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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Chitosan/Polyaniline Conductive Blends for Developing Packaging: Electrical, Morphological, Structural and Thermal Properties

The present study aim to evaluate the development of electrical conducting blends made from the biodegradable polymer, chitosan (Cs), and polyaniline (PANI) doped with dodecylbenzene sulfonic acid dissolved in acid solution chitosan, to enable development of conductive and smart packages that help to monitor exposure conditions of food aimed to reduce food waste. Concentration of Cs is fixed (2%), and PANI (80, 100 mg mL{sup −1}) and glutaraldehyde (Glut) (0.625 × 10{sup −3} μL) concentrations are alter. Morphological (SEM), structural (FTIR, RAMAN), thermal (TGA) and electrical (Hall effect) properties are evaluate. Blends were predominantly negative carriers, with conductivity in order of 10{sup −1} S cm{sup −1}. Best formulations are those make without of Glut. Analyses show an interaction between components. FTIR show bands characteristic of benzene and quinoid rings of PANI, and RAMAN exhibit a band related to PANI’s protonation. TGA show maintenance of maximum degradation temperature of PANI. This results evidence maintenance of PANI’s conducting structures even after blends synthesis.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Adsorption of Zn(II) and Pb(II) Ions from Aqueous Solution Using Chitosan Cross-Linked Formaldehyde Adsorbent to Protect the Environment

Synthesis of chitosan cross-linked formaldehyde was successfully prepared from shrimp chitosan. Characterization of the adsorbent using functional properties such as Fourier transform infrared spectroscopy and scanning electron microscope shows the present of amide and hydroxyl groups at their respective position, also the morphological structure of the adsorbent. Adsorption study of the above adsorbent was carry out for the removal of Zn(II) and Pb(II) from aqueous solution. The effect of cross-linked chitosan dosage, initial concentration, contact time, temperature and pH of the solution for the removal of Zn(II) and Pb(II) were discussed. The optimum dosage required for the removal of Zn(II) and Pb(II) were found to be at 0.4 g at the maximum temperature of 25 °C and the percentage removal were 20.34 and 13.54% respectively. The time required for equilibrium to be reached was 50 min. Effectiveness of the cross-linked adsorbent was observed to increase by increase in contact time. Further studies were also done on isotherms and kinetics of Zn(II) and Pb(II) removal from aqueous solution using chitosan cross-linked formaldehyde. Adsorption Isotherm study conducted from the cross-linked absorbent, shows that the Langmuir plot for the removal of Zn(II) was best fitted with R{sup 2} value of 0.9934, and the adsorption process follows the pseudo second order kinetics with an R{sup 2} value of 0.996. This adsorption process was established to be reversible with an R{sub L} values of zinc (0.8232) and lead (0.8853) respectively. Therefore this implies a successfully reduction in the adsorption of zinc and lead ions from cross-linked formaldehyde solution to protect our environment.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Multidrug Core–Shell Bead: A System for Bacterial Infection Treatment in Fish

This study was developed to improve the durability and bioavailability of polymer matrix containing the antibacterial agent’s bacitracin (BAC), berberine (BER) and sodium nitroprusside (SNP), an ionotropic gelation method was successfully applied to prepare alginate/chitosan core–shell beads. The structure and properties of different core–shell beads were characterized by scanning electron microscopy (SEM), zeta potential, Fourier transform infrared spectroscopy (FTIR), thermal analysis (DSC), swelling tests, bioadhesive assay, release kinetic profile and antibacterial/antibacteriostatic activity in bacterial model. The morphology of beads was investigated by SEM, display relatively spherical shape and revealed rough surface was also observed the appearance of cracks probably caused by partial collapsing of the polymer network during drying. The diameter means particle size observed was around 1.04 ± 0.13 mm, the particles showed a neutral value, around + 0.305 mV. Using UV–Vis technique was observed a high entrapment efficiency of compounds BAC, BER and SNP (> 95%) in the alginate/chitosan core–shell beads. As demonstrated, there is increase in the swelling degree in pH 6.2. The drug release profile showed a pH-dependent release kinetics. At pH 5.0 the most suitable kinetic model is Higuchi, at pH 6.2 a zero-order model is observed, while at pH 7.4 the Korsmeyer–Peppas model present a good fit. The presence of compounds on beads was confirmed using FTIR analyses, and the results indicated that there is no interaction between drugs and vehicle used in the formulation. We can consider after DSC analysis that beads containing BAC, BER and SNP are thermally more stable than separate formulations having the characteristics required for application at room temperature. The release system produced has physical characteristics that allow the storage of the drugs for long periods of time maintaining their chemical and pharmacological properties unchanged. The percentage of adhesion displayed value of 66%, that indicates the improvement in adherence time on the absorbing surfaces to improves drug bioavailability and effectiveness of compounds. In this study is displayed the additive effect between BAC, BER and SNP shown the potential application of compound combinations as an efficient, novel therapeutic tool for antibiotic-resistant bacterial infections. These results indicate that the proposed strategy improves drug bioavailability and effectiveness of compounds in the treatment of fish.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Magnetic Nanoparticles Impregnated, Cross-Linked, Porous Chitosan Microspheres for Efficient Adsorption of Methylene Blue from Pharmaceutical Waste Water

