Thermal-Responsive Carbon Monoxide (CO) Delivery Expedites Metabolic Exhaustion of Cancer Cells toward Reversal of Chemotherapy Resistance

A biomimetic dual-targeting nanomedicine for pancreatic cancer therapy

The physiological characteristics of pancreatic cancer (PC) involve the interplay between tumor cells, cancer-associated fibroblasts (CAF) and the extracellular matrix (ECM). This intricate microenvironment contributes to the cancer's resistance to conventional chemoradiotherapy and its poor prognosis. Carbon monoxide (CO), a promising molecule in gas therapy, can effectively penetrate solid tumors and induce tumor cell apoptosis at high concentrations. However, precise dosing control remains a significant challenge in the administration of exogenous CO, and its inherent toxicity at elevated concentrations presents substantial barriers to clinical translation. In this study, we developed a novel biomimetic nanomedical drug delivery system capable of simultaneously targeting CAF and PC tumor cells, degrading the ECM, and inhibiting tumor growth. The strategy integrates iron carbonyl (FeCO), an anti-cancer agent, and losartan (Lo), a drug that degrades tumor matrix, into a biodegradable nanomaterial-mesoporous polydopamine (MPDA). The resulting nanoparticles are then coated with CAF cell membranes (CAFM) and functionalized with plectin-1 targeted peptide (PTP), a molecule that targets PC cells, to construct the (Lo + FeCO)@MPDA@CAFM-PTP nanomedicine. This system utilizes the homologous adhesion properties of CAF membranes to target CAFs, delivering Lo to degrade the ECM. Following ECM degradation, the nanomedicine penetrates further to bind to PC tumor cells via PTP. Then anti-cancer drug FeCO is released to react with the excessive reactive oxygen species (ROS) in PC tumor cells to produce high concentrations of CO, effectively inducing tumor cell apoptosis. The (Lo + FeCO)@MPDA@CAFM-PTP nanomedicine demonstrated significant cytotoxicity against Panc-1 cells in vitro and effectively inhibited PC tumor growth in vivo. This innovative approach holds great promise for advancing pancreatic cancer treatment.

Intracellular Co-Delivery of Carbon Monoxide and Nitric Oxide Induces Mitochondrial Apoptosis for Cancer Therapy

Understanding the interplay between gasotransmitters is essential for unlocking their therapeutic potential. However, achieving spatiotemporally controlled co-delivery to target cells remains a significant challenge. Herein, we propose an innovative strategy for the intracellular co-delivery of carbon monoxide (CO) and nitric oxide (NO) gasotransmitters under clinically relevant wavelengths. This approach rationally couples aerobic photooxidative and anaerobic photocatalytic reactions within a polymeric micelle platform, using palladium(II) tetraphenyltetrabenzoporphyrin (PdTPTBP) as both photosensitizer and photocatalyst. Notably, the photooxidation-mediated release of CO generates a local hypoxic microenvironment, which facilitates the photoredox catalyzed release of NO. This self-adaptive micelle platform enables efficient uptake by tumor cells and intracellular co-delivery of CO and NO under 630 nm light irradiation, demonstrating potent anti-tumor activity in a 4T1 tumor-bearing mouse model via the synergistic induction of mitochondrial apoptosis.

A multifunctional cascade gas-nanoreactor with MnO2 as a gatekeeper to enhance starvation therapy and provoke antitumor immune response

Glucose oxidase (GOx)-mediated starvation therapy is an effective tumor treatment that blocks energy and activates the immune response. However, the insufficient tumor immunogenicity and immunosuppressive tumor microenvironment (TME) limited its therapeutic efficacy. To address this, we have designed a multifunctional cascade gas-nanoreactor with a MnO2 coating, which serves as an out gatekeeper to encapsulate both GOx and a carbon monoxide (CO) donor (denoted as GCM). Due to the protective effect of MnO2 coating, GCM maintains better stability in normal physiological environments, enhancing the catalytic activity of GOx and minimizing toxic side effects. Upon accumulation in the tumor, the degradation of MnO2 coating exposes the GOx enzyme, thereby initiating a cascade catalysis reaction to generate hydrogen peroxide (H2O2) and release CO in the hypoxic conditions. Additionally, the released Mn2+ reacts with H2O2 to generate toxic hydroxyl radical (•OH) as chemodynamic therapy (CDT). The synergistic treatments of starvation therapy, CO gas therapy and CDT effectively kill cancer cells and amplify immunogenic cell death (ICD), maturing DC cells and activating anti-tumor immune response. Furthermore, the released CO increases M1 macrophages infiltration and reduces myeloid-derived suppressor cells (MDSCs) infiltration, thus reversing the immunosuppressive TME. This multifunctional gas-nanoreactor provides a strategy for CO gas generation to trigger a robust anti-tumor immune response and has the potential for clinical application in cancer immunotherapy. STATEMENT OF SIGNIFICANCE: A multifunctional cascade gas-nanoreactor with a MnO2 gatekeeper was developed to perform synergistic treatments involving starvation therapy, CO gas therapy and chemodynamic therapy (CDT) for tumor elimination. The MnO2 gatekeeper enhanced the catalytic activity of GOx within the nanoreactor by generating oxygen, thereby minimizing toxic side effects after intravenous injection. The gas-nanoreactor amplified ICD through synergistic treatments to mature DC cells and activate anti-tumor immune response. Furthermore, the released CO could reverse the immunosuppression of the TME to enhance cancer immunotherapy. The combination strategy utilizing the gas-nanoreactor demonstrates clinical potential for facilitating cancer immunotherapy.

Gas immnuo-nanomedicines fight cancers

Certain gas molecules, including hydrogen (H2), nitric oxide (NO), carbon monoxide (CO), hydrogen sulfide (H2S), oxygen (O2) and sulfur dioxide (SO2) exhibit significant biological functionalities that can modulate the immune response. Strategies pertaining to gas-based immune therapy have garnered considerable attention in recent years. Nevertheless, delivering various gas molecules precisely into tumors, which leads to enhanced anti-tumor immunotherapeutic effect, is still a main challenge. The advent of gas treatment modality with desirable immunotherapeutic efficiency has been made possible by the rapid development of nanotechnology, which even derives the concept of the gas immnuo-nanomedicines (GINMs). In light of the fact, we herein aim to furnish a cutting-edge review on the latest progress of GINMs. The underlying mechanisms of action for several gases utilized in cancer immunotherapy are initially outlined. Additionally, it provides a succinct overview of the current clinical landscape of gas therapy, and introduces GINMs specifically designed for cancer treatment based on immunotherapeutic principles across multiple strategies. Last but not least, we address the challenges and opportunities associated with GINMs, exploring the potential future developments and clinical applications of this innovative approach.

Biomedical Metal-Organic Framework Materials: Perspectives and Challenges

Metal-organic framework (MOF) materials are gaining significant interest in biomedical research, owing to their high porosity, crystallinity, and structural and compositional diversity. Their versatile hybrid organic/inorganic chemistry endows MOFs with the capacity to retain organic (drug) molecules, metals, and gases, to effectively channel electrons and photons, to survive harsh physiological conditions such as low pH, and even to protect sensitive biomolecules. Extensive preclinical research has been carried out with MOFs to treat several pathologies and, recently, their integration with other biomedical materials such as stents and implants has demonstrated promising performance in regenerative medicine. However, there remains a significant gap between MOF preclinical research and translation into clinically and societally relevant medicinal products. Here, we outline the intrinsic features of MOFs and discuss how these are suited to specific biomedical applications like detoxification, drug and gas delivery, or as (combination) therapy platforms. We furthermore describe relevant examples of how MOFs have been engineered and evaluated in different medical indications, including cancer, microbial, and inflammatory diseases. Finally, we critically examine the challenges facing their translation into the clinic, with the goal of establishing promising research directions and more realistic approaches that can bridge the translational gap of MOFs and MOF-containing (nano)materials.

