Supramolecular red-light-photosensitized nitric oxide release with fluorescence self-reporting within biocompatible nanocarriers

The strict dependence of the biological effects of nitric oxide (NO) on its concentration and generation site requires this inorganic free radical to be delivered with precise spatiotemporal control. Light-activation by suitable NO photoprecursors represents an ideal approach. Developing strategies to activate NO release using long-wavelength excitation light in the therapeutic window (650-1300 nm) is challenging. In this contribution, we demonstrate that NO release by a blue-light activatable NO photodonor (NOPD) with self-fluorescence reporting can be triggered catalytically by the much more biocompatible red light exploiting a supramolecular photosensitization process. Different red-light absorbing photosensitizers (PSs) are co-entrapped with the NOPD within different biocompatible nanocarriers such as Pluronic® micelles, microemulsions and branched cyclodextrin polymers. The intra-carrier photosensitized NO release, involving the lowest, long-lived triplet state of the PS as the key intermediate and its quenching by the NOPD, is competitive with that by molecular oxygen. This allows NO to be released with good efficacy, even under aerobic conditions. Therefore, the adopted general strategy provides a valuable tool for generating NO from an already available NOPD, otherwise activatable with the poorly biocompatible blue light, without requiring any chemical modification and using sophisticated and expensive irradiation sources.

Exploring the power of nitric oxide and nanotechnology for prolonging postharvest shelf-life and enhancing fruit quality

Nitric oxide (NO) is a versatile signaling molecule that plays a crucial role in regulating postharvest fruit quality. The utilization of NO donors to elevate endogenous NO levels and induce NO-mediated responses represents a promising strategy for extending fruit shelf-life after harvest. However, the effectiveness of NO treatment is influenced by various factors, including formulation and application methods. In this review, we investigate the impact of NO supply on different fruits, aiming to prolong postharvest shelf-life and enhance fruit quality. Furthermore, we delve into the underlying mechanisms of NO action, particularly its interactions with ethylene and reactive oxygen species (ROS). Excitingly, we also highlight the emerging field of nanotechnology in postharvest applications, discussing the use of nanoparticles as a novel approach for achieving sustained release of NO and enhancing its effects. By harnessing the potential of nanotechnology, our review is a starting point to help identify gaps and future directions in this important, emerging field.

Red-Light-Photosensitized NO Release and Its Monitoring in Cancer Cells with Biodegradable Polymeric Nanoparticles

The role of nitric oxide (NO) as an "unconventional" therapeutic and the strict dependence of biological effects on its concentration require the generation of NO with precise spatiotemporal control. The development of precursors and strategies to activate NO release by excitation in the so-called "therapeutic window" with highly biocompatible and tissue-penetrating red light is desirable and challenging. Herein, we demonstrate that one-photon red-light excitation of Verteporfin, a clinically approved photosensitizer (PS) for photodynamic therapy, activates NO release, in a catalytic fashion, from an otherwise blue-light activatable NO photodonor (NOPD) with an improvement of about 300 nm toward longer and more biocompatible wavelengths. Steady-state and time-resolved spectroscopic and photochemical studies combined with theoretical calculations account for an NO photorelease photosensitized by the lowest triplet state of the PS. In view of biological applications, the water-insoluble PS and NOPD have been co-entrapped within water-dispersible, biodegradable polymeric nanoparticles (NPs) of mPEG-b-PCL (about 84 nm in diameter), where the red-light activation of NO release takes place even more effectively than in an organic solvent solution and almost independently by the presence of oxygen. Moreover, the ideal spectroscopic prerequisites and the restricted environment of the NPs permit the green-fluorescent co-product formed concomitantly to NO photorelease to communicate with the PS via Förster resonance energy transfer. This leads to an enhancement of the typical red emission of the PS offering the possibility of a double color optical reporter useful for the real-time monitoring of the NO release through fluorescence techniques. The suitability of this strategy applied to the polymeric NPs as potential nanotherapeutics was evaluated through biological tests performed by using HepG2 hepatocarcinoma and A375 melanoma cancer cell lines. Fluorescence investigation in cells and cell viability experiments demonstrates the occurrence of the NO release under one-photon red-light illumination also in the biological environment. This confirms that the adopted strategy provides a valuable tool for generating NO from an already available NOPD, otherwise activatable with the poorly biocompatible blue light, without requiring any chemical modification and the use of sophisticated irradiation sources.

Supramolecular Assemblies of Fluorescent Nitric Oxide Photoreleasers with Ultrasmall Cyclodextrin Nanogels

Developing biocompatible nitric oxide (NO) photoreleasing nanoconstucts is of great interest in view of the large variety of biological roles that NO plays and the unique advantage light offers in controlling NO release in space and time. In this contribution, we report the supramolecular assemblies of two NO photodonors (NOPDs), NBF-NO and RHD-NO, as water-dispersible nanogels, ca. 10 nm in diameter, based on γ-cyclodextrins (γ-CDng). These NOPDs, containing amino-nitro-benzofurazan and rhodamine chromophores as light harvesting antennae, can be activated by visible light, are highly hydrophobic and can be effectively entrapped within the γ-CDng. Despite being confined in a very restricted environment, neither NOPD suffer self-aggregation and preserve their photochemical and photophysical properties well. The blue light excitation of the weakly fluorescent γ-CDng/NBF-NO complex results in effective NO release and the concomitant generation of the highly green, fluorescent co-product, which acts as an optical NO reporter. Moreover, the green light excitation of the persistent red fluorescent γ-CDng/RHD-NO triggers NO photorelease without significantly modifying the emission properties. The activatable and persistent fluorescence emissions of the NOPDs are useful for monitoring their interactions with the Gram-positive methicillin-resistant Staphylococcus aureus, whose growth is significantly inhibited by γ-CDng/RHD-NO upon green light irradiation.

Structural insights into the interactions of glutathione transferases with a nitric oxide carrier and sodium nitroprusside

Glutathione transferases are detoxification enzymes with multifaceted roles, including a role in the metabolism and scavenging of nitric oxide (NO) compounds in cells. Here, we explored the ability of Trametes versicolor glutathione transferases (GSTs) from the Omega class (TvGSTOs) to bind metal-nitrosyl compounds. TvGSTOs have been studied previously for their ligandin role and are interesting models to study protein‒ligand interactions. First, we determined the X-ray structure of the TvGSTO3S isoform bound to the dinitrosyl glutathionyl iron complex (DNGIC), a physiological compound involved in the storage of nitric oxide. Our results suggested a different binding mode compared to the one previously described in human GST Pi 1 (GSTP1). Then, we investigated the manner in which TvGSTO3S binds three nonphysiological metal-nitrosyl compounds with different metal cores (iron, ruthenium and osmium). We assayed sodium nitroprusside, a well-studied vasodilator used in cases of hypertensive crises or heart failure. Our results showed that the tested GST can bind metal-nitrosyls at two distinct binding sites. Thermal shift analysis with six isoforms of TvGSTOs identified TvGSTO6S as the best interactant. Using the Griess method, TvGSTO6S was found to improve the release of nitric oxide from sodium nitroprusside in vitro, whereas the effects of human GST alpha 1 (GSTA1) and GSTP1 were moderate. Our results open new structural perspectives for understanding the interactions of glutathione transferases with metal-nitrosyl compounds associated with the biochemical mechanisms of NO uptake/release in biological systems.

