A reactive oxygen species (ROS)-responsive polymer for safe, efficient, and targeted gene delivery in cancer cells

ROS-responsive thioketal nanoparticles delivering system for targeted ulcerative colitis therapy with potent HDAC6 inhibitor, tubastatin A

Ulcerative colitis (UC) is a common gastrointestinal problem characterized by the mucosal injury primarily affecting the large intestine. Currently available therapies are not satisfactory as evidenced by high relapse rate and adverse effects. In this study we aimed to develop an effective drug delivery system using reactive oxygen species (ROS)-responsive thioketal nanoparticles (TKNP), to deliver tubastatin A, a potent HDAC6 inhibitor, to the inflamed colon in mice with ulcerative colitis (UC). TKNPs were synthesized by step-growth polymerization from an acetal exchange reaction while TUBA-TKNP was prepared using the single emulsion solvent evaporation technique. Our developed nanoparticle showed release of tubastatin A only in presence of ROS which is found to be highly present at the site of inflamed colon. Oral administration of TUBA-TKNP resulted in the higher accumulation of tubastatin A at the inflamed colon site and decreased the inflammation as evidenced by reduced infiltration of immune cells and decreased level of pro-inflammatory cytokines in TUBA-TKNP treated mice. In summary, our results show the successful localization of tubastatin A at the site of colon inflammation through TUBA-TKNP delivery, as well as resolution of clinical features of UC in mice.

Quantitative Factors Introduced in the Feasibility Analysis of Reactive Oxygen Species (ROS)-Sensitive Triggers

Reactive oxygen species (ROS) are critical for cellular signaling. Various pathophysiological conditions are also associated with elevated levels of ROS. Hence, ROS-sensitive triggers have been extensively used for selective payload delivery. Such applications are predicated on two key functions: (1) a sufficient magnitude of concentration difference for the interested ROS between normal tissue/cells and intended sites and (2) appropriate reaction kinetics to ensure a sufficient level of selectivity for payload release. Further, ROS refers to a group of species with varying reactivity, which should not be viewed as a uniform group. In this review, we critically analyze data on the concentrations of different ROS species under various pathophysiological conditions and examine how reaction kinetics affect the success of ROS-sensitive linker chemistry. Further, we discuss different ROS linker chemistry in the context of their applications in drug delivery and imaging. This review brings new insights into research in ROS-triggered delivery, highlights factors to consider in maximizing the chance for success and discusses pitfalls to avoid.

Tumor Microenvironment Specific Regulation Ca-Fe-Nanospheres for Ferroptosis-Promoted Domino Synergistic Therapy and Tumor Immune Response

Reactive oxygen species (ROS)-mediated emerging treatments exhibit unique advantages in cancer therapy in recent years. While the efficacy of ROS-involved tumor therapy is greatly restricted by complex tumor microenvironment (TME). Herein, a dual-metal CaO2@CDs-Fe (CCF) nanosphere, with TME response and regulation capabilities, are proposed to improve ROS lethal power by a multiple cascade synergistic therapeutic strategy with domino effect. In response to weak acidic TME, CCF will decompose, accompanied with intracellular Ca2+ upregulated and abundant H2O2 and O2 produced to reverse antitherapeutic TME. Then the exposed CF cores can act as both Fenton agent and sonosensitizer to generate excessive ROS in the regulated TME for enhanced synergistic CDT/SDT. In combination with calcium overloading, the augmented ROS induced oxidative stress will cause more severe mitochondrial damage and cellular apoptosis. Furthermore, CCF can also reduce GPX4 expression and enlarge the lipid peroxidation, causing ferroptosis and apoptosis in parallel. These signals of damage will finally initiate damage-associated molecular patterns to activate immune response and to realize excellent antitumor effect. This outstanding domino ROS/calcium loading synergistic effect endows CCF with excellent anticancer effect to efficiently eliminate tumor by apoptosis/ferroptosis/ICD both in vitro and in vivo.

Thioketal-Based Electrochemical Sensor Reveals Biphasic Effects of l-DOPA on Neuroinflammation

Neuroinflammation is linked closely to neurodegenerative diseases, with reactive oxygen species (ROS) exacerbating neuronal damage. Traditional electrochemical sensors show promise in targeting cellular ROS to understand their role in neuropathogenesis and assess therapies. Nevertheless, these sensors face challenges in mitigating the ROS oxidation overpotential. We herein introduce an ROS oxidation-independent nucleic acid sensor for in situ ROS analysis and therapeutic assessment. The sensor comprises ionizable and thioketal (TK)-based lipids with methylene blue-tagged nucleic acids on a glass carbon electrode. ROS exposure triggers cleavage within the sensor's thioketal moiety, detaching the nucleic acid from the electrode and yielding quantifiable results via square-wave voltammetry. Importantly, the sensor's low potential window minimizes interference, ensuring precise ROS measurements with high selectivity. Using this sensor, we unveil levodopa's dose-dependent biphasic effect on neuroinflammation: low doses alleviate oxidative stress, while high doses exacerbate it. The TK-based sensor offers a promising methodology for investigating neuroinflammation's pathogenesis and screening potential treatments, advancing neurodegenerative disease research.

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.

Engineering Nanosensitizer to Remodel the TME for Hypoimmunogenic "Cold"-"Hot" Tumor Transformations

α-PD-L1 therapy has shown encouraging results at harnessing the immune system to combat cancer. However, the treatment effect is relatively low due to the dense extracellular matrix (ECM) and tumor immunosuppressive microenvironment (TIME). Therefore, an ultrasound (US)-responsive nanosensitizer (URNS) is engineered to deliver losartan (LST) and polyethylenimine (PEI) to remolde the TME, driving "cold"-"hot" tumor transformation and enhancing the sensitivity of α-PD-L1 therapy. In the tumor site, noninvasive US can make MTNP generate ROS, which cleave ROS-sensitive bonds to dissociate MTNPtK@LST-PEI, shedding PEI and releasing LST from mesoporous spheres. The results demonstrated that URNS combined with α-PD-L1 therapy effectively inhibited tumor growth with an inhibition rate as high as 90%, which was 1.7-fold higher than that of the α-PD-L1 treatment in vivo. In summary, the URNS improves the sensitivity of α-PD-L1 therapy by remodeling the TME, which provides promising insights for optimizing cancer immunotherapy.

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.

Structural Determinants of Stimuli-Responsiveness in Amphiphilic Macromolecular Nano-assemblies

Stimuli-responsive nano-assemblies from amphiphilic macromolecules could undergo controlled structural transformations and generate diverse macroscopic phenomenon under stimuli. Due to the controllable responsiveness, they have been applied for broad material and biomedical applications, such as biologics delivery, sensing, imaging, and catalysis. Understanding the mechanisms of the assembly-disassembly processes and structural determinants behind the responsive properties is fundamentally important for designing the next generation of nano-assemblies with programmable responsiveness. In this review, we focus on structural determinants of assemblies from amphiphilic macromolecules and their macromolecular level alterations under stimuli, such as the disruption of hydrophilic-lipophilic balance (HLB), depolymerization, decrosslinking, and changes of molecular packing in assemblies, which eventually lead to a series of macroscopic phenomenon for practical purposes. Applications of stimuli-responsive nano-assemblies in delivery, sensing and imaging were also summarized based on their structural features. We expect this review could provide readers an overview of the structural considerations in the design and applications of nanoassemblies and incentivize more explorations in stimuli-responsive soft matters.

