Wound healing action of nitric oxide-releasing self-expandable collagen sponge.

Mounting evidence showing that local nitric oxide (NO) delivery may significantly improve the wound healing process has stimulated the development of wound dressings capable of releasing NO topically. Herein, we describe the preparation of a self-expandable NO-releasing hydrolyzed collagen sponge (CS), charged with the endogenously found NO donor, S-nitrosoglutathione (GSNO). We show that cold pressed and GSNO-charged CS (CS/GSNO) undergo self-expansion to its original 3D shape upon water absorption to a swelling degree of 2,300 wt%, triggering the release of free NO. Topical application of compressed CS/GSNO on wounds in an animal model showed that exudate absorption by CS/GSNO leads to the release of higher NO doses during the inflammatory phase and progressively lower NO doses at later stages of the healing process. Moreover, treated animals showed significant increase in the mRNA expression levels of monocyte chemoattractant protein-1 (MCP-1), murine macrophage marker (F4/80), transforming growth factor beta (TGF-ß), stromal cell-derived factor 1 (SDF-1), insulin-like growth factor-1 (IGF-1), nitric oxide synthase(iNOS), and matrix metalloproteinase(MMP-9). Cluster differentiation 31 (CD31), vascular endothelial growth factor (VEGF), and F4/80 were measured on Days 7 and 12 by immunohistochemistry in the cicatricial tissue. These results indicate that the topical delivery of NO enhances the migration and infiltration of leucocytes, macrophages, and keratinocytes to the wounded tissue, as well as the neovascularization and collagen deposition, which are correlated with an accelerated wound closure. Thus, self-expandable CS/GSNO may represent a novel biocompatible and active wound dress for the topical delivery of NO on wounds.

Copper-Based Metal-Organic Framework as a Controllable Nitric Oxide-Releasing Vehicle for Enhanced Diabetic Wound Healing.

Chronic wounds are one of the most serious complications of diabetes mellitus. Even though utilizing nitric oxide (NO) as a gas medicine to repair diabetic wounds presents a promising strategy, controlling the NO release behavior in the affected area, which is vital for NO-based therapy, still remains a significant challenge. In this work, a copper-based metal-organic framework, namely, HKUST-1, has been introduced as a NO-loading vehicle, and a NO sustained release system with the core-shell structure has been designed through the electrospinning method. The results show that the NO is quantificationally and stably loaded in the HKUST-1 particles, and the NO-loaded HKUST-1 particles are well incorporated into the core layer of the coaxial nanofiber. Therefore, NO can be controllably released with an average release rate of 1.74 nmol L-1 h-1 for more than 14 days. Moreover, the additional copper ions released from the degradable HKUST-1 play a synergistic role with NO to promote endothelial cell growth and significantly improve the angiogenesis, collagen deposition as well as anti-inflammatory property in the wound bed, which eventually accelerate the diabetic wound healing. These results suggest that such a copper-based metal-organic framework material as a controllable NO-releasing vehicle is a highly efficient therapy for diabetic wounds.

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.

Impaired l-arginine-nitric oxide pathway contributes to the pathogenesis of resistant hypertension.

The precise mechanisms underlying resistant hypertension remain elusive. Reduced nitric oxide (NO) bioavailability is frequently documented in chronic kidney disease, obesity, diabetes and advanced age, all of which are risk factors for resistant hypertension. Sympathetic overactivity and chronic activation of the renin-angiotensin system are salient features of resistant hypertension. Interestingly, recent data indicate that renal sympathetic overactivity can reduce the expression of neuronal nitric oxide synthase in the paraventricular nucleus. Reduced NO levels in the paraventricular nucleus can increase sympathetic outflow and this can create a vicious cycle contributing to resistant hypertension. Angiotensin II can reduce l-arginine transport and hence NO production. Reduced NO levels may reduce the formation of angiotensin 1-7 dampening the cardio-protective effects of the renin-angiotensin system contributing to resistant hypertension. In addition, interleukin-6 (IL-6) is demonstrated to be independently associated with resistant hypertension, and IL-6 can reduce NO synthesis. Despite this, NO levels have not been quantified in resistant hypertension. Findings from a small proof of concept study indicate that NO donors can reduce blood pressure in patients with resistant hypertension but more studies are required to validate these preliminary findings. In the present paper, we put forward the hypothesis that reduced NO bioavailability contributes substantially to the development of resistant hypertension.

