Singlet Oxygen-Triggered Release of Nitric Oxide in an Endoperoxide-Arginine Conjugate

Nitric oxide (NO) is an important signaling molecule in both healthy and pathological processes. In this work, we present the first example of a novel class of organic NO-donor compounds with minimal toxicity. The release is driven by the reaction of singlet oxygen spontaneously produced by the cycloreversion reaction of the endoperoxide. Cell culture and imaging data confirms the release of NO in this bimodular system.

Multi-component liquid-infused systems: a new approach to functional coatings

Antifouling liquid-infused surfaces have generated interest in multiple fields due to their diverse applications in industry and medicine. In nearly all reports to date, the liquid component consists of only one chemical species. However, unlike traditional solid surfaces, the unique nature of liquid surfaces holds the potential for synergistic and even adaptive functionality simply by including additional elements in the liquid coating. In this work, we explore the concept of multi-component liquid-infused systems, in which the coating liquid consists of a primary liquid and a secondary component or components that provide additional functionality. For ease of understanding, we categorize recently reported multi-component liquid-infused surfaces according to the size of the secondary components: molecular scale, in which the secondary components are molecules; nanoscale, in which they are nanoparticles or their equivalent; and microscale, in which the additional components are micrometer size or above. We present examples at each scale, showing how introducing a secondary element into the liquid can result in synergistic effects, such as maintaining a pristine surface while actively modifying the surrounding environment, which are difficult to achieve in other surface treatments. The review highlights the diversity of fabrication methods and provides perspectives on future research directions. Introducing secondary components into the liquid matrix of liquid-infused surfaces is a promising strategy with significant potential to create a new class of multifunctional materials. Keywords: Active surfaces; Antimicrobial; Antifouling; Interfaces; Sensing surfaces.

Can Nitric Oxide-Based Therapy Be Improved for the Treatment of Cancers? A Perspective

Since the early observations that nitric oxide (•NO) at high concentrations is cytotoxic to cancer cells and that it may play an important role in the treatment of human cancers, a significant number of compounds (NO-donors) have been prepared to deliver •NO to tumors. •NO also sensitizes various clinically active anticancer drugs and has been shown to induce the reversal of multi-drug resistance in tumor cells expressing ATP-binding cassette-transporter proteins. For the successful treatment of cancers, •NO needs to be delivered precisely to tumors, and its adverse toxicity must be limited. Like other chemotherapeutics, the precise delivery of drugs has been a problem and various attempts have been made, such as the encapsulation of drugs in lipid polymers, to overcome this. This prospective study examines the use of various strategies for delivering •NO (using NO-donors) for the treatment of cancers. Finding and utilizing such a delivery system is an important step in delivering cytotoxic concentrations of •NO to tumors without adverse reactions, leading to a successful clinical outcome for patient management.

Research progress on gas signal molecular therapy for Parkinson's disease

The pathogenesis of Parkinson's disease (PD) remains unclear. Among the pathological manifestations is the progressive degeneration of the nigrostriatal dopaminergic pathway, leading to massive loss of neurons in the substantia nigra pars compacta and dopamine (DA) depletion. Therefore, the current drug treatment is primarily based on DA supplementation and delaying the progression of the disease. However, as patients' symptoms continue to worsen, the drug effect will gradually decrease or even disappear, thereby further aggravating clinical symptoms. Gas signaling molecules, such as hydrogen sulfide (H2S), nitric oxide (NO), carbon monoxide (CO), and hydrogen (H2), exhibit pleiotropic biological functions and play crucial roles in physiological and pathological effects. In common neurodegenerative diseases including Alzheimer's disease and PD, gas signal molecules can prevent or delay disease occurrence via the primary mechanisms of antioxidation, anti-inflammatory response, and antiapoptosis. This article reviews the therapeutic progress of gas signaling molecules in PD models and discusses the possibility of their clinical applications.

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.

