

A DNA damage nanoamplifier for the chemotherapy of triple-negative breast cancer via DNA damage induction and repair blocking.

Due to a powerful DNA damage repair system and a lack of surface markers, there is currently no effective chemotherapy or tailored targeted therapies available for triple-negative breast cancer (TNBC) treatment. Herein, a tailored DNA damage nanoamplifier (Lipo@Nir/Pt(IV)C18) was engineered to simultaneously induce DNA damage and inhibit DNA reparation for highly efficient TNBC treatment. A newly synthesized Pt(IV)C18 prodrug, the DNA damaging inducer, and the hydrophobic poly(ADP-ribose) polymerases (PARPs) inhibitor niraparib, which is used as the DNA repair blocker, were concurrently encapsulated in highly biocompatible PEGylated liposomes to prepare Lipo@Nir/Pt(IV)C18, for enhanced cancer therapy and future clinical translation. Lipo@Nir/Pt(IV)C18 with an appropriate size and excellent stability, effectively accumulated at the tumor site. After internalization by tumor cells, niraparib, a highly-selective hydrophobic PARP1 inhibitor, could exacerbate the accumulation of platinum-induced DNA lesions to induce excessive genome damage for synergistic cell apoptosis, which was evidenced by the upregulated γ-H2AX and cleaved-PARP levels. Importantly, Lipo@Nir/Pt(IV)C18 exhibited remarkable antitumor efficacy on TNBC without BRCA mutants in vivo with little systemic toxicity. Inspired by the concept of "synthetic lethality", this study provides an inspirational and clinically transformable nanobased DNA damaging amplification strategy for the expansion of TNBC beneficiaries and highly efficient TNBC treatment via DNA damage induction and DNA repair blocking.

A Stimuli-Responsive Small-Molecule Metal-Carrying Prochelator: A Novel Prodrug Design Strategy for Metal Complexes.

Selective activation of prodrugs is an important approach to reduce the side effects of disease treatment. We report a prodrug design concept for metal complexes, termed "metal-carrying prochelator", which can co-carry a metal ion and chelator within a single small-molecule compound and remain inert until it undergoes a specifically triggered intramolecular chelation to synthesize a bioactive metal complex in situ for targeted therapy. As a proof-of-concept, we designed a H2 O2 -responsive small-molecule prochelator, DPBD, based on the strong chelator diethyldithiocarbamate (DTC) and copper. DPBD can carry Cu2+ (DPBD-Cu) and respond to elevated H2 O2 levels in tumor cells by releasing DTC, which rapidly chelates Cu2+ from DPBD-Cu affording a DTC-copper complex with high cytotoxicity, realizing potent antitumor efficacy with low systemic toxicity. Thus, with its unique intramolecularly triggered activation mechanism, this concept based on a small-molecule metal-carrying prochelator can help in the prodrug design of metal complexes.

Reactive oxygen species-activated self-amplifying prodrug nanoagent for tumor-specific Cu-chelate chemotherapy and cascaded photodynamic therapy.

Disulfiram (DSF), an effective FDA-approved anti-alcoholism drug, shows potent antitumor activity by producing Cu(DTC)2, a chelate of its metabolite diethyldithiocarbamate (DTC) and copper. However, the rapid metabolism and unselective distribution of DSF and the insufficient endogenous copper severely restrict enough bioactive Cu(DTC)2 generation in tumor tissues to achieve satisfactory antitumor effect. Moreover, directly Cu(DTC)2 administration also suffers from serious systemic toxicity. Herein, a reactive oxygen species (ROS)-activatable self-amplifying prodrug nanoagent (HA-DQ@MOF) was developed for the stable co-delivery of DTC prodrug and Cu-quenched photosensitizer, aiming to achieve tumor-specific dual-activation of highly-toxic Cu(DTC)2-mediated chemotherapy and cascaded photodynamic therapy (PDT). The ROS-cleavable hyaluronic acid-conjugated DTC prodrug (HA-DQ) was decorated on Cu2+ and photosensitizer Zn-TCPP coordinated MOF (PDT-shielded state) to construct HA-DQ@MOF. HA-DQ@MOF could specifically activated in ROS-overexpressed tumor cells to rapidly release DTC, while remaining relatively stable in normal cells. The free DTC immediately grabbed Cu2+ from MOF to in situ generate highly-cytotoxic Cu(DTC)2 chelate, accompanied by MOF dissociation to restore the PDT effect of Zn-TCPP. Importantly, ROS produced by PDT could in turn trigger more DTC release, which further promoted Zn-TCPP liberation, forming a self-amplifying prodrug/photosensitizer activation positive feedback loop. Experimental results confirmed the dual-activated and combined tumor-killing effect of Cu(DTC)2-mediated chemotherapy and Zn-TCPP-based PDT with little systemic toxicity. This work provides a dual-activated "low toxic-to-toxic" transformable treatment pattern for tumor-specific chemo-photodynamic therapy.