Biodegradable Ruthenium-Rhenium Complexes Containing Nanoamplifiers: Triggering ROS-Induced CO Release for Synergistic Cancer Treatment

The constrained effectiveness of photodynamic therapy (PDT) has impeded its widespread use in clinical practice. Urgent efforts are needed to address the shortcomings faced in photodynamic therapy, such as photosensitizer toxicity, short half-life, and limited action range of reactive oxygen species (ROS). In this study, a biodegradable copolymer nanoamplifier is reported that contains ruthenium complex (Ru-complex) as photosensitizer (PS) and rhenium complex (Re-complex) as carbon monoxide (CO)-release molecule (CORM). The well-designed nanoamplifier brings PS and CORM into close spatial proximity, significantly promotes the utilization of light-stimulated reactive oxygen species (ROS), and cascaded amplifying CO release, thus enabling an enhanced synergistic effect of PDT and gas therapy for cancer treatment. Moreover, owing to its intrinsic photodegradable nature, the nanoamplifier exhibits good tumor accumulation and penetration ability, and excellent biocompatibility in vivo. These findings suggest that the biodegradable cascaded nanoamplifiers pave the way for a synergistic and clinically viable integration of photodynamic and gas therapy.

Two-pronged anti-cancer nanovaccines enpowered by exogenous/endogenous tumor-associated antigens

Cancer vaccines based on single-source (exogenous or endogenous) tumor-associated antigens (TAAs) are often challenged by the insufficient T cell response and the immunosuppressive tumor microenvironment (TME). Herein, a dual TAAs-boosted nanovaccine based on cancer cell (4T1) membrane-cloaked, CO-immobilized Prussian blue nanoparticles (4T1-PB-CO NPs) is developed and coupled with anti-interleukin (IL)-10 therapy to maximize the efficacy of antitumor immunotherapy. 4T1 cell membrane not only endows NPs with tumor targeting ability, but also serves as exogenous TAAs to trigger CD4+ T cell response and M1-phenotype polarization of tumor-associated macrophages. Under near-infrared light irradiation, 4T1-PB-CO NPs release CO to induce immunogenic cell death (ICD) of tumor cells, thus generating endogenous TAAs to activate CD8+ T cell response. Meanwhile, ICD triggers release of damage-associated molecular patterns, which can promote DC maturation to amplify the antitumor T cell response. When combined with anti-IL-10 that reverses the immunosuppressive TME, 4T1-PB-CO NPs efficiently suppress the primary tumors and produce an abscopal effect to inhibit distant tumors in a breast tumor-bearing mouse model. Such a two-pronged cancer vaccine represents a promising paradigm for robust antitumor immunotherapy.

Removable Photocatalysis Microneedle Reactor for Carbon Monoxide Delivery to Enhance Chemosensitization

Carbon monoxide (CO) has emerged as a promising therapeutic agent, yet ensuring safe and precise CO delivery remains challenging. Here, we report a removable hydrogel-forming microneedle (MN) reactor for CO delivery via photocatalysis, with an emphasis on chemosensitization. Upon application, body fluids absorbed by the MNs dissolve the effervescent agents, leading to the generation of carbon dioxide (CO2) and triggering the release of the chemotherapeutics cisplatin. Meanwhile, the photocatalysts (PCs) trapped within MNs convert CO2 to CO under 660 nm light irradiation. These PCs can be removed by hydrogel-forming MNs, thereby mitigating potential biological risks associated with residual PCs. Both in vitro and in vivo experiments showed that MN-mediated CO delivery significantly improved tumor sensitivity to cisplatin by suppressing DNA repair, using an A375/CDDP melanoma model. This removable photocatalysis MN reactor offers safe and precise local delivery of CO, potentially creating new opportunities for CO or its combination therapies.

Gas Therapy: Generating, Delivery, and Biomedical Applications

Oxygen (O2), nitric oxide (NO), carbon monoxide (CO), hydrogen sulfide (H2S), and hydrogen (H2) with direct effects, and carbon dioxide (CO2) with complementary effects on the condition of various diseases are known as therapeutic gases. The targeted delivery and in situ generation of these therapeutic gases with controllable release at the site of disease has attracted attention to avoid the risk of gas poisoning and improve their performance in treating various diseases such as cancer therapy, cardiovascular therapy, bone tissue engineering, and wound healing. Stimuli-responsive gas-generating sources and delivery systems based on biomaterials that enable on-demand and controllable release are promising approaches for precise gas therapy. This work highlights current advances in the design and development of new approaches and systems to generate and deliver therapeutic gases at the site of disease with on-demand release behavior. The performance of the delivered gases in various biomedical applications is then discussed.

Gasotransmitters and noble gases in cardioprotection: unraveling molecular pathways for future therapeutic strategies

Despite recent progress, ischemic heart disease poses a persistent global challenge, driving significant morbidity and mortality. The pursuit of therapeutic solutions has led to the emergence of strategies such as ischemic preconditioning, postconditioning, and remote conditioning to shield the heart from myocardial ischemia/reperfusion injury (MIRI). These ischemic conditioning approaches, applied before, after, or at a distance from the affected organ, inspire future therapeutic strategies, including pharmacological conditioning. Gasotransmitters, comprising nitric oxide, hydrogen sulfide, sulfur dioxide, and carbon monoxide, play pivotal roles in physiological and pathological processes, exhibiting shared features such as smooth muscle relaxation, antiapoptotic effects, and anti-inflammatory properties. Despite potential risks at high concentrations, physiological levels of gasotransmitters induce vasorelaxation and promote cardioprotective effects. Noble gases, notably argon, helium, and xenon, exhibit organ-protective properties by reducing cell death, minimizing infarct size, and enhancing functional recovery in post-ischemic organs. The protective role of noble gases appears to hinge on their modulation of molecular pathways governing cell survival, leading to both pro- and antiapoptotic effects. Among noble gases, helium and xenon emerge as particularly promising in the field of cardioprotection. This overview synthesizes our current understanding of the roles played by gasotransmitters and noble gases in the context of MIRI and cardioprotection. In addition, we underscore potential future developments involving the utilization of noble gases and gasotransmitter donor molecules in advancing cardioprotective strategies.