A Comprehensive Review of Small Interfering RNAs (siRNAs): Mechanism, Therapeutic Targets, and Delivery Strategies for Cancer Therapy

Small interfering RNA (siRNA) delivery by nanocarriers has been identified as a promising strategy in the study and treatment of cancer. Short nucleotide sequences are synthesized exogenously to create siRNA, which triggers RNA interference (RNAi) in cells and silences target gene expression in a sequence-specific way. As a nucleic acid-based medicine that has gained popularity recently, siRNA exhibits novel potential for the treatment of cancer. However, there are still many obstacles to overcome before clinical siRNA delivery devices can be developed. In this review, we discuss prospective targets for siRNA drug design, explain siRNA drug properties and benefits, and give an overview of the current clinical siRNA therapeutics for the treatment of cancer. Additionally, we introduce the siRNA chemical modifications and delivery systems that are clinically sophisticated and classify bioresponsive materials for siRNA release in a methodical manner. This review will serve as a reference for researchers in developing more precise and efficient targeted delivery systems, promoting ongoing advances in clinical applications.

Smart chemistry for traceless release of anticancer therapeutics

In the design of delivery strategies for anticancer therapeutics, the controlled release of intact cargo at the destined tumor and metastasis locations is of particular importance. To this end, stimuli-responsive chemical linkers have been extensively investigated owing to their ability to respond to tumor-specific physiological stimuli, such as lowered pH, altered redox conditions, increased radical oxygen species and pathological enzymatic activities. To prevent premature action and off-target effects, anticancer therapeutics are chemically modified to be transiently inactivated, a strategy known as prodrug development. Prodrugs are reactivated upon stimuli-dependent release at the sites of interest. As most drugs and therapeutic proteins have the optimal activity when released from carriers in their native and original forms, traceless release mechanisms are increasingly investigated. In this review, we summarize the chemical toolkit for developing innovative traceless prodrug strategies for stimuli-responsive drug delivery and discuss the applications of these chemical modifications in anticancer treatment including cancer immunotherapy.

A Single Organic Fluorescent Probe for the Discrimination of Dual Spontaneous ROS in Living Organisms: Theoretical Approach

Single-organic-molecule fluorescent probes with double-lock or even multi-lock response modes have attracted the attention of a wide range of researchers. The number of corresponding reports has rapidly increased in recent years. The effective application of the multi-lock response mode single-molecule fluorescent probe has improved the comprehensive understanding of the related targets' functions or influences in pathologic processes. Building a highly efficient functional single-molecule fluorescent probe would benefit the diagnosis and treatment of corresponding diseases. Here, we conducted a theoretical analysis of the synthesizing and sensing mechanism of this kind of functional single-molecule fluorescent probe, thereby guiding the design and building of new efficient probes. In this work, we discuss in detail the electronic structure, electron excitation, and fluorescent character of a recently developed single-molecule fluorescent probe, which could achieve the discrimination and profiling of spontaneous reactive oxygen species (ROS, •OH, and HClO) simultaneously. The theoretical results provide insights that will help develop new tools for fluorescent diagnosis in biological and medical fields.

Polymeric Phthalocyanine-Based Nanosensitizers for Enhanced Photodynamic and Sonodynamic Therapies

Photodynamic therapy and sonodynamic therapy are two highly promising modalities for cancer treatment. The latter holds an additional advantage in deep-tumor therapy owing to the deep penetration of the ultrasonic radiation. The therapeutic efficacy depends highly on the photo/ultrasound-responsive properties of the sensitizers as well as their tumor-localization property and pharmacokinetics. A novel nanosensitizer system based on a polymeric phthalocyanine (pPC-TK) is reported herein in which the phthalocyanine units are connected with cleavable thioketal linkers. Such polymer could self-assemble in water forming nanoparticles with a hydrodynamic diameter of 48 nm. The degradable and flexible thioketal linkers could effectively inhibit the π-π stacking of the phthalocyanine units, rendering the resulting nanoparticles an efficient generator of reactive oxygen species upon light or ultrasonic irradiation. The nanosensitizer could be internalized into cancer cells readily, inducing cell death by efficient photodynamic and sonodynamic effects. The potency is significantly higher than that of the monomeric phthalocyanine (PC-4COOH). The nanosensitizer could also effectively inhibit the growth of tumor in liver tumor-bearing mice by these two therapies without causing noticeable side effects. More importantly, it could also retard the growth of a deep-located orthotopic liver tumor in vivo by sonodynamic therapy.

Research progress of nanoparticle targeting delivery systems in bacterial infections

Bacterial infection is a huge threat to the health of human beings and animals. The abuse of antibiotics have led to the occurrence of bacterial multidrug resistance, which have become a difficult problem in the treatment of clinical infections. Given the outstanding advantages of nanodrug delivery systems in cancer treatment, many scholars have begun to pay attention to their application in bacterial infections. However, due to the similarity of the microenvironment between bacterial infection lesions and cancer sites, the targeting and accuracy of traditional microenvironment-responsive nanocarriers are questionable. Therefore, finding new specific targets has become a new development direction of nanocarriers in bacterial prevention and treatment. This article reviews the infectious microenvironment induced by bacteria and a series of virulence factors of common pathogenic bacteria and their physiological functions, which may be used as potential targets to improve the targeting accuracy of nanocarriers in lesions.

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.

A Multiple Stimuli-Responsive NanoCRISPR Overcomes Tumor Redox Heterogeneity to Augment Photodynamic Therapy

Redox heterogeneity of tumor cells has become one of the key factors leading to the failure of conventional photodynamic therapy (PDT). Exploration of a distinctive therapeutic strategy addressing heterogeneous predicaments is an appealing yet highly challenging task. Herein, a multiple stimuli-responsive nanoCRISPR (Must-nano) with spatial arrangement peculiarities in nanostructure and intracellular delivery is fabricated to overcome redox heterogeneity at both genetic and phenotypic levels for tumor-specific activatable PDT. Must-nano consists of a redox-sensitive core loading CRISPR/Cas9 targeting hypoxia-inducible factors-1α (HIF-1α) and a rationally designed multiple-responsive shell anchored by chlorin e6 (Ce6). Benefiting from the perfect coordination of structure and function, Must-nano avoids enzyme/photodegradation of the CRISPR/Cas9 system and exerts prolonged circulation, precise tumor recognition, and cascade-responsive performances to surmount tumor extra/intracellular barriers. After internalization into tumor cells, Must-nano could undergo hyaluronidase-triggered self-disassembly with charge reversal and rapid endosomal escape, followed by site-specific release and spatially asynchronous delivery of Ce6 and CRISPR/Cas9 under stimulations of redox signals, which not only improves tumor vulnerability to oxidative stress by complete HIF-1α disruption but also destroys the intrinsic antioxidant mechanism through glutathione depletion, thereby homogenizing redox-heterogeneous cells into oxidative stress-sensitive cell subsets. Under laser irradiation, Must-nano eventually exhibits optimal potency to amplify oxidative damage, effectively inhibiting the growth and hypoxia survival of redox-heterogeneous tumor in vitro and in vivo. Overall, our redox homogenization tactic significantly maximizes PDT efficacy and offers a promising strategy to overcome tumor redox heterogeneity in the development of antitumor therapies.