Polymeric Amines Induce Nitric Oxide Release from S-Nitrosothiols

Catalytic generation of nitric oxide (NO) from NO donors by nanomaterials has enabled prolonged NO delivery for various biomedical applications, but this approach requires laborious synthesis routes. In this study, a new class of materials, that is, polymeric amines including polyethyleneimine (PEI), poly-L-lysine, and poly(allylamine hydrochloride), is discovered to induce NO generation from S-nitrosothiols (RSNOs) at physiological conditions. Controlled NO generation can be readily achieved by tuning the concentration of the NO donors (RSNOs) and polymers, and the type and molecular weight of the polymers. Importantly, the mechanism of NO generation by these polymers is deciphered to be attributed to the nucleophilic reaction between primary amines on polymers and the SNO groups of RSNOs. The NO-releasing feature of the polymers can be integrated into a suite of materials, for example, simply by embedding PEI into poly(vinyl alcohol) (PVA) hydrogels. The functionality of the PVA/PEI hydrogels is demonstrated for Pseudomonas aeruginosa biofilm prevention with a ≈4 log reduction within 6 h. As NO has potential therapeutic implications in various diseases, the identification of polymeric amines to induce NO release will open new opportunities in NO-generating biomaterials for antibacterial, antiviral, anticancer, antithrombotic, and wound healing applications.

Evaluation of an Imine-Linked Polymer Organic Framework for Storage and Release of H2S and NO

Hydrogen sulfide (H₂S) and nitric oxide (NO) are especially known as toxic and polluting gases, yet they are also endogenously produced and play key roles in numerous biological processes. These two opposing aspects of the gases highlight the need for new types of materials to be developed in addition to the most common materials such as activated carbons and zeolites. Herein, a new imine-linked polymer organic framework was obtained using the inexpensive and easy-to-access reagents isophthalaldehyde and 2,4,6-triaminopyrimidine in good yield (64%) through the simple and catalyst-free Schiff-base reaction. The polymeric material has microporosity, an A_BET surface area of 51 m²/g, and temperature stability up to 300 °C. The obtained 2,4,6-triaminopyrimidine imine-linked polymer organic material has a higher capacity to adsorb NO (1.6 mmol/g) than H₂S (0.97 mmol/g). Release studies in aqueous solution showed that H₂S has a faster release (3 h) from the material than NO, for which a steady release was observed for at least 5 h. This result is the first evaluation of the possibility of an imine-linked polymer organic framework being used in the therapeutic release of NO or H₂S.

Heavy metal toxicity in plants and the potential NO-releasing novel techniques as the impending mitigation alternatives

Environmental pollutants like heavy metals are toxic, persistent, and bioaccumulative in nature. Contamination of agricultural fields with heavy metals not only hampers the quality and yield of crops but also poses a serious threat to human health by entering the food chain. Plants generally cope with heavy metal stress by regulating their redox machinery. In this context, nitric oxide (NO) plays a potent role in combating heavy metal toxicity in plants. Studies have shown that the exogenous application of NO donors protects plants against the deleterious effects of heavy metals by enhancing their antioxidative defense system. Most of the studies have used sodium nitroprusside (SNP) as a NO donor for combating heavy metal stress despite the associated concerns related to cyanide release. Recently, NO-releasing nanoparticles have been tested for their efficacy in a few plants and other biomedical research applications suggesting their use as an alternative to chemical NO donors with the advantage of safe, slow and prolonged release of NO. This suggests that they may also serve as potential candidates in mitigating heavy metal stress in plants. Therefore, this review presents the role of NO, the application of chemical NO donors, potential advantages of NO-releasing nanoparticles, and other NO-release strategies in biomedical research that may be useful in mitigating heavy metal stress in plants.

Nanostructured Organosilica Nitric Oxide Donors Intrinsically Regulate Macrophage Polarization with Antitumor Effect

Nitric oxide (NO) has many important biological functions; however, it has been a long-standing challenge to utilize the exogenous NO donor itself in the activation of macrophages for cancer immunotherapy. Herein, we report the synthesis of a nanoparticle-based NO delivery platform with a rational design for effective NO delivery and macrophage activation. S-Nitrosothiol (SNO) modified organosilica nanoparticles with a tetrasulfide-containing composition produced a higher level of intracellular NO than their bare silica counterparts in macrophages. Enhanced intracellular delivery of NO resulted in mitochondrial dysfunction and disruption of the tricarboxylic acid cycle, leading to macrophage activation and delayed tumor growth. This study provides insights on intracellularly delivered NO for regulating the polarization of macrophages and cancer immunotherapy.

Enhanced treatment of cerebral ischemia-Reperfusion injury by intelligent nanocarriers through the regulation of neurovascular units

Reperfusion injury is one of the major causes of disability and death caused by ischemic stroke, and drug development focuses mainly on single neuron protection. However, different kinds of cells in the neurovascular units (NVUs), including neurons, microglia and vascular endothelial cells, are pathologically changed after cerebral ischemia-reperfusion injury, resulting in an urgent need to develop a drug delivery system to comprehensively protect the kinds of cells involved in the NVU. Herein, we have constructed a c(RGDyK) peptide modified, NF-κB inhibitor caffeic acid phenethyl ester (CAPE)-loaded and reactive nitrogen species (RNS) stimuli-responsive liposomal nanocarrier (R-Lipo-CAPE) to target ischemic lesions and then remodel the NVU to reduce the progression of cerebral ischemia-reperfusion injury. The R-Lipo-CAPE liposomes were approximately 170 nm with a zeta potential of -30.8 ± 0.2 mV. The in vitro CAPE release behavior from R-Lipo-CAPE showed an RNS-dependent pattern. For in vivo studies, transient middle cerebral artery occlusion/reperfusion (MCAO) model mice treated with R-Lipo-CAPE had the least neurological impairment and decreased brain tissue damage, with an infarct area of 13%, compared with those treated with saline of 53% or free CAPE of 38%. Furthermore, microglia in the ischemic brain were polarized to the tissue-repairing M2 phenotype after R-Lipo-CAPE treatment. In addition, R-Lipo-CAPE-treated mice displayed a prominent down-regulated expression of MMP-9 and restored expression of the tight junction protein claudin-5. This proof-of-concept indicates that R-Lipo-CAPE is a promising nanomedicine for the treatment of cerebral ischemia-reperfusion injury through the regulation of neurovascular units. STATEMENT OF SIGNIFICANCE: Based on the complex mechanism and difficulty in treatment of cerebral ischemia-reperfusion injury, the overall regulation of neurovascular unit has become an extremely important target. However, little nanomedicine has been directed to remodel the neurovascular units in targeted cerebral ischemia-reperfusion injury therapy. Here, c(RGDyK) peptide modified reactive nitrogen species (RNS) stimuli-responsive liposomal nanocarrier loaded with a NF-κB inhibitor (CAPE), was designed to simultaneously regulate various cells in the microenvironment of cerebral ischemia-reperfusion injury to remodel the neurovascular units. Our in vitro and in vivo data showed that the intelligent nanocarrier exerted the ability of pathological signal stimuli-responsive drug release, cerebral ischemia-reperfusion injury site targeting and neurovascular units remodeling through reducing neuron apoptosis, regulating microglia polarization and repairing vascular endothelial cell. Overall, the intelligent liposomal drug delivery system was a promising and safe nanomedicine in the perspective of cerebral ischemia-reperfusion injury treatment.

