Self-amplified chain-shattering cinnamaldehyde-based poly(thioacetal) boosts cancer chemo-immunotherapy

Harnessing Dual-Responsive Polymeric Micelles for Precision Oxidative Stress Amplification in Targeted Cancer Therapy

Targeting the altered redox balance in cancer cells, this study explores a strategy to induce selective cancer cell death by combining reactive oxygen species (ROS) generation with glutathione (GSH) depletion. We developed oxidative stress-amplifying polymeric (pCB) micelles that function both as therapeutic agents and carriers for GSH-depleting retinoic acid prodrug (BRDP). pCB incorporating ROS-generating cinnamaldehyde and a GSH-depleting quinone methide precursor could self-assemble into micelles encapsulating BRDP, delivering both ROS generators and GSH-depleting drugs. The micelles were surface-functionalized with the tripeptide Arg-Gly-Asp (RGD) for targeted delivery to integrin-overexpressing tumors. In a mouse xenograft model, RGD-decorated BRDP-loaded micelles significantly accumulated in tumor sites, enhancing anticancer efficacy without toxicity to normal tissues. This study marks significant advancement in the field of oxidative stress-amplifying polymeric precursors, presenting a novel and highly effective anticancer therapeutic approach that integrates multiple tumor-specific triggers and ROS-mediated mechanisms.

An in situ-activated and chemi-excited photooxygenation system based on G-poly(thioacetal) for Aβ1-42 aggregates

The abnormal aggregation of Aβ proteins, inflammatory responses, and mitochondrial dysfunction have been reported as major targets in Alzheimer's disease (AD). Photooxygenation of the amyloid-β peptide (Aβ) is viewed as a promising therapeutic intervention for AD treatment. However, the limitations of the depth of the external light source passing through the brain and the toxic side effects on healthy tissues are two significant challenges in the photooxidation of Aβ aggregates. We proposed a method to initiate the chemical stimulation of Aβ1-42 aggregate oxidation through H2O2 and correct the abnormal microenvironment of the lesions by eliminating the cascading reactions of oxidative stress. The degradable G-poly(thioacetal) undergoes cascade release of cinnamaldehyde (CA) and thioacetal triggered by endogenous H2O2, with CA in turn amplifying degradation by generating more H2O2 through mitochondrial dysfunction. A series of novel photosensitizers have been prepared and synthesized for use in the photodynamic oxidation of Aβ1-42 aggregates under white light activation. The nanoparticles (BD-6-QM/NPs) self-assembled from BD-6-QM, bis[2,4,5-trichloro-6-(pentoxycarbonyl) phenyl] ester (CPPO), and G-poly(thioacetal) not only exhibit H2O2-stimulated controlled release but also can be chemically triggered by H2O2 to generate singlet oxygen to inhibit Aβ1-42 aggregates, reducing the Aβ1-42-induced neurotoxicity.

Acetal-thiol Click-like Reaction: Facile and Efficient Synthesis of Dynamic Dithioacetals and Recyclable Polydithioacetals

Dithioacetals are heavily used in organic, material and medical chemistries, and exhibit huge potential to synthesize degradable or recyclable polymers. However, the current synthetic approaches of dithioacetals and polydithioacetals are overwhelmingly dependent on external catalysts and organic solvents. Herein, we disclose a catalyst- and solvent-free acetal-thiol click-like reaction for synthesizing dithioacetals and polydithioacetals. High conversion, higher than acid catalytic acetal-thiol reaction, can be achieved. High universality was confirmed by monitoring the reactions of linear and cyclic acetals (including renewable bio-sourced furan-acetal) with aliphatic and aromatic thiols, and the reaction mechanism of monomolecular nucleophilic substitution (SN1) and auto-protonation (activation) by thiol was clarified by combining experiments and density functional theory computation. Subsequently, we utilize this reaction to synthesize readily recyclable polydithioacetals. By simple heating and stirring, linear polydithioacetals withM ‾ ${\bar M}$ w of ~110 kDa were synthesized from acetal and dithiol, and depolymerization into macrocyclic dithioacetal and repolymerization into polydithioacetal can be achieved; through reactive extrusion, a semi-interpenetrating polymer dynamic network with excellent mechanical properties and continuous reprocessability was prepared from poly(vinyl butyral) and pentaerythritol tetrakis(3-mercaptopropionate). This green and high-efficient synthesis method for dithioacetals and polydithioacetals is beneficial to the sustainable development of chemistry.