Modulating synovial macrophage pyroptosis and mitophagy interactions to mitigate osteoarthritis progression using functionalized nanoparticles

Synovial macrophages play an important role in the progression of osteoarthritis (OA). In this study, we noted that synovial macrophages can activate pyroptosis in a gasdermin d-dependent manner and produce reactive oxygen species (ROS), aberrantly activating the mammalian target of rapamycin complex 1 (mTORC1) pathway and matrix metalloproteinase-9 (MMP9) expression in synovial tissue samples collected from both patients with OA and collagen-induced osteoarthritis (CIOA) mouse model. To overcome this, we constructed rapamycin- (RAPA, a mTORC1 inhibitor) loaded mesoporous Prussian blue nanoparticles (MPB NPs, for catalyzing ROS) and modified the NPs with MMP9-targeted peptides (favor macrophage targeting) to develop RAPA@MPB-MMP9 NPs. The inherent enzyme-like activity and RAPA released from RAPA@MPB-MMP9 NPs synergistically impeded the pyroptosis of macrophages and the activation of the mTORC1 pathway. In particular, the NPs decreased pyroptosis-mediated ROS generation, thereby inhibiting cGAS-STING signaling pathway activation caused by the release of mitochondrial DNA. Moreover, the NPs promoted macrophage mitophagy to restore mitochondrial stability, alleviate pyroptosis-related inflammatory responses, and decrease senescent synoviocytes. After the as-prepared NPs were intra-articularly injected into the CIOA mouse model, they efficiently attenuated synovial macrophage pyroptosis and cartilage degradation. In conclusion, our study findings provide a novel therapeutic strategy for OA that modulates the pyroptosis and mitophagy of synovial macrophage by utilizing functionalized NPs. STATEMENT OF SIGNIFICANCE: Osteoarthritis (OA) presents a significant global challenge owing to its complex pathogenesis and finite treatment options. Synovial macrophages have emerged as key players in the progression of OA, managing inflammation and tissue destruction. In this study, we discovered a novel therapeutic strategy in which the pyroptosis and mitophagy of synovial macrophages are targeted to mitigate OA pathology. For this, we designed and prepared rapamycin-loaded mesoporous Prussian blue nanoparticles (RAPA@MPB-MMP9 NPs) to specifically target synovial macrophages and modulate their inflammatory responses. These NPs could efficiently suppress macrophage pyroptosis, diminish reactive oxygen species production, and promote mitophagy, thereby alleviating inflammation and protecting cartilage integrity. Our study findings not only clarify the intricate mechanisms underlying OA pathogenesis but also present a promising therapeutic approach for effectively managing OA by targeting dysregulation in synovial macrophages.

H2O2-triggered CO release based on porphyrinic covalent organic polymers for photodynamic/gas synergistic therapy

A novel H2O2-responsive carbon monoxide nanogenerator was designed by effectively encapsulating a manganese carbonyl prodrug into porphyrinic covalent organic polymers for realizing the combined CO gas and photodynamic therapy under near infrared light irradiation.

Vacancy-Rich Bismuth-Based Nanosheets for Mitochondrial Destruction via CO Poisoning, Ca2+ Dyshomeostasis, and Oxidative Damage

Mitochondria are core regulators of tumor cell homeostasis, and their damage has become an arresting therapeutic modality against cancer. Despite the development of many mitochondrial-targeted pharmaceutical agents, the exploration of more powerful and multifunctional medications is still underway. Herein, oxygen vacancy-rich BiO2-x wrapped with CaCO3 (named BiO2-x@CaCO3/PEG, BCP) is developed for full-fledged attack on mitochondrial function. After endocytosis of BCP by tumor cells, the CaCO3 shell can be decomposed in the acidic lysosomal compartment, leading to immediate Ca2+ release and CO2 production in the cytoplasm. Near-infrared irradiation enhances the adsorption of CO2 onto BiO2-x defects, which enables highly efficient photocatalysis of CO2-to-CO. Meanwhile, such BiO2-x nanosheets possess catalase-, peroxidase- and oxidase-like catalytic activities under acidic pH conditions, allowing hypoxia relief and the accumulation of diverse reactive oxygen species (ROS) in the tumor microenvironment. Ca2+ overload-induced ion dyshomeostasis, CO-mediated respiratory chain poisoning, ROS-triggered oxidative stress aggravation, and cytosolic hyperoxia can cause severe mitochondrial disorders, which further lead to type I cell death in carcinoma. Not only does BCP cause irreversible apoptosis, but immunogenic cell death is simultaneously triggered to activate antitumor immunity for metastasis inhibition. Collectively, this platform promises high benefits in malignant tumor therapy and may expand the medical applications of bismuth-based nanoagents.

Current status of controlled onco-therapies based on metal organic frameworks

Despite consecutive efforts devoted to the establishment of innovative therapeutics for cancer control, cancer remains as a primary global public health concern. Achieving controlled release of anti-cancer agents may add great value to the field of oncology that requires the involvement of nanotechnologies. Metal organic frameworks (MOFs) hold great promise in this regard owing to their unique structural properties. MOFs can act as superior candidates for drug delivery given their porous structure and large loading area, and can be prepared into anti-cancer therapeutics by incorporating stimuli-sensitive components into the ligands or nodes of the framework. By combing through chemical and physical features of MOFs favorable for onco-therapeutic applications and current cancer treatment portfolios taking advantages of these characteristics, this review classified MOFs feasible for establishing controlled anti-cancer modalities into 6 categories, outlined the corresponding strategies currently available for each type of MOF, and identified understudied areas and future opportunities towards innovative MOF design for improved or expanded clinical anti-cancer applications.

Nanosized Prussian blue and its analogs for bioimaging and cancer theranostics

Prussian blue (PB) nanoparticles (NPs) and Prussian blue analogs (PBAs) can form metal-organic frameworks through the programmable coordination of ferrous ions with cyanide. PB and PBAs represent a burgeoning class of hybrid functional nano-systems with a wide-ranging application spectrum encompassing biomedicine, cancer diagnosis, and therapy. A comprehensive overview of recent advancements is crucial for gaining insights for future research. In this context, we reviewed the synthesis techniques and surface modification strategies employed to tailor the dimensions, morphology, and attributes of PB NPs. Subsequently, we explored advanced biomedical utilities of PB NPs, encompassing photoacoustic imaging, magnetic resonance imaging, ultrasound (US) imaging, and multimodal imaging. In particular, the application of PB NPs-mediated photothermal therapy, photodynamic therapy, and chemodynamic therapy to cancer treatment was reviewed. Based on the literature, we envision an evolving trajectory wherein the future of Prussian blue-driven biological applications converge into an integrated theranostic platform, seamlessly amalgamating bioimaging and cancer therapy. STATEMENT OF SIGNIFICANCE: Prussian blue, an FDA-approved coordinative pigment with a centuries-long legacy, has paved the way for Prussian blue nanoparticles (PB NPs), renowned for their remarkable biocompatibility and biosafety. These PB NPs have found their niche in biomedicine, playing crucial roles in both diagnostics and therapeutic applications. The comprehensive review goes beyond PB NP-based cancer therapy. Alongside in-depth coverage of PB NP synthesis and surface modifications, the review delves into their cutting-edge applications in the realm of biomedical imaging, encompassing techniques such as photoacoustic imaging, magnetic resonance imaging, ultrasound imaging, and multimodal imaging.

Recent advance in self-assembled polymeric nanomedicines for gaseous signaling molecule delivery

Gaseous signaling molecules such as nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2 S) have recently been recognized as essential signal mediators that regulate diverse physiological and pathological processes in the human body. With the evolution of gaseous signaling molecule biology, their therapeutic applications have attracted growing attention. One of the challenges in translational research of gaseous signaling molecules is the lack of efficient and safe delivery systems. To tackle this issue, researchers developed a library of gas donors, which are low molecular weight compounds that can release gaseous signaling molecules upon decomposition under physiological conditions. Despite the significant efforts to control gaseous signaling molecule release from gas donors, the therapeutic potential of gaseous signaling molecules cannot be fully explored due to their unfavorable pharmacokinetics and toxic side effects. Recently, the use of nanoparticle-based gas donors, especially self-assembled polymeric gas donors, have emerged as a promising approach. In this review, we describe the development of conventional small gas donors and the challenges in their therapeutic applications. We then illustrate the concepts and critical aspects for designing self-assembled polymeric gas donors and discuss the advantages of this approach in gasotransmistter delivery. We also highlight recent efforts to develop the delivery systems for those molecules based on self-assembled polymeric nanostructures. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Nanodelivery Systems as a Novel Strategy to Overcome Treatment Failure of Cancer

Despite the tremendous progress in cancer treatment in recent decades, cancers often become resistant due to multiple mechanisms, such as intrinsic or acquired multidrug resistance, which leads to unsatisfactory treatment effects or accompanying metastasis and recurrence, ultimately to treatment failure. With a deeper understanding of the molecular mechanisms of tumors, researchers have realized that treatment designs targeting tumor resistance mechanisms would be a promising strategy to break the therapeutic deadlock. Nanodelivery systems have excellent physicochemical properties, including highly efficient tissue-specific delivery, substantial specific surface area, and controllable surface chemistry, which endow nanodelivery systems with capabilities such as precise targeting, deep penetration, responsive drug release, multidrug codelivery, and multimodal synergy, which are currently widely used in biomedical researches and bring a new dawn for overcoming cancer resistance. Based on the mechanisms of tumor therapeutic resistance, this review summarizes the research progress of nanodelivery systems for overcoming tumor resistance to improve therapeutic efficacy in recent years and offers prospects and challenges of the application of nanodelivery systems for overcoming cancer resistance.

