ROS-induced NO generation for gas therapy and sensitizing photodynamic therapy of tumor

CeO2-Decorated Metal-Organic Framework for Enhanced Photodynamic Therapy

Photodynamic therapy (PDT) is quickly developing as a hopeful cancer treatment. However, hypoxic tumors, poor targeting, and photosensitizers (PS) aggregation limited the efficiency of PDT. Here, we report a hyaluronic acid (HA)-modified CeO₂-nanoparticle-decorated metal-organic framework (PCN-224@CeO₂-HA) to enhance PDT and achieve targeted treatment. CeO₂ catalyzes H₂O₂ to produce O₂ to solve hypoxia problems. HA could target the CD44 receptor, which is highly expressed on the tumor cell membranes. The growth of tumor cells 4T1 and MCF-7 was controlled distinctly after being incubated with PCN-224@CeO₂-HA under laser irradiation, while the survival ability of normal cell LO2 was nearly unchanged. Importantly, PCN-224@CeO₂-HA could be effectively aggregated within the tumor area after 12 h of injection, and the tumor growth was remarkably inhibited under laser irradiation. PCN-224@CeO₂-HA presented good biocompatibility and an excellent antitumor effect, providing a new strategy to produce O₂ in situ for enhanced PDT.

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.

Opportunities for Nitric Oxide in Potentiating Cancer Immunotherapy

Despite nearly 30 years of development and recent highlights of nitric oxide (NO) donors and NO delivery systems in anticancer therapy, the limited understanding of exogenous NO's effects on the immune system has prevented their advancement into clinical use. In particular, the effects of exogenously delivered NO differing from that of endogenous NO has obscured how the potential and functions of NO in anticancer therapy may be estimated and exploited despite the accumulating evidence of NO's cancer therapy-potentiating effects on the immune system. After introducing their fundamentals and characteristics, this review discusses the current mechanistic understanding of NO donors and delivery systems in modulating the immunogenicity of cancer cells as well as the differentiation and functions of innate and adaptive immune cells. Lastly, the potential for the complex modulatory effects of NO with the immune system to be leveraged for therapeutic applications is discussed in the context of recent advancements in the implementation of NO delivery systems for anticancer immunotherapy applications. SIGNIFICANCE STATEMENT: Despite a 30-year history and recent highlights of nitric oxide (NO) donors and delivery systems as anticancer therapeutics, their clinical translation has been limited. Increasing evidence of the complex interactions between NO and the immune system has revealed both the potential and hurdles in their clinical translation. This review summarizes the effects of exogenous NO on cancer and immune cells in vitro and elaborates these effects in the context of recent reports exploiting NO delivery systems in vivo in cancer therapy applications.

Self-assemblies with cascade effect to boost antitumor systemic immunotherapy

Bio-organic hybrid self-assemblies based on amino acids, conjugated polymers, Fe³⁺ and enzymes are fabricated with tumor environment-responsive and light-triggered NO release properties. By sequential energy consumption, NO attack and immune activation, FFPG shows boosted antitumor activity toward both primary and distant tumors. The three-level cascade strategy (starvation/NO/immunotherapy) adopted in this work offers a pathway to address the dilemma of low cure rate of malignant tumors.

The Advancement of Gas-Generating Nanoplatforms in Biomedical Fields: Current Frontiers and Future Perspectives

Diverse gases (NO, CO, H₂ S, H₂ , etc.) have been widely applied in the medical intervention of various diseases, including cancer, cardiovascular disease, ischemia-reperfusion injury, bacterial infection, etc., attributing to their inherent biomedical activities. Although many gases have many biomedical activities, their clinical use is still limited due to the rapid and free diffusion behavior of these gases molecules, which may cause potential side effects and/or ineffective treatment. Gas-generating nanoplatforms (GGNs) are effective strategies to address the aforementioned challenges of gas therapy by preventing gas production or release at nonspecific sites, enhancing GGNs accumulation at targeted sites, and controlling gas release in response to exogenous (UV, NIR, US, etc.) or endogenous (H₂ O₂ , GSH, pH, etc.) stimuli at the lesion site, further maintaining gas concentration within the effective range and achieving the purpose of disease treatment. This review comprehensively summarizes the advancements of "state-of-the-art" GGNs in the recent three years, with emphasis on the composition, structure, preparation process, and gas release mechanism of the nanocarriers. Furthermore, the therapeutic effects and limitations of GGNs in preclinical studies using cell/animal models are discussed. Overall, this review enlightens the further development of this field and promotes the clinical transformation of gas therapy.

Dual-responsive nano-prodrug micelles for MRI-guided tumor PDT and immune synergistic therapy

Micelles as nanocarriers not only offer new opportunities for early diagnosis and treatment of malignant cancers but also encounter numerous barriers in the path of efficient delivery of drugs to diseased areas in the body. To address these issues, we developed a pH/GSH responsive nano-prodrug micelle (NLG919/PGA-Cys-PPA@Gd) with a high drug-loading ratio and controlled drug release performance for MRI-guided tumor photodynamic therapy (PDT) and immune synergistic therapy. Under normal conditions, theranostic nanomicelles remained stable and in a photo-quenched state. Upon accumulation in the tumor site, however, the micelles demonstrated tumor microenvironment (TME) triggered photoactive formed-PPA (a photosensitizer) and NLG919 (an indoleamine 2,3-dioxygenase (IDO) inhibitor) release because the amide bonds of PGA-Cys-PPA and the disulfide linkage of Cys were sensitive to pH and GSH, respectively. More importantly, these micelles could avoid the undesired PPA leakage in blood circulation due to the conjugation between PPA and polymers. Furthermore, the obtained micelles could also enhance the contrast of T₁-weighted MRI of tumors by virtue of their high relaxivity (r₁ = 29.85 mM^-1 s^-1). In vitro and in vivo results illustrated that the micelles had good biocompatibility and biosafety. On the basis of the efficient drug delivery strategies in PDT and IDO pathway inhibition, this intelligent dual-drug delivery system could serve as an effective approach for MRI guided combination therapy of cancer.

Enhanced delivery of theranostic liposomes through NO-mediated tumor microenvironment remodeling

Highly efficient delivery of nanoagents to the tumor region remains the primary challenge for cancer nanomedicine. Herein, we propose a NO-mediated tumor microenvironment (TME) remodeling strategy for the high-efficient delivery of nanoagents into tumor. Quantum dots (QDs) with bright fluorescence in the near-infrared IIb (NIR-IIb, 1500-1700 nm) window and high photothermal conversion efficiency were encapsulated into liposomes for the imaging-guided photothermal therapy (PTT) of tumor. The fabrication of PEG and arginine-glycine-aspartate (RGD) peptide on liposomes ensured the prolonged circulation in vivo and active targeting to tumor. Moreover, the loading of a natural NO generator L-arginine in liposomes realized the continuous generation of NO in the acidic TME. By co-localization fluorescence imaging and western blot of tumor tissue, we confirmed that the release of NO activated the expression of metalloproteinases in TME and further degraded Collagen I in the peripheral region of the tumor, thus removing the barrier for the permeation of liposomes. Attributed to the enhanced accumulation of liposomes inside the tumor, NIR IIb imaging-guided PTT was achieved with remarkable therapeutic efficacy.