Free radical-releasing systems for targeting biofilms

The recent rise in antibiotic drug resistance and biofilm formation by microorganisms has driven scientists from different fields to develop newer strategies to target microorganisms responsible for infectious diseases. There is a growing interest in free radicals as therapeutic agents for antimicrobial applications. However, limitations such as short half-life has hindered their usage. Currently, several research groups are exploring various biomaterials that can prolong the half-life, increase storage duration and control the release of the therapeutic ranges of free radicals required for different applications, including biofilm eradication. This review paper initially provides a background to, and theoretical knowledge on, free radicals; and then proceeds to review studies that have employed various free radical-incorporated drug delivery systems as an approach to target biofilm formation and eradication. Some of the free radical releasing systems highlighted include polymers, nanoparticles and hydrogels, with a focus on biofilm eradication, where they impact significantly. The various challenges associated with their application are also discussed. Further, the review identifies future research and strategies that can potentiate the application of free radical-incorporated drug delivery systems for inhibiting biofilm formation and eradicating formed biofilms.

Natural Diatom Biosilica as Microshuttles in Drug Delivery Systems

Unicellular diatom microalgae are a promising natural resource of porous biosilica. These microorganisms produce around their membrane a highly porous and extremely structured silica shell called frustule. Once harvested from living algae or from fossil sediments of diatomaceous earth, this biocompatible and non-toxic material offers an exceptional potential in the field of micro/nano-devices, drug delivery, theranostics, and other medical applications. The present review focused on the use of diatoms in the field of drug delivery systems, with the aim of presenting the different strategies implemented to improve the biophysical properties of this biosilica in terms of drug loading and release efficiency, targeted delivery, or site-specific binding capacity by surface functionalization. The development of composite materials involving diatoms for drug delivery applications is also described.

Reduced Basal Nitric Oxide Production Induces Precancerous Mammary Lesions via ERBB2 and TGFβ

One third of newly diagnosed breast cancers in the US are early-stage lesions. The etiological understanding and treatment of these lesions have become major clinical challenges. Because breast cancer risk factors are often linked to aberrant nitric oxide (NO) production, we hypothesized that abnormal NO levels might contribute to the formation of early-stage breast lesions. We recently reported that the basal level of NO in the normal breast epithelia plays crucial roles in tissue homeostasis, whereas its reduction contributes to the malignant phenotype of cancer cells. Here, we show that the basal level of NO in breast cells plummets during cancer progression due to reduction of the NO synthase cofactor, BH₄, under oxidative stress. Importantly, pharmacological deprivation of NO in prepubertal to pubertal animals stiffens the extracellular matrix and induces precancerous lesions in the mammary tissues. These lesions overexpress a fibrogenic cytokine, TGFβ, and an oncogene, ERBB2, accompanied by the occurrence of senescence and stem cell-like phenotype. Consistently, normalization of NO levels in precancerous and cancerous breast cells downmodulates TGFβ and ERBB2 and ameliorates their proliferative phenotype. This study sheds new light on the etiological basis of precancerous breast lesions and their potential prevention by manipulating the basal NO level.

Glutathione Responsive β-Cyclodextrin Conjugated S-Nitrothiols as a Carrier for Intracellular Delivery of Nitric Oxide

Nitric oxide (NO) exerts multiple functions in many life processes and was of great significance in a variety of biomedical scenarios. However, the mismatches between releasing locations and NO active sites seriously limited the available NO at areas of interest and greatly dampen the overall efficiency of delivery systems. Therefore, in the present study, a NO donor was developed to achieve intracellular delivery and release of NO to overcome the aforementioned challenges. Enhanced uptake and effective intracellular release of NO were realized via β-cyclodextrin (β-CD) mediated endocytosis and high level glutathione (GSH) inside cells, respectively. We demonstrated that intracellularly delivered NO would exert stronger bioeffects than premature release of NO outside targeted cells. Besides, β-CD assisted cellular uptake proved indispensable in maximizing the influence of NO in modulating cellular behavior. These results demonstrated the significance of intracellular delivery and release of NO in improving its bioutilization. The carrier could efficiently inhibit proliferation of SMCs, while promoting the growth of ECs. Such cell-type-differed physiological effects were advantageous in re-endothelialization and might hold great potential in cardiovascular applications.