Self-assembled metal-phenolic network nanoparticles for delivery of a cisplatin prodrug for synergistic chemo-immunotherapy

Despite cisplatin's pivotal role in clinically proven anticancer drugs, its application has been hampered by severe side effects and a grim prognosis. Herein, we devised a glutathione (GSH)-responsive nanoparticle (PFS-NP) that integrates a disulfide bond-based amphiphilic polyphenol (PP-SS-DA), a dopamine-modified cisplatin prodrug (Pt-OH) and iron ions (Fe3+) through coordination reactions between Fe3+ and phenols. After entering cells, the responsively released Pt-OH and disulfide bonds eliminate the intracellular GSH, in turn disrupting the redox homeostasis. Meanwhile, the activated cisplatin elevates the intracellular H2O2 level through cascade reactions. This is further utilized to produce highly toxic hydroxyl radicals (˙OH) catalyzed by the Fe3+-based Fenton reaction. Thus, the amplified oxidative stress leads to immunogenic cell death (ICD), promoting the maturation of dendritic cells (DCs) and ultimately activating the anti-tumor immune system. This innovative cisplatin prodrug nanoparticle approach offers a promising reference for minimizing side effects and optimizing the therapeutic effects of cisplatin-based drugs.

A Triple-Responsive Polymeric Prodrug Nanoplatform with Extracellular ROS Consumption and Intracellular H2O2 Self-Generation for Imaging-Guided Tumor Chemo-Ferroptosis-Immunotherapy

High reactive oxygen species (ROS) levels in tumor microenvironment (TME) impair both immunogenic cell death (ICD) efficacy and T cell activity. Furthermore, tumor escapes immunosurveillance via programmed death-1/programmed death ligand-1 (PD-L1) signal, and the insufficient intracellular hydrogen peroxide weakens ferroptosis efficacy. To tackle the above issues, a glutathione (GSH)/ROS/pH triple-responsive prodrug nanomedicine that encapsulates Fe2O3 nanoparticle via electrostatic interaction is constructed for magnetic resonance imaging (MRI)-guided multi-mode theranostics with chemotherapy/ferroptosis/immunotherapy. The diselenide bond consumes ROS in TME to increase T cells and ICD efficacy, the cleavage of which facilitates PD-L1 antagonist D peptide release to block immune checkpoint. After intracellular internalization, Fe2O3 nanoparticle is released in the acidic endosome for MRI simultaneously with lipid peroxides generation for tumor ferroptosis. Doxorubicin is cleaved from polymers in the condition of high intracellular GSH level accompanied by tumor ICD, which simultaneously potentiates ferroptosis by NADPH oxidase mediated H2O2 self-generation. In vivo results indicate that the nanoplatform strengthens tumor ICD, induces cytotoxic T lymphocytes proliferation, inhibits 4T1 tumor regression and metastasis, and prolongs survival median. In all, a new strategy is proposed in strengthening ICD and T cells activity cascade with ferroptosis as well as immune checkpoint blockade for effective tumor immunotherapy.