The study demonstrates the preparation of MnFe{sub 2}O{sub 4} impregnated chitosan-microspheres (CMMS) as adsorbents for efficient removal of cationic thiazine dye, methylene blue. A facile approach with great economic and technical advantages to obtain highly crystalline manganese ferrite nanoparticles by solution combustion method is accounted. CMMS were characterized and evaluated for MB adsorption using linear forms of Freundlich and Langmuir adsorption isotherms, pseudo-first order, pseudo-second order and Elovich kinetic models. Application of CMMS to pharmaceutical waste, desorption of MB and reusability of CMMS are reported. Significantly, MB concentration in treated real sample was reduced by ~ 18 times to that of initial concentration. Graphic Abstract: .

36 MATERIALS SCIENCE↗
DOE OSTI2019

Cu(II) Sorption Performance of Novel Chitosan/Ter-(vinyl pivalate-maleic anhydride-N-tert-butylacrylamide) Microcapsules

In this study, first, the ter-polymerization reaction between vinyl pivalate (VP), maleic anhydride (MA), and N-tert-butylacrylamide (NTBA) was done in inert atmosphere (N{sub 2}). FT-IR and {sup 1}HNMR spectroscopy was applied to study the chemical composition of the obtained ter-polymers. MA content of the ter-polymers was determined by following the chemical titration method. Second, novel chitosan/ter-(vinyl-pivalate-maleic-anhydride-N-tert-butylacrylamide) microcapsules were synthesized. In microcapsule production, chitosan polymer served as a matrix for acrylamide ter-polymers with four different molar ratios. The microcapsules were characterized by FT-IR and SEM analyses. Cu(II) sorption efficiency of the microcapsules were tested at different pH levels, temperature, sorbent dosage, and metal ion concentration. Comparison with blank chitosan microbeads revealed that incorporation of acrylamide ter-polymers into the cross-linked chitosan matrix increased the metal sorption. Sorption capacities of the sorbents were recorded; blank chitosan microbeads: 67.03 mg g{sup −1}, and chitosan/acrylamide ter-polymer microcapsules: in range of 75.39–98.64 mg g{sup −1}. The findings demonstrated chitosan/acrylamide ter-polymer microcapsules can be utilized in sorption of Cu(II) ions in water treatment.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Physicochemical, Microstructural and Thermal Characterization of Chitosan from Blue Crab Shell Waste and Its Bioactivity Characteristics

The aim of the present study was to characterize the chitosan synthesized from blue crab (Callinectes sapidus, Rathbun, 1986) shell waste and to investigate its physicochemical and microstructural analyses as well as its antioxidant and antibacterial potentials. Microstructural and elemental characterization of the synthesized and commercial chitosan powders were performed using fourier transform infra-red spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. Thermal analysis were done using thermogravimetric analysis. Antioxidant and antimicrobial analysis were done using by DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical scavenging assay and agar well diffusion assay, respectively. The yield of the synthesized chitosan was calculated as 7.47% with moisture and ash contents of 0.151 ± 0.0025% and 0.19 ± 0.01%, respectively. Synthesized chitosan demonstrated the values of degree of deacetylation (71%), water (620.029 ± 52.59%) and fat (437.93 ± 15.92%) binding capacities, solubility (94.15 ± 2.84%), viscosity (463.25 ± 13.10 cPs) and whiteness (90.23 ± 0.27%). Antioxidant activity of synthesized chitosan was found to be moderate (55.30 ± 5.05%) when compared to ascorbic acid standard (87.61 ± 1.34). Chitosan obtained from blue crab shell also showed moderate antibacterial activity against Staphylococcus aureus and Escherichia coli. The findings of the study indicated that blue crab shell waste might be a potentially effective biopolymer source for commercial applications especially in food industry.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Metal Adsorbance in Abattoir Wastewater Using Cross-Linked Chitosan Derivatives