Solution or solid - it doesn't matter: visible light-induced CO release reactivity of zinc flavonolato complexes

Two types of zinc flavonolato complexes ([(6-Ph₂TPA)Zn(flavonolato)]ClO₄ and Zn(flavonolato)₂) of four extended flavonols have been prepared, characterized, and evaluated for visible light-induced CO release reactivity. Zinc coordination of each flavonolato anion results in a red-shift of the lowest energy absorption feature and in some cases enhanced molar absorptivity relative to the free flavonol. The zinc-coordinated flavonolato ligands undergo visible light-induced CO release with enhanced reaction quantum yields relative to the neutral flavonols. Most notable is the discovery that both types of zinc flavonolato derivatives undergo similar visible light-induced CO release reactivity in solution and in the solid state. A solid film of a Zn(flavonolato)₂ derivative was evaluated as an in situ CO release agent for aerobic oxidative palladium-catalyzed alkoxycarbonylation to produce esters in ethanol. The CO release product was found to undergo ester alcolysis under the conditions of the carbonylation reaction.

The renaissance of nitric oxide: from improvement of stability to enhancement of endocytosis

The local generation and intracellular release of NO is no less vital than improving the stability of carriers.

Phenotypic switching prevention and proliferation/migration inhibition of vascular smooth muscle cells by the ruthenium nitrosyl complex trans-[Ru(NO)Cl(cyclam](PF6 )2

OBJECTIVES

Vascular smooth muscle cell (VSMC) migration and proliferation at sites of vascular injury are both critical steps in the development of intimal hyperplasia (IH). Local delivery of nitric oxide (NO) largely prevents these events. Among the NO donors, tetraazamacrocyclic nitrosyl complexes, such as trans-[Ru(NO)Cl(cyclam)](PF₆ )₂ (cyclamNO), gained attention for their features, which include the possibility of being embedded in solid matrices, and ability to participate in a nitrite/NO catalytic conversion cycle.

METHODS

Methods used to evaluate cyclamNO activity: safety margin by NR and MTT; cell proliferation by 3H-thymidine incorporation and proliferating cell nuclear antigen (PCNA) expression; antimigratory properties by transwell and wound healing; prevention of cell phenotypic switching under platelet-derived growth factor type BB (PDGF-BB) stimuli by analysis of alpha smooth muscle actin (α-SMA) expression.

KEY FINDINGS

Cell proliferation and migration induced by PDGF-BB were significantly inhibited by cyclamNO. The ~60% reduction on expression of contractile protein α-SMA induced by PDGF-BB revealed VSMC phenotypic switching which is significantly prevented by cyclamNO. Compared to the NO donor sodium nitroprusside, cyclamNO showed to be significantly less cytotoxic.

CONCLUSIONS

With great potential to maintain VSMC functionality and prevent IH-associated events, cyclamNO might be a promissory drug for several applications in cardiovascular medicine, as in stents.

The Use of Hemoglobin Vesicles for Delivering Medicinal Gas for the Treatment of Intractable Disorders

Bioactive gaseous molecules, such as oxygen (O₂) and carbon monoxide (CO), are essential elements for most living organisms to maintain their homeostasis and biological activities. An accumulating body of evidence suggests that such molecules can be used in clinics as a medical gas in the treatment of various intractable disorders. Recent developments in hemoglobin-encapsulated liposomes, namely hemoglobin vesicles (HbV), possess great potential for retaining O₂ and CO and could lead to strategies for the development of novel pharmacological agents as medical gas donors. HbV with either O₂ or CO bound to it has been demonstrated to have therapeutic potential for treating certain intractable disorders and has the possibility to serve as diagnostic and augmenting product by virtue of unique physicochemical characteristics of HbV. The present review provides an overview of the present status of the use of O₂- or CO-binding HbV in experimental animal models of intractable disorders and discusses prospective clinical applications of HbV as a medical gas donor.

