Broaden sources and reduce expenditure: Tumor-specific transformable oxidative stress nanoamplifier enabling economized photodynamic therapy for reinforced oxidation therapy

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

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

Hyaluronic acid-based multifunctional nanoplatform for glucose deprivation-enhanced chemodynamic/photothermal synergistic cancer therapy

We present a hyaluronic acid (HA)-based nanoplatform (CMGH) integrating starvation therapy (ST), chemodynamic therapy (CDT), and photothermal therapy (PTT) for targeted cancer treatment. CMGH fabrication involved the encapsulation of glucose oxidase (GOx) within a copper-based metal-organic framework (CM) followed by surface modification with HA. CMGH exerts its antitumor effects by catalyzing glucose depletion at tumor sites, leading to tumor cell starvation and the concomitant generation of glucuronic acid and H2O2. The decreased pH and elevated H2O2 promote the Fenton-like reaction of Cu ions, leading to hydroxyl radical production. HA modification enables targeted accumulation of CMGH at tumor sites via the CD44 receptor. Under near-infrared light irradiation, CM exhibits photothermal conversion capability, enhancing the antitumor effects of CMGH. In vitro and in vivo studies demonstrate the effective inhibition of tumor growth by CMGH. This study highlights the potential of CMGH as a targeted cancer therapeutic platform.

Hyaluronic acid-based injectable formulation developed to mitigate metastasis and radiation-induced skin fibrosis in breast cancer treatment

The standard treatment for early-stage breast cancer involves breast-conserving surgery followed by adjuvant radiotherapy. However, approximately 20 % of patients experience distant metastasis, and adjuvant radiotherapy often leads to radiation-induced skin fibrosis (RISF). In this study, we develop an on-site injectable formulation composed of selenocystamine (SeCA) and hyaluronic acid (HyA), referred to as SeCA cross-linked HyA (SCH) agent, and investigate its potential to mitigate metastasis and prevent RISF associated with breast cancer therapy. SCH agents are synthesized using the nanoprecipitation method to modulate cell-cell tight junctions and tissue inflammation. The toxicity assessments reveal that SCH agents with a higher Se content (Se payload 17.4 μg/mL) are well tolerated by L929 cells compared to SeCA (Se payload 3.2 μg/mL). In vitro, SCH agents significantly enhance cell-cell tight junctions and effectively mitigate migration and invasion of breast cancer cells (4T1). In vivo, SCH agents mitigate distant lung metastasis. Furthermore, in animal models, SCH agents reduce RISF and promote wound repair. These findings highlight the potential of SCH agents as a novel therapeutic formulation for effectively mitigating metastasis and reducing RISF. This holds great promise for improving clinical outcomes in breast cancer patients undergoing adjuvant radiotherapy.

Tumor Cell-Targeting and Tumor Microenvironment-Responsive Nanoplatforms for the Multimodal Imaging-Guided Photodynamic/Photothermal/Chemodynamic Treatment of Cervical Cancer

Purpose

Phototherapy, known for its high selectivity, few side effects, strong controllability, and synergistic enhancement of combined treatments, is widely used in treating diseases like cervical cancer.

Methods

In this study, hollow mesoporous manganese dioxide was used as a carrier to construct positively charged, poly(allylamine hydrochloride)-modified nanoparticles (NPs). The NP was efficiently loaded with the photosensitizer indocyanine green (ICG) via the addition of hydrogen phosphate ions to produce a counterion aggregation effect. HeLa cell membrane encapsulation was performed to achieve the final M-HMnO2@ICG NP. In this structure, the HMnO2 carrier responsively degrades to release ICG in the tumor microenvironment, self-generates O2 for sensitization to ICG-mediated photodynamic therapy (PDT), and consumes GSH to expand the oxidative stress therapeutic effect [chemodynamic therapy (CDT) + PDT]. The ICG accumulated in tumor tissues exerts a synergistic PDT/photothermal therapy (PTT) effect through single laser irradiation, improving efficiency and reducing side effects. The cell membrane encapsulation increases nanomedicine accumulation in tumor tissues and confers an immune evasion ability. In addition, high local temperatures induced by PTT can enhance CDT. These properties of the NP enable full achievement of PTT/PDT/CDT and targeted effects.