Redox-Responsive Polymeric Nanoparticle for Nucleic Acid Delivery and Cancer Therapy: Progress, Opportunities, and Challenges

Cancer development and progression of cancer are closely associated with the activation of oncogenes and loss of tumor suppressor genes. Nucleic acid drugs (e.g., siRNA, mRNA, and DNA) are widely used for cancer therapy due to their specific ability to regulate the expression of any cancer-associated genes. However, nucleic acid drugs are negatively charged biomacromolecules that are susceptible to serum nucleases and cannot cross cell membrane. Therefore, specific delivery tools are required to facilitate the intracellular delivery of nucleic acid drugs. In the past few decades, a variety of nanoparticles (NPs) are designed and developed for nucleic acid delivery and cancer therapy. In particular, the polymeric NPs in response to the abnormal redox status in cancer cells have garnered much more attention as their potential in redox-triggered nanostructure dissociation and rapid intracellular release of nucleic acid drugs. In this review, the important genes or signaling pathways regulating the abnormal redox status in cancer cells are briefly introduced and the recent development of redox-responsive NPs for nucleic acid delivery and cancer therapy is systemically summarized. The future development of NPs-mediated nucleic acid delivery and their challenges in clinical translation are also discussed.

Multifunctional nanoparticle-mediated combining therapy for human diseases

Combining existing drug therapy is essential in developing new therapeutic agents in disease prevention and treatment. In preclinical investigations, combined effect of certain known drugs has been well established in treating extensive human diseases. Attributed to synergistic effects by targeting various disease pathways and advantages, such as reduced administration dose, decreased toxicity, and alleviated drug resistance, combinatorial treatment is now being pursued by delivering therapeutic agents to combat major clinical illnesses, such as cancer, atherosclerosis, pulmonary hypertension, myocarditis, rheumatoid arthritis, inflammatory bowel disease, metabolic disorders and neurodegenerative diseases. Combinatorial therapy involves combining or co-delivering two or more drugs for treating a specific disease. Nanoparticle (NP)-mediated drug delivery systems, i.e., liposomal NPs, polymeric NPs and nanocrystals, are of great interest in combinatorial therapy for a wide range of disorders due to targeted drug delivery, extended drug release, and higher drug stability to avoid rapid clearance at infected areas. This review summarizes various targets of diseases, preclinical or clinically approved drug combinations and the development of multifunctional NPs for combining therapy and emphasizes combinatorial therapeutic strategies based on drug delivery for treating severe clinical diseases. Ultimately, we discuss the challenging of developing NP-codelivery and translation and provide potential approaches to address the limitations. This review offers a comprehensive overview for recent cutting-edge and challenging in developing NP-mediated combination therapy for human diseases.

Engineered nanomaterials enhance drug delivery strategies for the treatment of osteosarcoma

Osteosarcoma (OS) is the most common malignant bone tumor in adolescents, and the clinical treatment of OS mainly includes surgery, radiotherapy, and chemotherapy. However, the side effects of chemotherapy drugs are an issue that clinicians cannot ignore. Nanomedicine and drug delivery technologies play an important role in modern medicine. The development of nanomedicine has ushered in a new turning point in tumor treatment. With the emergence and development of nanoparticles, nanoparticle energy surfaces can be designed with different targeting effects. Not only that, nanoparticles have unique advantages in drug delivery. Nanoparticle delivery drugs can not only reduce the toxic side effects of chemotherapy drugs, but due to the enhanced permeability retention (EPR) properties of tumor cells, nanoparticles can survive longer in the tumor microenvironment and continuously release carriers to tumor cells. Preclinical studies have confirmed that nanoparticles can effectively delay tumor growth and improve the survival rate of OS patients. In this manuscript, we present the role of nanoparticles with different functions in the treatment of OS and look forward to the future treatment of improved nanoparticles in OS.

Cyclic amplification of intracellular ROS boosts enzymatic prodrug activation for enhanced chemo-immunotherapy