Cardiovascular effects of gasotransmitter donors

Gasotransmitters represent a subfamily of the endogenous gaseous signaling molecules that include nitric oxide (NO), carbon monoxide (CO), and hydrogen sulphide (H(2)S). These particular gases share many common features in their production and function, but they fulfill their physiological tasks in unique ways that differ from those of classical signaling molecules found in tissues and organs. These gasotransmitters may antagonize or potentiate each other's cellular effects at the level of their production, their downstream molecular targets and their direct interactions. All three gasotransmitters induce vasodilatation, inhibit apoptosis directly or by increasing the expression of anti-apoptotic genes, and activate antioxidants while inhibiting inflammatory actions. NO and CO may concomitantly participate in vasorelaxation, anti-inflammation and angiogenesis. NO and H(2)S collaborate in the regulation of vascular tone. Finally, H(2)S may upregulate the heme oxygenase/carbon monoxide (HO/CO) pathway during hypoxic conditions. All three gasotransmitters are produced by specific enzymes in different cell types that include cardiomyocytes, endothelial cells and smooth muscle cells. As translational research on gasotransmitters has exploded over the past years, drugs that alter the production/levels of the gasotransmitters themselves or modulate their signaling pathways are now being developed. This review is focused on the cardiovascular effects of NO, CO, and H(2)S. Moreover, their donors as drug targeting the cardiovascular system are briefly described.

Potential use and perspectives of nitric oxide donors in agriculture

Nitric oxide (NO) has emerged in the last 30 years as a key molecule involved in many physiological processes in plants, animals and bacteria. Current research has shown that NO can be delivered via donor molecules. In such cases, the NO release rate is dependent on the chemical structure of the donor itself and on the chemical environment. Despite NO's powerful signaling effect in plants and animals, the application of NO donors in agriculture is currently not implemented and research remains mainly at the experimental level. Technological development in the field of NO donors is rapidly expanding in scope to include controlling seed germination, plant development, ripening and increasing shelf-life of produce. Potential applications in animal production have also been identified. This concise review focuses on the use of donors that have shown potential biotechnological applications in agriculture. Insights are provided into (i) the role of donors in plant production, (ii) the potential use of donors in animal production and (iii) future approaches to explore the use and applications of donors for the benefit of agriculture. © 2016 Society of Chemical Industry.

Characterization of the electronic states of the biological relevant SSNO molecule

Using configuration interaction ab initio methods, we investigate the lowest electronic states of doublet and quartet spin multiplicities of SSNO where the one-dimensional cuts of the six-dimensional potential energy surfaces of these electronic states along the stretching and bending coordinates are computed. Mainly, these electronic states are found to be repulsive along the central SN distance. A high density of electronic states is computed even at low excitation energies that may favor their couplings. Therefore, the dynamics of the SSNO electronic states is expected to be very complex. We also characterized the bound electronic states spectroscopically where we derived their equilibrium structures and vibrational frequencies. Our calculations show the importance of taking into account of dynamical correlation, in addition to static correlation, for the accurate description of SSNO electronic excited states and more generally for those of R-NO molecular species. Finally, we highlighted the potential role of SSNO in light-induced NO delivery from SSNO related species in biological media.

Fulvic acid promotes extracellular anti-cancer mediators from RAW 264.7 cells, causing to cancer cell death in vitro

Fulvic acid (FA) is known to promote electrochemical balance as a donor or a receptor possessing many biomedical functions. Nevertheless, the effect of FA on the anti-cancer activity has not been elucidated. In the current study, we first isolated FA from humus and investigated whether FA regulates immune-stimulating functions, such as production of nitric oxide (NO), in RAW 264.7 cells. Our data showed that FA slightly enhances cell viability in a dose-dependent manner and secretion of NO from RAW 264.7 cells. It upregulated the protein and mRNA expression of inducible NO synthesis (iNOS). In addition, FA enhanced the DNA-binding activity of nuclear factor-κB (NF-κB) in RAW 264.7 cells; the NF-κB inhibitor, pyrrolidine dithiocarbamate (PDTC) effectively attenuated the expression of FA-stimulated iNOS, suggesting that FA stimulates NF-κB to promote iNOS and NO production. Finally, FA-stimulated culture media (FA-CM) from RAW 264.7 cells were collected and MCA-102 fibrosarcoma cells were cultured in this media. The FA-CM augmented MCA-102 fibrosarcoma cell apoptosis; however, an NO inhibitor N(G)-monomethyl-l-arginine (NMMA) slightly inhibited the FA-CM-mediated MCA-102 fibrosarcoma cell apoptosis, which was accompanied by low levels of NO. In the present study, we found that FA induces the generation of NO and iNOS in RAW 264.7 cells by inducing NF-κB activation; however, NO did not significantly stimulate MCA-102 fibrosarcoma cell apoptosis in the current study. In addition, FA-CM enhanced cell death in various human cancer cells such as Hep3B, LNCaP, and HL60. Taken together, FA most likely stimulates immune-modulating molecules such as NO and induces cancer cell apoptosis.