Results

Mn2+ can serve as a magnetic resonance imaging agent to guide therapy, and ICG can be used for photothermal and fluorescence imaging. After its intravenous injection, M-HMnO2@ICG accumulated effectively at mouse tumor sites; the optimal timing of in-vivo laser treatment could be verified by near-infrared fluorescence, magnetic resonance, and photothermal imaging. The M-HMnO2@ICG NPs had the best antitumor effects among treatment groups under near-infrared light conditions, and showed good biocompatibility.

Conclusion

In this study, we designed a nano-biomimetic delivery system that improves hypoxia, responds to the tumor microenvironment, and efficiently loads ICG. It provides a new economical and convenient strategy for synergistic phototherapy and CDT for cervical cancer.

Ferroptosis inducers: A new frontier in cancer therapy

Ferroptosis represents a non-apoptotic form of programmed cell death characterized by iron-dependent lipid peroxidation. This cell death modality not only facilitates the direct elimination of cancer cells, but also enhances their susceptibility to other pharmacological anti-cancer agents. The burgeoning interest in ferroptosis has been driven by a growing body of evidence that underscores the efficiency and minimal toxicity of ferroptosis inducers. Traditional inducers, such as erastin and RSL3 have shown substantial promise in clinical applications due to their potent therapeutic effects. Their significant potential of these inducers has spurred the development of a variety of small molecule ferroptosis inducers. These novel inducers boast an enhanced structural variety, improved metabolic stability, the capability to initiate ferroptosis without triggering apoptosis, making them well-suited for in vivo use. Despite these advancements, challenges still remain, particularly concerning the drug delivery, tumor specificity, and circulation duration of these small molecules in vivo. Addressing these challenges, contemporary research has pivoted towards innovative delivery systems tailored for ferroptosis inducers to facilitate precise, targeted, and synegestic therapeutic delivery. This review scrutinizes the latest progress in small molecule ferroptosis inducers and nano drug delivery systems geared towards ferroptosis sensitization. Furthermore, it delineated the prospective therapeutic advantages and the existing hurdles in the development of ferroptosis inducers for malignant tumor treatment.

Different Valence States of Copper Ion Delivery against Triple-Negative Breast Cancer

Different valence states of copper (Cu) ions are involved in complicated redox reactions in vivo, which are closely related to tumor proliferation and death pathways, such as cuproptosis and chemodynamic therapy (CDT). Cu ion mediated Fenton-like reagents induced tumor cell death which presents compelling attention for the CDT of tumors. However, the superiority of different valence states of Cu ions in the antitumor effect is unknown. In this study, we investigated different valence states of Cu ions in modulating tumor cell death by Cu-chelated cyanine dye against triple-negative breast cancer. The cuprous ion (Cu+) and copper ion (Cu2+) were chelated with four nitrogen atoms of dipicolylethylenediamine-modified cyanine for the construction of Cu+ and Cu2+ chelated cyanine dyes (denoted as CC1 and CC2, respectively). Upon 660 nm laser irradiation, the CC1 or CC2 can generate reactive oxygen species, which could disrupt the cyanine structure, achieving the rapid release of Cu ions and initiating the Fenton-like reaction for CDT. Compared with Cu2+-based Fenton-like reagent, the CC1 with Cu+ exhibited a better therapeutic outcome for the tumor due to there being no need for a reduction by glutathione and a shorter route to generate more hydroxyl radicals. Our findings suggest the precision delivery of Cu+ could achieve highly efficient antitumor therapy.

Host-Guest Interaction-Based Supramolecular Self-Assemblies for H2O2 Upregulation Augmented Chemiluminescence Resonance Energy Transfer-Induced Cancer Therapy

Given that light is hard to reach deep tumor tissue, how to enhance photodynamic therapy (PDT) efficacy is a big challenge. Herein, we proposed the supramolecular polymer self-assemblies (HACP) with bis[2,4,5-trichloro-6 (pentyloxycar-bonyl) phenyl] oxalate as the cargos (HACP@CPPO) to realize the chemiluminescence resonance energy transfer (CRET)-induced generation of 1O2 in situ. HACP was prepared by cinnamaldehyde-modified hyaluronic acid (HA-CA) and β-cyclodextrin-modified protoporphyrin IX (β-CD-PPIX) via host-guest interactions. The CA moiety could elevate H2O2 levels for the enhanced production of chemical energy and macrocyclic CD could enhance the stacking distance of PPIX for enhanced 1O2 yield. Thus, HACP@CPPO exhibited excellent antitumor performance without light irradiation.

