Investigating the Poverty-Reducing Effects of SNAP on Non-nutritional Family Outcomes: A Scoping Review.

INTRODUCTION/PURPOSE: Poverty-reduction efforts that seek to support households with children and enable healthy family functioning are vital to produce positive economic, health, developmental, and upward mobility outcomes. The Supplemental Nutrition Assistance Program (SNAP) is an effective poverty-reduction policy for individuals and families. This study investigated the non-nutritional effects that families experience when receiving SNAP benefits. METHODS: We conducted a scoping review using the PRISMA Guidelines and strategic search terms across seven databases from 01 January 2008 to 01 February 2023 (n=2456). Data extraction involved two researchers performing title-abstract reviews. Full-text articles were assessed for eligibility (n=103). Forty articles were included for data retrieval. RESULTS: SNAP positively impacts family health across the five categories of the Family Stress Model (Healthcare utilization for children and parents, Familial allocation of resources, Impact on child development and behavior, Mental health, and Abuse or neglect). DISCUSSION/CONCLUSION: SNAP is a highly effective program with growing evidence that it positively impacts family health and alleviates poverty. Four priority policy actions are discussed to overcome the unintentional barriers for SNAP: distributing benefits more than once a month; increasing SNAP benefits for recipients; softening the abrupt end of benefits when wages increase; and coordinating SNAP eligibility and enrollment with other programs.

An Assessment of Blood Vessel Remodeling of Nanofibrous Poly(ε-Caprolactone) Vascular Grafts in a Rat Animal Model.

The development of an ideal vascular prosthesis represents an important challenge in terms of the treatment of cardiovascular diseases with respect to which new materials are being considered that have produced promising results following testing in animal models. This study focuses on nanofibrous polycaprolactone-based grafts assessed by means of histological techniques 10 days and 6 months following suturing as a replacement for the rat aorta. A novel stereological approach for the assessment of cellular distribution within the graft thickness was developed. The cellularization of the thickness of the graft was found to be homogeneous after 10 days and to have changed after 6 months, at which time the majority of cells was discovered in the inner layer where the regeneration of the vessel wall was found to have occurred. Six months following implantation, the endothelialization of the graft lumen was complete, and no vasa vasorum were found to be present. Newly formed tissue resembling native elastic arteries with concentric layers composed of smooth muscle cells, collagen, and elastin was found in the implanted polycaprolactone-based grafts. Moreover, the inner layer of the graft was seen to have developed structural similarities to the regular aortic wall. The grafts appeared to be well tolerated, and no severe adverse reaction was recorded with the exception of one case of cartilaginous metaplasia close to the junctional suture.

Control of Orthodontic Tooth Movement by Nitric Oxide Releasing Nanoparticles in Sprague-Dawley Rats.

Orthodontic treatment commonly requires the need to prevent movement of some teeth while maximizing movement of other teeth. This study aimed to investigate the influence of locally injected nitric oxide (NO) releasing nanoparticles on orthodontic tooth movement in rats. Materials and Methods: Experimental tooth movement was achieved with nickel-titanium alloy springs ligated between the maxillary first molar and ipsilateral incisor. 2.2 mg/kg of silica nanoparticles containing S-nitrosothiol groups were injected into the mucosa just mesial to 1st molar teeth immediately prior to orthodontic appliance activation. NO release from nanoparticles was measured in vitro by chemiluminescence. Tooth movement was measured using polyvinyl siloxane impressions. Bones were analyzed by microcomputed tomography. Local tissue was assessed by histomorphometry. Results: Nanoparticles released a burst of NO within the first hours at approximately 10 ppb/mg particles that diminished by 10 × to approximately 1 ppb/mg particles over the next 1-4 days, and then diminished again by tenfold from day 4 to day 7, at which point it was no longer measurable. Molar but not incisor tooth movement was inhibited over 50% by injection of the NO releasing nanoparticles. Inhibition of molar tooth movement occurred only during active NO release from nanoparticles, which lasted for approximately 1 week. Molar tooth movement returned to control levels of tooth movement after end of NO release. Alveolar and long bones were not impacted by injection of the NO releasing nanoparticles, and serum cyclic guanosine monophosphate (cGMP) levels were not increased in animals that received the NO releasing nanoparticles. Root resorption was decreased and periodontal blood vessel numbers were increased in animals with appliances that were injected with the NO releasing nanoparticles as compared to animals with appliances that did not receive injections with the nanoparticles. Conclusion: Nitric oxide (NO) release from S-nitrosothiol containing nanoparticles inhibits movement of teeth adjacent to the site of nanoparticle injection for 1 week. Additional studies are needed to establish biologic mechanisms, optimize efficacy and increase longevity of this orthodontic anchorage effect.