Smart pH-Sensitive Nanogels for Enhancing Synergistic Anticancer Effects of Integrin αvß3 Specific Apoptotic Peptide and Therapeutic Nitric Oxide.

Apoptotic peptide (kla), which can trigger the mitochondria-mediated apoptotic programmed cell death, has been widely recognized as a potential anticancer agent. However, its therapeutic potential has been significantly impaired by its poor biostability, lack of tumor specificity, and particularly low cellular uptake. Herein, a linear peptide Arg-Trp-d-Arg-Asn-Arg (RWrNR) was identified as an integrin αvß3 specific ligand with a nanomolar dissociation constant (Kd = 0.95 nM), which can greatly improve kla antitumor activity (IC50 = 8.81 µM) by improving its cellular uptake, compared to the classic integrin-recognition motif c-RGDyK (IC50 = 37.96 µM). Particularly, the RWrNR-kla conjugate can be entrapped in acidic sensitive nanogels (RK/Parg/CMCS-NGs), composed of poly-l-arginine (Parg) and carboxymethyl chitosan (CMCS, pI = 6.8), which can not only carry out controlled release of RWrNR-kla in response to the tumor acidic microenvironment, and consequently enhance its tumor specificity and cell internalization, but also trigger tumor-associated macrophages to generate nitric oxide, leading to enhanced synergistic anticancer efficacy. Importantly, RK/Parg/CMCS-NGs have been proven to effectively activate the apoptosis signaling pathway in vivo and significantly inhibit tumor growth with minimal adverse effects. To summarize, RK/Parg/CMCS-NGs are a promising apoptotic peptide-based therapeutics with enhanced tumor accumulation, cytosolic delivery, and synergistic anticancer effects, thereby holding great potential for the treatment of malignant tumors.

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.

The Effects of Beetroot Juice on Blood Pressure, Microvascular Function and Large-Vessel Endothelial Function: A Randomized, Double-Blind, Placebo-Controlled Pilot Study in Healthy Older Adults.

: Dietary nitrate (NO3-) has been reported to improve endothelial function (EF) and blood pressure (BP). However, most studies only assess large-vessel EF with little research on the microvasculature. Thus, the aim of the present pilot study is to examine NO3- supplementation on microvascular and large-vessel EF and BP. Twenty older adults (63 ± 6 years) were randomized to a beetroot juice (BRJ) or placebo (PLA) group for 28 (±7) days and attended three laboratory visitations. Across visitations, blood pressure, microvascular function and large-vessel EF were assessed by laser Doppler imaging (LDI) with iontophoresis of vasoactive substances and flow-mediated dilatation (FMD), respectively. Plasma NO3-concentrations, BP and the presence of NO3- reducing bacteria were also assessed. Plasma NO3- increased following two weeks of BRJ supplementation (p = 0.04) along with a concomitant decrease in systolic and diastolic BP of approximately -6 mmHg and -4 mmHg, respectively (p = 0.04; p = 0.01, respectively). BP remained unchanged in the PLA group. There were no significant differences in endothelium-dependent or endothelium-independent microvascular responses between groups. FMD increased by 1.5% following two weeks of BRJ (p = 0.04), with only a minimal (0.1%) change for the PLA group. In conclusion, this pilot study demonstrated that medium-term BRJ ingestion potentially improves SBP, DBP and large-vessel EF in healthy older adults. The improvements observed in the present study are likely to be greater in populations presenting with endothelial dysfunction. Thus, further prospective studies are warranted in individuals at greater risk for cardiovascular disease.

Enhancing analytical accuracy of intravascular electrochemical oxygen sensors via nitric oxide release using S-nitroso-N-acetyl-penicillamine (SNAP) impregnated catheter tubing.

