Light-Responsive Biodegradable Nanomedicine Overcomes Multidrug Resistance via NO-Enhanced Chemosensitization

Effects of nitric oxide donor N,N'-di-sec-butyl-N,N'-dinitroso-1,4-phenylenediamine on the expression of interferon-gamma in tumor infiltrating lymphocytes

Nitric oxide (NO) has been proven to be a key regulator in the mammalian immune response, such as the innate and adaptive immune responses to tumors. The messenger NO involves T helper cell differentiation and lymphocyte biofunctions. In this study, we employed N,N’-di-sec-butyl-N,N’-dinitroso-1,4-phenylenediamine as NO donor and released NO around tumor infiltrating lymphocytes in vitro by short-time blue light irradiation. The interferon-γ secretion of tumor infiltrating lymphocytes was investigated to study the functional changes caused by the accurate spatio-temporal delivery of NO. The downregulation of interferon-γ in tumor infiltrating lymphocytes after NO treatment indicates promising biological applications to potentially play a role in the treatment of autoimmune diseases. The study was approved by the Medical Ethics Committee of the Shenzhen Second People’s Hospital, the First Affiliated Hospital of Shenzhen University, China (approved No. 065) on February 12, 2018.

Near-Infrared Light-Responsive Nitric Oxide Delivery Platform for Enhanced Radioimmunotherapy

Radiotherapy (RT) is a widely used way for cancer treatment. However, the efficiency of RT may come with various challenges such as low specificity, limitation by resistance, high dose and so on. Nitric oxide (NO) is known a very effective radiosensitizer of hypoxic tumor. However, NO cannot circulate in body with high concentration. Herein, an NIR light-responsive NO delivery system is developed for controlled and precisely release of NO to hypoxic tumors during radiotherapy. Tert-Butyl nitrite, which is an efficient NO source, is coupled to Ag₂S quantum dots (QDs). NO could be generated and released from the Ag₂S QDs effectively under the NIR irradiation due to the thermal effect. In addition, Ag is also a type of heavy metal that can benefit the RT therapy. We demonstrate that Ag₂S NO delivery platforms remarkably maximize radiotherapy effects to inhibit tumor growth in CT26 tumor model. Furthermore, immunosuppressive tumor microenvironment is improved by our NO delivery system, significantly enhancing the anti-PD-L1 immune checkpoint blockade therapy. 100% survival rate is achieved by the radio-immune combined therapy strategy based on the Ag₂S NO delivery platforms. Our results suggest the promise of Ag₂S NO delivery platforms for multifunctional cancer radioimmunotherapy.

Strategies for engineering advanced nanomedicines for gas therapy of cancer

As an emerging and promising treatment method, gas therapy has attracted more and more attention for treatment of inflammation-related diseases, especially cancer. However, therapeutic/therapy-assisted gases (NO, CO, H₂S, H₂, O₂, SO₂ and CO₂) and most of their prodrugs lack the abilities of active intratumoral accumulation and controlled gas release, resulting in limited cancer therapy efficacy and potential side effects. Therefore, development of nanomedicines to realize tumor-targeted and controlled release of therapeutic/therapy-assisted gases is greatly desired, and also the combination of other therapeutic modes with gas therapy by multifunctional nanocarrier platforms can augment cancer therapy efficacy and also reduce their side effects. The design of nanomedicines with these functions is vitally important, but challenging. In this review, we summarize a series of engineering strategies for construction of advanced gas-releasing nanomedicines from four aspects: (1) stimuli-responsive strategies for controlled gas release; (2) catalytic strategies for controlled gas release; (3) tumor-targeted gas delivery strategies; (4) multi-model combination strategies based on gas therapy. Moreover, we highlight current issues and gaps in knowledge, and envisage current trends and future prospects of advanced nanomedicines for gas therapy of cancer. This review aims to inspire and guide the engineering of advanced gas-releasing nanomedicines.

Light-triggered nitric oxide (NO) release from photoresponsive polymersomes for corneal wound healing

Polymersomes have been extensively used in the delivery of both small and macromolecular payloads. However, the controlled delivery of gaseous therapeutics (e.g., nitric oxide, NO) remains a grand challenge due to its difficulty in loading of gaseous payloads into polymersomes without premature leakage. Herein, NO-releasing vesicles could be fabricated via the self-assembly of NO-releasing amphiphiles, which were synthesized by the direct polymerization of photoresponsive NO monomers (abbreviated as oNBN, pNBN, and BN). These monomers were rationally designed through the integration of the photoresponsive behavior of N-nitrosoamine moieties and the self-immolative chemistry of 4-aminobenzyl alcohol derivatives, which outperformed conventional NO donors such as diazeniumdiolates (NONOates) and S-nitrosothiols (SNOs) in terms of ease of preparation, stability of storage, and controllability of NO release. The unique design made it possible to selectively release NO by a light stimulus and to regulate the NO release rates. Importantly, the photo-mediated NO release could be manipulated in living cells and showed promising applications in the treatment of corneal wounds. In addition to delivering NO, the current design enabled the synergistic delivery of NO and other therapeutic payloads by taking advantage of NO release-mediated traceless crosslinking of the vesicles.