Dual Switch Mechanism of Erythropoietin as an Antiapoptotic and Pro-Angiogenic Determinant in the Retina.

Constant or intense light degenerates the retina and retinal pigment epithelial cells. Light generates reactive oxygen species and nitric oxide leading to initial reactions of retinal degeneration. Apoptosis is the primary mechanism of abnormal death of photoreceptors, retinal ganglion cells, or retinal pigment epithelium (RPE) in degenerative retinal diseases, including diabetic retinopathy and age-related macular degeneration. The current study evaluated the function of erythropoietin (EPO) on angiogenesis and apoptosis in the retina and RPE under oxidative stress. We determined the pro-angiogenic and antiapoptotic mechanism of EPO under stress conditions using a conditional EPO knockdown model using siRNA, EPO addition, proteomics, immunocytochemistry, and bioinformatic analysis. Our studies verified that EPO protected retinal cells from light-, hypoxia-, hyperoxia-, and hydrogen peroxide-induced apoptosis through caspase inhibition, whereas up-regulated angiogenic reactions through vascular endothelial growth factor (VEGF) and angiotensin pathway. We demonstrated that the EPO expression in the retina and subsequent serine/threonine/tyrosine kinase phosphorylations might be linked to oxidative stress response tightly to determining angiogenesis and apoptosis. Neuroprotective roles of EPO may involve the balance between antiapoptotic and pro-angiogenic signaling molecules, including BCL-xL, c-FOS, caspase-3, nitric oxide, angiotensin, and VEGF receptor. Our data indicate a new therapeutic application of EPO toward retinal degeneration based on the dual roles in apoptosis and angiogenesis at the molecular level under oxidative stress.

A case study exploring associations between popular media attention of scientific research and scientific citations.

The association between mention of scientific research in popular media (e.g., the mainstream media or social media platforms) and scientific impact (e.g., citations) has yet to be fully explored. The purpose of this study was to clarify this relationship, while accounting for some other factors that likely influence scientific impact (e.g., the reputations of the scientists conducting the research and academic journal in which the research was published). To accomplish this purpose, approximately 800 peer-reviewed articles describing original research were evaluated for scientific impact, popular media attention, and reputations of the scientists/authors and publication venue. A structural equation model was produced describing the relationship between non-scientific impact (popular media) and scientific impact (citations), while accounting for author/scientist and journal reputation. The resulting model revealed a strong association between the amount of popular media attention given to a scientific research project and corresponding publication and the number of times that publication is cited in peer-reviewed scientific literature. These results indicate that (1) peer-reviewed scientific publications receiving more attention in non-scientific media are more likely to be cited than scientific publications receiving less popular media attention, and (2) the non-scientific media is associated with the scientific agenda. These results may inform scientists who increasingly use popular media to inform the general public and scientists concerning their scientific work. These results might also inform administrators of higher education and research funding mechanisms, who base decisions partly on scientific impact.

S-Nitroso-N-Acetyl-D-Penicillamine Modified Hyperbranched Polyamidoamine for High-Capacity Nitric Oxide Storage and Release.