Nitric oxide-releasing nanomaterials: from basic research to potential biotechnological applications in agriculture

Nitric oxide (NO) is a multifunctional gaseous signal that modulates the growth, development and stress tolerance of higher plants. NO donors have been used to boost plant endogenous NO levels and to activate NO-related responses, but this strategy is often hindered by the relative instability of donors. Alternatively, nanoscience offers a new, promising way to enhance NO delivery to plants, as NO-releasing nanomaterials (e.g. S-nitrosothiol-containing chitosan nanoparticles) have many beneficial physicochemical and biochemical properties compared to non-encapsulated NO donors. Nano NO donors are effective in increasing tissue NO levels and enhancing NO effects both in animal and human systems. The authors believe, and would like to emphasize, that new trends and technologies are essential for advancing plant NO research and nanotechnology may represent a breakthrough in traditional agriculture and environmental science. Herein, we aim to draw the attention of the scientific community to the potential of NO-releasing nanomaterials in both basic and applied plant research as alternatives to conventional NO donors, providing a brief overview of the current knowledge and identifying future research directions. We also express our opinion about the challenges for the application of nano NO donors, such as the environmental footprint and stakeholder's acceptance of these materials.

Nitric oxide-releasing biomaterials for promoting wound healing in impaired diabetic wounds: State of the art and recent trends

Impaired diabetic wounds are serious pathophysiological complications associated with persistent microbial infections including failure in the closure of wounds, and the cause of a high frequency of lower limb amputations. The healing of diabetic wounds is attenuated due to the lack of secretion of growth factors, prolonged inflammation, and/or inhibition of angiogenic activity. Diabetic wound healing can be enhanced by supplying nitric oxide (NO) endogenously or exogenously. NO produced inside the cells by endothelial nitric oxide synthase (eNOS) naturally aids wound healing through its beneficial vasculogenic effects. However, during hyperglycemia, the activity of eNOS is affected, and thus there becomes an utmost need for the topical supply of NO from exogenous sources. Thus, NO-donors that can release NO are loaded into wound healing patches or wound coverage matrices to treat diabetic wounds. The burst release of NO from its donors is prevented by encapsulating them in polymeric hydrogels or nanoparticles for supplying NO for an extended duration of time to the diabetic wounds. In this article, we review the etiology of diabetic wounds, wound healing strategies, and the role of NO in the wound healing process. We further discuss the challenges faced in translating NO-donors as a clinically viable nanomedicine strategy for the treatment of diabetic wounds with a focus on the use of biomaterials for the encapsulation and in vivo controlled delivery of NO-donors.

Nitric Oxide Release and Antibacterial Efficacy Analyses of S-Nitroso-N-Acetyl-Penicillamine Conjugated to Titanium Dioxide Nanoparticles

Therapeutic agents can be linked to nanoparticles to fortify their selectivity and targeted delivery while impeding systemic toxicity and efficacy loss. Titanium dioxide nanoparticles (TiNPs) owe their rise in biomedical sciences to their versatile applicability, although the lack of inherent antibacterial properties limits its application and necessitates the addition of bactericidal agents along with TiNPs. Structural modifications can improve TiNP's antibacterial impact. The antibacterial efficacy of nitric oxide (NO) against a broad spectrum of bacterial strains is well established. For the first time, S-nitroso-N-acetylpenicillamine (SNAP), an NO donor molecule, was covalently immobilized on TiNPs to form the NO-releasing TiNP-SNAP nanoparticles. The TiNPs were silanized with 3-aminopropyl triethoxysilane, and N-acetyl-d-penicillamine was grafted to them via an amide bond. The nitrosation was carried out by t-butyl nitrite to conjugate the NO-rich SNAP moiety to the surface. The total NO immobilization was measured to be 127.55 ± 4.68 nmol mg^-1 using the gold standard chemiluminescence NO analyzer. The NO payload can be released from the TiNP-SNAP under physiological conditions for up to 20 h. The TiNP-SNAP exhibited a concentration-dependent antimicrobial efficiency. At 5 mg mL^-1, more than 99.99 and 99.70% reduction in viable Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria, respectively, were observed. No significant cytotoxicity was observed against 3T3 mouse fibroblast cells at all the test concentrations determined by the CCK-8 assay. TiNP-SNAP is a promising and versatile nanoparticle that can significantly impact the usage of TiNPs in a wide variety of applications, such as biomaterial coatings, tissue engineering scaffolds, or wound dressings.

Nitric oxide-releasing polyurethane/S-nitrosated keratin mats for accelerating wound healing

Nitric oxide (NO) plays an important role in wound healing, due to its ability to contract wound surfaces, dilate blood vessels, participate in inflammation as well as promote collagen synthesis, angiogenesis and fibroblast proliferation. Herein, keratin was first nitrosated to afford S-nitrosated keratin (KSNO). As a NO donor, KSNO was then co-electrospun with polyurethane (PU). These as-spun PU/KSNO biocomposite mats could release NO sustainably for 72 h, matching the renewal time of the wound dressing. Moreover, these mats exhibited excellent cytocompatibility with good cell adhesion and cell migration. Further, the biocomposite mats exhibited antibacterial properties without inducing severe inflammatory responses. The wound repair in vivo demonstrated that these mats accelerated wound healing by promoting tissue formation, collagen deposition, cell migration, re-epithelialization and angiogenesis. Overall, PU/KSNO mats may be promising candidates for wound dressing.

Zinc-Based Metal-Organic Frameworks in Drug Delivery, Cell Imaging, and Sensing

The design and structural frameworks for targeted drug delivery of medicinal compounds and improved cell imaging have been developed with several advantages. However, metal-organic frameworks (MOFs) are supplemented tremendously for medical uses with efficient efficacy. These MOFs are considered as an absolutely new class of porous materials, extensively used in drug delivery systems, cell imaging, and detecting the analytes, especially for cancer biomarkers, due to their excellent biocompatibility, easy functionalization, high storage capacity, and excellent biodegradability. While Zn-metal centers in MOFs have been found by enhanced efficient detection and improved drug delivery, these Zn-based MOFs have appeared to be safe as elucidated by different cytotoxicity assays for targeted drug delivery. On the other hand, the MOF-based heterogeneous catalyst is durable and can regenerate multiple times without losing activity. Therefore, as functional carriers for drug delivery, cell imaging, and chemosensory, MOFs' chemical composition and flexible porous structure allowed engineering to improve their medical formulation and functionality. This review summarizes the methodology for fabricating ultrasensitive and selective Zn-MOF-based sensors, as well as their application in early cancer diagnosis and therapy. This review also offers a systematic approach to understanding the development of MOFs as efficient drug carriers and provides new insights on their applications and limitations in utility with possible solutions.