Implantable medical devices are an integral part of primary/critical care. However, these devices carry a high risk for blood clots, caused by platelet aggregation on a foreign body surface. This study focuses on the development of a simplified approach to create nitric oxide (NO) releasing intravascular electrochemical oxygen (O2) sensors with increased biocompatibility and analytical accuracy. The implantable sensors are prepared by embedding S-nitroso-N-acetylpenacillamine (SNAP) as the NO donor molecule in the walls of the catheter type sensors. The SNAP-impregnated catheters were prepared by swelling silicone rubber tubing in a tetrahydrofuran solution containing SNAP. Control and SNAP-impregnated catheters were used to fabricate the Clark-style amperometric PO2 sensors. The SNAP-impregnated sensors release NO under physiological conditions for 18 d as measured by chemiluminescence. The analytical response of the SNAP-impregnated sensors was evaluated in vitro and in vivo. Rabbit and swine models (with sensors placed in both veins and arteries) were used to evaluate the effects on thrombus formation and analytical in vivo PO2 sensing performance. The SNAP-impregnated PO2 sensors were found to more accurately measure PO2 levels in blood continuously (over 7 and 20 h animal experiments) with significantly reduced thrombus formation (as compared to controls) on their surfaces.

PEI/NONOates-doped PLGA nanoparticles for eradicating methicillin-resistant Staphylococcus aureus biofilm in diabetic wounds via binding to the biofilm matrix.

Wounds infected with methicillin-resistant Staphylococcus aureus (MRSA) biofilm represent a high risk in patients with diabetes. Nitric oxide (NO) has shown promise in dispersing biofilm and wound healing. For an effective treatment of MRSA biofilm-infected wounds, however, NO needs to be supplied to the biofilm matrix in a sustainable manner due to a short half-life and limited diffusion distance of NO. In this study, polyethylenimine/diazeniumdiolate (PEI/NONOate)-doped PLGA nanoparticles (PLGA-PEI/NO NPs) with an ability to bind to the biofilm matrix are developed to facilitate the NO delivery to MRSA biofilm-infected wound. In simulated wound fluid, PLGA-PEI/NO NPs show an extended NO release over 4 days. PLGA-PEI/NO NPs firmly bind to the MRSA biofilm matrix, resulting in a greatly enhanced anti-biofilm activity. Moreover, PLGA-PEI/NO NPs accelerate healing of MRSA biofilm-infected wounds in diabetic mice along with complete biofilm dispersal and reduced bacterial burden. These results suggest that the biofilm-binding NO-releasing NPs represent a promising NO delivery system for the treatments of biofilm-infected chronic wounds.

NIR-Responsive Polypeptide Nanocomposite Generates NO Gas, Mild Photothermia, and Chemotherapy to Reverse Multidrug-Resistant Cancer.

Multidrug resistance (MDR) of cancers that results from overexpression of a P-glycoprotein (P-gp) transporter mainly causes chemotherapy (CT) failure and hinders clinical transitions of current polypeptide nanomedicines. Herein, a novel polypeptide nanocomposite PNOC-PDA that integrates heat-sensitive NO gas delivery and photothermal conversion attributes can overcome MDR and maximize CT; meanwhile the optimized CT and intracellular high-concentration NO gas can assist a mild photothermal therapy (PTT) to eradicate cancer cells. The triple therapies produced a superior and synergistic effect on MDR-reversal and killing MCF-7/ADR in vitro, and the P-gp expression level was downregulated to 46%, as confirmed by means of MTT, Western blot, flow cytometry, and confocal laser scanning microscopy. Significantly, by using one intravenous injection of PNOC-PDA/DOX and a single near-infrared irradiation, the triple therapies of mild PTT, NO gas therapy, and CT achieved complete MCF-7/ADR tumor ablation without skin damage, scarring, and tumor recurrence within 30 days. This work provides a versatile method for the fabrication of NIR-responsive polypeptide nanocomposite with intrinsic photothermal conversion and NO-releasing attributes, opening up a new avenue for reversing MDR in tumors.

72-Hour in vivo evaluation of nitric oxide generating artificial lung gas exchange fibers in sheep.