Synthetic nitric oxide (NO)-donating materials have been shown to have many beneficial effects when incorporated into biomedical materials. When released in the correct dosage, NO has been shown to increase the biocompatibility of blood and tissue contacting materials, but materials are often limited in the amount of NO that can be administered over a period of time. To address this, hyperbranched polyamidoamine (HPAMAM) was modified with the S-nitrosothiol, S-nitroso-N-acetyl-D-penicillamine, and nitrosated to form a controlled, high-capacity NO-donating compound (SNAP-HPAMAM). This compound has the potential of modifying polymers to release NO over long periods of time by being blended into a variety of base polymers. Nitric oxide release was triggered by photoinitiation and through passive ion-mediated release seen under physiological conditions. A material that delivers the beneficial dose of NO over a long period of time would be able to greatly increase the biocompatibility of long-term implantable devices. Structural analysis of a generation 2 HPAMAM molecule was done through Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance spectroscopy (NMR), and matrix assisted laser desorption ionization, time of flight (MALDI-TOF) mass spectrometry. The NO capacity of the finalized generation 2 SNAP-HPAMAM compound was approximately 1.90 ± 0.116 µmol NO/mg. Quantification of the functional groups in the compound proved that an average of 6.40 ± 0.309 reactive primary amine sites were present compared to the 8 reactive sites on a perfectly synthesized generation 2 dendrimer. There is a substantial advantage of using the hyper-branched HPAMAM over purified dendrimers in terms of reduced labor and expense while still providing a high-capacity NO donor that can be blended into different polymer matrices.

Magnetoelastic galfenol as a stent material for wirelessly controlled degradation rates.

The gold standard of care for coronary artery disease, a leading cause of death for in the world, is balloon angioplasty in conjunction with stent deployment. However, implantation injuries and long-term presence of foreign material often promotes significant luminal tissue growth, leading to a narrowing of the artery and severely restricted blood flow. A promising method to mitigate this process is the use of biodegradable metallic stents, but thus far they have either degraded too slowly (iron) or disappeared prematurely (magnesium). The present work investigates the use of a unique type of magnetic material, galfenol (iron-gallium), for postoperative wireless control of stent degradation rates. Due to its magnetoelastic property, galfenol experiences longitudinal micron-level elongations when exposed to applied magnetic fields, allowing generation of a microstirring effect that affect its degradation behavior. In vitro indirect cytotoxicity tests on primary rat aortic smooth muscle cells indicated that galfenol byproducts must be concentrated approximately seven times from collected 60 day degradation medium to cause ∼15% of death from all cells. Surface and cross-sectional characterization of the material indicate that galfenol (Fe80 Ga20 ) degradation rates (∼0.55% per month) are insufficient for stenting applications. While this material may not be ideal for comprising the entire stent, there is potential for use in combination with other materials. Furthermore, the ability to control degradation rates postimplantation opens new possibilities for biodegradable stents; additional magnetoelastic materials should be investigated for use in stenting applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 232-241, 2019.

Biomimetic recyclable microgels for on-demand generation of hydrogen peroxide and antipathogenic application.