The Biologically Relevant Coordination Chemistry of Iron and Nitric Oxide: Electronic Structure and Reactivity

Nitric oxide (NO) is an important signaling molecule that is involved in a wide range of physiological and pathological events in biology. Metal coordination chemistry, especially with iron, is at the heart of many biological transformations involving NO. A series of heme proteins, nitric oxide synthases (NOS), soluble guanylate cyclase (sGC), and nitrophorins, are responsible for the biosynthesis, sensing, and transport of NO. Alternatively, NO can be generated from nitrite by heme- and copper-containing nitrite reductases (NIRs). The NO-bearing small molecules such as nitrosothiols and dinitrosyl iron complexes (DNICs) can serve as an alternative vehicle for NO storage and transport. Once NO is formed, the rich reaction chemistry of NO leads to a wide variety of biological activities including reduction of NO by heme or non-heme iron-containing NO reductases and protein post-translational modifications by DNICs. Much of our understanding of the reactivity of metal sites in biology with NO and the mechanisms of these transformations has come from the elucidation of the geometric and electronic structures and chemical reactivity of synthetic model systems, in synergy with biochemical and biophysical studies on the relevant proteins themselves. This review focuses on recent advancements from studies on proteins and model complexes that not only have improved our understanding of the biological roles of NO but also have provided foundations for biomedical research and for bio-inspired catalyst design in energy science.

Coacervate microdroplet protocell-mediated gene transfection for nitric oxide production and induction of cell apoptosis

Liquid coacervate microdroplets have been widely explored as membrane-free compartment protocells for cargo delivery in therapeutic applications. In this study, coacervate protocells were developed as gene carriers for transfection of nitric oxide synthase (NOS) and overproduction of nitric oxide (NO) for killing of cancer cells. The coacervate microdroplet protocells were formed via the liquid-liquid phase separation of oppositely charged diethylaminoethyl-dextran/polyacrylic acids. The coacervate microdroplet protocells were found to facilitate gene transfection, which was demonstrated by cell imaging of the internalized coacervate microdroplets containing plasmids of enhanced green fluorescent protein. Due to their high transfection capability, the coacervate protocells were subsequently utilized for the delivery of NOS plasmids (pNOS). The cellular internalization of pNOS-containing coacervate carriers was found to result in high NOS expression coupled with NO overproduction, which then induced cell apoptosis and decreased cell viability. The cell apoptosis is associated with NO-mediated mitochondrial damage. The enhanced gene transfection was attributed to coacervate microdroplets' unique high sequestration capability and liquid-like fluidity. Overall, the incorporation of genes in coacervate microdroplets was demonstrated as a viable and novel strategy for the development of cargo biocarriers for biomedical applications.

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.

Light-Activated Biodegradable Covalent Organic Framework-Integrated Heterojunction for Photodynamic, Photothermal, and Gaseous Therapy of Chronic Wound Infection

Chronic wound healing, impeded by bacterial infections and drug resistance, poses a threat to global human health. Antibacterial phototherapy is an effective way to fight microbial infection without causing drug resistance. Covalent organic frameworks (COFs) are a class of highly crystalline functional porous carbon-based materials composed of light atoms (e.g., carbon, nitrogen, oxygen, and borane), showing potential applications in the biomedical field. Herein, we constructed porphyrin-based COF nanosheets (TP-Por CON) for synergizing photodynamic and photothermal therapy under red light irradiation (e.g., 635 nm). Moreover, a nitric oxide (NO) donor molecule, BNN6, was encapsulated into the pore volume of the crystalline porous framework structure to moderately release NO triggered by red light irradiation for realizing gaseous therapy. Therefore, we successfully synthesized a novel TP-Por CON@BNN6-integrated heterojunction for thoroughly killing Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus in vitro. Our research identified that TP-Por CON@BNN6 has favorable biocompatibility and biodegradability, low phototoxicity, anti-inflammatory properties, and excellent mice wound healing ability in vivo. This study indicates that the TP-Por CON@BNN6-integrated heterojunction with multifunctional properties provides a potential strategy for COF-based gaseous therapy and microorganism-infected chronic wound healing.

Development of Antimicrobial Nitric Oxide-Releasing Fibers

Nitric oxide (NO) is a highly reactive gas molecule, exhibiting antimicrobial properties. Because of its reactive nature, it is challenging to store and deliver NO efficiently as a therapeutic agent. The objective of this study was to develop NO-releasing polymeric fibers (NO-fibers), as an effective delivery platform for NO. NO-fibers were fabricated with biopolymer solutions of polyvinyl pyrrolidone (PVP) and ethylcellulose (EC), and derivatives of N-diazeniumdiolate (NONOate) as NO donor molecules, using an electrospinning system. We evaluated in vitro NO release kinetics, along with antimicrobial effects and cytotoxicity in microorganisms and human cell culture models. We also studied the long-term stability of NONOates in NO-fibers over 12 months. We demonstrated that the NO-fibers could release NO over 24 h, and showed inhibition of the growth of Pseudomonas aeruginosa (P. aeruginosa) and methicillin-resistant Staphylococcus aureus (MRSA), without causing cytotoxicity in human cells. NO-fibers were able to store NONOates for over 12 months at room temperature. This study presents the development of NO-fibers, and the feasibility of NO-fibers to efficiently store and deliver NO, which can be further developed as a bandage.

Green Synthesized Metal Oxide Nanoparticles Mediate Growth Regulation and Physiology of Crop Plants under Drought Stress

Metal oxide nanoparticles (MONPs) are regarded as critical tools for overcoming ongoing and prospective crop productivity challenges. MONPs with distinct physiochemical characteristics boost crop production and resistance to abiotic stresses such as drought. They have recently been used to improve plant growth, physiology, and yield of a variety of crops grown in drought-stressed settings. Additionally, they mitigate drought-induced reactive oxygen species (ROS) through the aggregation of osmolytes, which results in enhanced osmotic adaptation and crop water balance. These roles of MONPs are based on their physicochemical and biological features, foliar application method, and the applied MONPs concentrations. In this review, we focused on three important metal oxide nanoparticles that are widely used in agriculture: titanium dioxide (TiO2), zinc oxide (ZnO), and iron oxide (Fe3O4). The impacts of various MONPs forms, features, and dosages on plant growth and development under drought stress are summarized and discussed. Overall, this review will contribute to our present understanding of MONPs' effects on plants in alleviating drought stress in crop plants.

Potential Use of DMSA-Containing Iron Oxide Nanoparticles as Magnetic Vehicles against the COVID-19 Disease

Iron oxide magnetic nanoparticles have been employed as potential vehicles for a large number of biomedical applications, such as drug delivery. This article describes the synthesis, characterization and in vitro cytotoxic in COVID-19 cells evaluation of DMSA superparamagnetic iron oxide magnetic nanoparticles. Magnetite (Fe3O4) nanoparticles were synthesized by co-precipitation of iron salts and coated with meso-2,3-dimercaptosuccinic acid (DMSA) molecule. Structural and morphological characterizations were performed by X-ray diffraction (XRD), Fourier transformed infrared (FT-IR), magnetic measurements (SQUID), transmission electron microscopy (TEM), and dynamic light scattering (DLS). Our results demonstrate that the nanoparticles have a mean diameter of 12 nm in the solid-state and are superparamagnetic at room temperature. There is no toxicity of SPIONS-DMSA under the cells of patients with COVID-19. Taken together the results show that DMSA- Fe3O4 are good candidates as nanocarriers in the alternative treatment of studied cells.

Nitric oxide-releasing micelles with intelligent targeting for enhanced anti-tumor effect of cisplatin in hypoxia

Background

Hypoxic tumor microenvironment (TME) promotes tumor metastasis and drug resistance, leading to low efficiency of cancer chemotherapy. The development of targeted agents or multi-target therapies regulating hypoxic microenvironment is an important approach to overcome drug resistance and metastasis.