Nitric oxide generating/releasing materials

Harnessing the impressive therapeutic potential of nitric oxide (NO) remains an ongoing challenge. This paper describes several of the current strategies both with respect to the underlying chemistry and physics and to the applications where they have shown promise. Included in this overview are molecular systems such as NONOates that release NO through chemical reactions and delivery vehicles such as nanoparticles that can generate, store, transport and deliver NO and related bioactive forms of NO such as nitrosothiols. Although there has been much positive movement, it is clear that we are only at the early stages of knowing how to precisely produce, transport and deliver to targeted sites therapeutic levels of NO and related molecules.

On the role of HNS and HSN as light-sensitive NO-donors for delivery in biological media

Results are presented that suggest that thiazyl hydride (HSN)/thionitrosyl hydride (sulfimide, HNS) can be used as light-sensitive compounds for NO-delivery in biological media, as well as markers for the possible detection of intermediates in nitrites + H2S reactions at the cellular level. They are expected to be more efficient than the HNO/HON isovalent species and hence they should be considered instead. A set of characteristic spectroscopic features are identified that could aid in the possible detection of these species in the gas phase or in biological environments. The possibility of intramolecular dynamical processes involving excited states that are capable of interconverting HNS and its isomeric form HSN is examined.

Light-controlled release of nitric oxide from solid polymer composite materials using visible and near infra-red light

Composite materials were prepared using biocompatible polymers, upconverting nanoparticles, and a nitric oxide (NO) donor complex. We have demonstrated NO release from the solid composites after visible and near infra-red light irradiation.

Production of reactive oxygen and nitrogen species by light irradiation of a nitrosyl phthalocyanine ruthenium complex as a strategy for cancer treatment

Production of reactive oxygen species has been used in clinical therapy for cancer treatment in a technique known as Photodynamic Therapy (PDT). The success of this therapy depends on oxygen concentration since hypoxia limits the formation of reactive oxygen species with consequent clinical failure of PDT. Herein, a possible synergistic effect between singlet oxygen and nitric oxide (NO) is examined since this scenario may display increased tumoricidal activity. To this end, the trinuclear species [Ru(pc)(pz)2{Ru(bpy)2(NO)}2](PF6)6 (pc = phthalocyanine; pz = pyrazine; bpy = bipyridine) was synthesized to be a combined NO and singlet oxygen photogenerator. Photobiological assays using at 4 × 10(-6) M in the B16F10 cell line result in the decrease of cell viability to 21.78 ± 0.29% of normal under light irradiation at 660 nm. However, in the dark and at the same concentration of compound , viability was 91.82 ± 0.37% of normal. The potential application of a system like in clinical therapy against cancer may be as an upgrade to normal photodynamic therapy.

Nitric oxide-eluting nanocomposite for cardiovascular implants

Cardiovascular implants must resist thrombosis and intimal hyperplasia, but they are prone to such patency limiting conditions during graft implantation and prior to endothelialisation. Nitric oxide (NO) released from the endothelium has a complex protective role in the cardiovascular system, and this study has addressed: (1) in situ NO release profiles from S-nitrosothiols ((S-Nitroso-N-acetylpenicillamine (SNAP) and (S-Nitrosoglutathione (GSNO)) incorporated into polyhedral oligomeric silsesquioxanepoly(carbonate-urea)urethane (POSS-PCU) coronary artery bypass grafts (CABG) in a physiological pulsatile flow, and (2) the determination of their interaction with endothelial progenitor cells (EPCs), smooth muscle cells, platelets, whole blood kinetics. It was found that 1, 2, and 3 wt% SNAP/GSNO incorporated into POSS-PCU-CABG successfully eluted NO, but optimal elution was evident with 2 %-SNAP-POSS-PCU. NO release determined under static conditions using the Griess assay, and in situ measurements under pulsatile flow using amperometric probe was found to differ, thus confirming the significance of monitoring NO-elution under haemodynamic conditions. 2 %-SNAP-POSS-PCU demonstrated anti-thrombogenic kinetics through thromboelastography measurements, while metabolic activity using Alamar Blue™ assay and scanning electron microscopy demonstrated greater adhesion of EPCs and reduced adhesion of platelets.