Hyaluronic Acid-Based Bioconjugate Systems, Scaffolds, and Their Therapeutic Potential

In recent years, the development of hyaluronic acid or hyaluronan (HA) based scaffolds, medical devices, bioconjugate systems have expanded into a broad range of research and clinical applications. Research findings over the last two decades suggest that the abundance of HA in most mammalian tissues with distinctive biological roles and chemical simplicity for modifications have made it an attractive material with a rapidly growing global market. Besides its use as native forms, HA has received much interest on so-called "HA-bioconjugates" and "modified-HA systems". In this review, the importance of chemical modifications of HA, underlying rationale approaches, and various advancements of bioconjugate derivatives with their potential physicochemical, and pharmacological advantages are summarized. This review also highlights the current and emerging HA-based conjugates of small molecules, macromolecules, crosslinked systems, and surface coating strategies with their biological implications, including their potentials and key challenges discussed in detail.

Responsive manganese-based nanoplatform amplifying cGAS-STING activation for immunotherapy

BACKGROUND

The activation of the cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes (cGAS-STING) signaling pathway has attracted great attention for its ability to up-regulate innate immune response and thus enhance cancer immunotherapy. However, many STING agonists limit the further advancement of immunotherapy due to weak tumor responsiveness or low activation efficiency. The responsive and effective activation of cGAS-STING signaling in tumors is a highly challenging process.

METHODS

In this study, a manganese-based nanoplatform (MPCZ NPs) was constructed that could responsively and efficiently generate more manganese ions (Mn²⁺) and reactive oxygen species (ROS) to activate cGAS-STING signaling pathway. Briefly, manganese dioxide (MnO₂) was loaded with zinc protoporphyrin IX (ZPP) molecule and coated by polydopamine (PDA) embedded with NH₄HCO₃ to obtain MPCZ NPs. Additionally, MPCZ NPs were evaluated in vitro and in vivo for their antitumor effects by methyl thiazolyl tetrazolium (MTT) assay and TUNEL assays, respectively.

RESULTS

In this system, tumor responsiveness was achieved by exogenous (laser irradiation) and endogenous (high levels GSH) stimulation, which triggered the collapse or degradation of PDA and MnO₂. Moreover, the release of Mn²⁺ augmented the cGAS-STING signaling pathway and enhanced the conversion of hydrogen peroxide (H₂O₂) to hydroxyl radical (·OH) under NIR laser irradiation. Furthermore, the release of ZPP and the elimination of GSH by MPCZ NPs inhibited HO-1 activity and prevented ROS consumption, respectively.

CONCLUSIONS

This adopted open source and reduce expenditure strategy to effectively generate more ROS and Mn²⁺ to responsively activate cGAS-STING signaling pathway, providing a new strategy for improving immunotherapy.

Cinnamaldehyde-Contained Polymers and Their Biomedical Applications

Cinnamaldehyde, a natural product that can be extracted from a variety of plants of the genus Cinnamomum, exhibits excellent biological activities including antibacterial, antifungal, anti-inflammatory, and anticancer properties. To overcome the disadvantages (e.g., poor water solubility and sensitivity to light) or enhance the advantages (e.g., high reactivity and promoting cellular reactive oxygen species production) of cinnamaldehyde, cinnamaldehyde can be loaded into or conjugated with polymers for sustained or controlled release, thereby prolonging the effective action time of its biological activities. Moreover, when cinnamaldehyde is conjugated with a polymer, it can also introduce environmental responsiveness to the polymer through the form of stimuli-sensitive linkages between its aldehyde group and various functional groups of polymers. The environmental responsiveness provides the great potential of cinnamaldehyde-conjugated polymers for applications in the biomedical field. In this review, the strategies for preparing cinnamaldehyde-contained polymers are summarized and their biomedical applications are also reviewed.

Hyaluronic Acid-Based Nanomaterials Applied to Cancer: Where Are We Now?