Methods

In this study, chitosan oligosaccharide (COS)-coated and sialic acid (SA) receptor-targeted nano-micelles were prepared using film dispersion method to co-deliver cisplatin (CDDP) and nitric oxide (NO) (denoted as CTP/CDDP). In addition, we explored the mechanisms by which NO reversed CDDP resistance as well as enhanced anti-metastatic efficacy in hypoxic cancer cells.

Results

Because of the different affinities of COS and SA to phenylboronic acid (PBA) under different pH regimes, CTP/CDDP micelles with intelligent targeting property increased cellular uptake of CDDP and enhanced cytotoxicity to tumors, but reduced systemic toxicity to normal organs or tissues. In addition, CTP/CDDP showed stimulus-responsive release in TME. In terms of anti-tumor mechanism, CTP/CDDP reduced CDDP efflux and inhibited epithelial-mesenchymal transition (EMT) process of tumor by down-regulating hypoxia-inducible factor-1α (HIF-1α), glutathione (GSH), multidrug resistance-associated protein 2 (MRP2) and matrix metalloproteinase 9 (MMP9) expression, thus reversing drug resistance and metastasis of hypoxic tumor cells.

Conclusions

The designed micelles significantly enhanced anti-tumor effects both in vitro and in vivo. These results suggested that CTP/CDDP represented a promising strategy to treat resistance and metastatic tumors.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-00989-z.

Enhanced NO-induced angiogenesis via NO/H2S co-delivery from self-assembled nanoparticles

Nitric oxide (NO) and hydrogen sulfide (H2S) have been the focus of research as therapeutic agents because of their biological functions. The controlled release of NO and H2S can enhance NO-induced angiogenesis by H2S inhibiting PDE5A. Polymeric carriers have been researched to deliver gasotransmitters and used as therapeutic agents because of their important ability to help control the concentration of NO and H2S. Here, NO/H2S-releasing nanoparticles were self-assembled from carboxyl-functionalized mPEG-PLGH-thiobenzamide [(methoxy poly (ethylene glycol-b-lactic-co-glycolic-co-hydroxymethyl propionic acid)-thiobenzamide)], PTA copolymer and encapsulated diethylenetriamine NONOate (DETA NONOate). The PTA copolymers were characterized by FT-IR and 1H NMR, and the PTA-NO nanoparticles (PTA-NO-NPs) were confirmed to have core-shell structures with a size of about 140 nm. The PTA-NO-NPs were demonstrated to be biocompatible with viabilities above 100% in various cell types, with a sustained NO and H2S releasing behavior over 72 h. Co-releasing NO and H2S accelerated tube formation by HUVECs compared to the only NO- or H2S-releasing groups in vitro. Also, PTA-NO-NPs performed enhanced angiogenesis compared to the control groups with statistically significant differences ex vivo. These results indicate the feasibility of medical applications through NO and H2S crosstalk.

Nitric Oxide Photoreleasers with Fluorescent Reporting

Nitric oxide (NO) plays a multifaceted role in human physiology and pathophysiology, and its controlled delivery has great prospects in therapeutic applications. The light-activated uncaging of NO from NO caging compounds allows this free radical to be released with accurate control of site and dosage, which strictly determine its biological effects. Molecular constructs able to activate fluorescence concomitantly to NO release offer the important advantage of easy and real-time tracking of the amount of NO uncaged in a non-invasive fashion even in the cell environment. This contribution provides an overview of the advances in photoactivatable NO releasers bearing fluorescent reporting functionalities achieved in our and other laboratories, highlighting the rationale design and their potential therapeutic applications.

Tumor-Penetrable Nitric Oxide-Releasing Nanoparticles Potentiate Local Antimelanoma Therapy

Although nitric oxide (NO) has been emerging as a novel local anticancer agent because of its potent cytotoxic effects and lack of off-target side effects, its clinical applications remain a challenge because of the short effective diffusion distance of NO that limits its anticancer activity. In this study, we synthesized albumin-coated poly(lactic-co-glycolic acid) (PLGA)-conjugated linear polyethylenimine diazeniumdiolate (LP/NO) nanoparticles (Alb-PLP/NO NPs) that possess tumor-penetrating and NO-releasing properties for an effective local treatment of melanoma. Sufficient NO-loading and prolonged NO-releasing characteristics of Alb-PLP/NO NPs were acquired through PLGA-conjugated LP/NO copolymer (PLP/NO) synthesis, followed by nanoparticle fabrication. In addition, tumor penetration ability was rendered by the electrostatic adsorption of the albumin on the surface of the nanoparticles. The Alb-PLP/NO NPs showed enhanced intracellular NO delivery efficiency and cytotoxicity to B16F10 murine melanoma cells. In B16F10-tumor-bearing mice, the Alb-PLP/NO NPs showed improved extracellular matrix penetration and spatial distribution in the tumor tissue after intratumoral injection, resulting in enhanced antitumor activity. Taken together, the results suggest that Alb-PLP/NO NPs represent a promising new modality for the local treatment of melanoma.

Nitric oxide releasing halloysite nanotubes for biomedical applications

Halloysite nanotubes (HNTs) are natural aluminosilicate clay that have been extensivelyexplored fordelivery of bioactive agents in biomedical applications because of their desirable features including unique hollow tubular structure, good biocompatibility, high mechanical strength, and extensive functionality. For the first time, in this work, functionalized HNTs are developed as a delivery platform for nitric oxide (NO), a gaseous molecule, known for its important roles in the regulation of various physiological processes. HNTs were first hydroxylated and modified with an aminosilane crosslinker, (3-aminopropyl) trimethoxysilane (APTMS), to enable the covalent attachment of a NO donor precursor, N-acetyl-d-penicillamine (NAP). HNT-NAP particles were then converted to NO-releasing S-nitroso-N-acetyl-penicillamine HNT-SNAP by nitrosation. The total NO loading on the resulting nanotubes was 0.10 ± 0.07 μmol/mg which could be released using different stimuli such as heat and light. Qualitative (Fourier-transform infrared spectroscopy and Nuclear magnetic resonance) and quantitative (Ninhydrin and Ellman) analyses were performed to confirm successful functionalization of HNTs at each step. Field emission scanning electron microscopy (FE-SEM) showed that the hollow tubular morphology of the HNTs was preserved after modification. HNT-SNAP showed concentration-dependent antibacterial effects against Gram-positive Staphylococcus aureus (S. aureus), resulting in up to 99.6% killing efficiency at a concentration of 10 mg/mL as compared to the control. Moreover, no significant cytotoxicity toward 3T3 mouse fibroblast cells was observed at concentrations equal or below 2 mg/mL of HNT-SNAP according to a WST-8-based cytotoxicity assay. The SNAP-functionalized HNTs represent a novel and efficient NO delivery system that holds the potential to be used, either alone or in combination with polymers for different biomedical applications.