Light-triggered nitric oxide delivery to malignant sites and infection

The discovery of nitric oxide (NO) as a signalling molecule in various physiological and pathological pathways has spurred research in the design of exogenous NO donors as drugs. In recent years, metal nitrosyls (NO complexes of metals) have been investigated as NO-donating agents. Results from our laboratory during the past few years have demonstrated that metal nitrosyls derived from designed ligands can deliver NO under the total control of light of various frequencies. Careful incorporation of these photoactive nitrosyls into polymer matrices has afforded a set of nitrosyl-polymer composites that can be used to make such NO delivery site-specific. The composite materials have shown excellent antineoplastic and antimicrobial actions in several in vitro experiments. This review highlights our key results in the context of recent developments in this area of NO donors that deliver NO on demand.

Secondary amines containing one aromatic nitro group: preparation, nitrosation, sustained nitric oxide release, and the synergistic effects of released nitric oxide and an arginase inhibitor on vascular smooth muscle cell proliferation

Atherosclerosis, a leading cause of death worldwide, is associated with the excessive proliferation of vascular smooth muscle cells. Nitrogen monoxide, more commonly known as nitric oxide, inhibits this uncontrolled proliferation. Herein we report the preparation of two families of nitric oxide donors; beginning with the syntheses of secondary amine precursors, obtained through the reaction between 2 equiv of various monoamines with 2,4 or 2,6-difluoronitrobenzene. The purified secondary amines were nitrosated then subjected to a Griess reagent test to examine the slow and sustained nitric oxide release rate for each compound in both the absence and presence of reduced glutathione. The release rate profiles of these two isomeric families of NO-donors were strongly dependent on the number of side chain methylene units and the relative orientations of the nitro groups with respect to the N-nitroso moieties. The nitrosated compounds were then added to human aortic smooth muscle cell cultures, individually and in tandem with S-2-amino-6-boronic acid (ABH), a potent arginase inhibitor. Cell viability studies indicated a lack of toxicity of the amine precursors, in addition to anti-proliferative effects exhibited by the nitrosated compounds, which were enhanced in the presence of ABH.

Biopolymer-based nanoparticles for drug/gene delivery and tissue engineering

There has been a great interest in application of nanoparticles as biomaterials for delivery of therapeutic molecules such as drugs and genes, and for tissue engineering. In particular, biopolymers are suitable materials as nanoparticles for clinical application due to their versatile traits, including biocompatibility, biodegradability and low immunogenicity. Biopolymers are polymers that are produced from living organisms, which are classified in three groups: polysaccharides, proteins and nucleic acids. It is important to control particle size, charge, morphology of surface and release rate of loaded molecules to use biopolymer-based nanoparticles as drug/gene delivery carriers. To obtain a nano-carrier for therapeutic purposes, a variety of materials and preparation process has been attempted. This review focuses on fabrication of biocompatible nanoparticles consisting of biopolymers such as protein (silk, collagen, gelatin, β-casein, zein and albumin), protein-mimicked polypeptides and polysaccharides (chitosan, alginate, pullulan, starch and heparin). The effects of the nature of the materials and the fabrication process on the characteristics of the nanoparticles are described. In addition, their application as delivery carriers of therapeutic drugs and genes and biomaterials for tissue engineering are also reviewed.

Nitric oxide releasing-dendrimers: an overview

Platforms able to storage, release or scavenge NO in a controlled and specific manner is interesting for biological applications. Among the possible matrices for these purposes, dendrimers are excellent candidates for that. These molecules have been used as drug delivery systems and exhibit interesting properties, like the possibility to perform chemical modifications on dendrimers surface, the capacity of storage high concentrations of compounds of interest in the same molecule and the ability to improve the solubility and the biocompatibility of the compounds bonded to it. This review emphasizes the recent progress in the development and in the biological applications of different NO-releasing dendrimers and the nitric oxide release pathways in these compounds.