The large, densely packed artificial surface area of artificial lungs results in rapid clotting and device failure. Surface generated nitric oxide (NO) can be used to reduce platelet activation and coagulation on gas exchange fibers, while not inducing patient bleeding due to its short half-life in blood. To generate NO, artificial lungs can be manufactured with PDMS hollow fibers embedded with copper nanoparticles (Cu NP) and supplied with an infusion of the NO donor S-nitroso-N-acetyl-penicillamine (SNAP). The SNAP reacts with Cu NP to generate NO. This study investigates clot formation and gas exchange performance of artificial lungs with either NO-generating Cu-PDMS or standard polymethylpentene (PMP) fibers. One miniature artificial lung (MAL) made with 10 wt% Cu-PDMS hollow fibers and one PMP control MAL were attached to sheep in parallel in a veno-venous extracorporeal membrane oxygenation circuit (n = 8). Blood flow through each device was set at 300 mL/min, and each device received a SNAP infusion of 0.12 µmol/min. The ACT was between 110 and 180 s in all cases. Blood flow resistance was calculated as a measure of clot formation on the fiber bundle. Gas exchange experiments comparing the two groups were conducted every 24 h at blood flow rates of 300 and 600 mL/min. Devices were removed once the resistance reached 3x baseline (failure) or following 72 h. All devices were imaged using scanning electron microscopy (SEM) at the inlet, outlet, and middle of the fiber bundle. The Cu-PDMS NO generating MALs had a significantly smaller increase in resistance compared to the control devices. Resistance rose from 26 ±â€¯8 and 23 ±â€¯5 in the control and Cu-PDMS devices, respectively, to 35 ±â€¯8 mmHg/(mL/min) and 72 ±â€¯23 mmHg/(mL/min) at the end of each experiment. The resistance and SEM imaging of fiber surfaces demonstrate lower clot formation on Cu-PDMS fibers. Although not statistically significant, oxygen transfer for the Cu-PDMS MALs was 13.3% less than the control at 600 mL/min blood flow rate. Future in vivo studies with larger Cu-PDMS devices are needed to define gas exchange capabilities and anticoagulant activity over a long-term study at clinically relevant ACTs. STATEMENT OF SIGNIFICANCE: In artificial lungs, the large, densely-packed blood contacting surface area of the hollow fiber bundle is critical for gas exchange but also creates rapid, surface-generated clot requiring significant anticoagulation. Monitoring of anticoagulation, thrombosis, and resultant complications has kept permanent respiratory support from becoming a clinical reality. In this study, we use a hollow fiber material that generates nitric oxide (NO) to prevent platelet activation at the blood contacting surface. This material is tested in vivo in a miniature artificial lung and compared against the clinical standard. Results indicated significantly reduced clot formation. Surface-focused anticoagulation like this should reduce complication rates and allow for permanent respiratory support by extending the functional lifespan of artificial lungs and can further be applied to other medical devices.

Enhancement of gemcitabine cytotoxicity in pancreatic adenocarcinoma through controlled release of nitric oxide.

Gemcitabine (GEM) is the first-line treatment for pancreatic adenocarcinoma (PAC) yet chemoresistance is common. Nitric oxide (NO) is the predominant species responsible for the cytotoxic action of macrophages against cancer cells yet localized delivery is difficult given the short half-life. We sought to study the effect of locally delivered NO on GEM mediated PAC cytotoxicity and the potential role of SMAD4 in this effect. We hypothesized that NO would enhance the cytotoxicity of GEM in a SMAD4 dependent manner. NO-Silica nanoparticles (NO-Si) were synthesized via a co-condensation of tetraethoxysilane with aminoalkoxysilane under high-pressure nitrous oxide. NO release was measured using chemiluminescence. A SMAD4 negative PAC cell line (SMAD4-) was made using retroviral knockdown of Panc1 PAC cells. Panc1 and SMAD4- cells were treated with gemcitabine (100 nm (hi) to 30 µm (lo)), 30 mg NOSi particles, or both (NOSihi or NOSilo) and cell viability assessed. NoSi reduced cell viability by 25.99% in Panc1 and 24.38% in SMAD4-. When combined with gemcitabine, further reductions were seen in a dose dependent manner for both cell lines. We have demonstrated the in-vitro dose dependent cytotoxic effects of NOSi. When combined with GEM there is a synergistic effect resulting in improved cytotoxicity seen in both Panc1 and SMAD4- PAC cells with a differential pattern of cell death seen at high concentrations of NO. These findings suggest not only that NO is useful chemosensitizing agent but that SMAD4- may play a role in its synergism with GEM.