Enhanced luminescence intensity of near-infrared-sensitized upconversion nanoparticles via Ca2+ doping for a nitric oxide release platform

Light-induced NO release based on exogenous NO donors has attracted substantial attention in clinical applications; the induction light source usually converts near-infrared light to blue or ultraviolet light. However, the low efficiency of near-infrared light-assisted chemical light energy conversion remains a challenge, especially for NaYF4:Yb3+/Tm3+ photoconverting near-infrared light to ultraviolet (UV) and blue light. In this paper, a luminescence-enhanced strategy is reported by doping Ca2+ into NaYF4:Yb3+/Tm3+ and coating it with NaGdF4 through a two-step solvothermal method. Then, UCNPs modified with methyl-β-cyclodextrin (M-β-CD) are loaded on a ruthenium nitrosyl complex [(3)Ru(NO)(Cl)] as nitric oxide release-molecules (NORMs). X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS) data demonstrated that Ca2+ was successfully doped into NaYF4:Yb3+/Tm3+ nanoparticles as the core, and a pure hexagonal phase, NaYF4, was obtained from the doping of Ca2+. TEM revealed that the crystallinity was significantly improved after Ca2+ doping, and the core-shell structure was successfully synthesized, with NaGdF4 directionally grown on the NaYF4:Ca/Yb/Tm core. Fluorescence tests showed that, especially in the ultraviolet and blue light excitation wavelength regions, the UC emission intensity of the Ca-doped NaYF4:Yb3+/Tm3+@NaGdF4 core-shell UCNPs increased by 302.95 times vs. NaYF4:Yb3+/Tm3+ UCNPs. Finally, the release of NO was tested by the Griess method. Under 980 nm irradiation, the cell viability distinctly decreased with increasing UCNPs@M-β-CD-NORMs concentration. This study shows that NORM release of NO is triggered by enhanced up-converted UV and blue light, which can be used for the development of UV photo-sensitive drugs.

Highly hydrophobic polytetrafluoroethylene particle immobilization via polydopamine anchor layer on nitric oxide releasing polymer for biomedical applications

Biomedical surface-associated infections and thrombus formation are two major clinical issues that challenge patient safety and patient the fate of a medical device in the body . Single platform multifunctional surfaces are critical to address both these indwelling medical device-related problems. In this work, bio-inspired approaches are employed to fabricate a polymer composite with a versatile surface that can reduce bacterial infections and platelet adhesion in vitro. In the first bio-inspired approach, the functionality of nitric oxide (NO) produced by endothelial cell lining of blood vessels is mimicked through incorporation of S-nitroso-N-acetylpenicillamine (SNAP) within a CarboSil-2080A™ (CarboSil) polymer composite matrix. The second approach involves utilizing mussel adhesive chemistry, via polydopamine (PDA) to immobilize polytetrafluoroethylene (PTFE) particles on the polymer composite surface. The PTFE coating facilitates a decrease in wettability by making the polymer composite surface highly hydrophobic (contact angle ca. 120°). The surface of the fabricated polymer composite , CarboSil SNAP-PTFE, had a cobblestone-like structured appearance as characterized through scanning electron microscopy (SEM). Water contact angle (WCA) and surface tension measurements indicated no significant coating losses after 24 h under physiological conditions. NO surface flux was measured and analyzed for 5 days using a chemiluminescence-based nitric oxide analyzer and was found to be within the physiological range. CarboSil SNAP-PTFE reduced adhered bacteria (99.3 ± 0.5% for Gram-positive S. aureus and 99.1 ± 0.4% for Gram-negative E. coli) in a 24 h in vitro study. SEM analysis showed the absence of biofilm formation on CarboSil SNAP-PTFE polymer composites, while present on CarboSil in 24 h exposure to S. aureus. Platelet adhesion was reduced by 83.3 ± 4.5%. Overall, the results of this study suggest that a combination of NO-releasing CarboSil with PTFE coating can drastically reduce infection and platelet adhesion.

Nitric oxide and viral infection: Recent developments in antiviral therapies and platforms

Nitric oxide (NO) is a gasotransmitter of great significance to developing the innate immune response to many bacterial and viral infections, while also modulating vascular physiology. The generation of NO from the upregulation of endogenous nitric oxide synthases serves as an efficacious method for inhibiting viral replication in host defense and warrants investigation for the development of antiviral therapeutics. With increased incidence of global pandemics concerning several respiratory-based viral infections, it is necessary to develop broad therapeutic platforms for inhibiting viral replication and enabling more efficient host clearance, as well as to fabricate new materials for deterring viral transmission from medical devices. Recent developments in creating stabilized NO donor compounds and their incorporation into macromolecular scaffolds and polymeric substrates has created a new paradigm for developing NO-based therapeutics for long-term NO release in applications for bactericidal and blood-contacting surfaces. Despite this abundance of research, there has been little consideration of NO-releasing scaffolds and substrates for reducing passive transmission of viral infections or for treating several respiratory viral infections. The aim of this review is to highlight the recent advances in developing gaseous NO, NO prodrugs, and NO donor compounds for antiviral therapies; discuss the limitations of NO as an antiviral agent; and outline future prospects for guiding materials design of a next generation of NO-releasing antiviral platforms.

Influence of the capping of biogenic silver nanoparticles on their toxicity and mechanism of action towards Sclerotinia sclerotiorum

BACKGROUND

Biogenic nanoparticles possess a capping of biomolecules derived from the organism employed in the synthesis, which contributes to their stability and biological activity. These nanoparticles have been highlighted for the control of phytopathogens, so there is a need to understand their composition, mechanisms of action, and toxicity. This study aimed to investigate the importance of the capping and compare the effects of capped and uncapped biogenic silver nanoparticles synthesized using the filtrate of Trichoderma harzianum against the phytopathogenic fungus Sclerotinia sclerotiorum. Capping removal, investigation of the composition of the capping and physico-chemical characterization of the capped and uncapped nanoparticles were performed. The effects of the nanoparticles on S. sclerotiorum were evaluated in vitro. Cytotoxicity and genotoxicity of the nanoparticles on different cell lines and its effects on nontarget microorganisms were also investigated.

RESULTS

The capped and uncapped nanoparticles showed spherical morphology, with greater diameter of the uncapped ones. Functional groups of biomolecules, protein bands and the hydrolytic enzymes NAGase, β-1,3-glucanase, chitinase and acid protease from T. harzianum were detected in the capping. The capped nanoparticles showed great inhibitory potential against S. sclerotiorum, while the uncapped nanoparticles were ineffective. There was no difference in cytotoxicity comparing capped and uncapped nanoparticles, however higher genotoxicity of the uncapped nanoparticles was observed towards the cell lines. Regarding the effects on nontarget microorganisms, in the minimal inhibitory concentration assay only the capped nanoparticles inhibited microorganisms of agricultural importance, while in the molecular analysis of the soil microbiota there were major changes in the soils exposed to the uncapped nanoparticles.

CONCLUSIONS

The results suggest that the capping played an important role in controlling nanoparticle size and contributed to the biological activity of the nanoparticles against S. sclerotiorum. This study opens perspectives for investigations concerning the application of these nanoparticles for the control of phytopathogens.

Polymeric Nitric Oxide Delivery Nanoplatforms for Treating Cancer, Cardiovascular Diseases, and Infection

The shortened Abstract is as follows: Therapeutic gas nitric oxide (NO) has demonstrated the unique advances in biomedical applications due to its prominent role in regulating physiological/pathophysiological activities in terms of vasodilation, angiogenesis, chemosensitizing effect, and bactericidal effect. However, it is challenging to deliver NO, due to its short half-life (<5 s) and short diffusion distances (20-160 µm). To address these, various polymeric NO delivery nanoplatforms (PNODNPs) have been developed for cancer therapy, antimicrobial and cardiovascular therapeutics, because of the important advantages of polymeric delivery nanoplatforms in terms of controlled release of therapeutics and the extremely versatile nature. This reviews highlights the recent significant advances made in PNODNPs for NO storing and targeting delivery. The ideal and unique criteria that are required for PNODNPs for treating cancer, cardiovascular diseases and infection, respectively, are summarized. Hopefully, effective storage and targeted delivery of NO in a controlled manner using PNODNPs could pave the way for NO-sensitized synergistic therapy in clinical practice for treating the leading death-causing diseases.