Multifunctional Nanosystems Powered Photodynamic Immunotherapy

Photodynamic Therapy (PDT) with the intrinsic advantages including non-invasiveness, spatiotemporal selectivity, low side-effects, and immune activation ability has been clinically approved for the treatment of head and neck cancer, esophageal cancer, pancreatic cancer, prostate cancer, and esophageal squamous cell carcinoma. Nevertheless, the PDT is only a strategy for local control of primary tumor, that it is hard to remove the residual tumor cells and inhibit the tumor metastasis. Recently, various smart nanomedicine-based strategies are developed to overcome the barriers of traditional PDT including the drawbacks of traditional photosensitizers, limited tissue penetrability of light, inefficient induction of tumor cell death and tumor resistance to the therapy. More notably, a growing number of studies have focused on improving the therapeutic efficiency by eliciting host immune system with versatile nanoplatforms, which heralds a broader clinical application prospect of PDT in the future. Herein, the pathways of PDT induced-tumor destruction, especially the host immune response is summarized, and focusing on the recent progress of nanosystems-enhanced PDT through eliciting innate immunity and adaptive immunity. We expect it will provide some insights for conquering the drawbacks current PDT and expand the range of clinical application through this review.

Recent Advances in Poly(α-L-glutamic acid)-Based Nanomaterials for Drug Delivery

Poly(α-L-glutamic acid) (PGA) is a class of synthetic polypeptides composed of the monomeric unit α-L-glutamic acid. Owing to their biocompatibility, biodegradability, and non-immunogenicity, PGA-based nanomaterials have been elaborately designed for drug delivery systems. Relevant studies including the latest research results on PGA-based nanomaterials for drug delivery have been discussed in this work. The following related topics are summarized as: (1) a brief description of the synthetic strategies of PGAs; (2) an elaborated presentation of the evolving applications of PGA in the areas of drug delivery, including the rational design, precise fabrication, and biological evaluation; (3) a profound discussion on the further development of PGA-based nanomaterials in drug delivery. In summary, the unique structures and superior properties enables PGA-based nanomaterials to represent as an enormous potential in biomaterials-related drug delivery areas.

Mitochondria-Targeting and ROS-Responsive Nanocarriers via Amphiphilic TPP-PEG-TK-Ce6 for Nanoenabled Photodynamic Therapy

Designing targeted-delivering and stimuli-responsive nanocarriers for photodynamic therapy (PDT) is an appealing method, especially, targeting delivery of photosensitizers to mitochondria as the most sensitive cellular organelles to reactive oxygen species (ROS) could significantly enhance the therapeutic efficacy of PDT. In this study, we synthesized triphenylphosphonium bonded PEG-NH2 (TPP-PEG-NH2) and bridged to chlorin e6 (Ce6) via thioketal (TK) linkage to obtain red light-triggered, amphiphilic copolymer (TPP-PEG-TK-Ce6), which could self-assemble into micelles with an average size of 160 nm and zeta potential of +20.1 mV. The in vitro release behavior of TPP-PEG-TK-Ce6 nanocarriers showed a light-activated way and was dependent on the H2O2 concentration. TPP-PEG-TK-Ce6 nanocarriers exhibited high cytotoxicity against C6 cells with illumination. Confocal laser scanning microscopy observation indicated that TPP-PEG-TK-Ce6 nanocarriers were efficiently internalized into the mitochondrion of C6 cells, released Ce6 via light activated. By contrast, in the case of TPP-PEG-NH2 directly bonded Ce6 (TPP-PEG-Ce6) nanocarriers, little Ce6 was found in the mitochondrion. The stronger fluorescence in the mitochondrion of TPP-PEG-TK-Ce6 nanocarriers originated from the mitochondrial-targeting capability of TPP and the cleavage of TK linkages activated by light irradiation, which greatly improved the cellular uptake of TPP-PEG-TK-Ce6 nanocarriers and released more Ce6 in the mitochondrion. This work provided a facile strategy to improve PDT efficacy.

Multifunctional nanocarrier with self-catalytic production of nitric oxide for photothermal and gas-combined therapy of tumor

Single treatment often faces the problem that it cannot completely eradicate tumor and inhibit the tumor metastasis. In order to overcome this shortcoming, multi-modal tumor treatment has attracted widespread attention. In the present article, based on ascorbyl palmitate (PA) and l-arginine (l-Arg), a multifunctional nanocarrier is designed for synergetic treatment of tumor with photothermal and nitric oxide (NO) gas therapy. Firstly, PA and l-Arg were self-assembled to form novel functional micelles, PL, with high biosafety using electrostatic interaction and hydrogen bonding. The functional micelles could self-catalyze to produce NO at the tumor site. Then, Ag₂S quantum dots having fluorescence imaging and photothermal properties were encapsulated to obtain the nanocarrier, A@PL. The results show that A@PL had a hydrated size of around 78 nm and presented good stability within 30 d. Moreover, in vitro studies indicate that it was efficient with regards to NO self-generating capacity, whereas the photothermal conversion efficiency was as high as 34% under near-infrared light irradiation. The cytotoxicity results show that, when the concentration of A@PL was as high as 2 mM, the survival rate of 3 T3 cells was still 78.23%, proving that the probe has good safety characteristics. Fluorescence imaging results show that its maximum enrichment can be achieved at the tumor site after tail vein injection for 3 h, and out of the body after 24 h, indicating good internal circulation. The in vivo studies show that the rate of inhibition of tumor using the nanocarrier was as high as 98%, and almost overcame the problem of tumor recurrence caused by single treatment, thus presenting a significant tumor treatment effect. This new multifunctional nanocarrier with self-catalytic production of NO provides a new idea for the efficient treatment of tumors.

Photosensitized co-generation of nitric oxide and singlet oxygen Enhanced toxicity against ovarian cancer cells

Near micromolar concentrations of nitric oxide (NO) induce tumor cells death. However, an appropriate NO load has to be delivered selectively to the tumor site in order to avoid NO loss and secondary NO-induced effects. The encapsulation of millimolar concentrations of a NO source and an appropriate trigger of NO release within phospatidylcholine-based liposomes should provide an efficient tool for the selective release of the needed NO payload. In this work we report the photosensitized generation of singlet oxygen and NO from folate-targeted PEGylated liposomes, containing AlPcS4 as the sensitizer and S-nitrosoglutathione (GSNO), in millimolar amounts, as the NO source. Amounts of singlet oxygen detected outside the liposome when using PEGylated liposomes are near 200 % larger when GSNO is present inside the liposomes as compared to its absence. These liposomes, conjugated to folate, were found to enhance the photosensitized cytotoxicity to A2780CP20 ovarian cancer cells as compared to liposomes containing the sensitizer but no GSNO (30 % as compared to 70 % cell viability) under the conditions of this work. Fluorescense of AlPcS4 was observed inside cells incubated with folate-conjugated liposomes but not with liposomes without folate. The photosensitized activity enhancement by GSNO increased when light fluence or liposome concentration were increased. The majority of ovarian cancer patients are initially diagnosed with disseminated intra-abdominal disease (stages III-IV) and have a 5-year survival of less than 20%. This work suggests a novel ovarian cancer nodules treatment via the use of tumor-targeted liposome nanoparticles with the capability of generating simultaneously reactive oxygen and nitrogen species upon illumination with near-infrared light.