Peroxynitrite (ONOO−) generation from the HA-TPP@NORM nanoparticles based on synergistic interactions between nitric oxide and photodynamic therapies for elevating anticancer efficiency

Due to biological safety and negligible toxicity, nitric oxide (NO) therapy has gained increasing interest in the field of cancer therapy during the past few years.

Photo-degradable micelles for co-delivery of nitric oxide and doxorubicin

Photo-degradable triblock copolymers enable the co-delivery of nitric oxide and doxorubicin exerting an improved therapeutic effect.

Functional Biodegradable Nitric Oxide Donor-Containing Polycarbonate-Based Micelles for Reduction-Triggered Drug Release and Overcoming Multidrug Resistance

Nitric oxide (NO), as a bioeffector to improve chemosensitivity by reversing multidrug resistance (MDR), is highly attractive for developing combinational delivery systems to deal with MDR tumors, while it is highly challenged by the stability and controlled release of NO during the pathway. Here we design and synthesize a cyclic nitrate trimethylene carbonate monomer (NTC), followed by ring-opening polymerization to prepare amphiphilic biodegradable polycarbonate-based copolymers as polymeric NO donors with tailored contents. The copolymer with desirable molecular weight is readily self-assembled to biodegradable micelles (NO-M) with a uniform size of 130 nm for highly stabilizing NO donors at the physiological conditions, while triggered NO release from micelles is performed at the intracellular reduction conditions. More importantly, NO-M shows superior inhibition of P-gP expression to enhance the chemosensitivity of multidrug-resistant MCF7 cells (MCF7/DOX^R). DOX-loaded NO-M (NO-M@DOX) realizes fast DOX release at the intracellular conditions, resulting in more intracellular DOX accumulation and higher antitumor activity mediated by the reduction-triggered NO/DOX release and NO-induced MDR reversal. Furthermore, the in vivo results show that NO-M@DOX effectively suppresses the MCF7/DOX^R tumor growth by a combination of directly NO-induced therapy and NO-mediated enhanced chemotherapy; meanwhile, the treatment with NO-M systems have much fewer side effects.

Dual Stimuli-Responsive Controlled Release Nanocarrier for Multidrug Resistance Cancer Therapy

Multidrug resistance of cancer cells is a major obstacle for cancer chemotherapy. Herein, we present a nanocarrier that can release chemotherapeutic agents to induce tumor cell death and generate NO under NIR to overcome multidrug resistance in cancer chemotherapy. Owing to the unique structure of the water channel in this controlled release system for chemotherapeutic agents, the nanocarrier surface is equipped with more active sites to graft NO donor molecules. The released NO performs very well in reversing multidrug resistance by inhibiting P-gp expression. Our findings provide new insight into multidrug resistance cancer therapy and controlled release nanocarriers for multiple drugs.

Near-infrared light switching nitric oxide nanoemitter for triple-combination therapy of multidrug resistant cancer

The multidrug resistance (MDR) of tumor cells often leads to the failure of chemotherapy against cancer. It is urgently needed to develop a safe and effective strategy of overcoming MDR for enhancing chemotherapy efficiency. In this work, one type of new folic acid-polyethylene glycol (FA-PEG) modified polydopamine nanoparticles (FAPPs) was synthesized for gas/chemo/photothermal triple-combination therapy of multidrug resistant cancer. The nanoparticles loaded nitric oxide (NO) donor act as a NO nanoemitter to generate NO via a NIR light irradiation switch, which has a great capacity of reversing MDR via inhibiting the overexpression of P-glycoprotein (P-gp) and cell respiration with the reduction of both the adenosine triphosphate (ATP) content and mitochondrial membrane potential (ΔΨ_m) in MDR tumor cells. Moreover, the amount of generated NO can be regulated by changing the action time of the nanoparticles. After that, the nanoparticles loaded chemotherapeutic agent (DOX) act as a photothermal-chemotherapy nanomedicine, which can release DOX with a high concentration in tumor cell for chemotherapy and simultaneously produce a large amount of heat for photothermal therapy under NIR irradiation. Finally, the gas/chemo/photothermal triple-combination therapy with the nanomedicines displays an excellent therapeutic efficacy in nude mice bearing MDR tumors. STATEMENT OF SIGNIFICANCE: The multidrug resistance (MDR) of tumor cells frequently leads to the failure of chemotherapy against cancer. It is urgently needed to develop a safe and effective strategy of overcoming MDR for enhancing chemotherapy efficiency. In this paper, a NIR light switching nitric oxide nanoemitter is successfully developed for gas/chemo/photothermal triple-combination therapy of multidrug resistant cancer. The controllably generated NO under NIR irradiation can effectively reverse multidrug resistance by inhibiting the overexpression of P-gp and cell respiration, significantly enhancing the chemotherapeutic agent concentration in tumor cells, and simultaneously a large amount of heat is produced for photothermal therapy.