Microgels that can generate antipathogenic levels of hydrogen peroxide (H2O2) through simple rehydration in solutions with physiological pH are described herein. H2O2 is a widely used disinfectant but the oxidant is hazardous to store and transport. Catechol, an adhesive moiety found in mussel adhesive proteins, was incorporated into microgels, which generated 1-5 mM of H2O2 for up to four days as catechol autoxidized. The sustained release of low concentrations of H2O2 was antimicrobial against both gram-positive (Staphylococcus epidermidis) and gram-negative (Escherichia coli) bacteria and antiviral against both non-enveloped porcine parvovirus (PPV) and enveloped bovine viral diarrhea virus (BVDV). The amount of released H2O2 is several orders of magnitude lower than H2O2 concentration previously reported for antipathogenic activity. Most notably, these microgels reduced the infectivity of the more biocide resistant non-envelope virus by 3 log reduction value (99.9% reduction in infectivity). By controlling the oxidation state of catechol, microgels can be repeatedly activated and deactivated for H2O2 generation. These microgels do not contain a reservoir for storing the reactive H2O2 and can potentially function as a lightweight and portable dried powder source for the disinfectant for a wide range of applications. STATEMENT OF SIGNIFICANCE: Researchers have designed bioadhesives and coatings using the adhesive moiety catechol to mimic the strong adhesion capability of mussel adhesive proteins. During catechol autoxidation, hydrogen peroxide (H2O2) is generated as a byproduct. Here, catechol was incorporated into microgels, which can generate millimolar levels of H2O2 by simply hydrating the microgels in a solution with physiological pH. The sustained release of H2O2 was both antimicrobial and antiviral, inactivating even the more biocide resistant non-enveloped virus. These microgels can be repeatedly activated and deactivated for H2O2 generation by incubating them in solutions with different pH. This simplicity and recyclability will enable this biomaterial to function as a lightweight and portable source for the disinfectant for a wide range of applications.

Investigative Study on Nitric Oxide Production in Human Dermal Fibroblast Cells under Normal and High Glucose Conditions.

Diabetic foot ulcers (DFU) are a major health problem associated with diabetes mellitus. Impaired nitric oxide (NO) production has been shown to be a major contributor to the dysregulation of healing in DFU. The level of impairment is not known primarily due to challenges with measuring NO. Herein, we report the actual level of NO produced by human dermal fibroblasts cultured under normal and high glucose conditions. Fibroblasts produce the extracellular matrix, which facilitate the migration of keratinocytes to close wounds. The results show that NO production was significantly higher in normal glucose compared to high glucose conditions. The real-time NO detected was compared to the nitrite present in the culture media and there was a direct correlation between real-time NO and nitrite in normal glucose conditions. However, real-time NO detection and nitrite measurement did not correlate under high glucose conditions. The inducible nitric oxide synthase (iNOS) enzyme responsible for NO production was upregulated in normal and high glucose conditions and the proliferation rate of fibroblasts was not statistically different in all the treatment groups. Relying only on nitrite to assess NO production is not an accurate determinant of the NO present in the wound bed in pathological states such as diabetes mellitus.

Synthesis and Characterization of Controlled Nitric Oxide Release from S-Nitroso-N-Acetyl-d-Penicillamine Covalently Linked to Polyvinyl Chloride (SNAP-PVC).

Polyvinyl chloride (PVC) is one of the most widely used polymers in medicine but has very poor biocompatibility when in contact with tissue or blood. To increase biocompatibility, controlled release of nitric oxide (NO) can be utilized to mitigate and reduce the inflammatory response. A synthetic route is described where PVC is aminated to a specified degree and then further modified by covalently linking S-nitroso-N-acetyl-d-penicillamine (SNAP) groups to the free primary amine sites to create a nitric oxide releasing polymer (SNAP-PVC). Controllable release of NO from SNAP-PVC is described using photoinitiation from light emitting diodes (LEDs). Ion-mediated NO release is also demonstrated as another pathway to provide a passive mechanism for NO delivery. The large range of NO fluxes obtained from the SNAP-PVC films indicate many potential uses in mediating unwanted inflammatory response in blood- and tissue-contacting devices and as a tool for delivering precise amounts of NO in vitro.

Direct measurement of actual levels of nitric oxide (NO) in cell culture conditions using soluble NO donors.