Ultrasound and nanomaterial: an efficient pair to fight cancer

Ultrasounds are often used in cancer treatment protocols, e.g. to collect tumor tissues in the right location using ultrasound-guided biopsy, to image the region of the tumor using more affordable and easier to use apparatus than MRI and CT, or to ablate tumor tissues using HIFU. The efficacy of these methods can be further improved by combining them with various nano-systems, thus enabling: (i) a better resolution of ultrasound imaging, allowing for example the visualization of angiogenic blood vessels, (ii) the specific tumor targeting of anti-tumor chemotherapeutic drugs or gases attached to or encapsulated in nano-systems and released in a controlled manner in the tumor under ultrasound application, (iii) tumor treatment at tumor site using more moderate heating temperatures than with HIFU. Furthermore, some nano-systems display adjustable sizes, i.e. nanobubbles can grow into micro-bubbles. Such dual size is advantageous since it enables gathering within the same unit the targeting properties of nano bubbles via EPR effect and the enhanced ultrasound contrasting properties of micro bubbles. Interestingly, the way in which nano-systems act against a tumor could in principle also be adjusted by accurately selecting the nano-system among a large choice and by tuning the values of the ultrasound parameters, which can lead, due to their mechanical nature, to specific effects such as cavitation that are usually not observed with purely electromagnetic waves and can potentially help destroying the tumor. This review highlights the clinical potential of these combined treatments that can improve the benefit/risk ratio of current cancer treatments.

Near infrared light triggered ternary synergistic cancer therapy via L-arginine-loaded nanovesicles with modification of PEGylated indocyanine green

L-arginine (L-Arg) is an important nitric oxide (NO) donor, and its exploration in NO gas therapy has received widespread attention. Application of nano-platforms that can efficiently deliver L-Arg and induce its rapid conversion to NO becomes a predominant strategy to achieve promising therapeutic effects in tumor treatment. Herein, an enhanced nano-vesicular system of ternary synergistic treatment combining NO therapy, photodynamic therapy (PDT) along with mild photothermal therapy (MPTT) was developed for cancer therapy. We integrated photosensitizer PEGylated indocyanine green (mPEG-ICG) into polyphosphazene PEP nano-vesicles through co-assembly and simultaneously encapsulated NO donor L-Arg into the vesicle center chambers to form mPEG-ICG/L-Arg co-loaded system IA-PEP. The unique nanostructure of vesicle provided considerable loading capacity for mPEG-ICG and L-Arg with 15.9% and 17.95% loading content, respectively, and efficiently prevented mPEG-ICG and L-Arg from leaking. Significantly, the reactive oxygen species (ROS) was produced by IA-PEP under 808 nm laser irradiation to perform PDT against tumors, which concurrently reacted with L-Arg to release NO and arouse gas therapy effectively. Moreover, the mild heat produced by IA-PEP could exhibit cooperative anti-tumor effect with minimal damage. As a consequence, in vivo antitumor investigation on nude mice bearing xenograft MCF-7 tumors verified the potent anti-tumor efficacy of IA-PEP under 808 nm laser irradiation with complete tumor elimination. Taken together, the IA-PEP nano-vesicle system designed in this work may provide a promising treatment paradigm for synergistic cancer treatment. STATEMENT OF SIGNIFICANCE: Nitric oxide (NO) gas therapy has drawn widespread attention due to its "green" treatment paradigm with negligible side effects. L-arginine (L-Arg) is an important NO donor. However, how to efficiently deliver L-Arg and induce NO generation remains a big challenge since L-Arg is a water-soluble small molecule. Herein, we developed a nano-vesicle system IA-PEP to integrate photosensitizer PEGylated indocyanine green and L-Arg with high loading content and to produce a ternary synergistic treatment combining NO therapy, photodynamic therapy (PDT) along with mild-temperature photothermal therapy (MPTT) under 808 nm laser irradiation. The in vivo investigation on nude mice bearing xenograft MCF-7 tumors verified its potent anti-tumor efficacy with complete tumor elimination.

Mitochondria-Targeted Mesoporous Titanium Dioxide Nanoplatform for Synergistic Nitric Oxide Gas-Sonodynamic Therapy of Breast Cancer

Background

Sonodynamic therapy (SDT) has rapidly advanced as a promising alternative to conventional photodynamic therapy owing to its preferable therapeutic depth. However, single-modal SDT exhibits limited efficacy due to the long-term hypoxia in tumors.

Method and Results

To address these issues, we proposed a synergistic SDT strategy that integrates mitochondrial targeting with nitric oxide (NO) gas therapy by using multifunctional nanoplatforms. The nanoplatform, which was named as T-mTNPs@L-Arg, was composed of mesoporous titanium dioxide loaded with the NO donor precursor L-arginine (L-Arg) and modified with triphenyl phosphonium (TPP), a mitochondria-targeting ligand. Therefore, T-mTNPs@L-Arg could efficiently concentrate into mitochondria and release NO gas as well as generate reactive oxygen species (ROS) with ultrasound stimulus. Importantly, the released NO gas exerted multiple synergies with SDT, including inducing NO poisoning, generating more lethal reactive nitrogen species (RNS) by reaction with ROS, and alleviating hypoxia through NO-mediated mitochondrial respiration inhibition. On account of the synergistic effects, T-mTNPs@L-Arg showed an outstanding SDT efficacy and a reduced side effect.

Conclusion

This work designed a nanoplatform to integrate mitochondria targeting, SDT and NO gas therapy, providing a new strategy for highly efficient breast cancer therapy.

X-ray-Triggered CO Release Based on GdW10/MnBr(CO)5 Nanomicelles for Synergistic Radiotherapy and Gas Therapy

Carbon monoxide (CO) therapy has become a hot topic in the field of gas therapy because of its application prospect in the treatment of various diseases. Due to the high affinity for human hemoglobin, the main challenge of CO-loaded nanomedicine is the lack of selectivity and toxicity in the delivery process. Although many commercial CO-releasing molecules (CORMs) have been widely developed because of their ability to deliver CO, CORMs still have some disadvantages, including difficult on-demand controlled CO release, poor solubility, and potential toxicity, which are limiting their further application. Herein, an X-ray-triggered CO-releasing nanomicelle system (GW/MnCO@PLGA) based on GdW₁₀ nanoparticles (NPs) (GW) and MnBr(CO)₅ (MnCO) encapsulating in the poly(lactic-co-glycolic acid) (PLGA) polymer was constructed for synergistic CO radiotherapy (RT). The production of strongly oxidative superoxide anion (O₂^-•) active species can lead to cell apoptosis under the X-ray sensitization of GW. Moreover, strongly oxidative O₂^-• radicals further oxidize and compete with the Mn center, resulting in the on-demand release of CO. The radio/gas therapy synergy to enhance the efficient tumor inhibition of the nanomicelles was investigated in vivo and in vitro. Therefore, the establishment of an X-ray-triggered controlled CO release system has great application potential for further synergistic RT CO therapy in deep tumor sites.