Glutathione-responsive copper-disulfiram nanoparticles for enhanced tumor chemotherapy.

Disulfiram (DSF), a familiar FDA-approved drug used for alcohol withdrawal, has recently been verified with potent antitumor therapeutic effect by generating Cu(DTC)2, which is the complex of its metabolite diethyldithiocarbamate (DTC) and copper. However, its poor tumor selectivity and insufficient endogenous Cu2+ concentration within tumor site largely hinders the application of DSF-based antitumor therapy. Therefore, a GSH-responsive coordination nanoparticles (Cu-IXZ@DSF) was established as a copper carrier to achieve synchronous but separate delivery of Cu2+ and DSF without antitumor ability, further to realize selectively triggered tumor in situ Cu(DTC)2 generation for antitumor therapy. A widely-used proteasome inhibitor ixazomib (IXZ) was chosen as ligands and Cu2+ was used as coordination nodes to form nanosized Cu-IXZ@DSF. The DSF encapsulated in Cu-IXZ@DSF could be reduced to DTC by intracellular GSH, which could contend for Cu2+ and realize in situ high toxic Cu(DTC)2 generation. Meanwhile, the chelation could lead to the disassembly of Cu-IXZ@DSF and release of IXZ to eventually achieve tumor specific "transformation from low toxicity to high toxicity" chemotherapy. The results of in vitro and in vivo experiments demonstrated that the as-prepared nanoplatform Cu-IXZ@DSF showed good biosafety and excellent antitumor effect via endoplasmic reticulum stress (ERS) as well as reactive oxygen species (ROS) generation pathway. Therefore, this nanocarrier provides an inspiring strategy with specific-triggered antitumor Cu(DTC)2 generation for DSF-based chemotherapy with high therapeutic effect and biosafety and showing great potential of treating cancer.

"NIR-triggered ROS storage" photodynamic intraocular implant for high-efficient and safe posterior capsular opacification prevention.

Posterior capsular opacification (PCO) is the leading cause of vision loss after cataract, mainly caused by the adhesion, proliferation and trans-differentiation of post-operative residual lens epithelial cells (LECs). Effective PCO prevention remains a huge challenge to ophthalmologists and researches for decades. Herein, we developed a "NIR-triggered ROS storage" intraocular implant (CTR-Py-PpIX) based on capsular tension ring (CTR), which is concurrently linked with photosensitizer protophorphyrin IX (PpIX) and energy storage 2-pyridone derivative (Py), to guarantee instantaneous and sustainable ROS generation for LECs killing, aiming to achieve more efficient and safer photodynamic therapy (PDT) to effectively prevent PCO. The silylated PpIX-Si and Py-Si were covalently conjugated to the plasma activated CTR surface to obtain CTR-Py-PpIX. Results demonstrated that CTR-Py-PpIX had dual functions of PDT and battery, in which PpIX could generate ROS extracellularly under irradiation, with one part directly inhibiting LECs by lipid peroxidation (LPO) induction of cell membranes. Meanwhile, the excess ROS stored in Py could be continuously released to amplify LPO levels after the irradiation was removed. Ultimately, the proliferation of LECs in capsular bag was completely inhibited under mild irradiation conditions, achieving a sustainable and controlled PDT effect for effective PCO prevention with good biocompatibility. This NIR-triggered ROS storage intraocular implant would provide a more efficient and safer approach for long-term PCO prevention.

Reactive oxygen species-activatable self-amplifying Watson-Crick base pairing-inspired supramolecular nanoprodrug for tumor-specific therapy.