Applying soluble nitric oxide (NO) donors is the most widely used method to expose cells of interest to exogenous NO. Because of the complex equilibria that exist between components in culture media, the donor compound and NO itself, it is very challenging to predict the dose and duration of NO cells actually experience. To determine the actual level of NO experienced by cells exposed to soluble NO donors, we developed the CellNO Trap, a device that allows continuous, real-time monitoring of the level of NO adherent cells produce and/or experience in culture without the need to alter cell culturing procedures. Herein, we directly measured the level of NO that cells grown in the CellNO Trap experienced when soluble NO donors were added to solutions in culture wells and we characterized environmental conditions that effected the level of NO in in vitro culture conditions. Specifically, the dose and duration of NO generated by the soluble donors S-nitroso-N-acetylpenicillamine (SNAP), S-nitrosoglutathione (GSNO), S-nitrosocysteine (CysNO) and the diazeniumdiolate diethyltriamine (DETA/NO) were investigated in both phosphate buffered saline (PBS) and cell culture media. Other factors that were studied that potentially affect the ultimate NO level achieved with these donors included pH, presence of transition metals (ion species), redox level, presence of free thiol and relative volume of media. Then murine smooth muscle cell (MOVAS) with different NO donors but with the same effective concentration of available NO were examined and it was demonstrated that the cell proliferation ratio observed does not correlate with the half-lives of NO donors characterized in PBS, but does correlate well with the real-time NO profiles measured under the actual culture conditions. This data demonstrates the dynamic characteristic of the NO and NO donor in different biological systems and clearly illustrates the importance of tracking individual NO profiles under the actual biological conditions.

CellNO trap: Novel device for quantitative, real-time, direct measurement of nitric oxide from cultured RAW 267.4 macrophages.

Nitric oxide (NO), is arguably one of the most important small signaling molecules in biological systems. It regulates various biological responses in both physiological and pathological conditions, often time producing seemingly contradictory results. The details of the effects of NO are highly dependent on the level of NO that cells experience and the temporal aspect of when and how long cells are exposed to NO. Herein, we present a novel measurement system (CellNO trap) that allows real-time NO measurement via chemiluminescence detection from general adhesive cultured cells using standard cell culture media and reagents that does not perturb the cells under investigation. Highly controlled light-initiated NO releasing polymer SNAP-PDMS was used to characterize and validate the quantitative data nature of the device. The NO generation profile from the macrophage cell-line RAW264.7 stimulated by 100ng/ml LPS and 10ng/ml IFN-γ was recorded. Measured maximum NO flux from RAW264.7 varied between around 2.5-9pmol/10(6)cell/s under 100ng/ml LPS and 10ng/ml IFN-γ stimulation, and 24h cumulative NO varied between 157 and 406 nmol/10(6)cell depending on different culture conditions, indicating the conventional report of an average flux or maximum flux is not sufficient to represent the dynamic characters of NO. LPS and IFN-γ's synergistic effect to RAW264.7 NO generation was also directly observed with the CellNO trap. The real-time effect on the NO generation from RAW264.7 following the addition of arginine, nor-NOHA and L-NAME to the cultured cells is presented. There is great potential to further our understanding of the role NO plays in normal and pathological conditions clearly understanding the dynamic production of NO in response to different stimuli and conditions; use of CellNO trap makes it possible to quantitatively determine the precise NO release profile generated from cells in a continuous and real-time manner with chemiluminescence detection.

Transition-Metal-Mediated Release of Nitric Oxide (NO) from S-Nitroso-N-acetyl-d-penicillamine (SNAP): Potential Applications for Endogenous Release of NO at the Surface of Stents Via Corrosion Products.

Nitric oxide (NO), identified over the last several decades in many physiological processes and pathways as both a beneficial and detrimental signaling molecule, has been the subject of extensive research. Physiologically, NO is transported by a class of donors known as S-nitrosothiols. Both endogenous and synthetic S-nitrosothiols have been reported to release NO during interactions with certain transition metals, primarily Cu(2+) and Fe(2+). Ag(+) and Hg(2+) have also been identified, although these metals are not abundantly present in physiological systems. Here, we evaluate Pt(2+), Fe(2+), Fe(3+), Mg(2+), Zn(2+), Mn(2+), Co(2+), Ni(2+), and Cu(2+) for their ability to generate NO from S-nitroso-N-acetyl-d-penicillamine (SNAP) under physiological pH conditions. Specifically, we report NO generation from RSNOs initiated by three transition metal ions; Co(2+), Ni(2+), and Zn(2+), which have not been previously reported to generate NO. Additionally, preliminary in vivo evidence of zinc wires implanted in the rat arterial wall and circulating blood is presented which demonstrated inhibited thrombus formation after 6 months. One potentially useful application of these metal ions capable of generating NO from RSNOs is their use in the fabrication of biodegradable metallic stents capable of generating NO at the stent-blood interface, thereby reducing stent-related thrombosis and restenosis.