Ultrasound-Mediated Release of Gaseous Signaling Molecules for Biomedical Applications

Although nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H₂ S) have been considered as notorious gas pollutants for decades, they are considered as endogenous gaseous signaling molecules (GSMs), which have been widely recognized for their important signaling functions and prominent medical applications in human physiology. To achieve local delivery of GSMs to optimize therapeutic efficacy and reduce systemic side effects, stimuli-responsive nanocarriers have been successfully developed. Among them, ultrasound is considered as an attractive theranostic modality that can be used to track drug carriers, trigger drug release, and improve drug deposition, etc. In this minireview, we summarize recent achievements in designing ultrasound-responsive nanocarriers for the controlled delivery of GSMs and their biomedical applications. This emerging research direction enables the controlled delivery of GSMs to deep tissues, and the combination of ultrasound imaging techniques offers many possibilities for the fabrication of new theranostic platforms. This article is protected by copyright. All rights reserved.

Combinatorial Therapeutic Approaches with Nanomaterial-Based Photodynamic Cancer Therapy

Photodynamic therapy (PDT), in which a light source is used in combination with a photosensitizer to induce local cell death, has shown great promise in therapeutically targeting primary tumors with negligible toxicity and minimal invasiveness. However, numerous studies have shown that noninvasive PDT alone is not sufficient to completely ablate tumors in deep tissues, due to its inherent shortcomings. Therefore, depending on the characteristics and type of tumor, PDT can be combined with surgery, radiotherapy, immunomodulators, chemotherapy, and/or targeted therapy, preferably in a patient-tailored manner. Nanoparticles are attractive delivery vehicles that can overcome the shortcomings of traditional photosensitizers, as well as enable the codelivery of multiple therapeutic drugs in a spatiotemporally controlled manner. Nanotechnology-based combination strategies have provided inspiration to improve the anticancer effects of PDT. Here, we briefly introduce the mechanism of PDT and summarize the photosensitizers that have been tested preclinically for various cancer types and clinically approved for cancer treatment. Moreover, we discuss the current challenges facing the combination of PDT and multiple cancer treatment options, and we highlight the opportunities of nanoparticle-based PDT in cancer therapies.

Stapled Liposomes Enhance Cross-Priming of Radio-Immunotherapy

The release of tumor-associated antigens (TAAs) and their cross-presentation in dendritic cells (DCs) are crucial for radio-immunotherapy. However, the irradiation resistance of tumor cells usually results in limited TAA generation and release. Importantly, TAAs internalized by DCs are easily degraded in lysosomes, resulting in unsatisfactory extent of TAA cross-presentation. Herein, an antigen-capturing stapled liposome (ACSL) with a robust structure and bioactive surface is developed. The ACSLs capture and transport TAAs from lysosomes to the cytoplasm in DCs, thereby enhancing TAA cross-presentation. l-arginine encapsulated in ACSLs induces robust T cell-dependent antitumor response and immune memory in 4T1 tumor-bearing mice after local irradiation, resulting in significant tumor suppression and an abscopal effect. Replacing l-arginine with radiosensitizers, photosensitizers, and photothermal agents may make ACSL a universal platform for the rapid development of various combinations of anticancer therapies.

Mitochondrial Ca2+-overloading by oxygen/glutathione depletion-boosted photodynamic therapy based on a CaCO3 nanoplatform for tumor synergistic therapy

The Ca²⁺ buffering capacity of mitochondria maintains the balance of cell physiological activities. The exogenous reactive oxygen species (ROS) can be used to break the balance, resulting in mitochondrial dysfunction and irreversible cell apoptosis. Herein, the CaCO₃-based tumor microenvironment (TME) responsive nanoplatform (CaNP_CAT+BSO@Ce6-PEG) was designed for oxygen/GSH depletion-boosted photodynamic therapy (PDT) and mitochondrial Ca²⁺-overloading synergistic therapy. In acidic TME, CaCO₃ decomposed and released the cargos (catalase (CAT), buthionine sulfoximine (BSO), chlorin e6 (Ce6), and Ca²⁺). The tumor hypoxia and reductive microenvironment could be significantly reversed by CAT and BSO, which greatly enhanced the PDT efficacy. The generated ¹O₂ during PDT process not only directly killed cancer cells but also destroyed the Ca²⁺ buffering capacity, leading to the mitochondrial Ca²⁺-overloading. The increased Ca²⁺ concentration promoted the process of oxidative phosphorylation and inhibited the production of adenosine triphosphate (ATP), resulting in the acceleration of cell death. Under the joint action of enhanced PDT and mitochondrial Ca²⁺-overloading, the CaNP_CAT+BSO@Ce6-PEG NPs showed remarkable synergistic effects in tumor inhibition without any side effects. STATEMENT OF SIGNIFICANCE: In the manuscript, a CaCO₃-based nano-platform for tumor microenvironment response was designed. With the decomposition of CaNP_CAT+BSO@Ce6-PEG NPs in the acidic tumor microenvironment, the released catalase (CAT) and buthionine sulfoximine (BSO) could relieve the tumor hypoxia and inhibit GSH production. Under 660 nm laser irradiation, the photodynamic effect was enhanced and caused apoptosis. Meanwhile, the Ca²⁺ buffering capacity was destroyed which led to the mitochondrial Ca²⁺-overloading. The synergistic effect of enhanced PDT and mitochondrial Ca²⁺-overloading made the CaNP_CAT+BSO@Ce6-PEG NPs present remarkable antitumor performance.

Near-infrared light-triggered nano-prodrug for cancer gas therapy

Gas therapy (GT) has attracted increasing attention in recent years as a new cancer treatment method with favorable therapeutic efficacy and reduced side effects. Several gas molecules, such as nitric oxide (NO), carbon monoxide (CO), hydrogen (H2), hydrogen sulfide (H2S) and sulfur dioxide (SO2), have been employed to treat cancers by directly killing tumor cells, enhancing drug accumulation in tumors or sensitizing tumor cells to chemotherapy, photodynamic therapy or radiotherapy. Despite the great progress of gas therapy, most gas molecules are prone to nonspecific distribution when administered systemically, resulting in strong toxicity to normal tissues. Therefore, how to deliver and release gas molecules to targeted tissues on demand is the main issue to be considered before clinical applications of gas therapy. As a specific and noninvasive stimulus with deep penetration, near-infrared (NIR) light has been widely used to trigger the cleavage and release of gas from nano-prodrugs via photothermal or photodynamic effects, achieving the on-demand release of gas molecules with high controllability. In this review, we will summarize the recent progress in cancer gas therapy triggered by NIR light. Furthermore, the prospects and challenges in this field are presented, with the hope for ongoing development.