Nitric oxide (NO)-induced death of gram-negative bacteria from a light-controlled NO-releasing platform

A NO-delivery platform has been fabricated from polydimethylsiloxane (PDMS) and Pluronic(®) F127 gel that contains the light-sensitive NO donor, [Mn(PaPy(3))(NO)]ClO(4). The material was assembled layer-by-layer. First, a thin PDMS membrane was cast. It was then layered with cold 25% (w/v) Pluronic(®) F127 gel mixed with [Mn(PaPy(3))(NO)]ClO(4). Finally, it was covered with a thick layer (nearly impermeable to NO) of PDMS (=polydimethoxysiloxane) to allow release of NO only from the thinner side upon exposure to light. Light-induced NO release from this layered material has been confirmed via NO-specific electrode and by a modified soft Griess-agar assay. Incorporation of ca. 8 mg/g of [Mn(PaPy(3))(NO)]ClO(4) in the Pluronic gel layer affords a material that drastically reduces the microbial loads of Acinetobacter baumannii and Pseudomonas aeruginosa via the antibiotic effects of the photoreleased NO. Application of this flexible layered NO-donating composite as bandage material has been proposed.

Photolability of NO in designed metal nitrosyls with carboxamido-N donors: a theoretical attempt to unravel the mechanism

During the past few years, photoactive metal nitrosyls (NO complexes of metals) have drawn attention as potential drugs for delivery of nitric oxide (NO) to biological targets under the control of light. Major success in this area has been achieved with designed metal nitrosyls derived from ligands that contain carboxamide group(s). A number of iron, manganese and ruthenium {MNO}(6) nitrosyls of such kind exhibit excellent NO photolability under low-power visible and near-IR light. The results of theoretical studies on these NO-donors have provided insight into (a) the electronic transitions that lead to photorelease of NO and (b) the structural features of the ligands that dictate the sensitivity of the nitrosyls to light of specific wavelengths. In addition, the results have afforded clear understanding of the electronic configurations of the various nitrosyls. This article highlights these results in a coherent manner. Good matches between the predicted and observed spectral features and NO photolability strongly suggest that theoretical studies should be an integral part of the smart design of such NO-donors in the future research.

Nitric oxide release: part II. Therapeutic applications

A wide range of nitric oxide (NO)-releasing materials has emerged as potential therapeutics that exploit NO's vast biological roles. Macromolecular NO-releasing scaffolds are particularly promising due to their ability to store and deliver larger NO payloads in a more controlled and effective manner compared to low molecular weight NO donors. While a variety of scaffolds (e.g., particles, dendrimers, and polymers/films) have been cleverly designed, the ultimate clinical utility of most NO-releasing macromolecules remains unrealized. Although not wholly predictive of clinical success, in vitro and in vivo investigations have enabled a preliminary evaluation of the therapeutic potential of such materials. In this tutorial review, we review the application of macromolecular NO therapies for cardiovascular disease, cancer, bacterial infections, and wound healing.

Polymer-Based Nitric Oxide Therapies: Recent Insights for Biomedical Applications

Since the discovery of nitric oxide (NO) in the 1980s, this cellular messenger has been shown to participate in diverse biological processes such as cardiovascular homeostasis, immune response, wound healing, bone metabolism, and neurotransmission. Its beneficial effects have prompted increased research in the past two decades, with a focus on the development of materials that can locally release NO. However, significant limitations arise when applying these materials to biomedical applications. This Feature Article focuses on the development of NO-releasing and NO-generating polymeric materials (2006-2011) with emphasis on recent in vivo applications. Results are compared and discussed in terms of NO dose, release kinetics, and biological effects, in order to provide a foundation to design and evaluate new NO therapies.

Biochemistry of mobile zinc and nitric oxide revealed by fluorescent sensors

Biological mobile zinc and nitric oxide (NO) are two prominent examples of inorganic compounds involved in numerous signaling pathways in living systems. In the past decade, a synergy of regulation, signaling, and translocation of these two species has emerged in several areas of human physiology, providing additional incentive for developing adequate detection systems for Zn(II) ions and NO in biological specimens. Fluorescent probes for both of these bioinorganic analytes provide excellent tools for their detection, with high spatial and temporal resolution. We review the most widely used fluorescent sensors for biological zinc and nitric oxide, together with promising new developments and unmet needs of contemporary Zn(II) and NO biological imaging. The interplay between zinc and nitric oxide in the nervous, cardiovascular, and immune systems is highlighted to illustrate the contributions of selective fluorescent probes to the study of these two important bioinorganic analytes.