Immunostimulation with chemotherapy of a ruthenium-arene complex via blockading CD47 signal in chronic myelogenous leukemia cells

Combination of novel immunomodulation and traditional chemotherapy has become a new tendency in cancer treatment. Increasing evidence suggests that blocking the "don't eat me" signal transmitted by the CD47 can promote the phagocytic ability of macrophages to cancer cells, which might be promising for improved cancer chemoimmunotherapy. In this work, we conjugated CPI-alkyne modified by Devimistat (CPI-613) with ruthenium-arene azide precursor Ru-N₃ by copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction to construct Ru complex CPI-Ru. CPI-Ru exhibited satisfactory cytotoxicity towards the K562 cells while nearly non-toxic towards the normal HLF cells. CPI-Ru has been demonstrated to cause severe damage to mitochondria and DNA, ultimately inducing cancer cell death through the autophagic pathway. Moreover, CPI-Ru could significantly downregulate the expression of CD47 on the surface of K562 accompanied by the enhanced immune response by targeting the blockade of CD47. This work provides a new strategy for utilizing metal-based anticancer agents to block CD47 signal to achieve chemoimmunotherapy in chronic myeloid leukemia treatment.

A self-assembled nanophotosensitizer targets lysosomes and induces lysosomal membrane permeabilization to enhance photodynamic therapy

We report the self-assembly of amphiphilic BDQ photosensitizers into lysosome-targeting nanophotosensitizer BDQ-NP for highly effective photodynamic therapy (PDT). Molecular dynamics simulation, live cell imaging, and subcellular colocalization studies showed that BDQ strongly incorporated into lysosome lipid bilayers to cause continuous lysosomal membrane permeabilization. Upon light irradiation, the BDQ-NP generated a high level of reactive oxygen species to disrupt lysosomal and mitochondrial functions, leading to exceptionally high cytotoxicity. The intravenously injected BDQ-NP accumulated in tumours to achieve excellent PDT efficacy on subcutaneous colorectal and orthotopic breast tumor models without causing systemic toxicity. BDQ-NP-mediated PDT also prevented metastasis of breast tumors to the lungs. This work shows that self-assembled nanoparticles from amphiphilic and organelle-specific photosensitizers provide an excellent strategy to enhance PDT.

Targeting active sites of inflammation using inherent properties of tissue-resident mast cells

Mast cells play a pivotal role in initiating and directing host's immune response. They reside in tissues that primarily interface with the external environment. Activated mast cells respond to environmental cues throughout acute and chronic inflammation through releasing immune mediators via rapid degranulation, or long-term de novo expression. Mast cell activation results in the rapid release of a variety of unique enzymes and reactive oxygen species. Furthermore, the increased density of mast cell unique receptors like mas related G protein-coupled receptor X2 also characterizes the inflamed tissues. The presence of these molecules (either released mediators or surface receptors) are particular to the sites of active inflammation, and are a result of mast cell activation. Herein, the molecular design principles for capitalizing on these novel mast cell properties is discussed with the goal of manipulating localized inflammation. STATEMENT OF SIGNIFICANCE: Mast cells are immune regulating cells that play a crucial role in both innate and adaptive immune responses. The activation of mast cells causes the release of multiple unique profiles of biomolecules, which are specific to both tissue and disease. These unique characteristics are tightly regulated and afford a localized stimulus for targeting inflammatory diseases. Herein, these important mast cell attributes are discussed in the frame of highlighting strategies for the design of bioresponsive functional materials to target regions of inflammations.

Exploring the Application of Micellar Drug Delivery Systems in Cancer Nanomedicine

Various formulations of polymeric micelles, tiny spherical structures made of polymeric materials, are currently being investigated in preclinical and clinical settings for their potential as nanomedicines. They target specific tissues and prolong circulation in the body, making them promising cancer treatment options. This review focuses on the different types of polymeric materials available to synthesize micelles, as well as the different ways that micelles can be tailored to be responsive to different stimuli. The selection of stimuli-sensitive polymers used in micelle preparation is based on the specific conditions found in the tumor microenvironment. Additionally, clinical trends in using micelles to treat cancer are presented, including what happens to micelles after they are administered. Finally, various cancer drug delivery applications involving micelles are discussed along with their regulatory aspects and future outlooks. As part of this discussion, we will examine current research and development in this field. The challenges and barriers they may have to overcome before they can be widely adopted in clinics will also be discussed.

Topical Delivery of ROS-Responsive Methotrexate Prodrug Nanoassemblies by a Dissolvable Microneedle Patch for Psoriasis Therapy

Purpose

Oxidative stress, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and adenosine signaling are factors associated with psoriatic inflammation. Topical delivery of methotrexate (MTX) has become an option to overcome the side effects caused by systemic therapy in psoriasis, leading to the suppression of NF-κB activation through boosting adenosine release. However, thickened psoriatic skin is the primary restriction against local drug delivery.

Methods

In this study, a ROS responsive MTX prodrug (MTX-TK-HA) was synthesized with the feature of CD44 mediated active targeting to hyperproliferative keratinocytes. MTX prodrug and PLA-mPEG were formulated by nano-precipitation method to develop the MTX-TK-HA/PLA-mPEG nanoassemblies. To achieve painless transdermal delivery, a dissolving microneedle was applied for direct loading of these nanoassemblies by micromolding technique. The particle size, zeta potential, ROS-responsiveness, permeability, and mechanical strength of nanoassemblies and microneedle arrays were determined, respectively. Then, MTT assay, immunoblot analysis, ELISA assay, flow cytometry, and histological staining were utilized to thoroughly evaluate the efficacy of nanoassemblies-loaded microneedles in an imiquimod-induced psoriatic mouse model.

Results

Nanoassemblies-loaded microneedle arrays were capable of significantly penetrating imiquimod-induced psoriatic epidermis in mice. The efficient topical delivery of these nanoassemblies was achieved by potent mechanical strength and hyaluronic acid as the dissolvable matrix for microneedle arrays. CD44-mediated endocytosis enabled the intracellular uptake of nanoassemblies in keratinocytes, and methotrexate was released from MTX-TK-HA with ROS stimuli, followed by suppressing the proliferation of epidermal cells via NF-κB pathway blockade.

Conclusion

In a psoriatic mouse model, nanoassemblies loaded microneedle arrays relieve inflammatory skin disorders via regulation of adenosine and NF-κB signaling. Our study offered a rational design for the transdermal delivery of hydrophobic agents and defined an effective therapeutic option for psoriasis treatment.