Endogenous NO-releasing Carbon Nanodots for Tumor-specific Gas Therapy

Carbon nanodots based on L-arginine (L-Arg) were developed for enhanced nitric oxide (NO) gas therapy for cancer. The L-Arg-based carbon nanodots (Arg-dots) produced high levels of NO in the tumor environment rich in endogenous H₂O₂. In vitro cell experiments revealed that the Arg-dots could kill tumor cells (including human breast cancer cell line MCF-7, female gastric cancer cell line BGC-823, male lung cancer cell line A549, and female leukemic cell line K562) but did not affect the activity of normal cells (human normal lung epithelial cell line BEAS-2B). The Arg-dots produced twice the amount of NO for an equivalent amount of L-Arg. Theoretical calculations showed that the carbonization structure of the Arg-dots promoted significantly more electrons toward the guanidinium groups of L-Arg and boosted the adsorption of H₂O₂ molecules. In vitro and in vivo investigations confirmed that the Arg-dots reduced the multidrug resistance (MDR) effect of the tumor cells (MCF-7/ADR cells) and produced a combined antitumor efficacy with traditional chemotherapeutic drugs (adriamycin [ADR]). The fluorescence property (quantum yield, 6.88%) allows the Arg-dots to be used as a suitable fluorescent probe for fluorescence imaging of tumor cells. The ultra-small size of the Arg-dots (diameter: ca. 2.5 nm) enables them not only to penetrate deep tumors and provide enhanced antitumor activity but also to be removed through kidney filtration and have a renal clearance property. STATEMENT OF SIGNIFICANCE: Nitric oxide (NO), which serves as a biological messenger, can be used in gas therapy for cancer. The development of a safe and efficient NO cancer therapy is, however, challenging because of the low NO release amount and poor tumor specificity of most NO donors. Many efforts have been made to overcome these drawbacks, but solving both these limitations through a single approach has been seldom achieved. In the present work, carbon nanodots (Arg-dots) from L-arginine were used for gas therapy of cancer. The Arg-dots produced NO in the H₂O₂-rich tumor environment. Theoretical calculations were consistent with the mechanism of enhanced NO release amount. The Arg-dots also reduced the multidrug resistance effect in cancer chemotherapy. In vivo and in vitro toxicity assessments confirmed that the Arg-dots have excellent biosafety.

A Versatile Calcium Phosphate Nanogenerator for Tumor Microenvironment-activated Cancer Synergistic Therapy

Gas therapy is an emerging "green" cancer treatment strategy; however, its outcome often restricted by the complexity, diversity, and heterogeneity of tumor. Herein, a tumor targeting and tumor microenvironment-activated calcium phosphate nanotheranostic system (denoted as GCAH) is constructed for effective synergistic cancer starvation/gas therapy. GCAH is obtained by a facile biomineralization strategy using glucose oxidase (GOx) as a biotemplate, followed by loading of l-Arginine (L-Arg) and modification of hyaluronic acid (HA) to allow special selectivity for glycoprotien CD44 overexpressed cancer cells. This nanotheranostic system not only exhausts the glucose nutrients in tumor region by the GOx-triggered glucose oxidation, the generated H₂ O₂ can oxidize L-Arg into NO under acidic tumor microenvironment for enhanced gas therapy. As such, there are significant enhancement effects of starvation therapy and gas therapy through the cascade reactions of GOx and L-Arg, which yields a remarkable synergistic therapeutic effect for 4T1 tumor-bearing mice without discernible toxic side effects.

Engineering macromolecular nanocarriers for local delivery of gaseous signaling molecules

In addition to being notorious air pollutants, nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H₂S) have also been known as endogenous gaseous signaling molecules (GSMs). These GSMs play critical roles in maintaining the homeostasis of living organisms. Importantly, the occurrence and development of many diseases such as inflammation and cancer are highly associated with the concentration changes of GSMs. As such, GSMs could also be used as new therapeutic agents, showing great potential in the treatment of many formidable diseases. Although clinically it is possible to directly inhale GSMs, the precise control of the dose and concentration for local delivery of GSMs remains a substantial challenge. The development of gaseous signaling molecule-releasing molecules provides a great tool for the safe and convenient delivery of GSMs. In this review article, we primarily focus on the recent development of macromolecular nanocarriers for the local delivery of various GSMs. Learning from the chemistry of small molecule-based donors, the integration of these gaseous signaling molecule-releasing molecules into polymeric matrices through physical encapsulation, post-modification, or direct polymerization approach renders it possible to fabricate numerous macromolecular nanocarriers with optimized pharmacokinetics and pharmacodynamics, revealing improved therapeutic performance than the small molecule analogs. The development of GSMs represents a new means for many disease treatments with unique therapeutic outcomes.

Manipulating Intratumoral Fenton Chemistry for Enhanced Chemodynamic and Chemodynamic-Synergized Multimodal Therapy

Chemodynamic therapy (CDT) uses the tumor microenvironment-assisted intratumoral Fenton reaction for generating highly toxic hydroxyl free radicals (•OH) to achieve selective tumor treatment. However, the limited intratumoral Fenton reaction efficiency restricts the therapeutic efficacy of CDT. Recent years have witnessed the impressive development of various strategies to increase the efficiency of intratumoral Fenton reaction. The introduction of these reinforcement strategies can dramatically improve the treatment efficiency of CDT and further promote the development of enhanced CDT (ECDT)-based multimodal anticancer treatments. In this review, the authors systematically introduce these reinforcement strategies, from their basic working principles, reinforcement mechanisms to their representative clinical applications. Then, ECDT-based multimodal anticancer therapy is discussed, including how to integrate these emerging Fenton reinforcement strategies for accelerating the development of multimodal anticancer therapy, as well as the synergistic mechanisms of ECDT and other treatment methods. Eventually, future direction and challenges of ECDT and ECDT-based multimodal synergistic therapies are elaborated, highlighting the key scientific problems and unsolved technical bottlenecks to facilitate clinical translation.

Nanoscale covalent organic frameworks: from controlled synthesis to cancer therapy

Covalent organic frameworks (COFs), as a new type of crystalline porous materials, mainly consist of light-weight elements (H, B, C, N and O) linked by dynamic covalent bonds to form periodical structures of two or three dimensions. As an attribute of their low density, large surface area, and excellent adjustable pore size, COFs show great potential in many fields including energy storage and separation, catalysis, sensing, and biomedicine. However, compared with metal organic frameworks (MOFs), the relatively large size and irregular morphology of COFs affect their biocompatibility and bioavailability in vivo, thus impeding their further biomedical applications. This Review focuses on the controlled design strategies of nanoscale COFs (NCOFs), unique properties of NCOFs for biomedical applications, and recent progress in NCOFs for cancer therapy. In addition, current challenges for the biomedical use of NCOFs and perspectives for further improvements are presented.

Cross-linking of S-nitrosothiolated AIEgens inside cancer cells to monitor NO release and reverse chemo-resistance

Nitric oxide (NO)-releasing platforms have been demonstrated as promising approaches for the reversal of multidrug resistance (MDR) in cancer cells due to the suppression of P-glycoprotein (P-gp). However, the non-specific systemic release of NO and difficulty in estimating the precise NO amount in target sites hindered their translational applications. Traditional bioimaging techniques which are responsive to NO molecules cannot distinguish between exogenous and endogenous NO. Herein we introduce S-nitrosothiol-functionalized tetraphenylethene (TPE-RSNO) to specifically monitor exogenous NO release and synergistically reverse MDR. TPE-RSNO can specifically respond to NO release and visualize NO delivery with fluorescence in living cells. Moreover, the elevated reactive oxygen species (ROS) in cancer cells triggered rapid NO release to reduce P-gp and thus synergistically increase the therapeutic effect of doxorubicin (DOX).