Cancer cells normally develop the ability to rewire or reprogram themselves to become resistant to treatments that were previously effective. Despite progress in understanding drug resistance, knowledge gaps remain regarding the underlying biological causes of drug resistance and the design of cancer treatments to overcome it. So, resistance acquisition remains a major problem in cancer treatment. Targeted therapeutics are considered the next generation of cancer therapy because they overcome many limitations of traditional treatments. Numerous tumor cells overexpress several receptors that have a high binding affinity for hyaluronic acid (HA), while they are poorly expressed in normal body cells. HA and its derivatives have the advantage of being biocompatible and biodegradable and may be conjugated with a variety of drugs and drug carriers for developing various formulations as anticancer therapies such as micelles, nanogels, and inorganic nanoparticles. Due to their stability in blood circulation and predictable delivery patterns, enhanced tumor-selective drug accumulation, and decreased toxicity to normal tissues, tumor-targeting nanomaterial-based drug delivery systems have been shown to represent an efficacious approach for the treatment of cancer. In this review, we aim to provide an overview of some in vitro and in vivo studies related to the potential of HA as a ligand to develop targeted nanovehicles for future biomedical applications in cancer treatment.

ATP6AP1 is a potential prognostic biomarker and is associated with iron metabolism in breast cancer

Cancer occurrence and progression may be facilitated by aberrant expression of ATPase H+ transporting accessory protein 1 (ATP6AP1). However, the clinical relevance of ATP6AP1 in breast cancer remains unclear. In this study, we investigated the association between ATP6AP1 and breast cancer. Data collected from patients with breast cancer from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) were used in this study. To determine the relationship between ATP6AP1 and breast cancer survival rates, Kaplan-Meier analysis was used. To determine the prognostic value of ATP6AP1, a receiver operating characteristic (ROC) curve was constructed. To identify the major pathways involving ATP6AP1, we performed functional enrichment analysis using gene set enrichment analysis (GSEA). We analyzed the association between ATP6AP1 expression and tumor immunity using the ESTIMATE algorithm and single-sample GSEA (ssGSEA). A nomogram based on a Cox regression analysis was constructed to predict the impact of ATP6AP1 on prognosis. ATP6AP1 expression was significantly upregulated in breast cancer tissues. Moreover, patients with elevated ATP6AP1 expression had shorter total survival rates than those with lower expression levels (p = 0.032). The area under the receiver operating characteristic curve for ATP6AP1 was 0.939. Gene set enrichment analysis revealed that reaction iron uptake and transport, proteasome degradation, glutathione metabolism, and pyruvate metabolism were enriched in the ATP6AP1 high expression phenotype. The relationship between immune infiltration cells and ATP6AP1 expression, including macrophages, B cells, dendritic cells, cytotoxic cells, NK cells, and T cells, was found to be negative, suggesting that ATP6AP1 overexpression results in immunosuppression. Based on the Cox regression analyses, the calibration plot of the nomogram demonstrated effective performance in predicting breast cancer patients. ATP6AP1 may facilitate breast cancer progression by inhibiting antitumor immunity and promoting iron metabolism and may be a biomarker for breast cancer prognosis.

A reactive oxygen species-replenishing coordination polymer nanomedicine disrupts redox homeostasis and induces concurrent apoptosis-ferroptosis for combinational cancer therapy