Recent progress in the augmentation of reactive species with nanoplatforms for cancer therapy

Reactive species (RS), mainly including reactive oxygen species (ROS) and reactive nitrogen species (RNS), are indispensable in a wide variety of biological processes. RS often have elevated levels in cancer cells and tumor microenvironments. They also have a dual effect on cancer: on the one hand, they promote pro-tumorigenic signaling to facilitate tumor survival and on the other hand, they promote antitumorigenic pathways to induce cell death. Excessive RS would disrupt the cellular redox homeostasis balance and show partiality as oxidants, which would cause irreversible damage to the adjacent biomolecules such as lipids, proteins and nucleic acids. The altered redox environment and the corresponding increased antioxidant capacity in cancer cells render the cells susceptible to RS-manipulated therapies, especially the augmentation of RS. With the rapid development of nanotechnology and nanomedicine, a large number of cancer therapeutic nanoplatforms have been developed to trigger RS overproduction by exogenous and/or endogenous stimulation. In this review, we highlighted the latest progress in the nanoplatforms designed for the augmentation of RS in cancer therapy. Nanoplatforms based on strategies including disabling the antioxidant defense system, photodynamic therapy (PDT), sonodynamic therapy (SDT), and chemodynamic therapy (CDT) were introduced. The crucial obstacles involved in these strategies, such as the light penetration limitation of PDT, relatively low RS release by SDT, and strict conditions of Fenton reaction-mediated CDT, were also discussed, and feasible solutions for improvement were proposed. Furthermore, synergistic therapies among individual therapeutic modalities such as chemotherapy, photothermal therapy, and RS-based dynamic therapies were overviewed, which contributed to achieving more optimal anticancer efficacy than linear addition. This review sheds light on the development of non-invasive cancer therapy based on RS manipulation and provides guidance for establishing promising cancer therapeutic platforms in clinical settings.

Gas-Mediated Cancer Bioimaging and Therapy

Gas-involving cancer theranostics have attracted considerable attention in recent years due to their high therapeutic efficacy and biosafety. We have reviewed the recent significant advances in the development of stimuli-responsive gas releasing molecules (GRMs) and gas nanogenerators for cancer bioimaging, targeted and controlled gas therapy, and gas-sensitized synergistic therapy. We have focused on gases with known anticancer effects, such as oxygen (O₂), carbon monoxide (CO), nitric oxide (NO), hydrogen sulfide (H₂S), hydrogen (H₂), sulfur dioxide (SO₂), carbon dioxide (CO₂), and heavy gases that act via the gas-generating process. The GRMs and gas nanogenerators for each gas have been described in terms of the stimulation method, followed by their applications in ultrasound and multimodal imaging, and finally their primary and synergistic actions with other cancer therapeutic modalities. The current challenges and future possibilities of gas therapy and imaging vis-à-vis clinical translation have also been discussed.

Stimuli-Responsive Drug Release from Smart Polymers

Over the past 10 years, stimuli-responsive polymeric biomaterials have emerged as effective systems for the delivery of therapeutics. Persistent with ongoing efforts to minimize adverse effects, stimuli-responsive biomaterials are designed to release in response to either chemical, physical, or biological triggers. The stimuli-responsiveness of smart biomaterials may improve spatiotemporal specificity of release. The material design may be used to tailor smart polymers to release a drug when particular stimuli are present. Smart biomaterials may use internal or external stimuli as triggering mechanisms. Internal stimuli-responsive smart biomaterials include those that respond to specific enzymes or changes in microenvironment pH; external stimuli can consist of electromagnetic, light, or acoustic energy; with some smart biomaterials responding to multiple stimuli. This review looks at current and evolving stimuli-responsive polymeric biomaterials in their proposed applications.