Synthesis and Characterization of the Novel Nitric Oxide (NO) Donating Compound, S-nitroso-N-acetyl-D-penicillamine Derivatized Cyclam (SNAP-Cyclam).

Nitric oxide (NO) has been heavily studied over the past two decades due to its multitude of physiological functions and its potential therapeutic promise. Of major interest is the desire to fabricate or coat implanted devices with an NO releasing material that will impart the appropriate dose and duration of NO release to positively mediate the biological response to the medical device, thereby improving its safety and efficacy. To date, this goal has not yet been achieved, despite very promising early research. Herein, we describe the synthesis and NO release properties of a novel NO donor which covalently links the S-nitrosothiol, S-nitroso-N-acetyl-D-penicillamine (SNAP), to the macrocycle, cyclam (SNAP-cyclam). This compound can then be blended into a wide variety of polymer matrices, imparting NO release to the polymer system. This release can be initiated and controlled by transition metal catalysis, thermal degradation or photolytic release of NO from the composite NO-releasing material. SNAP-cyclam is capable of releasing physiologically relevant levels of NO for up to 3 months in vitro when blended into poly(l-lactic acid) thin films.

Fabrication and Short-Term in Vivo Performance of a Natural Elastic Lamina-Polymeric Hybrid Vascular Graft.

Although significant advances have been made in the development of artificial vascular grafts, small-diameter grafts still suffer from excessive platelet activation, thrombus formation, smooth muscle cell intimal hyperplasia, and high occurrences of restenosis. Recent discoveries demonstrating the excellent blood-contacting properties of the natural elastic lamina have raised the possibility that an acellular elastic lamina could effectively serve as a patent blood-contacting surface in engineered vascular grafts. However, the elastic lamina alone lacks the requisite mechanical properties to function as a viable vascular graft. Here, we have screened a wide range of biodegradable and biostable medical-grade polymers for their ability to adhere to the outer surface of the elastic lamina and allow cellular repopulation following engraftment in the rat abdominal aorta. We demonstrate a novel method for the fabrication of elastic lamina-polymeric hybrid small-diameter vascular grafts and identify poly(ether urethane) (PEU 1074A) as ideal for this purpose. In vivo results demonstrate graft patency over 21 days, with low thrombus formation, mild inflammation, and the general absence of smooth muscle cell hyperplasia on the graft's luminal surface. The results provide a new direction for developing small-diameter vascular grafts that are mass-producible, shelf-stable, and universally compatible due to a lack of immune response and inhibit the in-graft restenosis response that is common to nonautologous materials.

Real-Time Monitoring of Critical Care Analytes in the Bloodstream with Chemical Sensors: Progress and Challenges.

We review approaches and challenges in developing chemical sensor-based methods to accurately and continuously monitor levels of key analytes in blood related directly to the status of critically ill hospitalized patients. Electrochemical and optical sensor-based technologies have been pursued to measure important critical care species in blood [i.e., oxygen, carbon dioxide, pH, electrolytes (K(+), Na(+), Cl(-), etc.), glucose, and lactate] in real-time or near real-time. The two main configurations examined to date for achieving this goal have been intravascular catheter sensors and patient attached ex vivo sensors with intermittent blood sampling via an attached indwelling catheter. We discuss the status of these configurations and the main issues affecting the accuracy of the measurements, including cell adhesion and thrombus formation on the surface of the sensors, sensor drift, sensor selectivity, etc. Recent approaches to mitigate these nagging performance issues that have prevented these technologies from clinical use are also discussed.