Tumor-associated enzyme activated prodrug is a potential strategy to overcome the limitations of chemotherapeutic agents. However, the efficiency of enzymatic prodrug activation is limited by the inability to reach adequate enzyme levels in vivo. Herein, we report an intelligent nanoplatform with cyclic amplification of intracellular reactive oxygen species (ROS) that significantly up-regulates the expression of tumor-associated enzyme, NAD(P)H:quinone oxidoreductase 1 (NQO1), to efficiently activate the prodrug of doxorubicin (DOX) for enhanced chemo-immunotherapy. The nanoplatform termed as CF@NDOX was fabricated by self-assembly of the amphiphilic cinnamaldehyde (CA) containing poly(thioacetal) conjugated with ferrocene (Fc) and poly(ethylene glycol) (PEG) (TK-CA-Fc-PEG), which further encapsulated the NQO1 responsive prodrug of DOX (NDOX). After CF@NDOX accumulates in tumors, the TK-CA-Fc-PEG with ROS responsive thioacetal group responds to endogenous ROS in tumor to release CA, Fc or NDOX. CA induces mitochondria dysfunction and elevates the intracellular hydrogen peroxide (H2O2) levels, which react with Fc to generate highly oxidative hydroxyl radical (•OH) through Fenton reaction. The •OH not only promotes ROS cyclic amplification but also increase the expression of NQO1 through Keap1-Nrf2 pathway regulation, which further boost the prodrug activation of NDOX for enhanced chemo-immunotherapy. Overall, our well-designed intelligent nanoplatform provides a tactic to enhance the antitumor efficacy of tumor-associated enzyme activated prodrug. STATEMENT OF SIGNIFICANCE: In this work, a smart nanoplatform CF@NDOX with intracellular ROS cyclic amplification for continuous upregulation of NQO1 enzyme expression was innovatively designed. It could utilize Fenton reaction of Fc to increase the level of NQO1 enzyme and CA to increase the level of intracellular H2O2, thereby facilitating the continuous Fenton reaction. This design allowed for a sustained elevation of the NQO1 enzyme, and a more complete activation of the NQO1 enzyme in response to the prodrug NDOX. This smart nanoplatform can achieve a desirable anti-tumor effect with the combined therapy of chemotherapy and ICD effects.

Emerging biomaterials for tumor immunotherapy

BACKGROUND

The immune system interacts with cancer cells in various intricate ways that can protect the individual from overproliferation of cancer cells; however, these interactions can also lead to malignancy. There has been a dramatic increase in the application of cancer immunotherapy in the last decade. However, low immunogenicity, poor specificity, weak presentation efficiency, and off-target side effects still limit its widespread application. Fortunately, advanced biomaterials effectively contribute immunotherapy and play an important role in cancer treatment, making it a research hotspot in the biomedical field.

MAIN BODY

This review discusses immunotherapies and the development of related biomaterials for application in the field. The review first summarizes the various types of tumor immunotherapy applicable in clinical practice as well as their underlying mechanisms. Further, it focuses on the types of biomaterials applied in immunotherapy and related research on metal nanomaterials, silicon nanoparticles, carbon nanotubes, polymer nanoparticles, and cell membrane nanocarriers. Moreover, we introduce the preparation and processing technologies of these biomaterials (liposomes, microspheres, microneedles, and hydrogels) and summarize their mechanisms when applied to tumor immunotherapy. Finally, we discuss future advancements and shortcomings related to the application of biomaterials in tumor immunotherapy.

CONCLUSION

Research on biomaterial-based tumor immunotherapy is booming; however, several challenges remain to be overcome to transition from experimental research to clinical application. Biomaterials have been optimized continuously and nanotechnology has achieved continuous progression, ensuring the development of more efficient biomaterials, thereby providing a platform and opportunity for breakthroughs in tumor immunotherapy.

pH-sensitive charge-conversion cinnamaldehyde polymeric prodrug micelles for effective targeted chemotherapy of osteosarcoma in vitro