Visible light-responsive micelles enable co-delivery of nitric oxide and antibiotics for synergistic antibiofilm applications

Tetraphenylethylene (TPE) moieties have been employed as a light-absorbing antenna for the activation of photoresponsive N-nitrosamine derivatives, enabling visible light-triggered NO release and efficient biofilm dispersal.

Visible light-activatable cyclodextrin-conjugates for the efficient delivery of nitric oxide with fluorescent reporter and their inclusion complexes with betaxolol

Water-soluble β-CD conjugates release NO with high performances with blue and green light, liberate a fluorescent co-products useful for the real-time monitoring of the NO concentration and encapsulate additional guests within the hydrophobic cavity.

Advances in inorganic-based colloidal nanovehicles functionalized for nitric oxide delivery

Nitric oxide (NO) is an important pharmaceutical agent of considerable therapeutic interest ascribed to its vasodilative, tumoricidal and antibacterial effects. Rapid development of functional nanomaterials has provided opportunities for us to achieve controllable exogenous delivery of NO. In the current review, a variety of functionalized colloidal nanovehicles that have been developed to date for nitric oxide delivery are reported. Specifically, we focus on inorganic nanomaterials such as semiconductor quantum dots, silica nanoparticles, upconversion nanomaterials, carbon/graphene nanodots, gold nanoparticles, iron oxide nanoparticles as the functional or/and supporting materials to carry NO donors. N-diazeniumdiolates, S-nitrosothiols, nitrosyl metal complexes and organic nitrates as main types of NO donors have their own unique properties and molecular structures. Conjugating the NO donors of different forms with appropriate nanomaterials results in NO delivery nanovehicles capable of releasing NO in a dose-controllable or/and on-demand manner. We also consider the therapeutic applications of those NO delivery nanovehicles, especially their applications for cancer therapy. In the end, we discuss possible future directions for developing exogenous NO delivery systems with more desired structure and improved performance. This review aims to offer the readers an overall view of the advances in functionalized colloidal nanovehicles for NO delivery. It will be attractive to scientists and researchers in the areas of material science, nanotechnology, biomedical engineering, chemical biology, etc.

Silk Nanoparticles: A Natural Polymeric Platform for Nitric Oxide Delivery in Biomedical Applications

In this study, the preparation and characterization of nitric oxide (NO) releasing silk fibroin nanoparticles (SF NPs) are described for the first time. S-Nitroso-N-acetylpenicillamine (SNAP)-loaded SF NPs (SNAP-SF NPs) were prepared via an antisolvent/self-assembling method by adding a SNAP/ethanol solution to an aqueous SF solution and freeze-thawing. The prepared SNAP-SF NPs had a diameter ranging from 300 to 400 nm and an overall negative charge of -28.76 ± 0.73 mV. Among the different SNAP/SF ratios tested, the highest encapsulation efficiency (18.3 ± 1.3%) and loading capacity (9.1 ± 0.6%) values were attributed to the 1:1 ratio. The deconvolution of the amide I band in the FTIR spectra of SF NPs and SNAP-SF NPs showed an increase in the β-sheet content for SNAP-SF NPs, confirming the hydrophobic interactions between SNAP and silk macromolecules. SNAP-SF NPs released up to 1.31 ± 0.02 × 10^-10 mol min^-1 mg^-1 NO over a 24 h period. Moreover, SNAP-SF NPs showed concentration-dependent antibacterial effects against methicillin-resistant Staphylococcus aureus and Escherichia coli. Furthermore, they did not elicit any marked cytotoxicity against 3T3 mouse fibroblast cells at concentrations equal to or below 2 mg/mL. Overall, these results demonstrated that SNAP-SF NPs have great potential to be used as a NO delivery platform for biomedical applications such as tissue engineering and wound healing, where synergistic properties of SF and NO are desired.

Photorelease Dynamics of Nitric Oxide from Cysteine-Bound Roussin's Red Ester

Nitric oxide (NO) can either boost or impede the growth of cancer cells depending on its concentration. Therefore, any anticancer treatment using NO requires precisely controlled NO administration to the target cells in terms of dosage and timing. In this context, photochemically activated NO donors were actively explored, but their detailed NO-releasing dynamics, which is crucial for their use, is not known yet. We determined detailed photoexcitation dynamics of a stable, nontoxic, and water-soluble NO precursor, cysteine-bound Roussin's Red Ester (Cys-RRE), including secondary reactions of the nascent photoproducts. The primary quantum yields of the NO dissociation from the photoexcited Cys-RRE were found to be 24-54% depending on the excitation wavelength; however, the geminate rebinding of NO with the nascent radical reduced the level of biologically available NO to as low as 12%. Such information is useful to achieve efficient NO delivery to practical chemical and biological targets.

Quantitative Modeling Extends the Antibacterial Activity of Nitric Oxide

Numerous materials have been developed to try and harness the antimicrobial properties of nitric oxide (NO). However, the short half-life and reactivity of NO have made precise, tunable delivery difficult. As such, conventional methodologies have generally relied on donors that spontaneously release NO at different rates, and delivery profiles have largely been constrained to decaying dynamics. In recent years, the possibility of finely controlling NO release, for instance with light, has become achievable and this raises the question of how delivery dynamics influence therapeutic potential. Here we investigated this relationship using Escherichia coli as a model organism and an approach that incorporated both experimentation and mathematical modeling. We found that the best performing delivery mode was dependent on the NO payload, and developed a mathematical model to quantitatively dissect those observations. Those analyses suggested that the duration of respiratory inhibition was a major determinant of NO-induced growth inhibition. Inspired by this, we constructed a delivery schedule that leveraged that insight to extend the antimicrobial activity of NO far beyond what was achievable by traditional delivery dynamics. Collectively, these data and analyses suggest that the delivery dynamics of NO have a considerable impact on its ability to achieve and maintain bacteriostasis.

ROS and GSH-responsive S-nitrosoglutathione functionalized polymeric nanoparticles to overcome multidrug resistance in cancer

Multidrug resistance of cancer cells is one of the major obstacle for chemotherapeutic efficiency. Nitric oxide (NO) has raised the potential to overcome multidrug resistance (MDR) with low side effects. Herein, we report a reactive oxygen species (ROS) and glutathione (GSH) responsive nanoparticle for the delivery of NO prodrug such as S-nitrosoglutathione (GSNO), which was chemically conjugated to an amphiphilic block copolymer. The GSNO functionalized nanoparticles show high NO loading capacity, good stability and sustained NO release with specific GSH activated NO-releasing kinetics. Such GSNO functionalized nanoparticles delivered doxorubicin (DOX) in a ROS triggered manner and increased the intracellular accumulation of DOX. However, in normal healthy cells, showing physiological concentrations of ROS, these nanoparticles presented good biocompatibility. The present work indicated that these multifunctional nanoparticles can serve as effective co-delivery platforms of NO and DOX to selectively kill chemo-resistant cancer cells through increasing chemo-sensitivity. STATEMENT OF SIGNIFICANCE: In this work, we constructed nitric oxide donor (S-nitrosoglutathione, GSNO) functionalized amphiphilic copolymer (PEG-PPS-GSNO) to deliver doxorubicin (DOX). The developed PEG-PPS-GSNO@DOX nanoparticles presented high NO capacity, ROS triggered DOX release and GSH triggered NO release. Thus NO reversed the chemo-resistance in HepG2/ADR cells increasing intrcellular accumulation of DOX. Furthermore, these PEG-PPS-GSNO@DOX nanoparticles exhibited biocompatibility to healthy cells and toxicity to cancer cells, due to elevated ROS.