Stimuli Responsive Nitric Oxide-Based Nanomedicine for Synergistic Therapy

Gas therapy has received widespread attention from the medical community as an emerging and promising therapeutic approach to cancer treatment. Among all gas molecules, nitric oxide (NO) was the first one to be applied in the biomedical field for its intriguing properties and unique anti-tumor mechanisms which have become a research hotspot in recent years. Despite the great progress of NO in cancer therapy, the non-specific distribution of NO in vivo and its side effects on normal tissue at high concentrations have impaired its clinical application. Therefore, it is important to develop facile NO-based nanomedicines to achieve the on-demand release of NO in tumor tissue while avoiding the leakage of NO in normal tissue, which could enhance therapeutic efficacy and reduce side effects at the same time. In recent years, numerous studies have reported the design and development of NO-based nanomedicines which were triggered by exogenous stimulus (light, ultrasound, X-ray) or tumor endogenous signals (glutathione, weak acid, glucose). In this review, we summarized the design principles and release behaviors of NO-based nanomedicines upon various stimuli and their applications in synergistic cancer therapy. We also discuss the anti-tumor mechanisms of NO-based nanomedicines in vivo for enhanced cancer therapy. Moreover, we discuss the existing challenges and further perspectives in this field in the aim of furthering its development.

Light-triggered nitric oxide release and structure transformation of peptide for enhanced intratumoral retention and sensitized photodynamic therapy

Tumor-targeted delivery of nanomedicine is of great importance to improve therapeutic efficacy of cancer and minimize systemic side effects. Unfortunately, nowadays the targeting efficiency of nanomedicine toward tumor is still quite limited and far from clinical requirements. In this work, we develop an innovative peptide-based nanoparticle to realize light-triggered nitric oxide (NO) release and structural transformation for enhanced intratumoral retention and simultaneously sensitizing photodynamic therapy (PDT). The designed nanoparticle is self-assembled from a chimeric peptide monomer, TPP-RRRKLVFFK-Ce6, which contains a photosensitive moiety (chlorin e6, Ce6), a β-sheet-forming peptide domain (Lys-Leu-Val-Phe-Phe, KLVFF), an oligoarginine domain (RRR) as NO donor and a triphenylphosphonium (TPP) moiety for targeting mitochondria. When irradiated by light, the constructed nanoparticles undergo rapid structural transformation from nanosphere to nanorod, enabling to achieve a significantly higher intratumoral accumulation by 3.26 times compared to that without light irradiation. More importantly, the conversion of generated NO and reactive oxygen species (ROS) in a light-responsive way to peroxynitrite anions (ONOO^-) with higher cytotoxicity enables NO to sensitize PDT in cancer treatment. Both in vitro and in vivo studies demonstrate that NO sensitized PDT based on the well-designed transformable nanoparticles enables to eradicate tumors efficiently. The light-triggered transformable nanoplatform developed in this work provides a new strategy for enhanced intratumoral retention and improved therapeutic outcome.

Gas and gas-generating nanoplatforms in cancer therapy

Gas therapy is the usage of certain gases with special therapeutic effects for the treatment of diseases. Hydrogen (H₂), nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H₂S) acting as gas signalling molecules are representative gases in cancer therapy. They act directly on mitochondria or nuclei to lead to cell apoptosis. They can also alleviate immuno-suppression in the tumour microenvironment and promote phenotype conversion of tumour-associated macrophages. Moreover, the combination of gas therapy and other traditional therapy methods can reduce side effects and improve therapeutic efficacy. Here, we discuss the roles of NO, CO, H₂S and H₂ in cancer biology. Considering the rapidly developing nanotechnology, gas-generating nanoplatforms which can achieve targeted delivery and controlled release were also discussed. Finally, we highlight the current challenges and future opportunities of gas-based cancer therapy.

Pesticide exposure and related health problems among farmworkers' children: a case-control study in southeast Iran

Pesticides are potentially hazardous chemicals that can cause injury to human health and the environment. The purpose of this study was to evaluate organophosphate pesticides (OPPs) and organochlorine pesticides (OCPs) exposure in farmworkers' children aged 6 to 11 years in Jiroft city in southeastern Iran. One hundred twenty farmworkers' children as case and 53 non-farmworkers' children aged 6 to 11 years as control were selected and the serum levels of OCPs were measured by using gas chromatography in all participants. In addition, erythrocyte acetylcholinesterase (AChE) and arylesterase activity of paraoxonase-1 (PON-1) were measured to evaluate OPPs effects. Catalase (CAT), superoxide dismutase3 (SOD3), glutathione peroxidase (GPx3) activities, and the levels of serum malondialdehyde (MDA), total antioxidant capacity (TAC), nitric oxide (NO), and protein carbonyl (PC) were measured to investigate OCPs and OPPs effects on oxidative stress (OS). The serum levels of beta-HCH, 4,4 DDE, and 4,4 DDT in the case group were significantly higher than the control group. In addition, in the case group, AChE, PON-1, CAT, SOD3, and GPx3 activities and the levels TAC were significantly lower, while MDA, PC, and NO levels were significantly higher than the control group. OCPs as illegal pesticides are present in southeast Iran and children are exposed to OCPs and OPPs in the studied area. In addition, higher serum levels of pesticides may be a major contributor in OS development, as a cause of many diseases.

Riboflavin-based carbon dots with high singlet oxygen generation for photodynamic therapy

Photodynamic therapy, as an effective treatment for superficial tumors, has attracted more and more attention. The development of safe, biocompatible and in vivo photosensitive materials is helpful to promote photodynamic therapy. Here we report green fluorescent carbon quantum dots prepared from a natural vitamin, riboflavin (VB2), as a photosensitizer. The VB2-based carbon dots have excellent water solubility and biocompatibility, and their singlet oxygen generation ability is much stronger than that of riboflavin itself. Through endocytosis, the carbon dots can easily enter the cells and show bright green fluorescence. In vivo experiments show that after photodynamic therapy the carbon dots can significantly inhibit the growth of tumors, and will not have toxic and side effects on other organs.

L-Arg-Rich Amphiphilic Dendritic Peptide as a Versatile NO Donor for NO/Photodynamic Synergistic Treatment of Bacterial Infections and Promoting Wound Healing

The development of alternative strategies for the efficient treatment of subcutaneous abscesses that do not require the massive use of antibiotics and surgical intervention is urgently needed. Herein, a novel synergistic antibacterial strategy based on photodynamic (PDT) and NO gas therapy is reported, in which, a PDT-driven NO controllable generation system (Ce6@Arg-ADP) is developed with l-Arg-rich amphiphilic dendritic peptide (Arg-ADP) as a carrier. This carrier not only displays superior bacterial association and biofilm penetration performance, but also acts as a versatile NO donor. Following efficient penetration into the interior of the biofilms, Ce6@Arg-ADP can rapidly produce massive NO via utilizing the H₂ O₂ generated during PDT to oxidize Arg-ADP to NO and l-citrulline, without affecting singlet oxygen (¹ O₂ ) production. The combination of ¹ O₂ and the reactive by-products of NO offers notable synergistic antibacterial and biofilm eradication effects. Importantly, following efficient elimination of all bacteria from the abscess site, Arg-ADP can further generate trace quantities of NO to facilitate the angiogenesis and epithelialization of the wound tissues, thereby notably promotes wound healing. Together, this study clearly suggests that Arg-ADP is a versatile NO donor, and the combination of PDT and NO represents a promising strategy for the efficient treatment of subcutaneous abscesses.