Pleiotropic effects of a mitochondrion-targeted glutathione reductase inhibitor on restraining tumor cells

Mitochondria has been identified as a target for tumor therapy. Agents preferentially concentrated in mitochondria may exert more potent antitumor effects by interfering with the normal function of mitochondria. Glutathione reductase (GR) in mitochondria is a crucial antioxidant enzyme to maintain mitochondrial function, and has been recognized as an important target for the development of anticancer drugs. Herein, we present a triphenylphosphonium-modified anticancer agent, MT-1, which can preferentially accumulate in mitochondria and bind to GR by covalent binding manner. As a result, morphology and function of mitochondria were severely damaged, as well as cellular energy supply was severely impeded due to the simultaneously inhibition against mitochondrial respiration and glycolysis. Moreover, MT-1 was found to bind to a completely new site of GR (C278) that has never considered as binding site of inhibitors before. This new binding mode led to the change of GR structure, which affected the stability of the transition state of the catalytic process, and finally led to the inhibition of GR activity. Thus, current study provided a potentially novel tumor therapeutic strategy by targeting novel sites of GR in mitochondrion.

The progress of research on the application of redox nanomaterials in disease therapy

Redox imbalance can trigger cell dysfunction and damage and plays a vital role in the origin and progression of many diseases. Maintaining the balance between oxidants and antioxidants in vivo is a complicated and arduous task, leading to ongoing research into the construction of redox nanomaterials. Nanodrug platforms with redox characteristics can not only reduce the adverse effects of oxidative stress on tissues by removing excess oxidants from the body but also have multienzyme-like activity, which can play a cytotoxic role in tumor tissues through the catalytic oxidation of their substrates to produce harmful reactive oxygen species such as hydroxyl radicals. In this review, various redox nanomaterials currently used in disease therapy are discussed, emphasizing the treatment methods and their applications in tumors and other human tissues. Finally, the limitations of the current clinical application of redox nanomaterials are considered.

Reactive Oxygen Species-Responsive Polypeptide Drug Delivery System Targeted Activated Hepatic Stellate Cells to Ameliorate Liver Fibrosis

Hepatic fibrosis is a chronic liver disease that lacks effective pharmacotherapeutic treatments. As part of the disease's mechanism, hepatic stellate cells (HSCs) are activated by damage-related stimuli to secrete excessive extracellular matrix, leading to collagen deposition. Currently, the drug delivery system that targets HSCs in the treatment of liver fibrosis remains an urgent challenge due to the poor controllability of drug release. Since the level of reactive oxygen species (ROS) increases sharply in activated HSCs (aHSCs), we designed ROS-responsive micelles for the HSC-specific delivery of a traditional Chinese medicine, resveratrol (RES), for treatment of liver fibrosis. The micelles were prepared by the ROS-responsive amphiphilic block copolymer poly(l-methionine-block-N^ε-trifluoro-acetyl-l-lysine) (PMK) and a PEG shell modified with a CRGD peptide insertion. The CRGD-targeted and ROS-responsive micelles (CRGD-PMK-MCs) could target aHSCs and control the release of RES under conditions of high intracellular ROS in aHSCs. The CRGD-PMK-MCs treatment specifically enhanced the targeted delivery of RES to aHSCs both in vitro and in vivo. In vitro experiments show that CRGD-PMK-MCs could significantly promote ROS consumption, reduce collagen accumulation, and avert activation of aHSCs. In vivo results demonstrate that CRGD-PMK-MCs could alleviate inflammatory infiltration, prevent fibrosis, and protect hepatocytes from damage in fibrotic mice. In conclusion, CRGD-PMK-MCs show great potential for targeted and ROS-responsive controlled drug release in the aHSCs of liver fibrosis.

Two-Stage SN38 Release from a Core-Shell Nanoparticle Enhances Tumor Deposition and Antitumor Efficacy for Synergistic Combination with Immune Checkpoint Blockade

Long-circulating nanomedicines efficiently deliver chemotherapies to tumors to reduce general toxicity. However, extended blood circulation of nanomedicines can increase drug exposure to leukocytes and lead to hematological toxicity. Here, we report a two-stage release strategy to enhance the drug deposition and antitumor efficacy of OxPt/SN38 core-shell nanoparticles with a hydrophilic oxaliplatin (OxPt) prodrug coordination polymer core and a lipid shell containing a hydrophobic cholesterol-conjugated SN38 prodrug (Chol-SN38). By conjugating cholesterol to the phenol group of SN38 via an acetal linkage and protecting the 20-hydroxy position with a trimethylsilyl (TMS) group, Chol-SN38 releases SN38 in two stages via esterase-catalyzed cleavage of the acetal linkage in the liver followed by acid-mediated hydrolysis of the TMS group to preferentially release SN38 in tumors. Compared to irinotecan, OxPt/SN38 reduces SN38 blood exposure by 9.0 times and increases SN38 tumor exposure by 4.7 times. As a result, OxPt/SN38 inhibits tumor growth on subcutaneous, spontaneous, and metastatic tumor models by causing apoptotic and immunogenic cell death. OxPt/SN38 exhibits strong synergy with the immune checkpoint blockade to regress subcutaneous colorectal and pancreatic tumors with 33-50% cure rates and greatly inhibits tumor growth and invasion in a spontaneous prostate cancer model and a liver metastasis model of colorectal cancer without causing side effects. Mechanistic studies revealed important roles of enhanced immunogenic cell death and upregulated PD-L1 expression by OxPt/SN38 in activating the tumor immune microenvironment to elicit potent antitumor immunity. This work highlights the potential of combining innovative prodrug design and nanomedicine formulation to address unmet needs in cancer therapy.

Spatiotemporal Control of Biology: Synthetic Photochemistry Toolbox with Far-Red and Near-Infrared Light

The complex network of naturally occurring biological pathways motivates the development of new synthetic molecules to perturb and/or detect these processes for fundamental research and clinical applications. In this context, photochemical tools have emerged as an approach to control the activity of drug or probe molecules at high temporal and spatial resolutions. Traditional photochemical tools, particularly photolabile protecting groups (photocages) and photoswitches, rely on high-energy UV light that is only applicable to cells or transparent model animals. More recently, such designs have evolved into the visible and near-infrared regions with deeper tissue penetration, enabling photocontrol to study biology in tissue and model animal contexts. This Review highlights recent developments in synthetic far-red and near-infrared photocages and photoswitches and their current and potential applications at the interface of chemistry and biology.

Multifunctional ROS-Responsive and TME-Modulated Lipid-Polymer Hybrid Nanoparticles for Enhanced Tumor Penetration

PURPOSE

To enhance tumor penetration by formulation design and tumor microenvironment (TME) modulation, herein a novel reactive oxygen species (ROS)-responsive size/shape transformable lipid-polymer hybrid nanoparticle (LPN) has been fabricated for the co-delivery of an anticancer and collagen-inhibition drug.