Incorporation of Nitroprusside on Silica Nanoparticles-A Strategy for Safer Use of This NO Donor in Therapy

Silica-based nanoparticles have been developed as powerful platforms for drug delivery and might also prevent undesired side effects of drugs. Here, a fast method to synthesize positively charged mesoporous silica nanoparticles (ζ = 20 ± 0.5 mV, surface area = 678 m² g^-1, and 2.3 nm of porous size) was reported. This nanomaterial was employed to anchor sodium nitroprusside (SNP), a vasodilator drug with undesired cyanide release. A remarkable incorporation of 323.9 ± 7.55 μmol of SNP per gram of nanoparticle was achieved, and a series of studies of NO release were conducted, showing efficient release of NO along with major cyanide retention (ca. 64% bound to nanoparticle). Biological assays with mammalian cells showed only a slight drop in cell viability (13%) at the highest concentration (1000 μM), while SNP exhibited an LC₅₀ of 228 μM. Moreover, pharmacological studies demonstrated similar efficacy for vasodilation and sGC-PKG-VASP pathway activation when compared to SNP alone. Altogether, this new SNP silica nanoparticle has great potential as an alternative for wider and safer use of SNP in medicine with lower cyanide toxicity.

Near-Infrared Light-Triggered Sulfur Dioxide Gas Therapy of Cancer

The exploitation of gas therapy platforms holds great promise as a "green" approach for selective cancer therapy, however, it is often associated with some challenges, such as uncontrolled or insufficient gas generation and unclear therapeutic mechanisms. In this work, a gas therapy approach based on near-infrared (NIR) light-triggered sulfur dioxide (SO₂) generation was developed, and the therapeutic mechanism as well as in vivo antitumor therapeutic efficacy was demonstrated. A SO₂ prodrug-loaded rattle-structured upconversion@silica nanoparticles (RUCSNs) was constructed to enable high loading capacity without obvious leakage and to convert NIR light into ultraviolet light so as to activate the prodrug for SO₂ generation. In addition, SO₂ prodrug-loaded RUCSNs showed high cell uptake, good biocompatibility, intracellular tracking ability, and high NIR light-triggered cytotoxicity. Furthermore, the cytotoxic SO₂ was found to induce cell apoptosis accompanied by the increase of intracellular reactive oxygen species levels and the damage of nuclear DNA. Moreover, efficient inhibition of tumor growth was achieved, associated with significantly prolonged survival of mice. Such NIR light-triggered SO₂ therapy may provide an effective strategy to stimulate further development of synergistic cancer therapy platforms.

Intracellular NO-Generator Based on Enzyme Trigger for Localized Tumor-Cytoplasm Rapid Drug Release and Synergetic Cancer Therapy

Nitric oxide (NO) is an important biological messenger implicated in tumor therapy. However, current NO release systems suffer from some disadvantages, such as hydrolysis during blood circulation, poor specificity, and robust irradiation for stimuli. Accordingly, we constructed an intracellular enzyme-triggered NO-generator to achieve tumor cytoplasm-specific disruption and localized rapid drug release. Diethylamine NONOate (DEA/NO) was used as a NO donor and conjugated with hyaluronic acid (HA) to form self-assembly micelle (HA-DNB-DEA/NO), and encapsulate chemotherapeutic agent (doxorubicin (DOX)) into its hydrophobic core (DOX@HA-DNB-DEA/NO). After HA receptor mediated internalization into tumor cells, HA shell would undergo digestion into small conjugated pieces by hyaluronidase. Meanwhile, DOX@HA-DNB-DEA/NO also responded to the intratumoral overexpressed glutathion and glutathione S-transferase π, leading to the intracellular NO production and controlled DOX rapid release. In vitro and in vivo results proved the enzyme-dependent and enhanced targeting delivery profile, and demonstrated that NO and DOX could colocate in specific tumor site, which provided a precondition for exerting their synergistic efficacy. Moreover, expression of p53 protein was upregulated in tumor tissue after treatment, indicating that NO induced cell apoptosis mediated by tumor suppressor gene p53. Overall, this intelligent drug loaded NO-generator might perform as an enhancer to realize better clinical outcomes.

Controlled Delivery of Nitric Oxide for Cancer Therapy

Nitric oxide (NO) is a short-lived, endogenously produced, signaling molecule which plays multiple roles in mammalian physiology. Underproduction of NO is associated with several pathological processes; hence a broad range of NO donors have emerged as potential therapeutics for cardiovascular and respiratory disorders, wound healing, the immune response to infection, and cancer. However, short half-lives, chemical reactivity, rapid systemic clearance, and cytotoxicity have hindered the clinical development of most low molecular weight NO donors. Hence, for controlled NO delivery, there has been extensive effort to design novel NO-releasing biomaterials for tumor targeting. This review covers the effects of NO in cancer biology, NO releasing moieties which can be used for NO delivery, and current advances in the design of NO releasing biomaterials focusing on their applications for tumor therapy.

