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

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.

Advances and perspectives in phototherapy-based combination therapy for cancer treatment

Phototherapy, including photothermal therapy (PTT) and photodynamic therapy (PDT), has the advantages of spatiotemporal selectivity, non-invasiveness, and negligible drug resistance. Phototherapy has been approved for treating superficial epidermal tumors. However, its therapeutic efficacy is limited by the hypoxic tumor microenvironment and the highly expressed heat shock protein. Moreover, poor tissue penetration and focused irradiation laser region in phototherapy make treating deep tissues and metastatic tumors challenging. Combination therapy strategies, which integrate the advantages of each treatment and overcome their disadvantages, can significantly improve the therapeutic efficacy. Recently, many combination therapy strategies have been reported. Our study summarizes the strategies used for combining phototherapy with other cancer treatments such as chemotherapy, immunotherapy, sonodynamic therapy, gas therapy, starvation therapy, and chemodynamic therapy. Some research cases were selected to analyze the combination therapy effect, delivery platform feature, and synergetic anticancer mechanisms. Moreover, additional research cases are summarized in the tables. This review provides strong evidence that phototherapy-based combination strategies can enhance the anticancer effect compared with phototherapy alone. Additionally, the challenges and future perspectives associated with these combinational therapies are discussed.

Near-Infrared Light-Triggered NO Nanogenerator for Gas-Enhanced Photodynamic Therapy and Low-Temperature Photothermal Therapy to Eliminate Biofilms

Purpose

Owing to its noninvasive nature, broad-spectrum effectiveness, minimal bacterial resistance, and high efficiency, phototherapy has significant potential for antibiotic-free antibacterial interventions and combating antibacterial biofilms. However, finding effective strategies to mitigate the detrimental effects of excessive temperature and elevated concentrations of reactive oxygen species (ROS) remains a pressing issue that requires immediate attention.

Methods

In this study, we designed a pH-responsive cationic polymer sodium nitroside dihydrate/branched polyethylenimine-indocyanine green@polyethylene glycol (SNP/PEI-ICG@PEG) nanoplatform using the electrostatic adsorption method and Schiff's base reaction. Relevant testing techniques were applied to characterize and analyze SNP/PEI-ICG@PEG, proving the successful synthesis of the nanomaterials. In vivo and in vitro experiments were performed to evaluate the antimicrobial properties of SNP/PEI-ICG@PEG.

Results

The morphology and particle size of SNP/PEI-ICG@PEG were observed via TEM. The zeta potential and UV-visible (UV-vis) results indicated the synthesis of the nanomaterials. The negligible cytotoxicity of up to 1 mg/mL of SNP/PEI-ICG@PEG in the presence or absence of light demonstrated its biosafety. Systematic in vivo and in vitro antimicrobial assays confirmed that SNP/PEI-ICG@PEG had good water solubility and biosafety and could be activated by near-infrared (NIR) light and synergistically treated using four therapeutic modes, photodynamic therapy (PDT), gaseous therapy (GT), mild photothermal therapy (PTT, 46 °C), and cation. Ultimately, the development of Gram-positive (G+) Staphylococcus aureus (S. aureus) and Gram-negative (G-) Escherichia coli (E. coli) were both completely killed in the free state, and the biofilm that had formed was eliminated.

Conclusion

SNP/PEI-ICG@PEG demonstrated remarkable efficacy in achieving controlled multimodal synergistic antibacterial activity and biofilm infection treatment. The nanoplatform thus holds promise for future clinical applications.

Development of a solid-supported light-triggered nitric oxide donor

Nitric Oxide (NO) photocleavable donors are useful tools for interrogating nitric oxide signalling and have potential use in photopharmacological applications. There is currently intensive research into newer methods to improve NO release and kinetic profiles. Herein, we report the design and synthesis of a solid-supported photocleavable NO donor synthesized by ligating an N-nitroso photocleavable nitric oxide derivative to a TentaGel® polymer resin bead. Illumination with 365 nm light released nitric oxide that could be tracked via a turn-on fluorescence response (λex = 450 nm, λem = 545 nm) and measured using the Griess assay and diaminorhodamine derivatives. These beads were further shown to be compatible with living A549 cells and had the ability to deliver greater concentrations of nitric oxide to cells proximal to a bead versus cells at more distal locations within the same well.