METHODS

A ROS-responsive poly(D, L-lactide)-thioketal-polyethylene glycol (PLA-TK-PEG) co-polymer was synthesized. LPNs were then fabricated by encapsulation of losartan (LST)-loaded micelles as the core to support paclitaxel (PTX)-loaded liposomes. The PEG content in the lipid shell of LPNs was then adjusted to obtain the size-/shape-transformable LPNs (M/LST-Lip/PTX-PEG5%). The ROS-responsiveness was observed in vitro by transmission electron microscopy and the tumor-penetration of the LPNs was evaluated in 3D tumor spheroids by confocal laser scanning microscopy. Tumor-targeting, tumor-penetrating, and antitumor efficacies of the NPs in 4T1 tumor-bearing mice were determined by in vivo imaging.

RESULTS

ROS-responsive micellar core degradation and the transformation of spherical LPNs (120nm) to smaller 40 mm discoid nanoparticles (NP) were observed. The transformable LPNs exhibited enhanced capacity of penetration in contrast to the un-transformable preparations in three-dimensional (3D) tumor spheroids. Furthermore, synergetic penetrating enhancement was achieved by LST-loaded transformable LPNs in 4T1 and fibroblast cell mixed 3D tumor spheroids. The improved tumor penetration of LST-loaded transformable LPNs was observed in vivo, which could be due to their collagen inhibiting and size/shape transformable effect. Due to their enhanced penetrability, LST and PTX-loaded transformable LPNs demonstrated significant in vivo antitumor efficacy in comparison to other preparations.

CONCLUSION

The results confirmed the efficacy of M/LST-Lip/PTX-PEG5% in tumor targeting, collagen inhibition in TME, and enhanced tumor penetration. This novel drug delivery system can therefore play a substantial role in improving the therapeutic efficacy of antitumor drugs combined with TME-improving agents.

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

The selective activation of stimuli-responsive polymers in the tumor microenvironment is a great concern to achieve intelligent cancer therapy, but most of them show inadequate response due to insufficient endogenous triggering agents. Herein, we rationally designed a reactive oxygen species (ROS)-responsive cinnamaldehyde (CA)-based poly(thioacetal), consisting of ROS-responsive thioacetal (TA) and ROS-generating agent CA, with self-amplified chain-shattering polymer degradation. The mechanism of self-amplified chain-shattering is that endogenous ROS as a triggering agent facilitates chain cleavage of TA with the release of CA, which in turn produces more ROS through mitochondrial dysfunction, resulting in an exponential polymer degradation cascade. The polymer can be further modified with anticancer drug doxorubicin (DOX) for cooperative amplification of oxidative stress and immunogenic cell death (ICD) of tumor cells, thereby boosting the effect of chemo-immunotherapy. The self-amplified chain-shattering polymer designed in this work holds great promise in developing stimuli-responsive polymers for efficient drug delivery. STATEMENT OF SIGNIFICANCE: This study presented an approach to utilize self-amplified chain-shattering cinnamaldehyde-based poly (thioacetal) as a drug delivery system to restrain tumor growth and boost chemo-immunotherapy. The endogenous ROS as a triggering agent initiates the chain cleavage with the release of CA, which in turn produces ROS through mitochondria dysfunction, resulting in an exponential polymer degradation cascade and rapid drug release.

Recent advances of bioresponsive polymeric nanomedicine for cancer therapy

A bioresponsive polymeric nanocarrier for drug delivery is able to alter its physical and physicochemical properties in response to a variety of biological signals and pathological changes, and can exert its therapeutic efficacy within a confined space. These nanosystems can optimize the biodistribution and subcellular location of therapeutics by exploiting the differences in biochemical properties between tumors and normal tissues. Moreover, bioresponsive polymer-based nanosystems could be rationally designed as precision therapeutic platforms by optimizing the combination of responsive elements and therapeutic components according to the patient-specific disease type and stage. In this review, recent advances in smart bioresponsive polymeric nanosystems for cancer chemotherapy and immunotherapy will be summarized. We mainly discuss three categories, including acidity-sensitive, redox-responsive, and enzyme-triggered polymeric nanosystems. The important issues regarding clinical translation such as reproducibility, manufacture, and probable toxicity, are also commented.

Unprotonatable and ROS-Sensitive Nanocarrier for NIR Spatially Activated siRNA Therapy with Synergistic Drug Effect

Although small interfering RNA (siRNA) therapy has achieved great progress, unwanted gene inhibition in normal tissues severely limits its extensive clinical applications due to uncontrolled siRNA biodistribution. Herein, a spatially controlled siRNA activation strategy is developed to achieve tumor-specific siRNA therapy without gene inhibition in the normal tissues. The quaternary ammonium moieties are conjugated to amphiphilic copolymers via reactive oxygen species (ROS)-sensitive thioketal (TK) linkers for co-delivery of siRNA and photosensitizer chlorin e6 (Ce6), showing excellent siRNA complexation capacity and near infrared (NIR)-controlled siRNA release. In the normal tissue, siRNAs are trapped and degraded in the endo-lysosomes due to the unprotonatable property of quaternary ammonium moiety, showing the siRNA activity "off" state. When NIR irradiation is spatially applied to the tumor tissue, the NIR irradiation/Ce6-induced ROS trigger siRNA endo-lysosomal escape and cytosolic release through the photochemical internalization effect and cleavage of TK bonds, respectively, showing the siRNA activity "on" state. The siRNA-mediated glutathione peroxidase 4 gene inhibition enhances ROS accumulation. The synergistic antitumor activity of Ce6 photodynamic therapy and gene inhibition is confirmed in vivo. Spatially controlled tumor-specific siRNA activation and co-delivery with Ce6 using unprotonatable and ROS-sensitive cationic nanocarriers provide a feasible strategy for tumor-specific siRNA therapy with synergistic drug effects.

Inflammatory environment-adaptive patterned surface for spatiotemporal immunomodulation of macrophages

Designing biomaterials with precise immunomodulation can help to decipher the dynamic interactions between macrophages and biomaterials to match the tissue healing process. Although some advanced stimuli-responsive immunomodulatory biomaterials were reported for cell dynamic modulation, while most triggers need external stimuli by manual intervention, there would be the inevitable errors and uncertainties. Thus, developing immunomodulatory biomaterials with adaptive abilities, which can recognize the inflammation signals, change their properties spatiotemporally under the microenvironment triggers, and provide feedback to realize macrophages modulation in different healing stages, has become a promising strategy. In this work, we developed an inflammation-adaptive Arg-Gly-Asp (RGD) -patterned surface for spatiotemporal immunomodulation of macrophage. We fabricated a methacrylated hyaluronic acid (MA-HA) hydrogel with thiol-functionalized RGD-patterned surface by employing photolithography technology. Then, thiol-functionalized RGD contained ROS-cleavable linker was filled the remaining sites and consequently, a dynamic surface with temporary homogeneous RGD was obtained. Under the overproduction of ROS by the inflammation-activated macrophages, the linker was cleaved, and the homogeneous RGD surface was transformed to the RGD patterned surface, which triggered elongation of macrophages and consequently the upregulated expressions of arginase-1, IL-10 and TNF-β1, indicating the polarization toward to anti-inflammatory phenotype. Developing inflammatory environment-adaptive surface for spatiotemporal modulation of macrophages polarization provides a precise and smart strategy for the healing-matched immunomodulation to facilitate healing outcomes. STATEMENT OF SIGNIFICANCE: Designing biomaterials with precise immunomodulation can help to decipher the dynamic interactions between macrophages and biomaterials to match tissue repair process. Some immunomodulatory biomaterials were reported for cell dynamic modulation, while most triggers need external manual intervention. Thus, we developed an immunomodulatory biomaterial with inflammation-adaptive patterned surface, which can recognize abnormal signals and change its properties spatiotemporally under the microenvironment triggers, and provide feedback to realize macrophages modulation in different stages. The dynamic surface can adapt to the changes of microenvironment and dynamically to match the cell behavior and tissue healing process on demand without external manual intervention. Additionally, the surface achieves the balance of macrophages with pro- and anti-inflammatory phenotypes in the tissue repair process.