Zwitterionic dendrimer self-assembled nanodrugs with high drug loading for enhanced anti-tumor ability

Zwitterionic dendrimers have been used to construct many nanomedicines due to their ability to achieve controlled drug release, but their low drug loading content limits their application in nanodrug delivery. To solve this problem, the surface of second generation polypropylimine (G2 PPI) was modified with mercapturized paclitaxel (PTX-SH) and zwitterionic groups to prepare zwitterionic prodrug molecule (PPIMPC), and then zwitterionic dendrimer self-assembled nanodrugs (PPIMPC-DOX micelles) were prepared by incorporating doxorubicin (DOX) into the micelles. The DOX loading and paclitaxel (PTX) loading in PPIMPC-DOX micelles was 6.7% and 26.2%, respectively, and the total drug loading of PPIMPC-DOX was high to 32.9%. In addition, PPIMPC-DOX micelles showed enhanced cytotoxicity due to improved cell uptake of DOX. More importantly, the inhibition rate of tumor was much higher than free DOX. The zwitterionic property and high drug loading of PPIMPC-DOX micelles enhanced anti-tumor ability of chemotherapeutic drugs. The method of preparation of zwitterionic and high drug loading of nanodrugs shows good application prospects in the future.

Tumor Abnormality-Oriented Nanomedicine Design

Anticancer nanomedicines have been proven effective in mitigating the side effects of chemotherapeutic drugs. However, challenges remain in augmenting their therapeutic efficacy. Nanomedicines responsive to the pathological abnormalities in the tumor microenvironment (TME) are expected to overcome the biological limitations of conventional nanomedicines, enhance the therapeutic efficacies, and further reduce the side effects. This Review aims to quantitate the various pathological abnormalities in the TME, which may serve as unique endogenous stimuli for the design of stimuli-responsive nanomedicines, and to provide a broad and objective perspective on the current understanding of stimuli-responsive nanomedicines for cancer treatment. We dissect the typical transport process and barriers of cancer drug delivery, highlight the key design principles of stimuli-responsive nanomedicines designed to tackle the series of barriers in the typical drug delivery process, and discuss the "all-into-one" and "one-for-all" strategies for integrating the needed properties for nanomedicines. Ultimately, we provide insight into the challenges and future perspectives toward the clinical translation of stimuli-responsive nanomedicines.

BODIPY-Based Mitochondrial Targeted NIR-Responsive CO-Releasing Platform for the On-Demand Release of CO to Treat Cancer

It is an established fact that cancer is one of the most serious public health issues after coronary artery disease. Thus, exploring more effective and efficient therapeutic protocols over the traditional chemotherapeutic strategy is imperative to improving cancer survivorship and patient quality of life. In this respect, recent reports on molecularly engineered meso-substituted BODIPY have shown remarkable effects as a photoresponsive CO-releasing platform for the on-demand release of CO to treat cancer. Herein, we designed and synthesized two meso-substituted BODIPY photoresponsive CO-releasing molecules (photoCORMs). These BODIPY derivatives were tethered to a phenoxymethylpyridine moiety and oligoethylene glycol to maintain a hydrophilic-hydrophobic balance and improved cell permeability. The cell imaging experiments demonstrated that oligoethylene glycol containing photoCORM-1 efficiently internalized and preferentially localized at the mitochondria. To understand the mechanistic aspect of preferential localization into the mitochondria, live cell imaging was also carried out. Photorelease of CO was directly monitored by the inline IR spectroscopic technique. Finally, in vitro cytotoxicity and apoptosis assays on MDA-MB-231 cell lines clearly showed that photoCORM-1 induced apoptosis-mediated cell killing on account of photoreleased CO, which otherwise showed insignificant toxicity even at a very high concentration of ∼50 μM.

Strategies to overcome cancer multidrug resistance (MDR) through targeting P-glycoprotein (ABCB1): An updated review

The emergence of multidrug resistance (MDR) in malignant tumors is one of the leading threats encountered currently in many chemotherapeutic agents. The overexpression of the ATP-binding cassette (ABC) transporters is involved in MDR. P-glycoprotein (P-gp)/ABCB1 is a member of the ABC transporter family that significantly increases the efflux of various anticancer drugs from tumor cells. Therefore, targeting P-gp with small molecule inhibitors is an effective therapeutic strategy to overcome MDR. Over the past four decades, diverse compounds with P-gp inhibitory activity have been identified to sensitize drug-resistant cells, but none of them has been proven clinically useful to date. Research efforts continue to discover an effective approach for circumventing MDR. This review has provided an overview of the most recent advances (last three years) in various strategies for circumventing MDR mediated by P-gp. It may be helpful for the scientists working in the field of drug discovery to further synthesize and discover new chemical entities/therapeutic modalities with less toxicity and more efficacies to overcome MDR in cancer chemotherapy.

The Triple Crown: NO, CO, and H2S in cancer cell biology

Nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) are three endogenously produced gases with important functions in the vasculature, immune defense, and inflammation. It is increasingly apparent that, far from working in isolation, these three exert many effects by modulating each other's activity. Each gas is produced by three enzymes, which have some tissue specificities and can also be non-enzymatically produced by redox reactions of various substrates. Both NO and CO share similar properties, such as activating soluble guanylate cyclase (sGC) to increase cyclic guanosine monophosphate (cGMP) levels. At the same time, H2S both inhibits phosphodiesterase 5A (PDE5A), an enzyme that metabolizes sGC and exerts redox regulation on sGC. The role of NO, CO, and H2S in the setting of cancer has been quite perplexing, as there is evidence for both tumor-promoting and pro-inflammatory effects and anti-tumor and anti-inflammatory activities. Each gasotransmitter has been found to have dual effects on different aspects of cancer biology, including cancer cell proliferation and apoptosis, invasion and metastasis, angiogenesis, and immunomodulation. These seemingly contradictory actions may relate to each gas having a dual effect dependent on its local flux. In this review, we discuss the major roles of NO, CO, and H2S in the context of cancer, with an effort to highlight the dual nature of each gas in different events occurring during cancer progression.