Light-responsive polymeric nanoparticles for retinal drug delivery: design cues, challenges and future perspectives

A multitude of sight-threatening retinal diseases, affecting hundreds of millions around the globe, lack effective pharmacological treatments due to ocular barriers and common drug delivery limitations. Polymeric nanoparticles (PNPs) are versatile drug carriers with sustained drug release profiles and tunable physicochemical properties which have been explored for ocular drug delivery to both anterior and posterior ocular tissues. PNPs can incorporate a wide range of drugs and overcome the challenges of conventional retinal drug delivery. Moreover, PNPs can be engineered to respond to specific stimuli such as ultraviolet, visible, or near-infrared light, and allow precise spatiotemporal control of the drug release, enabling tailored treatment regimens and reducing the number of required administrations. The objective of this study is to emphasize the therapeutic potential of light-triggered drug-loaded polymeric nanoparticles to treat retinal diseases through an exploration of ocular pathologies, challenges in drug delivery, current production methodologies and recent applications. Despite challenges, light-responsive PNPs hold the promise of substantially enhancing the treatment landscape for ocular diseases, aiming for an improved quality of life for patients.

Current trends in gas-synergized phototherapy for improved antitumor theranostics

Phototherapy, such as photothermal therapy (PTT) and photodynamic therapy (PDT), has been considered an elegant solution to eradicate tumors due to its minimal invasiveness and low systemic toxicity. Nevertheless, it is still challenging for phototherapy to achieve ideal outcomes and clinical translation due to its inherent drawbacks. Owing to the unique biological functions, diverse gases have attracted growing attention in combining with phototherapy to achieve super-additive therapeutic effects. Specifically, gases such as nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) have been proven to kill tumor cells by inducing mitochondrial damage in synergy with phototherapy. Additionally, several gases not only enhance the thermal damage in PTT and the reactive oxygen species (ROS) production in PDT but also improve the tumor accumulation of photoactive agents. The inflammatory responses triggered by hyperthermia in PTT are also suppressed by the combination of gases. Herein, we comprehensively review the latest studies on gas-synergized phototherapy for cancer therapy, including (1) synergistic mechanisms of combining gases with phototherapy; (2) design of nanoplatforms for gas-synergized phototherapy; (3) multimodal therapy based on gas-synergized phototherapy; (4) imaging-guided gas-synergized phototherapy. Finally, the current challenges and future opportunities of gas-synergized phototherapy for tumor treatment are discussed. STATEMENT OF SIGNIFICANCE: 1. The novelty and significance of the work with respect to the existing literature. (1) Strategies to design nanoplatforms for gas-synergized anti-tumor phototherapy have been summarized for the first time. Meanwhile, the integration of various imaging technologies and therapy modalities which endow these nanoplatforms with advanced theranostic capabilities has been summarized. (2) The mechanisms by which gases synergize with phototherapy to eradicate tumors are innovatively and comprehensively summarized. 2. The scientific impact and interest. This review elaborates current trends in gas-synergized anti-tumor phototherapy, with special emphases on synergistic anti-tumor mechanisms and rational design of therapeutic nanoplatforms to achieve this synergistic therapy. It aims to provide valuable guidance for researchers in this field.

A double-gain theranostic nanoplatform based on self-supplying H2O2 nanocomposites for synergistic chemodynamic/gas therapy

Chemodynamic therapy (CDT) based on hydroxyl radicals (•OH) to suppress tumor cells is a promising strategy due to its efficacy and safety. Nevertheless, in tumor cells, CDT still faces challenges such as insufficient •OH and weak killing effect of tumor cells under physiological conditions due to inadequate amounts of endogenous hydrogen peroxide (H2O2) and heightened glutathione expression. These challenges limit the therapeutic potential of CDT. To improve the effects of CDT, combination treatment strategies have been developed. Here, we report a rationally designed nanocomposite (CaO2@Cu-LA) with self-supplying H2O2 ability from calcium peroxide, and nitric oxide (NO) generation ability from l-arginine. NO molecules not only exhibit a strong killing effect, but also have the potential to transfer into the more cytotoxic substance peroxynitrite anion by reacting with reactive oxygen species. The results showed that CaO2@Cu-LA could significantly suppress tumor growth by increasing •OH radicals and NO molecules. Taken together, the strategy developed here provides a good application foreground to yield a remarkable synergistic antitumor effect of CDT and NO gas therapy.