Recent advances in redox-responsive nanoparticles for combined cancer therapy

The combination of multiple therapeutic modalities has attracted increasing attention as it can achieve better therapeutic effects through different treatment mechanisms. However, traditional small molecule agents are non-specific to the tumor tissue, which leads to off-target toxic effects for healthy tissues. To solve this problem, a number of stimuli-responsive nanoscale drug-delivery systems have been developed. Among these stimuli, a high concentration of reactive oxygen species (ROS) and glutathione (GSH) are characteristic of the tumor microenvironment (TME), which can distinguish it from normal tissue. In this review, we summarize the redox-responsive nanoparticles (NPs) reported in the past three years classified by different functional groups, including GSH-responsive disulfide, ditelluride, and multivalent metal ions, ROS-responsive thioketal, arylboronic ester, aminoacrylate, and bilirubin as well as GSH/ROS dual-responsive diselenide and dicarbonyl thioethers. The prospects and challenges of redox-responsive NPs are also discussed.

Advances towards Cell‐Specific Gene Transfection: A Small‐Molecule Approach Allows Order‐of‐Magnitude Selectivity

A transfection vector that can home in on tumors is reported. Whereas previous vectors that allow moderately cell selective gene transfection used larger systems, this small‐molecule approach paved the way for precise structure‐activity relationship optimization. For this, biotin, which mediates cell selectivity, was combined with the potent DNA‐binding motif tetralysine‐guanidinocarbonypyrrol via a hydrophilic linker, thus enabling SAR‐based optimization. The new vector mediated biotin receptor (BR)‐selective transfection of cell lines with different BR expression levels. Computer‐based analyses of microscopy images revealed a preference of one order of magnitude for the BR‐positive cell lines over the BR‐negative controls.

Tumor microenvironment responsive nanocarriers for gene therapy

Stimuli responsive nanocarriers are important non-viral gene carriers for gene therapy. We discuss the stimulus conditions and then highlight various stimuli responsive nanocarriers in the tumor microenvironment for cancer gene therapy. We hope that this review will inspire readers to develop more effective stimuli responsive nanocarriers for delivering genes.

Tumor microenvironment responsive polypeptide-based supramolecular nanoprodrugs for combination therapy

Tumor microenvironment responsive nanomedicine has drawn considerable attention for combination therapy, but still remains a significant challenge for less side effects and enhanced anti-tumor efficiency. Herein, we develop a pH/ROS dual-responsive supramolecular polypeptide nanoprodrug (PFW-DOX/GOD) by using pillar[5]arene-based host-guest strategy for combined glucose degradation, chemodynamic therapy (CDT), and chemotherapy (CT). The PFW-DOX/GOD consists of a pH-responsive ferrocene/pillar[5]arene-containing polypeptide, a ROS-responsive polyprodrug, and encapsulated glucose oxidase (GOD). Upon into intracellular acidic environment, PFW-DOX/GOD exhibits rapid pH-triggered disassembly behavior. Simultaneously, the released GOD can catalyze intratumoral glucose into massive H₂O₂, which are further converted into highly toxic hydroxyl radicals (•OH) by the catalysis of ferrocene via the Fenton reaction. Thereafter, induced by the ROS-responsive cleavage of thioketal linkage, the conjugated DOX prodrug was released and activated. The combined glucose degradation, chemodynamic therapy (CDT), and chemotherapy (CT) of PFW-DOX/GOD present anti-tumor effect with 96% of tumor inhibitory rate (TIR). Therefore, such tumor microenvironment-responsive supramolecular polypeptide nanoprodrugs represent a potential candidate for combination therapy with minimal side effects. STATEMENT OF SIGNIFICANCE: In this work, a tumor microenvironment-responsive supramolecular polypeptide nanoprodrug (PFW-DOX/GOD) was prepared via pillar[5]arene-based host-guest interactions, and presented low side effects and high tumor accumulation owing to the diameters of about 200 nm and surface PEG segment. After pH-responsive release of GOD in the intracellular acidic environment, the cascade catalytic reactions including GOD-catalyzed degradation of intratumoral glucose and Fenton reaction, effectively happened to generate •OH for chemodynamic therapy (CDT), which subsequently induced the cleavage of thioketal linkage to activate free DOX for chemotherapy (CT). Collectively, this supramolecular polypeptide nanoprodrugs provide a promising strategy for combination therapy with synergetic anti-tumor effect.

Promising Colloidal Rhenium Disulfide Nanosheets: Preparation and Applications for In Vivo Breast Cancer Therapy

Photothermal therapy (PTT) has become an important therapeutic strategy in the treatment of cancer. However, exploring novel photothermal nanomaterials with satisfactory biocompatibility, high photothermal conversion efficiency, and efficient theranostic outcomes, remains a major challenge for satisfying clinical application. In this study, poly-ethylene glycol modified rhenium disulfide (PEG-ReS₂) nanosheets are constructed by a simple-liquid phase exfoliation method. The PEG-ReS₂ nanosheets were demonstrated to have good solubility, good biocompatibility, low toxicity, and strong capability of accumulating near-infrared (NIR) photons. Under 808 nm laser irradiation, the PEG-ReS₂ nanosheets were found to have an excellent photothermal conversion efficiency (PTCE) of 42%. Moreover, the PEG-ReS₂ nanosheets were demonstrated to be ideal photothermal transduction agents (PTAs), which promoted rapid cancer cell death in vitro and efficiently ablated tumors in vivo. Interestingly, the potential utility of up-regulation or down-regulation of miRNAs was proposed to evaluate the therapeutic outcomes of PEG-ReS₂ nanosheets. The expression levels of a set of miRNAs in tumor-bearing mice were restored to normal levels after PTT therapy with PEG-ReS₂ nanosheets. Both down-regulation miRNAs (miR-125a-5p, miR-34a-5p, miR-132-3p, and miR-148b-3p) and up-regulation miRNAs (miR-133a-3p, miR-200c-5p, miR-9-3p, and miR-150-3p) were suggested to be important clinical biomarkers for evaluating therapeutic outcomes of breast cancer-related PTT. This work highlights the great significance of PEG-ReS₂ nanosheets as therapeutic nanoagents for cancer therapy.