Intratumoral upregulated reactive oxygen species (ROS) has been extensively exploited as exclusive stimulus to activate drug release for tumor-specific therapy. However, insufficient endogenous ROS and tumor heterogeneity severely restrict clinical translation of current ROS-responsive drug delivery systems. Herein, a tailored ROS-activatable self-amplifying supramolecular nanoprodrug was developed for reinforced ROS-responsiveness and highly selective antitumor therapy. A novel ROS-cleavable CA-based thioacetal linker CASOH was synthesized with ROS generator cinnamaldehyde (CA) incorporated into its molecular structure, to skillfully realize self-amplifying positive feedback loop of "ROS-activated CA release with CA-induced ROS regeneration". CASOH was modified with a cytosine analogue gemcitabine (GEM) to obtain ROS-activatable self-immolative prodrug CAG, which could be selectively activated in tumor cells and further achieve self-boosting "snowballing" activation via ROS compensation, while keep inactive in normal cells. Through Watson-Crick nucleobase pairing (G≡C)-like hydrogen bonds, CAG efficiently crosslinked with a matched guanine-rich acyclovir-modified hyaluronic acid conjugate HA-ACV, to self-assemble into pH/ROS dual-responsive supramolecular nanoprodrug HCAG. With high stability, beneficial tumor targeting capacity and pH/ROS-responsiveness, HCAG nanoformulation exhibited remarkable in vivo antitumor efficacy with minimal systemic toxicity. Based on unique tumor-specific self-amplifying prodrug activation and Watson-Crick base pairing-inspired supramolecular self-assembly, this study provides an inspirational strategy of exploiting novel ROS-responsive nanoplatform with reinforced responsiveness and specificity for future clinical translation.

Discovery of a Potent Glutathione Peroxidase 4 Inhibitor as a Selective Ferroptosis Inducer.

Potent and selective ferroptosis regulators promote an intensive understanding of the regulation and mechanisms underlying ferroptosis, which is highly associated with various diseases. In this study, through a stepwise structure optimization, a potent and selective ferroptosis inducer was developed targeting to inhibit glutathione peroxidase 4 (GPX4), and the structure-activity relationship (SAR) of these compounds was uncovered. Compound 26a exhibited outstanding GPX4 inhibitory activity with a percent inhibition up to 71.7% at 1.0 µM compared to 45.9% of RSL-3. At the cellular level, 26a could significantly induce lipid peroxide (LPO) increase and effectively induce ferroptosis with satisfactory selectivity (the value of 31.5). The morphological analysis confirmed the ferroptosis induced by 26a. Furthermore, 26a significantly restrained tumor growth in a mouse 4T1 xenograft model without obvious toxicity.

Phototriggered Self-Adaptive Functionalized MOC-Based Drug Delivery Platform Promises High Antitumor Efficacy.

Due to their great stability and special cavities, metal-organic cages (MOCs) are increasingly considered as promising nanocarriers for drug delivery. However, the size and surface dilemmas restrict their further biomedical applications. The ultrasmall size of MOCs facilitates tumor penetration but suffers from quick clearance and poor accumulation at the tumor site. Hydrophobicity of MOC surfaces improves internalization into tumor cells while causing low blood circulation time as well as poor biocompatibility. Therefore, it remains challenging for the MOC-based drug delivery nanoplatform to realize high therapeutic efficacy because it requires different or even opposite dimensions and surface characteristics in different steps of circulation, penetration, accumulation, and internalization processes. In this study, an unprecedented phototriggered self-adaptive platform (ZnPc@polySCage) is developed by integrating functionalized MOCs and a photodynamic therapy based reactive oxygen species responsive strategy to realize high-efficiency tumor-specific therapy. ZnPc@polySCage remains hydrophilic and stealthy during circulation, and retains its small original size for tumor penetration, while transforming to a larger size for effective accumulation and hydrophobic for enhanced internalization under laser irradiation in tumor tissue. With these essential transitions, ZnPc@polySCage demonstrates prominent antitumor effects. Overall, the work provides an advantageous strategy for functional MOC-based platforms and biomedical applications.

Engineered macrophages as near-infrared light activated drug vectors for chemo-photodynamic therapy of primary and bone metastatic breast cancer.