One-pot synthesis of dynamically cross-linked polymers for serum-resistant nucleic acid delivery

Cationic polymers used for nucleic acid delivery often suffer from complicated syntheses, undesired intracellular cargo release and low serum stability. Herein, a series of ternary polymers were synthesized via facile green chemistry to achieve efficient plasmid DNA and mRNA delivery in serum. During the one-pot synthesis of the ternary polymer, acetylphenylboric acid (APBA), polyphenol and low-molecular weight polyethyleneimine (PEI 1.8k) were dynamically cross-linked with each other due to formation of an imine between PEI 1.8k and APBA and formation of a boronate ester between APBA and polyphenol. Series of polyphenols, including ellagic acid (EA), epigallocatechin gallate (EGCG), nordihydroguaiaretic acid (NDGA), rutin (RT) and rosmarinic acid (RA), and APBA molecules, including 2-acetylphenylboric acid (2-APBA), 3-acetylphenylboric acid (3-APBA) and 4-acetylphenylboric acid (4-APBA), were screened and the best-performing ternary polymer, 2-PEI-RT, constructed from RT and 2-APBA, was identified. The ternary polymer featured efficient DNA condensation to favor cellular internalization, and the acidic environment in endolysosomes triggered effective degradation of the polymer to promote cargo release. Thus, 2-PEI-RT showed robust plasmid DNA transfection efficiencies in various tumor cells in serum, outperforming the commercial reagent PEI 25k by 1-3 orders of magnitude. Moreover, 2-PEI-RT mediated efficient cytosolic delivery of Cas9-mRNA/sgRNA to enable pronounced CRISPR-Cas9 genome editing in vitro. Such a facile and robust platform holds great potential for non-viral nucleic acid delivery and gene therapy.

Development of pH-Responsive Hyaluronic Acid-Conjugated Cyclodextrin Nanoparticles for Chemo-/CO-Gas Dual Therapy

In this study, we fabricated γ-cyclodextrin (γCD)-based nanoparticles (NPs) for dual antitumor therapy. First, γCD (the backbone biopolymer) was chemically conjugated with low-molecular-weight hyaluronic acid (HA; a tumoral CD44 receptor-targeting molecule) and 3-(diethylamino)propylamine (DEAP; a pH-responsive molecule), termed as γCD-(DEAP/HA). The obtained γCD-(DEAP/HA) self-assembled in aqueous solution, producing the γCD-(DEAP/HA) NPs. These NPs efficiently entrapped paclitaxel (PTX; an antitumor drug) and triiron dodecacarbonyl (FeCO; an endogenous cytotoxic gas molecule) via hydrophobic interactions between PTX and FeCO with the unprotonated DEAP molecules in γCD-(DEAP/HA) and a possible host-guest interaction in the γCD rings. The release of PTX and FeCO from the NPs resulted from particle destabilization at endosomal pH, probably owing to the protonation of DEAP in the NPs. In vitro studies using MCF-7 tumor cells demonstrated that these NPs were efficiently internalized by the cells expressing CD44 receptors and enhanced PTX/FeCO-mediated tumor cell apoptosis. Importantly, local light irradiation of FeCO stimulated the generation of cytotoxic CO, resulting in highly improved tumor cell death. We expect that these NPs have potential as dual-modal therapeutic candidates with enhanced antitumor activity in response to acidic pH and local light irradiation.

Anti-inflammatory strategies for photothermal therapy of cancer

High temperature generated by photothermal therapy (PTT) can trigger an inflammatory response at the tumor site, which not only limits the efficacy of PTT but also increases the risk of tumor metastasis and recurrence. In light of the current limitations posed by inflammation in PTT, several studies have revealed that inhibiting PTT-induced inflammation can significantly improve the efficacy of cancer treatment. In this review, we summarize the research progress made in combining anti-inflammatory strategies to enhance the effectiveness of PTT. The goal is to offer valuable insights for developing better-designed photothermal agents in clinical cancer therapy.

Research development of porphyrin-based metal-organic frameworks: targeting modalities and cancer therapeutic applications

Porphyrins are naturally occurring organic molecules that have attracted widespread attention for their potential in the field of biomedical research. Porphyrin-based metal-organic frameworks (MOFs) that utilize porphyrin molecules as organic ligands have gained attention from researchers due to their excellent results as photosensitizers in tumor photodynamic therapy (PDT). Additionally, MOFs hold significant promise and potential for other tumor therapeutic approaches due to their tunable size and pore size, excellent porosity, and ultra-high specific surface area. Active delivery of nanomaterials via targeted molecules for tumor therapy has demonstrated greater accumulation, lower drug doses, higher therapeutic efficacy, and reduced side effects relative to passive targeting through the enhanced permeation and retention effect (EPR). This paper presents a comprehensive review of the targeting methods employed by porphyrin-based MOFs in tumor targeting therapy over the past few years. It further discusses the applications of porphyrin-based MOFs for targeted cancer therapy through various therapeutic methods. The objective of this paper is to provide a valuable reference and source of ideas for targeted therapy using porphyrin-based MOF materials and to inspire further exploration of their potential in the field of cancer therapy.

Cytoprotective Role of Heme Oxygenase-1 in Cancer Chemoresistance: Focus on Antioxidant, Antiapoptotic, and Pro-Autophagy Properties

Chemoresistance remains the foremost challenge in cancer therapy. Targeting reactive oxygen species (ROS) manipulation is a promising strategy in cancer treatment since tumor cells present high levels of intracellular ROS, which makes them more vulnerable to further ROS elevation than normal cells. Nevertheless, dynamic redox evolution and adaptation of tumor cells are capable of counteracting therapy-induced oxidative stress, which leads to chemoresistance. Hence, exploring the cytoprotective mechanisms of tumor cells is urgently needed to overcome chemoresistance. Heme oxygenase-1 (HO-1), a rate-limiting enzyme of heme degradation, acts as a crucial antioxidant defense and cytoprotective molecule in response to cellular stress. Recently, emerging evidence indicated that ROS detoxification and oxidative stress tolerance owing to the antioxidant function of HO-1 contribute to chemoresistance in various cancers. Enhanced HO-1 expression or enzymatic activity was revealed to promote apoptosis resistance and activate protective autophagy, which also involved in the development of chemoresistance. Moreover, inhibition of HO-1 in multiple cancers was identified to reversing chemoresistance or improving chemosensitivity. Here, we summarize the most recent advances regarding the antioxidant, antiapoptotic, and pro-autophagy properties of HO-1 in mediating chemoresistance, highlighting HO-1 as a novel target for overcoming chemoresistance and improving the prognosis of cancer patients.

Gas therapy potentiates aggregation-induced emission luminogen-based photoimmunotherapy of poorly immunogenic tumors through cGAS-STING pathway activation

The immunologically "cold" microenvironment of triple negative breast cancer results in resistance to current immunotherapy. Here, we reveal the immunoadjuvant property of gas therapy with cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway activation to augment aggregation-induced emission (AIE)-active luminogen (AIEgen)-based photoimmunotherapy. A virus-mimicking hollow mesoporous tetrasulfide-doped organosilica is developed for co-encapsulation of AIEgen and manganese carbonyl to fabricate gas nanoadjuvant. As tetra-sulfide bonds are responsive to intratumoral glutathione, the gas nanoadjuvant achieves tumor-specific drug release, promotes photodynamic therapy, and produces hydrogen sulfide (H₂S). Upon near-infrared laser irradiation, the AIEgen-mediated phototherapy triggers the burst of carbon monoxide (CO)/Mn²⁺. Both H₂S and CO can destroy mitochondrial integrity to induce leakage of mitochondrial DNA into the cytoplasm, serving as gas immunoadjuvants to activate cGAS-STING pathway. Meanwhile, Mn²⁺ can sensitize cGAS to augment STING-mediated type I interferon production. Consequently, the gas nanoadjuvant potentiates photoimmunotherapy of poorly immunogenic breast tumors in female mice.