Tregs biomimetic nanoparticle to reprogram inflammatory and redox microenvironment in infarct tissue to treat myocardial ischemia reperfusion injury in mice

Background

At present, patients with myocardial infarction remain an increased risk for myocardial ischemia/reperfusion injury (MI/RI). There lacks effectively method to treat MI/RI in clinic. For the treatment of MI/RI, it is still a bottleneck to effectively deliver drug to ischemic myocardium. In this paper, a regulatory T cells (Tregs) biomimetic nanoparticle (CsA@PPTK) was prepared by camouflaging nanoparticle with platelet membrane.

Results

CsA@PPTK actively accumulated in ischemic myocardium of MI/RI mice. CsA@PPTK significantly scavenged reactive oxygen species (ROS) and increased the generation of Tregs and the ratio of M2 type macrophage to M1 type macrophage in ischemic myocardium. Moreover, CsA@PPTK significantly attenuated apoptosis of cardiomyocytes and reduced the infarct size and fibrosis area in ischemic myocardium. CsA@PPTK markedly decreased the protein expression of MMP-9 and increased the protein expression of CX43 in ischemic myocardium tissue. Subsequently, the remodeling of the left ventricle was significant alleviated, and heart function of MI/RI mice was markedly improved.

Conclusion

CsA@PPTK showed significant therapeutic effect on MI/RI, and it has great potential application in the treatment of MI/RI.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01445-2.

Plaque-Targeted Rapamycin Spherical Nucleic Acids for Synergistic Atherosclerosis Treatment

Atherosclerosis with unstable plaques is the dominant pathological basis of lethal cardio-cerebrovascular diseases, which can cause acute death due to the rupture of plaques. Plaque-targeted drug delivery to achieve promoted treatment remains the main challenge because of the systemic occurrence of atheroma. Herein, a rapamycin (RAP) spherical nucleic acid (SNA) structure, capable of specifically accumulating in plaques for synergistic atherosclerosis treatment is constructed. By designing consecutive phosphorothioate (PS) at 3' terminus of the deoxyribonucleic acid (DNA) strand, multiple hydrophobic RAPs are covalently grafted onto the PS segment to form an amphiphilic drug-grafted DNA (RAP-DNA), which successively self-assembles into micellar SNA (RAP-SNA). Moreover, the phosphodiester-DNA segment constitutes the outer shell of RAP-SNA, enabling further hybridization with functional siRNA (targeting lectin-like oxidized low-density lipoprotein receptor-1, LOX-1) to obtain the drug codelivered SNA (LOX-1/RAP-SNA). With two active ingredients inside, LOX-1/RAP-SNA can not only induce robust autophagy and decrease the evil apoptosis of the pathological macrophages, but also simultaneously prohibit the LOX-1-mediated formation of damageable foam cells, realizing the effect of synergistic therapy. As a result, the LOX-1/RAP-SNA significantly reduces the progression of atheroma and stabilizes the plaques, providing a new strategy for synergistically targeted atherosclerosis treatment.

An Ultrasound-Induced Self-Clearance Hydrogel for Male Reversible Contraception

Nearly half of pregnancies worldwide are unintended mainly due to failure of contraception, resulting in negative effects on women's health. Male contraception techniques, primarily condoms and vasectomy, play a crucial role in birth control, but cannot be both highly effective and reversible at the same time. Herein, an ultrasound (US)-induced self-clearance hydrogel capable of real-time monitoring is utilized for in situ injection into the vas deferens, enabling effective contraception and noninvasive recanalization whenever needed. The hydrogel is composed of (i) sodium alginate (SA) conjugated with reactive oxygen species (ROS)-cleavable thioketal (SA-tK), (ii) titanium dioxide (TiO₂), which can generate a specific level of ROS after US treatment, and (iii) calcium chloride (CaCl₂), which triggers the formation of the hydrogel. For contraception, the above mixture agents are one-time injected into the vas deferens, which can transform from liquid to hydrogel within 160 s, thereby significantly physically blocking the vas deferens and inhibiting movability of sperm. When fertility is needed, a noninvasive remedial ultrasound can make TiO₂ generate ROS, which cleaves SA-tK to destroy the network of the hydrogel. Owing to the recanalization, the refertility rate is restored to 100%. Meanwhile, diagnostic ultrasound (D-US, 22 MHz) can monitor the occlusion and recanalization process in real-time. In summary, the proposed hydrogel contraception can be a reliable, safe, and reversible male contraceptive strategy that addresses an unmet need for men to control their fertility.

Reactive oxygen species-degradable polythioketal urethane foam dressings to promote porcine skin wound repair

Porous, resorbable biomaterials can serve as temporary scaffolds that support cell infiltration, tissue formation, and remodeling of nonhealing skin wounds. Synthetic biomaterials are less expensive to manufacture than biologic dressings and can achieve a broader range of physiochemical properties, but opportunities remain to tailor these materials for ideal host immune and regenerative responses. Polyesters are a well-established class of synthetic biomaterials; however, acidic degradation products released by their hydrolysis can cause poorly controlled autocatalytic degradation. Here, we systemically explored reactive oxygen species (ROS)-degradable polythioketal (PTK) urethane (UR) foams with varied hydrophilicity for skin wound healing. The most hydrophilic PTK-UR variant, with seven ethylene glycol (EG7) repeats flanking each side of a thioketal bond, exhibited the highest ROS reactivity and promoted optimal tissue infiltration, extracellular matrix (ECM) deposition, and reepithelialization in porcine skin wounds. EG7 induced lower foreign body response, greater recruitment of regenerative immune cell populations, and resolution of type 1 inflammation compared to more hydrophobic PTK-UR scaffolds. Porcine wounds treated with EG7 PTK-UR foams had greater ECM production, vascularization, and resolution of proinflammatory immune cells compared to polyester UR foam-based NovoSorb Biodegradable Temporizing Matrix (BTM)-treated wounds and greater early vascular perfusion and similar wound resurfacing relative to clinical gold standard Integra Bilayer Wound Matrix (BWM). In a porcine ischemic flap excisional wound model, EG7 PTK-UR treatment led to higher wound healing scores driven by lower inflammation and higher reepithelialization compared to NovoSorb BTM. PTK-UR foams warrant further investigation as synthetic biomaterials for wound healing applications.

pH/ROS dual-responsive supramolecular polypeptide prodrug nanomedicine based on host-guest recognition for cancer therapy