A cyotosol-selective nitric oxide bomb as a new paradigm of an anticancer drug

Dual pH and redox-sensitive polymeric NO delivery micelles act as a cytosol-selective NO bomb for efficient anticancer therapy.

Gas-Generating Nanoplatforms: Material Chemistry, Multifunctionality, and Gas Therapy

The fast advances of theranostic nanomedicine enable the rational design and construction of diverse functional nanoplatforms for versatile biomedical applications, among which gas-generating nanoplatforms (GGNs) have emerged very recently as unique theranostic nanoplatforms for broad gas therapies. Here, the recent developments of the rational design and chemical construction of versatile GGNs for efficient gas therapies by either exogenous physical triggers or endogenous disease-environment responsiveness are reviewed. These gases involve some therapeutic gases that can directly change disease status, such as oxygen (O₂ ), nitric oxide (NO), carbon monoxide (CO), hydrogen (H₂ ), hydrogen sulfide (H₂ S) and sulfur dioxide (SO₂ ), and other gases such as carbon dioxide (CO₂ ), dl-menthol (DLM), and gaseous perfluorocarbon (PFC) for supplementary assistance of the theranostic process. Abundant nanocarriers have been adopted for gas delivery into lesions, including poly(d,l-lactic-co-glycolic acid), micelles, silica/mesoporous silica, organosilica, MnO₂ , graphene, Bi₂ Se₃ , upconversion nanoparticles, CaCO₃ , etc. Especially, these GGNs have been successfully developed for versatile biomedical applications, including diagnostic imaging and therapeutic use. The biosafety issue, challenges faced, and future developments on the rational construction of GGNs are also discussed for further promotion of their clinical translation to benefit patients.

Local generation of hydrogen for enhanced photothermal therapy

By delivering the concept of clean hydrogen energy and green catalysis to the biomedical field, engineering of hydrogen-generating nanomaterials for treatment of major diseases holds great promise. Leveraging virtue of versatile abilities of Pd hydride nanomaterials in high/stable hydrogen storage, self-catalytic hydrogenation, near-infrared (NIR) light absorption and photothermal conversion, here we utilize the cubic PdH0.2 nanocrystals for tumour-targeted and photoacoustic imaging (PAI)-guided hydrogenothermal therapy of cancer. The synthesized PdH0.2 nanocrystals have exhibited high intratumoural accumulation capability, clear NIR-controlled hydrogen release behaviours, NIR-enhanced self-catalysis bio-reductivity, high NIR-photothermal effect and PAI performance. With these unique properties of PdH0.2 nanocrystals, synergetic hydrogenothermal therapy with limited systematic toxicity has been achieved by tumour-targeted delivery and PAI-guided NIR-controlled release of bio-reductive hydrogen as well as generation of heat. This hydrogenothermal approach has presented a cancer-selective strategy for synergistic cancer treatment.

Gas Therapy: An Emerging “Green” Strategy for Anticancer Therapeutics

As an emerging area, gas therapy has attracted more and more attention in treating many diseases including cancer. The fabrication of stimuli‐responsive delivery systems with on‐demand release behavior is very promising for precision gas therapy, which can obtain optimal therapeutic performance without gas poisoning risks. In this review, the authors introduce the recent progress in the preparation of different kinds of gas carriers for efficient delivery of gaseous molecules (NO, H2S, CO, O2). Particularly, in order to achieve targeted accumulation of gaseous molecules in tumor tissues, gaseous molecules–integrated nanoparticles were constructed. Most importantly, by combination of gas therapy with other therapeutic modalities such as chemotherapy, photodynamic therapy (PDT), and radiotherapy, various multifunctional nanocarriers have been designed for synergistic cancer therapy. Especially, the recent developments of multifunctional gas‐carrying nanocarriers for synergistic cancer therapy are discussed in detail.

Intracellular NO-Releasing Hyaluronic Acid-Based Nanocarriers: A Potential Chemosensitizing Agent for Cancer Chemotherapy