Recent advances in Prussian blue-based photothermal therapy in cancer treatment

Malignant tumours are a serious threat to human health. Traditional chemotherapy has achieved breakthrough improvements but also has significant detrimental effects, such as the development of drug resistance, immunosuppression, and even systemic toxicity. Photothermal therapy (PTT) is an emerging cancer therapy. Under light irradiation, the phototherapeutic agent converts optical energy into thermal energy and induces the hyperthermic death of target cells. To date, numerous photothermal agents have been developed. Prussian blue (PB) nanoparticles are among the most promising photothermal agents due to their excellent physicochemical properties, including photoacoustic and magnetic resonance imaging properties, photothermal conversion performance, and enzyme-like activity. By the construction of suitably designed PB-based nanotherapeutics, enhanced photothermal performance, targeting ability, multimodal therapy, and imaging-guided cancer therapy can be effectively and feasibly achieved. In this review, the recent advances in PB-based photothermal combinatorial therapy and imaging-guided cancer therapy are comprehensively summarized. Finally, the potential obstacles of future research and clinical translation are discussed.

A photocatalytic carbon monoxide-generating effervescent microneedle patch for improved transdermal chemotherapy

Carbon monoxide (CO) is regarded as a promising therapeutic agent for chemotherapy sensitization. To simultaneously achieve controllable in situ CO production and efficient chemotherapeutics delivery is of great significance. Here, we presented a polyvinylpyrrolidone (PVP) core-shell microneedle (MN) system that encapsulated the effervescent component, photocatalyst, and doxorubicin hydrochloride (Dox·HCl) for CO-sensitized chemotherapy. Upon the insertion of MNs, the effervescent component, composed of sodium bicarbonate and tartaric acid, was exposed to interstitial fluid, leading to the burst release of carbon dioxide (CO₂). The generated gas not only enhanced the diffusion of Dox·HCl but also served as a substrate for the photocatalytic generation of CO. From the experimental results, the photocatalyst CuS atomic layers (CAL) displayed an effective CO₂ photoreduction performance, which could realize an irradiation time/intensity-dependent CO-controlled release. Ex vivo permeation studies demonstrated that effervescent CO₂ production markedly enhanced the intradermal diffusion of Dox·HCl. Eventually, the robust antitumor efficacy of this versatile MN platform was proved in B16F10-bearing nude mice. This CO-sensitized chemotherapeutic MN system offered a novel strategy for transdermal gas/drug delivery, which might provide a new direction in tumor suppression.

Vesicular Antibodies: Shedding Light on Antibody Therapeutics with Cell Membrane Nanotechnology

The high stability of antibodies and their ability to precisely bind to antigens and endogenous immune receptors, as well as their susceptibility to protein engineering, enable antibody-based therapeutics to be widely applied in cancer, inflammation, infection, and other disorders. Nevertheless, the application of traditional antibody-based therapeutics has certain limitations, such as high price, limited permeability, and protein engineering complexity. Recent breakthroughs in cell membrane nanotechnology have deepened the understanding of the critical role of membrane protein receptors in disease treatment, enabling vesicular-antibody-based therapeutics. Here, the concept of vesicular antibodies that are obtained by modifying target antibodies onto cell membranes for biomedical applications is proposed. Given that an antibody is basically a protein, as an extension of this concept, vesicles or membrane-coated nanoparticles that use surface antibodies and protein receptors on cell membranes for biomedical applications as vesicular antibodies are defined. Furthermore, several engineering strategies for vesicular antibodies are summarized and how vesicular antibodies can be used in a variety of situations is highlighted. In addition, current challenges and future prospects of vesicular antibodies are also discussed. It is anticipated this perspective will provide new insights on the development of next-generation antibodies for enhanced therapeutics.

Research Progress on the Anti-Tumor Mechanism and Reversal of Multidrug Resistance of Zuojin Pill and its Main Components, Evodiamine and Berberine

Background

Cancer is one of the most serious diseases worldwide that threatens human health and leads to death. Chemotherapy is the main clinical method to treat tumors, but, despite the development of new chemotherapeutic drugs, the multidrug resistance (MDR) of cancer cells to conventional chemotherapeutic drugs remains a major cause of failure in cancer prevention and treatment. Therefore, overcoming this resistance has become a major challenge in cancer prevention and treatment.

Method

With the in-depth study of traditional Chinese medicines (TCMs) for the treatment of tumors, many such medicines have been found that can reverse MDR and enhance the sensitivity of chemotherapy. ZJW is a famous traditional medicine formula from China, recorded first in an ancient medicine book named Danxi Xinfa. It is composed of Huanglian and Wuzhuyu in a ratio of 6:1 by mass.

Conclusion

ZJW can inhibit proliferation, induce apoptosis, inhibit invasion and metastasis, and reverse MDR of tumor cells through multiple pathways and multiple targets. In this paper, we briefly review recent research on ZJW and its main components, evodiamine and berberine, in the anti-tumor mechanism and reversal of multidrug resistance.

Carbon monoxide therapy: a promising strategy for cancer

Cancer is one of the acute life-threatening diseases endangering the whole of humanity. The treatment modalities for cancer are various. However, in most cases, a single treatment choice provides multiple side effects, poor targeting, and ineffective treatment. In recent years, the physiological regulatory function of carbon monoxide (CO) in the cancer process has been reported gradually, and CO-related nano-drugs have been explored. It shows better application prospects in cancer treatment and provides new ideas for treatment. The present review introduces the pathophysiological role of CO. The recent advances in cancer therapy, such as CO-mediated gas therapy, combined application of CO chemotherapy, photodynamic therapy (PDT), photothermal therapy (PTT), and immunotherapy, are described. Current challenges and future developments in CO-based treatment are also discussed. This review provides comprehensive information on recent advances in CO therapy and also some valuable guidance for promoting the progress of gas therapy nanomedicine.

Enhanced Tumor Accumulation of Multimodal Magneto-Plasmonic Nanoparticles via an Implanted Micromagnet-Assisted Delivery Strategy

One of the major shortcomings of nano carriers-assisted cancer therapeutic strategies continues to be the inadequate tumor penetration and retention of systemically administered nanoformulations and its off-target toxicity. Stromal parameters-related heterogeneity in enhanced permeability and retention effect and physicochemical properties of the nanoformulations immensely contributes to their poor tumor extravasation. Herein, a novel tumor targeting strategy, where an intratumorally implanted micromagnet can significantly enhance accumulation of magneto-plasmonic nanoparticles (NPs) at the micromagnet-implanted tumor in bilateral colorectal tumor models while limiting their off-target accumulation, is demonstrated. To this end, novel multimodal gold/iron oxide NPs comprised of an array of multifunctional moieties with high therapeutic, sensing, and imaging potential are developed. It is also discovered that cancer cell targeted NPs in combination with static magnetic field can selectively induce cancer cell death. A multimodal caspase-3 nanosensor is also developed for real-time visualization of selective induction of apoptosis in cancer cells. In addition, the photothermal killing capability of these NPs in vitro is evaluated, and their potential for enhanced photothermal ablation in tissue samples is demonstrated. Building on current uses of implantable devices for therapeutic purposes, this study envisions the proposed micromagnet-assisted NPs delivery approach may be used to accelerate the clinical translation of various nanoformulations.