A near-infrared light-triggered nano-domino system for efficient biofilm eradication: Activation of dispersing and killing functions by generating nitric oxide and peroxynitrite via cascade reactions

One of the serious threats to global public health is the bacterial biofilm, which results in numerous persistent and recurrent infections. Herein, we proposed a near-infrared (NIR) light-triggered "nano-domino" system with "dispersing and killing" functionality for biofilm eradication. The nanoplatform was fabricated by the self-assembly of chitosan conjugated with L-arginine (L-Arg, a natural nitric oxide (NO) donor) and indocyanine green (ICG, a phototherapy agent). Using an NIR irradiation "trigger", a series of reactive oxygen species (ROS) including singlet oxygen (1O2), hydrogen peroxide (H2O2), and superoxide anions (·O2-), as well as heat were generated from ICG aggregates. Subsequently, 1O2 and H2O2 catalyzed L-Arg to produce NO, which dispersed the biofilm and reacted with ·O2- to form peroxynitrite to kill bacteria with ROS collaboratively. Meanwhile, the generated heat increased the permeability of bacterial membranes, aggravating the damage to biofilm bacteria. The experiments on biofilm eradication demonstrated that this "nano-domino" system was capable to eradicate over 99.99% of biofilms formed by Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa under 5-min NIR irradiation. Notably, these integrated benefits allowed the system to promote the healing of MRSA biofilm-infected wounds in vivo with negligible toxicity. Overall, this reported NIR-triggered "nano-domino" system holds great promise for addressing the difficulties associated with bacterial biofilm eradication. STATEMENT OF SIGNIFICANCE: Novel agents for biofilm eradication are urgently needed due to the alarming rise in antimicrobial resistance to conventional antibiotics and the critical shortage of new drugs. In this study, we created a nano-domino system that uses near-infrared (NIR) light as a trigger to eradicate mature biofilms. In response to a short-term NIR irradiation, the proposed nanoplatform could generate nitric oxide and peroxynitrite to disperse the biofilm and kill the bacteria inside, respectively, leading to efficient eradication of Methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa biofilms with minimal cytotoxicity. The findings, therefore, indicate that this nanoplatform with enhanced antibiofilm performance might provide a reliable and promising solution to biofilm-related problems.

L-Arginine self-delivery supramolecular nanodrug for NO gas therapy

NO gas therapy is a supplementary approach for tumor treatment due to the advantages of minimal invasion, little drug resistance, low side effect and amplified efficacy. l-Arginine (L-Arg), a natural NO source with good biocompatibility, can release NO under the stimulation of H2O2 in tumor microenvironment. However, the conventional l-Arg delivery systems via noncovalent loading usually lead to inevitable premature leakage of nano-cargos during blood circulation. In this work, an efficient l-Arg self-delivery supramolecular nanodrug (SDSND) for tumor treatment is demonstrated by combining Mannich reaction and π-π stacking. l-Arg links to (-)-epigallocatechin gallate (EGCG) with the assistance of formaldehyde through Mannich reaction, and then assembles into nanometer-sized particles via π-π stacking. The guanidine group of l-Arg and the phenolic hydroxyl groups of EGCG are preserved in the SDSNDs, which allows for accomplishing gas therapy by provoking tumor cell apoptosis and combining with EGCG to amplify apoptosis, respectively. In addition, the SDSNDs exhibit high biocompatibility and avoid the premature leakage of l-Arg in blood circulation, providing an alternative l-Arg delivery system for NO gas therapy. STATEMENT OF SIGNIFICANCE: NO gas therapy has attracted emerging interest in tumor treatment. However, the controlled NO release and the avoidance of premature leakage of NO donors remain challenging. In this work, L-Arginine (L-Arg) self-delivery supramolecular nanodrug for efficient tumor therapy is demonstrated through the Mannich reaction of L-Arg, (-)-epigallocatechin gallate (EGCG) and formaldehyde. Stimulated by tumor microenvironment, the guanidine groups of L-Arg allow for accomplishing NO release and thus provoking tumor cell apoptosis. The nanodrug also avoids the premature leakage of L-Arg in blood circulation. Moreover, the preserved phenolic hydroxyl groups of EGCG combine with L-Arg to amplify apoptosis. The nanodrug exhibits high biocompatibility and good therapeutic effect, providing an alternative L-Arg delivery system for NO gas therapy.