Reactive oxygen species (ROS) are important signal molecules and imbalanced ROS level could lead to cell death. Elevated ROS levels in tumor tissues offer an opportunity to design ROS-responsive drug delivery systems (DDSs) or ROS-based cancer therapy such as chemodynamic therapy. However, their anticancer efficacies are hampered by the ROS-consuming nature of these DDSs as well as the high concentration of reductive agents like glutathione (GSH). Here we developed a doxorubicin (DOX)-incorporated iron coordination polymer nanoparticle (PCFD) for efficient chemo-chemodynamic cancer therapy by using a cinnamaldehyde (CA)-based ROS-replenishing organic ligand (TCA). TCA can ROS-responsively release CA to supplement intracellular ROS and deplete GSH by a thiol-Michael addition reaction, which together with DOX-triggered ROS upregulation and Fe³⁺-enabled GSH depletion facilitated efficient DOX release and enhanced Fenton reaction, thereby inducing redox dyshomeostasis and cancer cell death in a concurrent apoptosis-ferroptosis way. Both in vitro and in vivo study revealed that ROS-replenishing PCFD exhibited much better anticancer effect than ROS-consuming control nanoparticle PAFD. The ingenious ROS-replenishing strategy could be expanded to construct versatile ROS-responsive DDSs and ROS-based nanomedicines with potentiated anticancer activity. STATEMENT OF SIGNIFICANCE: We develop a doxorubicin (DOX)-incorporated iron coordination polymer nanoparticle (PCFD) for efficient chemo-chemodynamic cancer therapy by using a cinnamaldehyde-based reactive oxygen species (ROS)-replenishing organic ligand. This functional ligand can ROS-responsively release cinnamaldehyde to supplement intracellular H₂O₂ and deplete glutathione (GSH) by a thiol-Michael addition reaction, which together with DOX-triggered ROS upregulation and Fe³⁺-enabled GSH depletion facilitates efficient DOX release and enhanced Fenton reaction, thereby inducing redox dyshomeostasis and cancer cell death in a concurrent apoptosis-ferroptosis way. Both in vitro and in vivo study reveal that ROS-replenishing PCFD exhibit much better anticancer effect than ROS consuming counterpart. This study provides a facile and straightforward strategy to design ROS amplifying nanoplatforms for cancer treatment.

One-pot fabrication of a polydopamine-based nanoplatform for GSH triggered trimodal ROS-amplification for cancer therapy

Reactive oxygen species (ROS) based nanoplatforms have been considered as attractive and feasible candidates for cancer therapy. However, the activated endogenous antioxidant defense of cancer cells in response to the ROS attack greatly hinders their therapeutic efficacy. Although cancer-specific ROS amplification strategies have been widely explored, most of them suffer from tedious synthesis procedures and complex components, which will bring about undesired side effects and unsatisfactory results. Herein, we design a cancer-specific oxidative stress amplification nanomedicine (CA-Cu-PDA), which is simply fabricated through integrating the glutathione (GSH) responsive/depleting nanocarrier of copper-polydopamine (Cu-PDA) nanoparticles with a ROS-generating drug cinnamaldehyde (CA) via a facile one-pot polymerization route. It is verified that GSH could trigger the breakage of CA-Cu-PDA networks and the subsequent release of both copper ions and CA in cancer cells. The released copper ions efficiently oxidize GSH, thereby weakening the antioxidant system of cancer cells and increasing the ROS levels. On the other hand, extra ROS are generated by the reduced copper ions through a Fenton reaction, so that a synergistic ROS therapy with CA is achieved. Consequently, oxidative stress is specifically increased within cancer cells, leading to efficient cancer cell apoptosis, significant tumor suppression and minimized side effects. Such an ingenious structure realizes the interlocking cooperation and full utilization of each component's function, presenting promising perspectives for nanomedicine design.

Tumor-targeted hyaluronic acid-based oxidative stress nanoamplifier with ROS generation and GSH depletion for antitumor therapy

Tumor cells with innate oxidative stress are more susceptible to exogenous ROS-mediated oxidative damage than normal cells. However, the generated ROS could be scavenged by the overexpressed GSH in cancer cells, thus causing greatly restricted efficiency of ROS-mediated antitumor therapy. Herein, using cinnamaldehyde (CA) as a ROS generator while β-phenethyl isothiocyanate (PEITC) as a GSH scavenger, we designed a tumor-targeted oxidative stress nanoamplifier to elevate intracellular ROS level and synchronously suppress antioxidant systems, for thorough redox imbalance and effective tumor cells killing. First, an amphiphilic acid-sensitive cinnamaldehyde-modified hyaluronic acid conjugates (HA-CA) were synthesized, which could self-assemble into nano-assembly in aqueous media via strong hydrophobic interaction and π-π stacking. Then, aromatic PEITC was appropriately encapsulated into HA-CA nano-assembly to obtain HA-CA/PEITC nanoparticles. Through enhanced permeability retention (EPR) effect and specific CD44 receptor-mediated endocytosis, HA-CA/PEITC nanoparticles could accumulate in tumor tissues and successfully release CA and PEITC under acidic lysosomal environment. Both in vitro and in vivo results showed that the nanoparticles could efficiently boost oxidative stress of tumor cells via generating ROS and depleting GSH, and finally achieve superior antitumor efficacy. This nanoamplifier with good biosafety provides a potential strategy to augment ROS generation and suppress GSH for enhanced oxidation therapy.