Glucose oxidase-amplified CO generation for synergistic anticancer therapy via manganese carbonyl-caged MOFs

Carbon monoxide (CO) as one of the therapeutic gaseous molecules has been widely applied for treating various diseases, especially in cancer therapy. However, the in situ-triggered and efficient transport of CO to tumors are the primary obstacles that limit its clinical applicability. To address this obstacle, herein, a H₂O₂-triggered CO gas releasing nanoplatform has been designed by embedding manganese carbonyl (MnCO) into Zr (IV)-based metal-organic frameworks (MOFs). The porous structures of MOFs provide encapsulation capacity for glucose oxidase (GOx) loading, thereby catalyzing the endogenous glucose into gluconic acid and H₂O₂ to accelerate CO release and energy depletion. In the meantime, the Mn²⁺ produced by MnCO can react with intracellular H₂O₂ via the Fenton reaction to form cytotoxic •OH. Therefore, the synthesized gas nanogenerator demonstrated a synergistic efficacy of CO gas therapy, reactive oxygen species (ROS)-mediated therapy, and energy starvation to prevent tumor growth. Both in vitro and in vivo studies indicated that this multifunctional nanoplatform not only successfully inhibited tumors through a synergistic effect, but also provided a new technique for the creation of starvation/gas/chemodynamic combination therapy in a single material. STATEMENT OF SIGNIFICANCE: In this study, we developed a H₂O₂ responsive CO gas nanogenerator to augment the in-situ generation of CO gas for combined modality therapy of tumors. The nanogenerator was constructed by encapsulating glucose oxidase (GOx) and manganese carbonyl (MnCO) into UiO-67-bpy, which can catalyze the conversion of intracellular glucose to H₂O₂ for cutting off energy supply of cancer cells. Meanwhile, the cumulated H₂O₂ can trigger the release of CO for gas therapy and generation of •OH for chemodynamic therapy (CDT) via the Fenton-like reaction, thereby resulting in apoptosis of the cancer cells. Collectively, our designed nanotherapeutic agent not only displays the synergistic therapy efficacy of starvation-enhanced CO gas therapy and CDT, but also provides an efficient strategy for developing the intelligent nanocarrier for CO gas delivery and release.

Amplifying Dendritic Cell Activation by Bioinspired Nanometal Organic Frameworks for Synergistic Sonoimmunotherapy

Despite recent advancements of sonodynamic therapy (SDT) in cancer immunotherapy, challenges have yet to be surmounted to further boost its immunotherapeutic efficacy due to the low-level tumor antigens presentation of dendritic cells (DCs). Cell membrane camouflaged-nanoparticles can integrate the neoantigens of the cancer cell membrane with the multifunctionalities of synthetic nanocores. Herein, sono-responsive nanoparticles coated with DC-targeted antibody chimeric cancer cell membrane are investigated for multimodal therapy. The nanometal organic frameworks (MOFs) that respond to ultrasound are loaded successfully inside the vesicles displaying an anti-DEC205 antibody. The anti-DEC205 chimeric vesicles can directly target and activate DCs, promote tumor antigens cross-presentation, and then produce a cascade amplified T-cell immune response. Upon deep tissue-penetrating sonication, AMR-MOF@AuPt generates large amounts of reactive oxygen species that directly kill cancer cells, further initiating an anti-cancer T cell immune response. Such synergistic sono-immunotherapies effectually inhibit tumor growth and induce strong systemic and long-term immune memory against cancer recurrence and distant metastasis. The authors findings provide DCs and tumor cells of a dual active-targeting cell membrane-coated sono-immunotherapeutic nanoplatform for cancer therapy.

Multistage-Responsive Gene Editing to Sensitize Ion-Interference Enhanced Carbon Monoxide Gas Therapy

As a promising therapeutic modality targeting cancer, gas therapy still faces critical challenges, especially in enhancing therapeutic efficacy and avoiding gas poisoning risks. Here, a pH/glutathione (GSH) dual stimuli-responsive CRISPR/Cas9 gene-editing nanoplatform combined with calcium-enhanced CO gas therapy for precise anticancer therapy, is established. In the tumor microenvironment (TME), the fast biodegradation of the CaCO₃ layer via pH-induced hydrolyzation allows glucose oxidase (GOx) to catalyze glucose for H₂ O₂ production, which further reacts with manganese carbonyl (MnCO) and achieves the precise release of CO gas. Simultaneously, in situ Ca²⁺ overload from CaCO₃ degradation disturbs mitochondrial Ca²⁺ homeostasis, resulting in Ca²⁺ -driven reactive oxygen species (ROS) formation and subsequent mitochondrial apoptosis signaling pathway activation. Subsequently, by GSH-induced cleavage of a disulfide bond, the released Cas9/sgRNA (RNP) can achieve nuclear factor E2-related factor 2 (Nrf2) gene ablation to sensitize gas therapy by interfering with ROS signaling. This therapeutic modality endows codelivery of CRISPR, ions, and gas with smart control features, which demonstrates great potential for future clinical applications in precise nanomedicine.

Emerging Biomaterials Imaging Antitumor Immune Response

Immunotherapy is one of the most promising clinical modalities for the treatment of malignant tumors and has shown excellent therapeutic outcomes in clinical settings. However, it continues to face several challenges, including long treatment cycles, high costs, immune-related adverse events, and low response rates. Thus, it is critical to predict the response rate to immunotherapy by using imaging technology in the preoperative and intraoperative. Here, the latest advances in nanosystem-based biomaterials used for predicting responses to immunotherapy via the imaging of immune cells and signaling molecules in the immune microenvironment are comprehensively summarized. Several imaging methods, such as fluorescence imaging, magnetic resonance imaging, positron emission tomography imaging, ultrasound imaging, and photoacoustic imaging, used in immune predictive imaging, are discussed to show the potential of nanosystems for distinguishing immunotherapy responders from nonresponders. Nanosystem-based biomaterials aided by various imaging technologies are expected to enable the effective prediction and diagnosis in cases of tumors, inflammation, and other public diseases.

Therapeutic gas-releasing nanomedicines with controlled release: Advances and perspectives

Nanoparticle-based drug delivery has become one of the most popular approaches for maximising drug therapeutic potentials. With the notable improvements, a greater challenge hinges on the formulation of gasotransmitters with unique challenges that are not met in liquid and solid active ingredients. Gas molecules upon release from formulations for therapeutic purposes have not really been discussed extensively. Herein, we take a critical look at four key gasotransmitters, that is, carbon monoxide (CO), nitric oxide (NO), hydrogen sulphide (H2S) and sulphur dioxide (SO2), their possible modification into prodrugs known as gas-releasing molecules (GRMs), and their release from GRMs. Different nanosystems and their mediatory roles for efficient shuttling, targeting and release of these therapeutic gases are also reviewed extensively. This review thoroughly looks at the diverse ways in which these GRM prodrugs in delivery nanosystems are designed to respond to intrinsic and extrinsic stimuli for sustained release. In this review, we seek to provide a succinct summary for the development of therapeutic gases into potent prodrugs that can be adapted in nanomedicine for potential clinical use.

A multifunctional nanoplatform delivering carbon monoxide and a cysteine protease inhibitor to mitochondria under NIR light shows enhanced synergistic anticancer efficacy

Photoactivated chemotherapy has attracted widespread attention due to its ability to circumvent the shortcomings of hypoxia in tumor tissues compared with traditional photodynamic therapy. In this work, novel multifunctional nanoplatform (1), Ru-inhibitor@TPPMnCO@N-GQDs, was designed and prepared, which was capable of mitochondria-targeted co-delivery of the cysteine protease inhibitor and carbon monoxide (CO) stimulated with an 808 nm near infrared (NIR) laser. Nanoplatform (1) was prepared by covalent attachment of a mitochondria-targeted CO donor (TPPMnCO) and a Ru(II)-caged cysteine protease inhibitor (Ru-inhibitor) on the surface of fluorescent N-doped graphene quantum dots (N-GQDs). Nanoplatform (1) preferentially accumulated in the mitochondria of cancer cells and instantly delivered CO and the cysteine protease inhibitor upon 808 nm NIR light irradiation, thus damaging mitochondria and leading to significant in vitro and in vivo anticancer efficacy. In addition, nanoplatform (1) has good biocompatibility and did not exert any toxic side effects on mice during the period of treatment. The targeted subcellular mitochondrial co-delivery of CO and the cysteine protease inhibitor may provide new insights into CO and enzyme inhibitor combined therapies for cancer treatment.