Dairy milk proteins attenuate hyperglycemia-induced impairments in vascular endothelial function in adults with prediabetes by limiting increases in glycemia and oxidative stress that reduce nitric oxide bioavailability.

Postprandial hyperglycemia (PPH) transiently impairs vascular endothelial function (VEF) in an oxidative stress-dependent manner by decreasing nitric oxide (NO•) bioavailability. Dairy milk and its proteins attenuate PPH, but whether this improves VEF is unknown. We hypothesized that dairy milk, mediated by its whey and/or casein proteins, improves VEF by attenuating PPH-induced oxidative stress that otherwise decreases NO• bioavailability. A randomized, cross-over trial was conducted in adults with prediabetes (n=23) who ingested glucose (75 g, GLU) alone or with 473 mL of non-fat dairy milk (MILK) or isonitrogenous (16.5 g) amounts of whey (WHEY) or casein (CASEIN) in 473 mL of water. Prior to and at 30 min intervals for 180 min postprandially, we assessed brachial artery flow-mediated dilation (FMD) and measured biomarkers of glycemic control, oxidative stress, and NO• homeostasis. FMDAUC decreased to the greatest extent during GLU, which was similarly improved in dairy trials. Compared with GLU, AUCs for glucose, malondialdehyde, F2-isoprostanes, methylglyoxal, and endothelin-1 were similarly lower in dairy trials. Plasma arginine and NO• metabolites were greater but methylated arginine metabolites were lower in dairy trials compared with GLU. Postprandial insulin, lipids, and tetrahydrobiopterin redox status did not differ among trials. Thus, dairy milk, mediated by its whey and casein proteins, attenuates PPH-mediated impairments in VEF by limiting oxidative stress. This improves NO• bioavailability to the vascular endothelium by increasing arginine availability and limiting competitive inhibition on NO• biosynthesis by asymmetric dimethylarginine. These findings support observational studies that dairy milk lowers cardiovascular disease risk.

Dairy milk, regardless of fat content, protects against postprandial hyperglycemia-mediated impairments in vascular endothelial function in adults with prediabetes by limiting oxidative stress responses that reduce nitric oxide bioavailability.

Postprandial hyperglycemia (PPH) transiently impairs vascular endothelial function (VEF) in an oxidative-stress-dependent manner by decreasing nitric oxide (NO•) bioavailability. Dairy milk, regardless of fat content, attenuates PPH, but whether this improves VEF by limiting oxidative stress responses that otherwise decrease NO• bioavailability is not known. We hypothesized that nonfat and full-fat dairy milk would similarly improve VEF by attenuating PPH-induced oxidative stress that otherwise decreases NO• biosynthesis and bioavailability. A randomized, crossover trial was conducted in adults with prediabetes (n=22) who ingested glucose (75 g) dissolved in 473 ml of water (GLU), or glucose with an equal volume of nonfat dairy milk (NFM) or full-fat dairy milk (FFM). Prior to and at 30-min intervals for 180 min postprandially, we assessed brachial artery flow-mediated dilation (FMD) and measured circulating biomarkers of glycemic control, oxidative stress and NO• homeostasis. AUC0-180 min for FMD and NO• metabolites was lowest in GLU but relatively greater in NFM and FFM. Compared with GLU, AUCs for glucose, malondialdehyde, F2-isoprostanes and endothelin-1 were similarly lower in dairy trials. Milk-mediated vasoprotection was accompanied by greater levels of plasma arginine and lower levels of asymmetric dimethylarginine and symmetric dimethylarginine. Postprandial insulin, lipids and tetrahydrobiopterin redox status did not differ among trials. Thus, dairy milk, regardless of its fat content, attenuates PPH-mediated impairments in VEF by limiting oxidative stress. This improves NO• bioavailability to the vascular endothelium by increasing arginine availability and limiting competitive inhibition on NO• biosynthesis by asymmetric dimethylarginine.