Biocatalytic Nanomaterials: A New Pathway for Bacterial Disinfection

Clinical treatment of pathogenic infection has emerged as a growing challenge in global public health. Such treatment is currently limited to antibiotics, but abuse of antibiotics have induced multidrug resistance and high fatality rates in anti-infection therapies. Thus, it is vital to develop alternative bactericidal agents to open novel disinfection pathways. Drawing inspiration from elements of the human immune system that show great potential for controlling pathogens or regulating cell apoptosis, the design of biocatalytic nanomaterials (BCNs) have provided unrivaled opportunities for future antibacterial therapies. More significantly, BCNs exhibit various superior properties to immune cells and natural enzymes, such as higher biocatalytic performance, extraordinary stability against harsh conditions, and scalable production. In this review, the most recent efforts toward developing BCN-based biomedical applications in combating bacterial infections are focused upon. BCNs' antibacterial mechanisms, the classification of BCNs, antibacterial activities that can be triggered or augmented by energy conversion, and the eradication of biofilms with BCNs are systematically introduced and discussed. The current challenges and prospects of BCNs for biocatalytic disinfection are also summarized. It is anticipated this review will provide new therapeutic insights into combating bacteria and biofilms and offer significant new inspiration for designing future biocatalytic nanomaterials.

The recent progress on metal-organic frameworks for phototherapy

Some infectious or malignant diseases such as cancers are seriously threatening the health of human beings all over the world. The commonly used antibiotic therapy cannot effectively treat these diseases within a short time, and also bring about adverse effects such as drug resistance and immune system damage during long-term systemic treatment. Phototherapy is an emerging antibiotic-free strategy to treat these diseases. Upon light irradiation, phototherapeutic agents can generate cytotoxic reactive oxygen species (ROS) or induce a temperature increase, which leads to the death of targeted cells. These two kinds of killing strategies are referred to as photodynamic therapy (PDT) and photothermal therapy (PTT), respectively. So far, many photo-responsive agents have been developed. Among them, the metal-organic framework (MOF) is becoming one of the most promising photo-responsive materials because its structure and chemical compositions can be easily modulated to achieve specific functions. MOFs can have intrinsic photodynamic or photothermal ability under the rational design of MOF construction, or serve as the carrier of therapeutic agents, owing to its tunable porosity. MOFs also provide feasibility for various combined therapies and targeting methods, which improves the efficiency of phototherapy. In this review, we firstly investigated the principles of phototherapy, and comprehensively summarized recent advances of MOF in PDT, PTT and synergistic therapy, from construction to modification. We expect that our demonstration will shed light on the future development of this field, and bring it one step closer to clinical trials.

A NO/ROS/RNS cascaded-releasing nano-platform for gas/PDT/PTT/immunotherapy of tumors

Nitric oxide (NO) gas treatment offers a promising strategy for tumor therapy; however, its practical application is still limited due to its poor efficacy and biotoxicity which were caused by gas leakage during blood delivery. Herein, a nano-platform (CMH-OBN) composed of chlorin e6-melanin-hyaluronic acid nanoparticles (Ce6-MNP-HA, CMH) and oxidized bletilla striata polysaccharide microcapsules (Oxi-BSP) carrying NO donors was prepared for responsive and cascaded release of NO, reactive oxygen species (ROS) and its secondary metabolite reactive nitrogen species (RNS) in tumor sites. Melanin not only endowed CMH with good photothermal properties, but also helped Ce6 to produce a large number of ROS under near-infrared (NIR) irradiation. OBN microcapsules, which were sensitive to ROS, can release NO donors under the stimulation of ROS released by CMH nanoparticles under NIR irradiation and can further release NO in the tumor microenvironment (TME) with high expression of glutathione (GSH). NO could further up-regulate soluble guanylate cyclase-cyclic guanosine monophosphate (sGC-cGMP) signal pathways to relieve hypoxia, thus further enhancing the photodynamic therapy (PDT). Moreover, the cascaded release of ROS and NO could produce RNS with higher lethality, which could sequentially initiate the cellular apoptotic procedure and promote immunotherapy by activating T cells at the tumor sites. More interestingly, the CMH-OBN nano-platform could supply magnetic resonance imaging (MRI) and infrared photothermal imaging guidance for tumor therapy. In conclusion, the development of a CMH-OBN nano-platform provides a satisfactory demonstration by combining NO therapy with photothermal therapy (PTT), PDT and immunotherapy for the treatment of cancer.

Nitric oxide release activated near-Infrared photothermal agent for synergistic tumor treatment

Activatable phototherapeutic agents (PTA) in one system with synergistic gas therapy (GT) and photothermal therapy (PTT) hold great promise for highly efficient tumor treatments. In this study, an activatable multifunctional platform with photothermal conversion "turn on" features via nitric oxide (NO) release for synergistic GT and PTT was rationally designed using an aryl N-nitrosamine (NO-donating unit) functionalized aza-BODIPY framework (S-NO). As expected, after NO release from S-NO, the product (Red-S) showed obviously enhanced heat production performance under a longer excited wavelength via improved near-infrared light absorption and decreased fluorescence emission. Furthermore, water-soluble and biocompatible S-NO nanoparticles (S-NO NPs) with negligible dark cytotoxicity successfully suppressed tumor growth and enhanced the survival rate of mice via synergistic GT and PTT under the guidance of multimode imaging. The study offered rational guidance to design better platforms for synergistic tumor treatments and validated that S-NO NPs can act as potential PTAs in biological applications.

Enhancing the Antitumor Effect of Doxorubicin with Photosensitive Metal-Organic Framework Nanoparticles against Breast Cancer

Breast cancer is one of the most common malignant tumors in women. The existence of multiple breast cancer subtypes often leads to chemotherapy failure or the development of drug resistance. In recent years, photodynamic therapy has been proven to enhance the sensitivity of tumors to chemotherapeutic drugs. Porphyrin-based metal-organic framework (MOF) materials could simultaneously be used as carriers for chemotherapy and photosensitizers in photodynamic therapy. In this paper, doxorubicin hydrochloride (DOX) was loaded in porphyrin MOFs, and the mechanism of the synergistic effect of the DOX carriers and photodynamic therapy on breast cancer was investigated. In vitro and in vivo experiments have shown that MOFs could prolong the residence time of DOX in tumor tissues and promote the endocytosis of DOX by tumor cells. In addition, adjuvant treatment with photodynamic therapy can promote breast cancer tumors to resensitize to DOX and synergistically enhance the chemotherapy effect of DOX. Therefore, this study can provide effective development ideas for reversing drug resistance during breast cancer chemotherapy and improving the therapeutic effect of chemotherapy on breast cancer.

Recent Advances on Stimuli-Responsive Combination Therapy against Multidrug-Resistant Bacteria and Biofilm

The widespread occurrence of infections from multidrug-resistant (MDR) bacteria is a global health problem. It has been amplified over the past few years due to the increase in adaptive traits in bacteria and lack of advanced treatment strategies. Because of the low bioavailability and limited penetration at infected sites, the existing antibiotics often fail to resist bacterial growth. Recently, developed stimuli-responsive drug delivery systems and combinatorial therapeutic systems based on nanoparticles, metal-organic frameworks, hydrogels, and organic chromophores offer the ability to improve the therapeutic efficacy of antibiotics by reducing drug resistance and other side effects. These therapeutic systems have been designed with the relevant chemical and physical properties that respond to specific triggers resulting in spatiotemporal controlled release and site-specific transportability. This review highlights the latest development of single and dual/multistimuli-responsive antibiotic delivery systems for combination therapies to treat MDR bacterial infections and biofilm eradication.