In this work, we investigate whether S-nitrosoglutathione (GSNO)-conjugated hyaluronic acid-based self-assembled nanoparticles (GSNO-HANPs) can be useful as a chemosensitizing agent to improve the anticancer activity of doxorubicin (DOX). The GSNO-HANPs were prepared by aqueous assembly of GSNO-conjugated HA with grafted poly(lactide- co-glycolide). Aqueous GSNO stability shielded within the assembled environments of the GSNO-HANPs was greatly enhanced, compared to that of free GSNO. The NO release from the GSNO-HANPs was facilitated in the presence of hyaluronidase-1 (Hyal-1) and ascorbic acid at intracellular concentrations. Microscopic analysis showed GSNO-HANPs effectively generated NO within the cells. We observed that NO made the human MCF-7 breast cancer cells vulnerable to DOX. This chemosensitizing activity was supported by the observation of an increased level of ONOO^- (peroxynitrite), a highly reactive oxygen species, upon co-treatment with the GSNO-HANPs and DOX. Apoptosis assays showed that GSNO-HANP alone exhibited negligible cytotoxic effects and reinforced apoptotic activity of DOX. Animal experiments demonstrated the effective accumulation of GSNO-HANPs in solid MCF-7 tumors and effectively suppressed tumor growth in combination with DOX. This hyaluronic acid-based intracellularly NO-releasing nanoparticles may serve as a significant chemosensitizing agent in treatments of various cancers.

Triple Stimuli-Responsive Magnetic Hollow Porous Carbon-Based Nanodrug Delivery System for Magnetic Resonance Imaging-Guided Synergistic Photothermal/Chemotherapy of Cancer

The premature leakage of anticancer drugs during blood circulation may the damage immune system, normal cells, and tissues. Constructing targeted nanocarriers with pH, glutathione, and NIR triple-responsive property can effectively avoid the leakage of anticancer drugs before they arrive at the targeted site. In this paper, magnetic hollow porous carbon nanoparticles (MHPCNs) were successfully fabricated as nanocarrier. Poly(γ-glutamic acid) was used to cap the pores of MHPCNs. The photothermal conversion property of carbon and iron oxide (Fe₃O₄) nanomaterials was utilized to perform photothermal therapy to overcome multidrug-resistance produced by chemotherapy. The biodistribution of nanoparticles was investigated by magnetic resonance imaging. Experiments in vivo confirm the efficient accumulations of nanoparticles at tumor sites. Meanwhile, tumor growth was effectively inhibited via synergistic photothermal/chemotherapy with minimal side effects.

Platinum nanoparticles: an avenue for enhancing the release of nitric oxide from S-nitroso-N-acetylpenicillamine and S-nitrosoglutathione

Nitric oxide (NO) is an endogenous bioregulator with established roles in diverse fields. The difficulty in the modulation of NO release is still a significant obstacle to achieving successful clinical applications. We report herein our initial work using electron spin resonance (ESR) spectroscopy to detect NO generated from S-nitroso-N-acetylpenicillamine (SNAP) and S-nitrosoglutathione (GSNO) donors catalyzed by platinum nanoparticles (Pt NPs, 3 nm) under physiological conditions. With ESR spectroscopy coupled with spin trapping and spin labeling techniques, we identified that Pt NPs can significantly promote the generation of NO from SNAP and GSNO under physiological conditions. A classic NO colorimetric detection kit was also employed to verify that Pt NPs truly triggered the release of NO from its donors. Pt NPs can act as promising delivery vehicles for on-demand NO delivery based on time and dosage. These results, along with the detection of the resulting disulfide product, were confirmed with mass spectrometry. In addition, cellular experiments provided a convincing demonstration that the triggered release of NO from its donors by Pt NPs is efficient in killing human cancer cells in vitro. The catalytic mechanism was elucidated by X-ray photo-electron spectroscopy (XPS) and ultra-high performance liquid chromatography/high-resolution mass spectrometry (UHPLC-HRMS), which suggested that Pt-S bond formation occurs in the solution of Pt NPs and NO donors. Identification of Pt NPs capable of generating NO from S-nitrosothiols (RSNOs) is an important step in harnessing NO for investigations into its clinical applications and therapies.

Precision gas therapy using intelligent nanomedicine

Gas therapy is an emerging and promising field, utilizing the unique therapeutic effects of several kinds of gases (NO, CO, H₂S and H₂) towards many major diseases, including cancer and cardiovascular diseases, and it is also facing challenges relating to enhancing gas therapy efficacy and avoiding gas poisoning risks. Here, we have proposed a new concept for precision gas therapy using a nanomedicine strategy to overcome the challenges. In this perspective, we have addressed a series of existing and potential solutions from the point of view of nanomedicine, and conveyed a collection of opinions about future expandable research into precision gas therapy.