Minimizing adverse effects of Cerenkov radiation induced photodynamic therapy with transformable photosensitizer-loaded nanovesicles

Background

Photodynamic therapy (PDT) is a promising antitumor strategy with fewer adverse effects and higher selectivity than conventional therapies. Recently, a series of reports have suggested that PDT induced by Cerenkov radiation (CR) (CR-PDT) has deeper tissue penetration than traditional PDT; however, the strategy of coupling radionuclides with photosensitizers may cause severe side effects.

Methods

We designed tumor-targeting nanoparticles (¹³¹I-EM@ALA) by loading 5-aminolevulinic acid (ALA) into an ¹³¹I-labeled exosome mimetic (EM) to achieve combined antitumor therapy. In addition to playing a radiotherapeutic role, ¹³¹I served as an internal light source for the Cerenkov radiation (CR).

Results

The drug-loaded nanoparticles effectively targeted tumors as confirmed by confocal imaging, flow cytometry, and small animal fluorescence imaging. In vitro and in vivo experiments demonstrated that ¹³¹I-EM@ALA produced a promising antitumor effect through the synergy of radiotherapy and CR-PDT. The nanoparticles killed tumor cells by inducing DNA damage and activating the lysosome-mitochondrial pathways. No obvious abnormalities in the hematology analyses, blood biochemistry, or histological examinations were observed during the treatment.

Conclusions

We successfully engineered a nanocarrier coloaded with the radionuclide ¹³¹I and a photosensitizer precursor for combined radiotherapy and PDT for the treatment of breast cancer.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01401-0.

Liposomal cyanine dyes with enhanced nonradiative transition for synergistic phototherapy of tumor

Organic photosensitizers are of great interest in cancer diagnose and treatment such as fluorescence imaging, photodynamic therapy (PDT), and photothermal therapy (PTT). However, their poor aqueous solubility, inadequate photostability and...

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.

Tumor-selective new piperazine-fragmented silicon phthalocyanines initiate cell death in breast cancer cell lines

A new silicon phthalocyanine with piperazine-furan ring and its quaternized form were synthesized. All compounds were analyzed by spectroscopic techniques (FT-IR, ¹H-NMR, MS, and UV-vis), and the absorbance characteristics of silicon phthalocyanines were evaluated with the expected strong typical absorption bands in the far-red spectrum. The cytotoxic effects of these phthalocyanines induced by photodynamic therapy (PDT) were determined in a dose-dependent manner. Following cytotoxicity analysis, flow cytometric research of cell death was performed. The formation of reactive oxygen species (ROS) was determined by confocal microscopy. High levels of cytotoxicity and decreased viable cell population have been detected in cancer cells after treatment. In addition, ROS formation was observed in PDT treated cancer cells. However, low levels of cell death and ROS formation were observed in non-tumorigenic cells. According to western blot data, PDT-mediated treatment was found to provide different expression patterns of the cleaved PARP1 protein. The presented study demonstrates that PDT-mediated treatment of newly synthesized phthalocyanines has significant anti-cancer effects on breast cancer cells and may induce different cell death pathways.

Recent advances in innovative strategies for enhanced cancer photodynamic therapy

Photodynamic therapy (PDT), a non-invasive therapeutic modality, has received increasing attention owing to its high selectivity and limited side effects. Although significant clinical research progress has been made in PDT, the breadth and depth of its clinical application have not been fully realized due to the limitations such as inadequate light penetration depth, non-targeting photosensitizers (PSs), and tumor hypoxia. Consequently, numerous investigations put their emphasis on innovative strategies to overcome the aforementioned limitations and enhance the therapeutic effect of PDT. Herein, up-to-date advances in these innovative methods for PDT are summarized by introducing the design of PS systems, their working mechanisms and application examples. In addition, current challenges of these innovative strategies for clinical application, and future perspectives on further improvement of PDT are also discussed.