Chemiexcitation-Triggered Prodrug Activation for Targeted Carbon Monoxide Delivery

Photolysis-based prodrug strategy can address some critical drug delivery issues, which otherwise are very challenging to tackle with traditional prodrug strategy. However, the need for external light irradiation significantly hampers its in vivo application due to the poor light accessibility of deep tissue. Herein, we propose a new strategy of chemiexcitation-triggered prodrug activation, wherein a photoresponsive prodrug is excited for drug payload release by chemiexcitation instead of photoirradiation. As such, the bond-cleavage power of photolysis can be employed to address some critical drug delivery issues while obviating the need for external light irradiation. We have established the proof of concept by the successful development of a chemiexcitation responsive carbon monoxide delivery platform, which exhibited specific CO release at the tumor site and pronounced tumor suppression effects. We anticipate that such a concept of chemiexcitation-triggered prodrug activation can be leveraged for the targeted delivery of other small molecule-based drug payloads.

Self-Confirming Magnetosomes for Tumor-Targeted T1 /T2 Dual-Mode MRI and MRI-Guided Photothermal Therapy

Nanomaterials as T₁ /T₂ dual-mode magnetic resonance imaging (MRI) contrast agents have great potential in improving the accuracy of tumor diagnosis. Applications of such materials, however, are limited by the complicated chemical synthesis process and potential biosafety issues. In this study, the biosynthesis of manganese (Mn)-doped magnetosomes (MagMn) that not only can be used in T₁ /T₂ dual-mode MR imaging with self-confirmation for tumor detection, but also improve the photothermal conversion efficiency for MRI-guided photothermal therapy (PTT) is reported. The MagMn nanoparticles (NPs) are naturally produced through the biomineralization of magnetotactic bacteria by doping Mn into the ferromagnetic iron oxide crystals. In vitro and in vivo studies demonstrated that targeting peptides functionalized MagMn enhanced both T₁ and T₂ MRI signals in tumor tissue and significantly inhibited tumor growth by the further MRI-guided PTT. It is envisioned that the biosynthesized multifunctional MagMn nanoplatform may serve as a potential theranostic agent for cancer diagnosis and treatment.

Two-Pronged Intracellular Co-Delivery of Antigen and Adjuvant for Synergistic Cancer Immunotherapy

Nanovaccines have emerged as promising alternatives or complements to conventional cancer treatments. Despite the progresses, specific co-delivery of antigen and adjuvant to their corresponding intracellular destinations for maximizing the activation of antitumor immune responses remains a challenge. Herein, a lipid-coated iron oxide nanoparticle is delivered as nanovaccine (IONP-C/O@LP) that can co-deliver peptide antigen and adjuvant (CpG DNA) into cytosol and lysosomes of dendritic cells (DCs) through both membrane fusion and endosome-mediated endocytosis. Such two-pronged cellular uptake pattern enables IONP-C/O@LP to synergistically activate immature DCs. Iron oxide nanoparticle also exhibits adjuvant effects by generating intracellular reactive oxygen species, which further promotes DC maturation. IONP-C/O@LP accumulated in the DCs of draining lymph nodes effectively increases the antigen-specific T cells in both tumor and spleen, inhibits tumor growth, and improves animal survival. Moreover, it is demonstrated that this nanovaccine is a general platform of delivering clinically relevant peptide antigens derived from human papilloma virus 16 to trigger antigen-specific immune responses in vivo.

Therapeutic implication of carbon monoxide in drug resistant cancers

Drug resistance is the major obstacle that undermines effective cancer treatment. Recently, the application of gas signaling molecules, e.g., carbon monoxide (CO), in overcoming drug resistance has gained significant attention. Growing evidence showed that CO could inhibit mitochondria respiratory effect and glycolysis, two major ATP production pathways in cancer cells, and suppress angiogenesis and inhibit the activity of cystathionine β-synthase that is important in regulating cancer cells homeostasis, leading to synergistic effects when combined with cisplatin, doxorubicin, or phototherapy, etc. in certain resistant cancer cells. In the current review, we attempted to have a summary of these research conducted in the past decade using CO in treating drug resistant cancers, and have a detailed interpretation of the underlying mechanisms. The critical challenges will be discussed and potential solutions will also be provided. The information collected in this work will hopefully evoke more effects in using CO for the treatment of drug resistant cancers.

Emergence of Responsive Surface-Enhanced Raman Scattering Probes for Imaging Tumor-Associated Metabolites

As a core hallmark of cancer, metabolic reprogramming alters the metabolic networks of cancer cells to meet their insatiable appetite for energy and nutrient. Tumor-associated metabolites, the products of metabolic reprogramming, are valuable in evaluating tumor occurrence and progress timely and accurately because their concentration variations usually happen earlier than the aberrances demonstrated in tissue structure and function. As an optical spectroscopic technique, surface-enhanced Raman scattering (SERS) offers advantages in imaging tumor-associated metabolites, including ultrahigh sensitivity, high specificity, multiplexing capacity, and uncompromised signal intensity. This review first highlights recent advances in the development of stimuli-responsive SERS probes. Then the mechanisms leading to the responsive SERS signal triggered by tumor metabolites are summarized. Furthermore, biomedical applications of these responsive SERS probes, such as the image-guided tumor surgery and liquid biopsy examination for tumor molecular typing, are summarized. Finally, the challenges and prospects of the responsive SERS probes for clinical translation are also discussed.

One- and Two-Photon Uncaging of Carbon Monoxide (CO) with Real-Time Monitoring: On-Demand Carbazole-Based Dual CO-Releasing Platform to Test over Single and Combinatorial Approaches for the Efficient Regression of Orthotopic Murine Melanoma In Vivo

Herein, we report three new metal-free, photochemically active single, dual, and combinatorial CORMs (photoCORMs) based on a carbazole-fused 1,3-dioxol-2-one moiety which released one equivalent of CO, two equivalent of CO, and a combination of one equivalent of each CO and anticancer drug upon one- and two-photon excitation, respectively. The photoCORMs exhibited good cellular uptake and real-time monitoring ability of CO uncaging by a color change approach in cancerous B16F10 cells. Interestingly, the cytotoxicity assay on B16F10 cells indicated that the dual photoCORM has increased anticancer activity over the single and combinatorial photoCORMs upon irradiation. Our results also showed that CO could accelerate the effectiveness of the well-known anticancer drug (chlorambucil). Finally, the in vivo evaluation of the dual photoCORM on an established murine melanoma tumor (C57BL/6J mouse model) manifested a significant regression of tumor volume and led to significant improvement (>50%) in the overall survivability.

Targeted carbon monoxide delivery combined with chemodynamic, chemotherapeutic and photothermal therapies for enhanced antitumor efficacy

Polydopamine-coated hollow mesoporous copper sulfide loaded with DHA and CO-releasing molecules selectively delivered DHA and CO to tumor cells under 808 nm light irradiation, demonstrating multimodal synergistic antitumor efficacy.