Synthesis and Characterization of Nitric Oxide-Releasing Platinum(IV) Prodrug and Polymeric Micelle Triggered by Light

Herein, we report the proof of concept of photoresponsive chemotherapeutics comprising nitric oxide-releasing platinum prodrugs and polymeric micelles. Photoactivatable nitric oxide-releasing donors were integrated into the axial positions of a platinum(IV) prodrug, and the photolabile hydrophobic groups were grafted in the block copolymers. The hydrophobic interaction between nitric oxide donors and the photolabile groups allowed for the loading of platinum drugs and nitric oxide-releasing donors in the photolabile polymeric micelles. After cellular uptake of micelles, light irradiation induced the release of nitric oxide, which sensitized the cancer cells. Simultaneously, photolabile hydrophobic groups were cleaved from micelles, and the nitric oxide-releasing donor was altered to be more hydrophilic, resulting in the rapid release of platinum(IV) prodrugs. The strategy of using platinum(IV) prodrugs and nitric oxide led to enhanced anticancer effects.

Stimuli-Responsive Nanomedicines for Overcoming Cancer Multidrug Resistance

Chemotherapy is still a main option for cancer therapy, but its efficacy is often unsatisfying due to multidrug resistance (MDR). The tumor microenvironment is considered a dominant factor causing MDR. Stimuli-responsive nanomedicines exhibit many superiorities for reversal of MDR. As smart systems, stimuli-responsive nanomedicines are desirable for achieving site-specific accumulation and triggered drug release in response to slight changes in physicochemical properties in pathological conditions or to exogenous stimuli. In this review, we highlight the current progress of various nanomedicines with different stimuli-responsive capabilities for overcoming MDR. The materials, design, construction as well as efficacy in overcoming MDR of these nanomedicines are discussed. Eventually, we look forward to forthcoming intelligent nanoparticle systems with new mechanisms to deliver drugs for practical applications in conquering cancer MDR.

A novel phosphoester-based cationic co-polymer nanocarrier delivers chimeric antigen receptor plasmid and exhibits anti-tumor effect

Chimeric antigen receptor T cells (CAR-T cells) targeting of CD19 antigen has been proven to be effective and successful in B cell acute lymphoblastic leukemia. The traditional CAR delivery systems have several problems such as poor biosafety, low loading capacity, and low transfection efficiency. Utilization of nanocarriers for CAR delivery offers new possibilities for CAR-T treatment. In the present study, an anti-CD19 CAR expression lentivirus plasmid was constructed for CAR delivery and immunotherapy. In addition, a three-segment amphiphilic co-polymer, methoxy polyethylene glycol-branched polyethyleneimine-poly(2-ethylbutyl phospholane) (mPEG-bPEI-PEBP) was synthesized via click reaction as the carrier with cationic PEI, capable of delivering the CAR and packaging plasmids to co-transfect Jurkat cells and undergo expression. The PEBP and mPEG parts of the co-polymer provide hydrophobic and hydrophilic interfaces and lead to the co-polymer self-assembly into micelles in water and encapsulation of the DNA plasmids. The mPEG-bPEI-PEBP-DNA composites with different N/P ratios were incubated with the CD19 overexpression K562 cells to identify the CAR functions. The obtained CAR-Jurkat cells had the ability to secrete interferon-γ and interleukin-2. The cytotoxic effects to CD19-K562 cells suggest that the induced CAR-Jurkat cells have an excellent targeted antitumor activity.

A three-segment amphiphilic co-polymer mPEG-bPEI-PEBP was synthesized as the nanocarrier with cationic PEI, capable of delivering the CAR and packaging plasmids into Jurkat cells to generate the CAR-T cells for anti-CD19 immunotherapy study.

A simple reduction-sensitive micelles co-delivery of paclitaxel and dasatinib to overcome tumor multidrug resistance

Multidrug resistance (MDR) is one of the major obstacles in successful chemotherapy. The combination of chemotherapy drugs and multidrug-resistant reversing agents for treating MDR tumor is a good strategy to overcome MDR. In this work, we prepared the simple redox-responsive micelles based on mPEG-SS-C18 as a co-delivery system to load the paclitaxel (PTX) and dasatinib (DAS) for treatment of MCF-7/ADR cells. The co-loaded micelles had a good dispersity and a spherical shape with a uniform size distribution, and they could quickly disassemble and rapidly release drugs under the reduction environment. Compared with MCF-7 cells, the DAS and PTX co-loaded redox-sensitive micelle (SS-PDNPs) showed stronger cytotoxicity and a more improving intracellular drug concentration than other drug formulations in MCF-7/ADR cells. In summary, the results suggested that the simple co-delivery micelles of PTX and DAS possessed significant potential to overcome drug resistance in cancer therapy.