Semiconductor Quantum Dots as Components of Photoactive Supramolecular Architectures

Luminescent quantum dots (QDs) are colloidal semiconductor nanocrystals consisting of an inorganic core covered by a molecular layer of organic surfactants. Although QDs have been known for more than thirty years, they are still attracting the interest of researchers because of their unique size-tunable optical and electrical properties arising from quantum confinement. Moreover, the controlled decoration of the QD surface with suitable molecular species enables the rational design of inorganic-organic multicomponent architectures that can show a vast array of functionalities. This minireview highlights the recent progress in the use of surface-modified QDs - in particular, those based on cadmium chalcogenides - as supramolecular platforms for light-related applications such as optical sensing, triplet photosensitization, photocatalysis and phototherapy.

Nanosized copper(ii) oxide/silica for catalytic generation of nitric oxide from S-nitrosothiols

The findings of this study suggest that copper(ii) oxide–silica nanoparticles produce NO from the GSNO species at physiological conditions in situ and could be used for designing biomedical materials with NO generating activity.

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.

Effects of nitric oxide-releasing nanoparticles on neotropical tree seedlings submitted to acclimation under full sun in the nursery

Polymeric nanoparticles have emerged as carrier systems for molecules that release nitric oxide (NO), a free radical involved in plant stress responses. However, to date, nanoencapsulated NO donors have not been applied to plants under realistic field conditions. Here, we verified the effects of free and nanoencapsulated NO donor, S-nitroso-mercaptosuccinic acid (S-nitroso-MSA), on growth, physiological and biochemical parameters of neotropical tree seedlings kept under full sunlight in the nursery for acclimation. S-nitroso-MSA incorporation into chitosan nanoparticles partially protected the NO donor from thermal and photochemical degradation. The application of nanoencapsulated S-nitroso-MSA in the substrate favoured the growth of seedlings of Heliocarpus popayanensis, a shade-intolerant tree. In contrast, free S-nitroso-MSA or nanoparticles containing non-nitrosated mercaptosuccinic acid reduced photosynthesis and seedling growth. Seedlings of Cariniana estrellensis, a shade-tolerant tree, did not have their photosynthesis and growth affected by any formulations, despite the increase of foliar S-nitrosothiol levels mainly induced by S-nitroso-MSA-loaded nanoparticles. These results suggest that depending on the tree species, nanoencapsulated NO donors can be used to improve seedling acclimation in the nursery.

Nitric Oxide Stimulated Programmable Drug Release of Nanosystem for Multidrug Resistance Cancer Therapy

Nitric oxide (NO) molecular messenger can reverse the multidrug resistance (MDR) effect of cancer cells through reducing P-glycoprotein (P-gp) expression, beneficial for creating a favorable microenvironment for the treatment of doxorubicin (Dox)-resistant cancer cells. Development of sophisticated nanosystems to programmably release NO and Dox becomes an efficient strategy to overcome the MDR obstacles and achieve promising therapeutic effects in Dox-resistant cancer. Herein, a NO stimulated nanosystem was designed to engineer a significant time gap between NO and Dox release, promoting MDR cancer therapy. A o-phenylenediamine-containing lipid that can hydrolyze in response to NO was embedded in the phospholipid bilayer structure of liposome to form NO-responsive liposome, which could further encapsulate l-arginine (l-Arg)/Dox-loaded gold@copper sulfide yolk-shell nanoparticls (_ADAu@CuS YSNPs) to form _ADLAu@CuS YSNPs. Under 808 nm laser irradiation, the unique resonant energy transfer (RET) process and reactive oxygen species (ROS) generation in the confined space of _ADLAu@CuS YSNPs could effectively convert l-Arg into NO, regionally destabilizing the phospholipid bilayer structure, as a result of NO release. However, at this early stage Dox could not be released from YSNPs due to the molecular scaffold limit. As the NO release progressed, the NO-responsive liposome layer was deteriorated more severely, allowing Dox to escape. This NO and Dox sequential release of _ADLAu@CuS YSNPs could significantly inhibit P-gp expression and enhance Dox accumulation in Dox-resistant MCF-7/ADR cells, leading to promising in vitro and in vivo therapeutic effects and presenting their great potential for MDR cancer therapy.

Multifunctional S-Nitroso-N-acetylpenicillamine-Incorporated Medical-Grade Polymer with Selenium Interface for Biomedical Applications

Modern crises in implantable or indwelling blood-contacting medical devices are mainly due to the dual problems of infection and thrombogenicity. There is a paucity of biomaterials that can address both problems simultaneously through a singular platform. Taking cues from the body's own defense mechanism against infection and blood clotting (thrombosis) via the endogenous gasotransmitter nitric oxide (NO), both of these issues are addressed through the development of a layered S-nitroso-N-acetylpenicillamine (SNAP)-doped polymer with a blended selenium (Se)-polymer interface. The unique capability of the SNAP-Se-1 polymer composites to explicitly release NO from the SNAP reservoir as well as generate NO via the incorporated Se is reported for the first time. The NO release from the SNAP-doped polymer increased substantially in the presence of the Se interface. The Se interface was able to generate NO in the presence of S-nitrosoglutathione (GSNO) and glutathione (GSH), demonstrating the capability of generating NO from endogenous S-nitrosothiols (RSNO). Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) traced distribution of elemental Se nanoparticles on the interface and the surface properties were evaluated by surface wettability and roughness. The SNAP-Se-1 efficiently inhibited the growth of bacteria and reduced platelet adhesion while showing minimal cytotoxicity, thus potentially eliminating the risks of systemic antibiotic and blood coagulation therapy. The SNAP-Se-1 exhibited antibacterial activity of ∼2.39 and ∼2.25 log reductions in the growth of clinically challenging adhered Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. SNAP-Se-1 also significantly reduced platelet adhesion by 85.5% compared to corresponding controls. A WST-8-based cell viability test performed on NIH 3T3 mouse fibroblast cells provided supporting evidence for the potential biocompatibility of the material in vitro. These results highlight the prospective utility of SNAP-Se-1 as a blood-contacting infection-resistant biomaterial in vitro which can be further tuned by application specificity.

Near-infrared photothermally activated nanomachines for cancer theragnosis

Near-infrared photothermal-activated nanomaterials are emerging as a promising tool in precise cancer theranostics. This Frontier article highlights the recent advances of photothermal-activated nanoagents in biomedical applications, namely photothermal-initiated drug/contrast agent release, gene silencing, programmed targeting and gas theranostics. In the end, we give a perspective on the further development of photothermal-sensitive nanomedicines.