Nitric oxide-releasing semi-crystalline thermoplastic polymers: preparation, characterization and application to devise anti-inflammatory and bactericidal implants.

Semi-crystalline thermoplastics are an important class of biomaterials with applications in creating extracorporeal and implantable medical devices. In situ release of nitric oxide (NO) from medical devices can enhance their performance via NO's potent anti-thrombotic, bactericidal, anti-inflammatory, and angiogenic activity. However, NO-releasing semi-crystalline thermoplastic systems are limited and the relationship between polymer crystallinity and NO release profile is unknown. In this paper, the functionalization of poly(ether-block-amide) (PEBA), Nylon 12, and polyurethane tubes, as examples of semi-crystalline polymers, with the NO donor S-nitroso-N-acetylpenicillamine (SNAP) within, is demonstrated via a polymer swelling method. The degree of crystallinity of the polymer plays a crucial role in both SNAP impregnation and NO release. Nylon 12, which has a relatively high degree of crystallinity, exhibits an unprecedented NO release duration of over 5 months at a low NO level, while PEBA tubing exhibits NO release over days to weeks. As a new biomedical application of NO, the NO-releasing PEBA tubing is examined as a cannula for continuous subcutaneous insulin infusion. The released NO is shown to enhance insulin absorption into the bloodstream probably by suppressing the tissue inflammatory response, and thereby could benefit insulin pump therapy for diabetes management.

Plant-inspired gallolamine catalytic surface chemistry for engineering an efficient nitric oxide generating coating.

A novel concept of generating therapeutic gas, nitric oxide (NO) via catalytic phenolic-amine "gallolamine" surface chemistry is developed. The concept is realized using plant polyphenol, gallic acid, and a glutathione peroxidase-like organoselenium compound cystamine or selenocystamine through one-step phenol-amine molecular assembling process. The resulting NO-generating coating with phenolic-cystamine or -selenocystamine framework showed the ability for long-term, steady and controllable range of NO release rates being unparalleled with any existing NO-releasing or NO-generating surface engineering toolkits. STATEMENT OF SIGNIFICANCE: Developing a facile and versatile strategy for a NO-generating coating with long-term, stable and adjustable NO release is of great interest for the application of blood-contacting materials and devices. Covalent immobilization of glutathione peroxidase (GPx)-like compound to generate NO from a material surface by exposure of endogenously existed S-nitrothiol (RSNO) is a popular strategy. However, it is generally involved in multi-step and complicated processes. Moreover, the amount of immobilized GPx-like compounds is limited by the density of introduced reactive functional groups on a surface. Herein, we propose a novel concept of catalytic plant-inspired gallolamine surface chemistry for material-independent NO-generating coatings. The concept is realized using plant polyphenol, gallic acid, and a GPx-like organoselenium compound cystamine or selenocystamine through one-step phenol-amine molecular assembling process. Without tedious multi-step synthesis, complicated surface treatments, and leakage of toxic chemicals, our unprecedentedly simple, histocompatible and biocompatible phenolic-cystamine or -selenocystamine framework demonstrated long-term, on-demand and facile dose controls of NO generated from the engineering surfaces. These unique features of such a NO-generating coating imparted a material with ability to impressively improve anti-thrombogenicity in vivo. This work constitutes the first report of an interfacial catalytic coating based on material-independent surface chemistry by plant polyphenols. This concept not only expands the application of material-independent surface chemistry in an interfacial catalytic area, but also can be a new platform for antithrombotic materials.

Nitric Oxide-Releasing Macromolecular Scaffolds for Antibacterial Applications.

Exogenous nitric oxide (NO) represents an attractive antibacterial agent because of its ability to both disperse and directly kill bacterial biofilms while avoiding resistance. Due to the challenges associated with administering gaseous NO, NO-releasing macromolecular scaffolds are developed to facilitate NO delivery. This progress report describes the rational design and application of NO-releasing macromolecular scaffolds as antibacterial therapeutics. Special consideration is given to the role of the physicochemical properties of the NO storage vehicles on antibacterial or anti-biofilm activity.