Patients with primary and bone metastatic breast cancer have significantly reduced survival and life quality. Due to the poor drug delivery efficiency of anti-metastasis therapy and the limited response rate of immunotherapy for breast cancer, effective treatment remains a formidable challenge. In this work, engineered macrophages (Oxa(IV)@ZnPc@M) carrying nanomedicine containing oxaliplatin prodrug and photosensitizer are designed as near-infrared (NIR) light-activated drug vectors, aiming to achieve enhanced chemo/photo/immunotherapy of primary and bone metastatic tumors. Oxa(IV)@ZnPc@M exhibits an anti-tumor M1 phenotype polarization and can efficiently home to primary and bone metastatic tumors. Additionally, therapeutics inside Oxa(IV)@ZnPc@M undergo NIR triggered release, which can kill primary tumors via combined chemo-photodynamic therapy and induce immunogenic cell death simultaneously. Oxa(IV)@ZnPc@M combined with anti-PD-L1 can eliminate primary and bone metastatic tumors, activate tumor-specific antitumor immune response, and improve overall survival with limited systemic toxicity. Therefore, this all-in-one macrophage provides a treatment platform for effective therapy of primary and bone metastatic tumors.

Reduction-responsive dehydroepiandrosterone prodrug nanoparticles loaded with camptothecin for cancer therapy by enhancing oxidation therapy and cell replication inhibition.

The pentose phosphate pathway (PPP) plays a critical role by providing ribulose-5-phosphate (Ru5P) and NADPH for nucleotide synthesis and reduction energy, respectively. Accordingly, blocking the PPP process may be an effective strategy for enhancing oxidation therapy and inhibiting cell replication. Here, we designed a novel reduction-responsive PEGylated prodrug and constructed nanoparticles PsD@CPT to simultaneously deliver a PPP blocker, dehydroepiandrosterone (DHEA), and chemotherapeutic camptothecin (CPT) to integrate amplification of oxidation therapy and enhance cell replication inhibition. Following cellular uptake, DHEA and CPT were released from PsD@CPT in the presence of high glutathione (GSH) levels. As expected, DHEA-mediated reduction level decreases and CPT-induced oxidation level increases synergistically, breaking the redox balance to aggravate cancer oxidative stress. In addition, suppressing nucleotide synthesis by DHEA through the reduction of Ru5P and blocking DNA replication by CPT further motivates a synergistic inhibition effect on tumor cell proliferation. The results showed that PsD@CPT featuring multimodal treatment has satisfactory antitumor activity both in vitro and in vivo. This study provides a new tumor treatment strategy, which combines the amplification of oxidative stress and enhancement of inhibition of cell proliferation based on inhibition of the PPP process.

NIR-triggered thermo-responsive biodegradable hydrogel with combination of photothermal and thermodynamic therapy for hypoxic tumor.

Hypoxia is a typical feature of solid tumors, which highly limits the application of the oxygen-dependent therapy. Also, the dense and hyperbaric tumor tissues impede the penetration of nanoparticles into the deep tumor. Thereby, we designed a novel localized injectable hydrogel combining the photothermal therapy (PTT) and the thermodynamic therapy (TDT), which is based on the generation of free radicals even in the absence of oxygen for hypoxic tumor therapy. In our study, gold nanorods (AuNRs) and 2,2'-Azobis[2-(2-imidazalin-2-yl)propane] dihydrochlaride (AIPH) were incorporated into the hydrogel networks, which were formed by the copolymerization of hydrophobic N-isopropyl acrylamide (NIPAM) and hydrophilic glycidyl methacrylate modified hyaluronic acid (HA-GMA) to fabricate an injectable and near-infrared (NIR) responsive hydrogel. The crosslinked in situ forming hydrogel could not only realize PTT upon the NIR laser irradiation, but also generate free radicals even in hypoxic condition. Meanwhile the shrink of hydrogels upon thermal could accelerate the generation of free radicals to further damage the tumors, achieving the controlled drug release on demand. The designed hydrogel with a sufficient loading capacity, excellent biocompatibility and negligible systemic toxicity could serve as a long-acting implant for NIR-triggered thermo-responsive free radical generation. The in vitro cytotoxicity result and the in vivo antitumor activity illustrated the excellent therapeutic effect of hydrogels even in the absence of oxygen. Therefore, this innovative oxygen-independent platform combining the antitumor effects of PTT and TDT would bring a new insight into hypoxic tumor therapy by the application of alkyl free radical.