Introduction: Chemotherapy is a common strategy for the treatment of osteosarcoma. However, its therapeutic efficacy is not ideal due to the low targeting, lowbioavailability, and high toxicity of chemotherapy drugs. Nanoparticles can improve the residence time of drugs at tumor sites through targeted delivery. This new technology can reduce the risk to patients and improve survival rates. To achieve this goal, we developed a pHsensitive charge-conversion polymeric micelle [mPEG-b-P(C7-co-CA) micelles] for osteosarcoma-targeted delivery of cinnamaldehyde (CA). Methods: First, an amphiphilic cinnamaldehyde polymeric prodrug [mPEG-b-P(C7-co-CA)] was synthesized through Reversible Addition-Fragmentation Chain Transfer Polymerization (RAFT) polymerization and post-modification, and self-assembled into mPEG-b-P(C7-co-CA) micelles in an aqueous solution. The physical properties of mPEG-b-P(C7-co-CA) micelles, such as critical micelle concentration (CMC), size, appearance, and Zeta potential were characterized. The CA release curve of mPEG-b-P(C7-co-CA) micelles at pH 7.4, 6.5 and 4.0 was studied by dialysis method, then the targeting ability of mPEG-b-P(C7-co-CA) micelles to osteosarcoma 143B cells in acidic environment (pH 6.5) was explored by cellular uptakeassay. The antitumor effect of mPEG-b-P(C7-co-CA) micelles on 143B cells in vitro was studied by MTT method, and the level of reactive oxygen species (ROS) in 143B cells after mPEG-b-P(C7-co-CA) micelles treatment was detected. Finally, the effects of mPEG-b-P(C7-co-CA) micelles on the apoptosis of 143B cells were detected by flow cytometry and TUNEL assay. Results: An amphiphilic cinnamaldehyde polymeric prodrug [mPEG-b-P(C7-co-CA)] was successfully synthesized and self-assembled into spheric micelles with a diameter of 227 nm. The CMC value of mPEG-b-P(C7-co-CA) micelles was 25.2 mg/L, and it showed a pH dependent release behavior of CA. mPEG-b-P(C7-co-CA) micelles can achieve chargeconversion from a neutral to a positive charge with decreasing pHs. This charge-conversion property allows mPEG-b-P(C7-co-CA) micelles to achieve 143B cell targeting at pH 6.5. In addition, mPEG-b-P(C7-co-CA) micelles present high antitumor efficacy and intracellular ROS generation at pH 6.5 which can induce 143B cell apoptosis. Discussion: mPEG-b-P(C7-co-CA) micelles can achieve osteosarcoma targeting effectively and enhance the anti-osteosarcoma effect of cinnamaldehyde in vitro. This research provides a promising drug delivery system for clinical application and tumor treatment.

ROS-Responsive Self-activatable Photosensitizing Agent for Photodynamic-Immunotherapy of cancer

Photodynamic therapy (PDT), as a non-invasive and spatiotemporally controllable modality, exhibits great potential in cancer treatment. However, the efficiency of reactive oxygen species (ROS) production was restricted to the hydrophobic characteristics and aggregation-caused quenching (ACQ) of photosensitizers. Herein, we designed a ROS self-activatable nano system (denoted as PTKPa) based on poly(thioketal) conjugated with photosensitizers (PSs) pheophorbide A (Ppa) on the polymer side chains for suppressing ACQ and enhancing PDT. The process of self-activation is that ROS, which is derived from laser irradiated PTKPa, as an activating agent accelerates poly(thioketal) cleavage with the release of Ppa from PTKPa. This in turn generates abundant ROS, accelerates degradation of the remaining PTKPa and amplifies the efficacy of PDT with more tremendous ROS generated. Moreover, these abundant ROS can amplify PDT-induced oxidative stress, cause irreversible damage to tumor cells and achieve immunogenic cell death (ICD), thereby boosting the efficacy of photodynamic-immunotherapy. These findings provide new insights into ROS self-activatable strategy for enhancing cancer photodynamic- immunotherapy. STATEMENT OF SIGNIFICANCE: This work described an approach to utilize ROS-responsive self-activatable poly(thioketal) conjugated with pheophorbide A (Ppa) for suppressing aggregation-caused quenching (ACQ) and enhancing photodynamic-immunotherapy. The ROS, generated from the conjugated Ppa upon 660nm laser irradiation, as a triggering agent which initiates the release of Ppa with poly(thioketal) degradation. That in turn generates abundant ROS and facilitates degradation of the remaining PTKPa, resulting in oxidative stress to tumor cells and achieving immunogenic cell death (ICD). This work provides a promising solution to improve tumor photodynamic therapeutic effects.