Supramolecular poly(acrylic acid)/F127 hydrogel with hydration-controlled nitric oxide release for enhancing wound healing.

Topical nitric oxide (NO) delivery has been shown to accelerate wound healing. However, delivering NO to wounds at appropriate rates and doses requires new biomaterial-based strategies. Here, we describe the development of supramolecular interpolymer complex hydrogels comprising PEO-PPO-PEO (F127) micelles embedded in a poly(acrylic acid) (PAA) matrix, with S-nitrosoglutathione (GSNO) molecules dissolved in the hydrophilic domain. We show that PAA:F127/GSNO hydrogels start releasing NO upon hydration at rates controlled by their rates of water absorption. SAXS measurements indicate that the supramolecular structure of the hydrogels retains long-range order domains of F127 micelles. The PAA/F1227 hydrogels displayed dense morphologies and reduced rates of hydration. The NO release rates remain constant over the first 200 min, are directly correlated with the hydration rates of the PAA:F127/GSNO hydrogels, and can be modulated in the range of 40 nmol/g h to 1.5 µmol/g h by changing the PAA:F127 mass ratio. Long-term NO-release profiles over 5 days are governed by the first-order exponential decay of GSNO, with half-lives in the range of 0.5-3.4 days. A preliminary in vivo study on full-thickness excisional wounds in mice showed that topical NO release from the PAA:F127/GSNO hydrogels is triggered by exudate absorption and leads to increased angiogenesis and collagen fiber organization, as well as TGF-ß, IGF-1, SDF-1, and IL-10 gene expressions in the cicatricial tissue. In summary, these results suggest that hydration-controlled NO release from topical PAA:F127/GSNO hydrogels is a potential strategy for enhancing wound healing. STATEMENT OF SIGNIFICANCE: The topical delivery of nitric oxide (NO) to wounds may provide significant beneficial results and represent a promising strategy to treat chronic wounds. However, wound dressings capable of releasing NO after application and allowing the modulation of NO release rates, demand new platforms. Here, we describe a novel strategy to overcome these challenges, based on the use of supramolecular poly(acrylic acid) (PAA):F127 hydrogels charged with the NO donor S-nitrosoglutathione (GSNO) from whereby the NO release can be triggered by exudate absorption and delivered to the wound at rates controlled by the PAA:F127 mass ratio. Preliminary in vivo results offer a proof of concept for this strategy by demonstrating increased angiogenesis; collagen fibers organization; and TGF-ß, IGF-1, SDF-1, and IL-10 gene expressions in the cicatricial tissue after topical treatment with a PAA:F127/GSNO hydrogel.

Endothelial nitric oxide synthase polymorphisms affect the changes in blood pressure and nitric oxide bioavailability induced by propofol.

Propofol anesthesia is usually accompanied by hypotension, which is at least in part related to enhanced endothelial nitric oxide synthase (NOS3)-derived NO bioavailability. We examined here whether NOS3 polymorphisms (rs2070744, 4b/4a VNTR, rs3918226 and rs1799983) and haplotypes affect the changes in blood pressure and NO bioavailability induced by propofol. Venous blood samples were collected from 168 patients at baseline and after 10 min of anesthesia with propofol 2 mg/kg administered intravenously by bolus injection. Genotypes were determined by polymerase chain reaction and haplotype frequencies were estimated. Nitrite concentrations were measured by using an ozone-based chemiluminescence assay, while NOx (nitrites + nitrates) levels were determined by using the Griess reaction. We found that CT + TT genotypes for the rs3918226 polymorphism, the ba + aa genotypes for the 4b/4a VNTR and the CTbT haplotype were associated with lower decreases in blood pressure and lower increases in nitrite levels after propofol anesthesia. On the other hand, the TCbT and CCbT haplotypes were associated with more intense decreases in blood pressure and higher increases in nitrite levels in response to propofol. Our results suggest that NOS3 polymorphisms and haplotypes influence the hypotensive responses to propofol, possibly by affecting NO bioavailability.