Increasing mechanical strength of gelatin hydrogels by divalent metal ion removal.

The usage of gelatin hydrogel is limited due to its instability and poor mechanical properties, especially under physiological conditions. Divalent metal ions present in gelatin such as Ca(2+) and Fe(2+) play important roles in the gelatin molecule interactions. The objective of this study was to determine the impact of divalent ion removal on the stability and mechanical properties of gelatin gels with and without chemical crosslinking. The gelatin solution was purified by Chelex resin to replace divalent metal ions with sodium ions. The gel was then chemically crosslinked by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). Results showed that the removal of divalent metal ions significantly impacted the formation of the gelatin network. The purified gelatin hydrogels had less interactions between gelatin molecules and form larger-pore network which enabled EDC to penetrate and crosslink the gel more efficiently. The crosslinked purified gels showed small swelling ratio, higher crosslinking density and dramatically increased storage and loss moduli. The removal of divalent ions is a simple yet effective method that can significantly improve the stability and strength of gelatin hydrogels. The in vitro cell culture demonstrated that the purified gelatin maintained its ability to support cell attachment and spreading.

Novel device for continuous spatial control and temporal delivery of nitric oxide for in vitro cell culture.

Nitric oxide (NO) is an ubiquitous signaling molecule of intense interest in many physiological processes. Nitric oxide is a highly reactive free radical gas that is difficult to deliver with precise control over the level and timing that cells actually experience. We describe and characterize a device that allows tunable fluxes and patterns of NO to be generated across the surface upon which cells are cultured. The system is based on a quartz microscope slide that allows for controlled light levels to be applied to a previously described photosensitive NO-releasing polydimethylsiloxane (PDMS). Cells are cultured in separate wells that are either NO-releasing or a chemically similar PDMS that does not release NO. Both wells are then top coated with DowCorning RTV-3140 PDMS and a polydopamine/gelatin layer to allow cells to grow in the culture wells. When the waveguide is illuminated, the surface of the quartz slide propagates light such that the photosensitive polymer is evenly irradiated and generates NO across the surface of the cell culture well and no light penetrates into the volume of the wells where cells are growing. Mouse smooth muscle cells (MOVAS) were grown in the system in a proof of principle experiment, whereby 60% of the cells were present in the NO-releasing well compared to control wells after 17 h. The compelling advantage of illuminating the NO-releasing polymers with the waveguide system is that light can be used to tunably control NO release while avoiding exposing cells to optical radiation. This device provides means to quantitatively control the surface flux, timing and duration of NO cells experience and allows for systematic study of cellular response to NO generated at the cell/surface interface in a wide variety of studies.

S-nitroso-N-acetylpenicillamine (SNAP) derivatization of peptide primary amines to create inducible nitric oxide donor biomaterials.

An S-nitroso-N-acetylpenicillamine (SNAP) derivatization approach was used to modify existing free primary amines found in fibrin (a natural protein-based biomaterial) to generate a controlled nitric oxide (NO) releasing scaffold material. The duration of the derivatization reaction affects the NO release kinetics, the induction of controlled NO-release, hydrophobicity, swelling behavior, elastic moduli, rheometric character, and degradation behavior. These properties were quantified to determine changes in fibrin hydrogels following covalent attachment of SNAP. NO-releasing materials exhibited minimal cytotoxicity when cultured with fibroblasts or osteoblasts. Cells maintained viability and proliferative character on derivatized materials as demonstrated by Live/Dead cell staining and counting. In addition, SNAP-derivatized hydrogels exhibited an antimicrobial character indicative of NO-releasing materials. SNAP derivatization of natural polymeric biomaterials containing free primary amines offers a means to generate inducible NO-releasing biomaterials for use as an antimicrobial and regenerative support for tissue engineering.