Nitric oxide-driven nanotherapeutics for cancer treatment

Nitric oxide (NO) is a gaseous molecule endowed with diverse biological functions, offering vast potential in the realm of cancer treatment. Considerable efforts have been dedicated to NO-based cancer therapy owing to its good biosafety and high antitumor activity, as well as its efficient synergistic therapy with other antitumor modalities. However, delivering this gaseous molecule effectively into tumor tissues poses a significant challenge. To this end, nano drug delivery systems (nano-DDSs) have emerged as promising platforms for in vivo efficient NO delivery, with remarkable achievements in recent years. This review aims to provide a summary of the emerging NO-driven antitumor nanotherapeutics. Firstly, the antitumor mechanism and related clinical trials of NO therapy are detailed. Secondly, the latest research developments in the stimulation of endogenous NO synthesis are presented, including the regulation of nitric oxide synthases (NOS) and activation of endogenous NO precursors. Moreover, the emerging nanotherapeutics that rely on tumor-specific delivery of NO donors are outlined. Additionally, NO-driven combined nanotherapeutics for multimodal cancer theranostics are discussed. Finally, the future directions, application prospects, and challenges of NO-driven nanotherapeutics in clinical translation are highlighted.

Sequential Diagnosis and Treatment for Colon Cancer via Derived Iridium and Indocyanine Green Hybrid Nanomicelles

Indocyanine green (ICG) has been widely explored for the theranostics of tumors. However, ICG mainly accumulates in the liver, spleen, or kidney in addition to in tumors, causing inaccurate diagnoses and impaired therapeutic effects under NIR irradiation. Herein, a hybrid nanomicelle was constructed by integrating hypoxia-sensitive iridium(III) and ICG for precise tumor localization and photothermal therapy in sequence. In this nanomicelle, the amphiphilic iridium(III) complex (BTPH)₂Ir(SA-PEG) was synthesized through the coordination substitution of hydrophobic (BTPH)₂IrCl₂ and hydrophilic PEGlyated succinylacetone (SA-PEG). Meanwhile, PEGlyated ICG (ICG-PEG) as a derivative of the photosensitizer ICG was also synthesized. (BTPH)₂Ir(SA-PEG) and ICG-PEG were coassembled by dialysis to form the hybrid nanomicelle M-Ir-ICG. Hypoxia-sensitive fluorescence, ROS generation, and the photothermal effect of M-Ir-ICG were investigated in vitro and in vivo. The experimental results indicated that M-Ir-ICG nanomicelles could locate at the tumor site first and then perform photothermal therapy with 83.90% TIR, demonstrating great potential for clinical applications.

Recent Advances in Functional Nanomaterials for Catalytic Generation of Nitric Oxide: A Mini Review

As a gaseous second messenger, nitric oxide (NO) plays an important role in a series of signal pathways. Research on the NO regulation for various disease treatments has aroused wide concern. However, the lack of accurate, controllable, and persistent release of NO has significantly limited the application of NO therapy. Profiting from the booming development of advanced nanotechnology, a mass of nanomaterials with the properties of controllable release have been developed to seek new and effective NO nano-delivery approaches. Nano-delivery systems that generate NO through catalytic reactions exhibit unique superiority in terms of precise and persistent release of NO. Although certain achievements have been made in the catalytically active NO delivery nanomaterials, some basic but critical issues, such as the concept of design, are of low attention. Herein, an overview of the generation of NO through catalytic reactions and the design principles of related nanomaterials are summarized. Then, the nanomaterials that generate NO through catalytic reactions are classified. Finally, the bottlenecks and perspectives are also discussed in depth for the future development of catalytical NO generation nanomaterials.