Combination of nitric oxide and drug delivery systems: tools for overcoming drug resistance in chemotherapy

Chemotherapeutic drugs have made significant contributions to anticancer therapy, along with other therapeutic methods including surgery and radiotherapy over the past century. However, multidrug resistance (MDR) of cancer cells has remained as a significant obstacle in the achievement of efficient chemotherapy. Recently, there has been increasing evidence for the potential function of nitric oxide (NO) to overcome MDR. NO is an endogenous and biocompatible molecule, contrasting with other potentially toxic chemosensitizing agents that reverse MDR effects, which has raised expectations in the development of efficient therapeutics with low side effects. In particular, nanoparticle-based drug delivery systems not only facilitate the delivery of multiple therapeutic agents, but also help bypass MDR pathways, which are conducive for the efficient delivery of NO and anticancer drugs, simultaneously. Therefore, this review will discuss the mechanism of NO in overcoming MDR and recent progress of combined NO and drug delivery systems.

X-Ray responsive nanoparticles with triggered release of nitrite, a precursor of reactive nitrogen species, for enhanced cancer radiosensitization

Remotely and locally triggered release of therapeutic species by X-ray irradiation is highly desired to enhance the efficacy of radiotherapy. However, the development of such X-ray responsive nanosystems remains a challenge, especially in response to high energy clinically relevant X-ray radiation. Herein, we report novel nitroimidazole ligated gold nanoparticles (AuNPs) that synergistically function to release nitrite, an important precursor for nitric oxide and reactive nitrogen species that sensitize cancer cells, upon radiation with clinically used 6 MeV X-rays, while no release was detected without radiation. These functional AuNPs were prepared with surface-grafted nitroimidazole as the nitrite-releasing agent, cell-penetrating peptide (CPP) to induce nucleus localization, and poly(ethylene glycol) for water solubility. In vitro radiotherapy using such nanoparticles showed enhanced sensitivity of hypoxic cancer cells to X-ray radiation, presumably due to the generation of both reactive oxygen and nitrogen species. The dose modifying factor (DMF) was found to be 0.71 for the dual-functionalized nanoparticle, which indicates that significant lower X-ray doses are required to achieve the same therapeutic effects. Thus, X-ray triggered nitrite release from gold-nitroimidazole nanosystems offers a novel strategy to sensitize cancer cells for improved radiotherapy.

Injectable hydrogels for cartilage and bone tissue engineering

Tissue engineering has become a promising strategy for repairing damaged cartilage and bone tissue. Among the scaffolds for tissue-engineering applications, injectable hydrogels have demonstrated great potential for use as three-dimensional cell culture scaffolds in cartilage and bone tissue engineering, owing to their high water content, similarity to the natural extracellular matrix (ECM), porous framework for cell transplantation and proliferation, minimal invasive properties, and ability to match irregular defects. In this review, we describe the selection of appropriate biomaterials and fabrication methods to prepare novel injectable hydrogels for cartilage and bone tissue engineering. In addition, the biology of cartilage and the bony ECM is also summarized. Finally, future perspectives for injectable hydrogels in cartilage and bone tissue engineering are discussed.

MRI-guided and ultrasound-triggered release of NO by advanced nanomedicine

Nitric oxide (NO) has been well identified as a specific free radical molecule possessing wide-ranging therapeutic effects. Targeted delivery and controlled release of NO are highly desired to realize precision gas therapy, but are still challenging owing to the non-targetability and uncontrollability of NO itself. Herein, we propose a new concept of MRI-guided and ultrasound-triggered gas release for precision gas therapy. Based on this concept, we develop a novel ultrasound-responsive BNN-type NO-releasing molecule (NORM) and an advanced rattle-type nano-carrier of superparamagnetic iron oxide-encapsulated mesoporous silica nanoparticles (SPION@hMSN), and use them to construct a new intelligent nanomedicine (BNN6-SPION@hMSN) for the first time. The BNN6-SPION@hMSN nanomedicine exhibits excellent passive tumor-targeting capability, high MRI-guided tumor localization performance and a unique ultrasound-triggered NO release profile. The tumor-targeted, MRI-guided and ultrasound-triggered release profiles of the developed nanomedicine enable the tumor site-specific controlled release of NO in favor of high-efficacy and safe NO gas therapy of tumor.

Intratumoral H2O2-triggered release of CO from a metal carbonyl-based nanomedicine for efficient CO therapy

H₂O₂-triggered release of CO: an intratumoral H₂O₂-responsive nanomedicine is constructed by effectively encapsulating the hydrophilic manganese carbonyl prodrug into an advanced hollow mesoporous silica nanoparticle carrier to realize selective killing of tumor cells, exhibiting high in vitro and in vivo efficacies of CO gas therapy.

Synthesis of biocompatible polymeric nanomaterial dually loaded with paclitaxel and nitric oxide for anti-MDR cancer therapy

A copolymer nanomedicine mPEG–PEI–PLLA–PTX–NO was synthesized and studied in an OVCAR-8/ADR MDR cancer model.