Recent advances in porous nanostructures for cancer theranostics

Porous nanomaterials with high surface area, tunable porosity, and large mesopores have recently received particular attention in cancer therapy and imaging. Introduction of additional pores to nanostructures not only endows the tunability of optoelectronic and optical features optimal for tumor treatment, but also modulates the loading capacity and controlled release of therapeutic agents. In recognition, increasing efforts have been made to fabricate various porous nanomaterials and explore their potentials in oncology applications. Thus, a systematic and comprehensive summary is necessary to overview the recent progress, especially in last ten years, on the development of various mesoporous nanomaterials for cancer treatment as theranostic agents. While outlining their individual synthetic mechanisms after a brief introduction of the structures and properties of porous nanomaterials, the current review highlighted the representative applications of three main categories of porous nanostructures (organic, inorganic, and organic-inorganic nanomaterials). In each category, the synthesis, representative examples, and interactions with tumors were further detailed. The review was concluded with deliberations on the key challenges and future outlooks of porous nanostructures in cancer theranostics.

Photodynamic immunotherapy of cancers based on nanotechnology: recent advances and future challenges

Photodynamic therapy (PDT) is a non-invasive or minimally-invasive treatment which applies photosensitizers (PSs) to create reactive oxygen species (ROS) exposed to light trigger to destroy cancer cells. PDT can activate host anti-tumor immune responses but not powerful enough to kill metastatic tumors. Because of its carrier advantage, imaging, and therapeutic function together with enhanced permeability and retention (EPR) effect, nano-materials have already been used in photo-immunotherapy. Herein, photodynamic immunotherapy (PDIT) based on nanotechnology seems to be a hopeful new form of cancer therapy. In this article, we firstly summarize the recent development in photodynamic immunotherapy based on nanotechnology.

In Situ Imaging of Cellular Reactive Oxygen Species and Caspase-3 Activity Using a Multifunctional Theranostic Probe for Cancer Diagnosis and Therapy

In this work, a multifunctional theranostic nanoprobe (Au-Ag-HM) was skillfully designed for simultaneous imaging of intracellular reactive oxygen species (ROS) and caspase-3 activity. The Au-Ag-HM was fabricated by coloading of silver nanoparticles (AgNPs) and hematoporphyrin monomethyl ether (HMME) to Au nanoflowers (AuNFs). When Au-Ag-HM was devoured by cancer cells, HepG2 cells were used as the model, and under laser irradiation, the photogenerated intracellular ROS by the photosensitizer HMME would induce the apoptosis of cancer cells. Meanwhile, the intracellular ROS triggered the oxidative etching of AgNPs on Au-Ag-HM, which led to a tremendous localized surface plasmon resonance response and scattering color changes in Au-Ag-HM, allowing in situ dark-field imaging of the ROS level in cancer cells. On the other hand, the ROS-induced activation of cellular caspase-3, which cleaved the C-peptide-containing caspase-3-specific recognition sequence (DEVD) and allowed HMME to release from the nanoprobe, resulted in a significant fluorescence recovery related to caspase-3 activity. Both photogenerated ROS and enhanced caspase-3 activity contributed to the synergistic effect of laser-mediated chemotherapy and photodynamic therapy. Therefore, the as-prepared theranostic probe could be used for simultaneous detection of cellular ROS and caspase-3 activity, distinguishing between tumor cells and normal cells, inducing the apoptosis of cancer cells, and providing a new method for diagnosis and therapy of cancer.

Recent Advances in Nanoscale Metal-Organic Frameworks Towards Cancer Cell Cytotoxicity: An Overview

Abstract

The fight against cancer has always been a prevalent research topic. Nanomaterials have the ability to directly penetrate cancer cells and potentially achieve minimally invasive, precise and efficient tumor annihilation. As such, nanoscale metal organic frameworks (nMOFs) are becoming increasingly attractive as potential therapeutic agents in the medical field due to their high structural variability, good biocompatibility, ease of surface functionalization as well as their porous morphologies with tunable cavity sizes. This overview addresses five different common strategies used to find cancer therapies, while summarizing the recent progress in using nMOFs as cytotoxic cancer cell agents largely through in vitro studies, although some in vivo investigations have also been reported. Chemo and targeted therapies rely on drug encapsulation and delivery inside the cell, whereas photothermal and photodynamic therapies depend on photosensitizers. Concurrently, immunotherapy actively induces the body to destroy the tumor by activating an immune response. By choosing the appropriate metal center, ligands and surface functionalization, nMOFs can be utilized in all five types of therapies. In the last section, the future prospects and challenges of nMOFs with respect to the various therapies will be presented and discussed.

Graphic Abstract

Multishell Nanoparticles with "Linkage Mechanism" for Thermal Responsive Photodynamic and Gas Synergistic Therapy

The strategies of combining photodynamic therapy (PDT) with other therapeutics are considered to be the most suitable methods in improving the antitumor therapeutic efficiency. Herein, a "Linkage Mechanism" strategy based on thermal controllable multishell nanoparticles (CuS@SiO₂ -l-Arg (l-arginine)@PCM (phase-change material)-Ce6 (chiorin e6)) is proposed for combing PDT and NO-based gas therapy. Upon 1060 nm laser irradiation, the PCMs will melt under the photothermal effect induced by CuS and the loaded Ce6 and l-Arg can accurately release from the nanoparticles. Under further 660 nm laser irradiation, the released Ce6 will produce plenty of singlet oxygen (¹ O₂ ) for PDT, while the generated ¹ O₂ can oxidize l-Arg to release NO for the synergy of PDT and gas therapy. The "Linkage Mechanism" can achieve precise release of the payloads under the control of photothermal effect at tumor site, and the chain reaction of PDT and gas therapy overcomes the problem of premature release of gas during transportation. Benefiting from the guidance of fluorescence imaging and second near infrared photoacoustic imaging by Ce6 and CuS, both in vitro and in vivo experiments present effective antitumor efficiencies. The nanoparticles provide new ideas for controllable release of drugs and the synergistic effect of multiple treatments, possessing great application prospects.

Gadolinium-doped hollow silica nanospheres loaded with curcumin for magnetic resonance imaging-guided synergistic cancer sonodynamic-chemotherapy

Curcumin is a kind of anti-cancer chemotherapeutic drug and has been demonstrated to be able to produce reactive oxygen species (ROS) under the stimuli of ultrasound (US). Herein, gadolinium-doped hollow mesoporous silica nanospheres (Gd-HMSNs) loaded with curcumin (Cur) and conjugated with carboxymethyl dextran (CMD) have been facilely fabricated and applied for magnetic resonance imaging (MRI)-guided synergistic cancer sonodynamic-chemotherapy. The as-prepared multifunctional theranostic nanoplatform (Cur@Gd-HMSNs-CMD) shows high drug loading capacity, satisfactory biocompatibility, pH-responsive degradation, and US-triggered drug release. Due to the release of Gd³⁺ ions or oligomers during degradation, the nanoplatform Cur@Gd-HMSNs-CMD could serve as an effective contrast agent for T₁-weighted MRI to guide cancer treatment. More significantly, in vivo experiments show that the Cur@Gd-HMSNs-CMD can efficiently inhibit the tumor growth by a high inhibition rate of ~85.6% under US irradiation, mainly resulting from the synergistic effect of sonodynamic-chemotherapy. This innovative "two-in-one" theranostic nanoplatform using a single drug provides a new strategy for developing "all-in-one" nanomaterials for combined cancer treatment.