Renal-Clearable Probe with Water Solubility and Photostability for Biomarker-Activatable Detection of Acute Kidney Injuries via NIR-II Fluorescence and Optoacoustic Imaging

Acute kidney injuries (AKI) have serious short-term or long-term complications with high morbidity and mortality rate, thus posing great health threats. Developing high-performance NIR-II probes for noninvasive in situ detection of AKI via NIR-II fluorescent and optoacoustic dual-mode imaging is of great significance. Yet NIR-II chromophores often feature long conjugation and hydrophobicity, which prevent them from being renal clearable, thus limiting their applications in the detection and imaging of kidney diseases. To fully exploit the advantageous features of heptamethine cyanine dye, while overcoming its relatively poor photostability, and to strive to design a NIR-II probe for the detection and imaging of AKI with dual-mode imaging, herein, we have developed the probe PEG3-HC-PB, which is renal clearable, water soluble, and biomarker activatable and has good photostability. As for the probe, its fluorescence (900-1200 nm) is quenched due to the existence of the electron-pulling phenylboronic group (responsive element), and it exhibits weak absorption with a peak at 830 nm. Meanwhile, in the presence of the overexpressed H₂O₂ in the renal region in the case of AKI, the phenylboronic group is converted to the phenylhydroxy group, which enhances NIR-II fluorescent emission (900-1200 nm) and absorption (600-900 nm) and eventually produces conspicuous optoacoustic signals and NIR-II fluorescent emission for imaging. This probe enables detection of contrast-agent-induced and ischemia/reperfusion-induced AKI in mice using real-time 3D-MSOT and NIR-II fluorescent dual-mode imaging via response to the biomarker H₂O₂. Hence, this probe can be used as a practicable tool for detecting AKI; additionally, its design strategy could provide insight into the design of other large-conjugation NIR-II probes with multifarious biological applications.

Metal-based nanomaterials and nanocomposites as promising frontier in cancer chemotherapy

Cancer is a disease associated with complex pathology and one of the most prevalent and leading reasons for mortality in the world. Current chemotherapy has challenges with cytotoxicity, selectivity, multidrug resistance, and the formation of stemlike cells. Nanomaterials (NMs) have unique properties that make them useful for various diagnostic and therapeutic purposes in cancer research. NMs can be engineered to target cancer cells for early detection and can deliver drugs directly to cancer cells, reducing side effects and improving treatment efficacy. Several of NMs can also be used for photothermal therapy to destroy cancer cells or enhance immune response to cancer by delivering immune-stimulating molecules to immune cells or modulating the tumor microenvironment. NMs are being modified to overcome issues, such as toxicity, lack of selectivity, increase drug capacity, and bioavailability, for a wide spectrum of cancer therapies. To improve targeted drug delivery using nano-carriers, noteworthy research is required. Several metal-based NMs have been studied with the expectation of finding a cure for cancer treatment. In this review, the current development and the potential of plant and metal-based NMs with their effects on size and shape have been discussed along with their more effective usage in cancer diagnosis and treatment.