Supramolecular nanomedicine assembly combined with polypeptide prodrug could become a powerful strategy to minimize drug leakage in blood circulation and trigger sufficient drug release at tumor tissue. Here, we developed a charge-reversal amphiphilic pillar[5]arene-modified polypeptide (P5-PLL-DMA), and reactive oxygen species (ROS)-sensitive polypeptide prodrug (P-PLL-DOX) including a ROS-cleavable thioketal (TK) linker between doxorubicin (DOX) and poly(_L-lysine) (PLL), which could assemble via pillar[5]arene host-guest recognition, and further encapsulate chlorin e6 (Ce6) to obtain a supramolecular polypeptide prodrug (SPP-DOX/Ce6). The chemical conjugation to load drugs of DOX and the negatively charge of SPP-DOX/Ce6 could prevent premature drug leakage, and reduce undesirable interaction with serum proteins to enhance stability under physiological conditions (pH 7.4). Simultaneously, the carried charge of SPP-DOX/Ce6 reversed from negative to positive could effectively enhance the cellular internalization for efficient DOX delivery under acidic tumor microenvironment (pH 6.5). Upon 660 nm near-infrared light (NIR) irradiation, the ROS generated by encapsulated Ce6 rapidly cleaved the TK linker to release activated DOX, inducing the tumor-specific drug delivery. This intelligent supramolecular polypeptide prodrug based on pillar[5]arene host-guest recognition represents new avenues to develop stimulus responsive prodrug for enhanced cancer therapy with minimized the side effect. STATEMENT OF SIGNIFICANCE: In this work, a pH/ROS dual-sensitive supramolecular polypeptide prodrug (SPP-DOX/Ce6) was developed to minimize drug leakage in blood circulation and trigger sufficient drug release at tumor tissue. The chemical conjugation to load drugs of DOX via a ROS-cleavable thioketal (TK) linker and the distinctive charge-reversal capacity of SPP-DOX/Ce6 significantly enhances the stability under physiological conditions (pH 7.4), while facilitates cellular uptake at tumor site (pH 6.8). Upon 660 nm near-infrared light (NIR) irradiation, the ROS generated by encapsulated Ce6 induces the rapid cleavage of TK linker to release activated DOX, achieving a tumor-specific drug delivery. This intelligent supramolecular polypeptide prodrug SPP-DOX/Ce6 provides an effective strategy to construct stimulus responsive prodrug for enhanced cancer therapy.

Liposome-Based Nanoencapsulation of a Mitochondria-Stapling Photosensitizer for Efficient Photodynamic Therapy

Mitochondria-targeting photodynamic therapy (PDT) can block mitochondrial function and trigger the inherent proapoptotic cascade signal of mitochondria, which has been considered to have the potential to amplify the efficiency of PDT. However, the dynamic change of mitochondrial membrane potential (MMP) makes most cationic photosensitizers easily fall off from the mitochondria, which greatly limits the efficiency of PDT. Here, we have developed a smart liposome encapsulation method based on a mitochondria-stapling photosensitizer for efficient theranostic photodynamic therapy. The stapling photosensitizer can be covalently bound inside mitochondria via two reaction sites without a falloff effect, regardless of the change of MMP. As a result, the liposome-based nanophotosensitizer showed a high efficiency of PDT (IC₅₀ = 0.98 μM) under 630 nm light. At the same time, the nanophotosensitizer had fluorescence imaging-guided ability to monitor abnormal mitochondrial morphology during PDT. Importantly, the results of mice experiments also showed that the liposome-based nanophotosensitizer possessed excellent antitumor PDT activity because the released photosensitizer can stay inside mitochondria during the whole process of PDT.

Multifunctional Immunoliposomes Enhance the Immunotherapeutic Effects of PD-L1 Antibodies against Melanoma by Reprogramming Immunosuppressive Tumor Microenvironment

The immunosuppressive tumor microenvironment (TME) can significantly limit the immunotherapeutic effects of the PD-L1 antibody (aPDL1) by inhibiting the infiltration of CD8⁺ cytotoxic T cells (CTLs) into the tumor tissues. However, how to reprogram the immunosuppressive TME and promote the infiltration of CTLs remains a huge challenge for aPDL1 to achieve the maximum benefits. Herein, the authors design a multifunctional immunoliposome that encapsulates the adrenergic receptor blocker carvedilol (CAR) and connects the "don't eat me" signal antibody (aCD47) and aPDL1 in series via a reactive oxygen species (ROS)-sensitive linker on the surface. In ROS-enriched immunosuppressive TME, the multifunctional immunoliposome (CAR@aCD47/aPDL1-SSL) can first release the outer aCD47 to block the "do not eat me" pathway, promote the phagocytosis of tumor cells by phagocytic cells, and activate CTLs. Then, the aPDL1 on the liposome surface is exposed to block the PD-1/PD-L1 signaling pathway, thereby inducing CTLs to kill tumor cells. CAR encapsulated in CAR@aCD47/aPDL1-SSL can block the adrenergic nerves in the tumor tissues and reduce their densities, thereby inhibiting angiogenesis in the tumor tissues and reprogramming the immunosuppressive TME. According to the results, CAR@aCD47/aPDL1-SSL holds an effective way to reprogram the immunosuppressive TME and significantly enhance immunotherapeutic efficiency of aPDL1 against the primary cancer and metastasis.

Applications of the ROS-Responsive Thioketal Linker for the Production of Smart Nanomedicines

Reactive oxygen species (ROS)-sensitive drug delivery systems (DDS) specifically responding to altered levels of ROS in the pathological microenvironment have emerged as an effective means to enhance the pharmaceutical efficacy of conventional nanomedicines, while simultaneously reducing side effects. In particular, the use of the biocompatible, biodegradable, and non-toxic ROS-responsive thioketal (TK) functional group in the design of smart DDS has grown exponentially in recent years. In the design of TK-based DDS, different technological uses of TK have been proposed to overcome the major limitations of conventional DDS counterparts including uncontrolled drug release and off-target effects. This review will focus on the different technological uses of TK-based biomaterials in smart nanomedicines by using it as a linker to connect a drug on the surface of nanoparticles, form prodrugs, as a core component of the DDS to directly control its structure, to control the opening of drug-releasing gates or to change the conformation of the nano-systems. A comprehensive view of the various uses of TK may allow researchers to exploit this reactive linker more consciously while designing nanomedicines to be more effective with improved disease-targeting ability, providing novel therapeutic opportunities in the treatment of many diseases.

Novel Prodrug Supramolecular Nanoparticles Capable of Rapid Mitochondrial-Targeted and ROS-Responsive for Pancreatic Cancer Therapy

Mitochondrial dysfunction is a feature of cancer cells and targeting cancer mitochondria has emerged as a promising anticancer therapy. In this study, a novel mitochondria-targeted and ROS-responsive drug delivery nanoplatform...

Delivery of therapeutic oligonucleotides in nanoscale

Therapeutic oligonucleotides (TOs) represent one of the most promising drug candidates in the targeted cancer treatment due to their high specificity and capability of modulating cellular pathways that are not readily druggable. However, efficiently delivering of TOs to cancer cellular targets is still the biggest challenge in promoting their clinical translations. Emerging as a significant drug delivery vector, nanoparticles (NPs) can not only protect TOs from nuclease degradation and enhance their tumor accumulation, but also can improve the cell uptake efficiency of TOs as well as the following endosomal escape to increase the therapeutic index. Furthermore, targeted and on-demand drug release of TOs can also be approached to minimize the risk of toxicity towards normal tissues using stimuli-responsive NPs. In the past decades, remarkable progresses have been made on the TOs delivery based on various NPs with specific purposes. In this review, we will first give a brief introduction on the basis of TOs as well as the action mechanisms of several typical TOs, and then describe the obstacles that prevent the clinical translation of TOs, followed by a comprehensive overview of the recent progresses on TOs delivery based on several various types of nanocarriers containing lipid-based nanoparticles, polymeric nanoparticles, gold nanoparticles, porous nanoparticles, DNA/RNA nanoassembly, extracellular vesicles, and imaging-guided drug delivery nanoparticles.