Two-dimensional porous vermiculite-based nanocatalysts for synergetic catalytic therapy

This study reports an ultrasound-mediated and two-dimensional (2D) porous vermiculite nanosheets (VMT NSs)-based nanocatalyst platform (Arg@VMT@PDA-PEG) that synergistically harnessed the Fenton reaction-based chemodynamic therapy (CDT), 2D semiconductor-based sonodynamic therapy (SDT) and nitric oxide (NO)-based gas therapy for combination cancer therapy. The tumor microenvironment responsive degradation of polydopamine (PDA) shell could not only prevent L-Arg, a NO donor, leakage during blood circulation, but also selectively release the active sites of VMT NSs for catalytic reactions in tumor cells. Additionally, the Fenton reactions mediated by the abundant Fe²⁺/Fe³⁺ in VMT NSs could efficiently produce ·OH and consume glutathione (GSH) for CDT. Moreover, the reactive oxygen species (ROS, ·OH and ·O₂^-) produced by ultrasound-triggered Arg@VMT@PDA-PEG could not only execute SDT but also oxidize L-Arg to NO for synergetic gas therapy. The results show that the transformation of ROS to NO can enhance curative efficacy owing to the ability of NO with much longer life-time in freely diffusing into cells from intercellular space. This biodegradable Arg@VMT@PDA-PEG nanocatalytic platform integrating three different catalytic reactions provides a new therapeutic paradigm for combination cancer therapy.

Photodynamic therapy: Innovative approaches for antibacterial and anticancer treatments

Photodynamic therapy is an alternative treatment mainly for cancer but also for bacterial infections. This treatment dates back to 1900 when a German medical school graduate Oscar Raab found a photodynamic effect while doing research for his doctoral dissertation with Professor Hermann von Tappeiner. Unexpectedly, Raab revealed that the toxicity of acridine on paramecium depends on the intensity of light in his laboratory. Photodynamic therapy is therefore based on the administration of a photosensitizer with subsequent light irradiation within the absorption maxima of this substance followed by reactive oxygen species formation and finally cell death. Although this treatment is not a novelty, there is an endeavor for various modifications to the therapy. For example, selectivity and efficiency of the photosensitizer, as well as irradiation with various types of light sources are still being modified to improve final results of the photodynamic therapy. The main aim of this review is to summarize anticancer and antibacterial modifications, namely various compounds, approaches, and techniques, to enhance the effectiveness of photodynamic therapy.

Research Progress of Nanomedicine-Based Mild Photothermal Therapy in Tumor

With the booming development of nanomedicine, mild photothermal therapy (mPTT, 42-45°C) has exhibited promising potential in tumor therapy. Compared with traditional PTT (>50°C), mPTT has less side effects and better biological effects conducive to tumor treatment, such as loosening the dense structure in tumor tissues, enhancing blood perfusion, and improving the immunosuppressive microenvironment. However, such a relatively low temperature cannot allow mPTT to completely eradicate tumors, and therefore, substantial efforts have been conducted to optimize the application of mPTT in tumor therapy. This review extensively summarizes the latest advances of mPTT, including two sections: (1) taking mPTT as a leading role to maximize its effect by blocking the cell defense mechanisms, and (2) regarding mPTT as a supporting role to assist other therapies to achieve synergistic antitumor curative effect. Meanwhile, the special characteristics and imaging capabilities of nanoplatforms applied in various therapies are discussed. At last, this paper puts forward the bottlenecks and challenges in the current research path of mPTT, and possible solutions and research directions in future are proposed correspondingly.

Recent progress in nitric oxide-generating nanomedicine for cancer therapy

Nitric oxide (NO) is an endogenous, multipotent biological signaling molecule that participates in several physiological processes. Recently, exogenous supplementation of tumor tissues with NO has emerged as a potential anticancer therapy. In particular, it induces synergistic effects with other conventional therapies (such as chemo-, radio-, and photodynamic therapies) by regulating the activity of P-glycoprotein, acting as a vascular relaxant to relieve tumor hypoxia, and participating in the metabolism of reactive oxygen species. However, NO is highly reactive, and its half-life is relatively short after generation. Meanwhile, NO-induced anticancer activity is dose-dependent. Therefore, the targeted delivery of NO to the tumor is required for better therapeutic effects. In the past decade, NO-generating nanomedicines (NONs), which enable sustained and specific NO release in tumor tissues, have been developed for enhanced cancer therapy. This review describes the recent efforts and preclinical achievements in the development of NON-based cancer therapies. The chemical structures employed in the fabrication of NONs are summarized, and the strategies involved in NON-based cancer therapies are elaborated.