Isolation of different elements from effluent water obtained from the red meat and the poultry industry was done using a series of modified chitosan cross-linked with glutaraldehyde, formaldehyde, epichlorohydrine, maleic anhydride, p-benzoquinone, poly-(ethylene) glycoldiglycidyl ether (PEG diglycidyl ether), 1-vinyl-2-pyrrolidone, 1,3-dichloroaceone, acrylic acid and s-methylbutylamine. Some parameters of the '22' chitosan derivatives crosslinked products each of red meat and poultry wastewater samples were analyzed like electrical conductance, pH, biochemical oxygen demand, chemical oxygen demand and total dissolved solids. All these parameters values were within the permissible values of effluent discharge in the literature study. Different cross-linked chitosan products were tested for their ability to adsorb different elements from the red meat and poultry effluent wastewaters. ICP-OES analysis revealed the presence of up to '18' elements in both samples (Ca, Mg, Na, K, Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Si, Sr and Zn). Both results also showed the presence of alkali and alkaline earth group metals (Ca, Mg, Na and K) as major elements (> 100 mg/L). The performance of each cross linked chitosan product was assessed based on the amount (concentration) and the quantity of elements adsorbed. Amongst the '22' of cross-linked chitosan products tested in this study, shrimp chitosan cross-linked with maleic anhydride (J1), shrimp chitosan cross-linked with acrylic acid (I2) chitosan products were shown to be better adsorbants for Cr and Ni due to the possible influence of the amino, carboxylic, hydroxyl, etc. functional groups in these chitosan products. Results also showed the presence of smaller concentrations (0.05–0.2 mg/L) of heavy metals (Cr, Ni, Cu and Pb) in the eluted solution which suggests the versatility of the adsorbent to different elements.

36 MATERIALS SCIENCE↗
DOE OSTI2019

A Simple Approach for the Synthesis of Cellulose Nanofiber Reinforced Chitosan/PVP Bio Nanocomposite Film for Packaging

The development of chitosan-based food packaging film has been increasing due to its wider availability, biodegradability, low-cost, and renewability. The purpose of this study was to develop cellulose nanofibers (CNFs) reinforced Chitosan/PVP(CHP) green bio nanocomposite film by solvent casting method with enhanced barrier and mechanical property. CNFs of dimension 9–11 nm and 100–200 nm were extracted from jute fibers by directly treating it with HNO{sub 3}–NaNO{sub 2} mixture. Bio nanocomposite films were synthesized with various concentrations of CNFs and evaluated using SEM, TGA/DTG and XRD to analyze the morphology, thermal behavior and crystallinity of bio nanocomposite films. SEM analysis revealed the uniform dispersion of CNFs in CHP matrix. Thermal stability of prepared bio nanocomposite films was improved with the loading of 5 wt% of cellulose nanofibers. ATR(FT-IR) spectra shows physical interaction between all the components of bio nanocomposite film. The bio nanocomposite films were also characterized for physical property like thickness, mechanical testing and barrier properties. The addition of CNFs significantly enhanced the mechanical property of bio nanocomposite films. Furthermore, water and oxygen transmission rate of bio nanocomposite film decreased with the increase in CNFs concentration. Overall the performed studies confirmed, the use of CNFs in polymer matrix makes it possible to produce a flexible, transparent, thermally stable bio nanocomposite film with enhanced mechanical and barrier properties for food packaging applications.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Preparation and Characterization of Magnetite–Chitosan Nanoparticles and Evaluation of Their Cytotoxicity Effects on MCF7 and Fibroblast Cells

Nowadays, magnetic nanoparticles play a key role in drug treatment. However, if they are uncoated, they might aggregate and cause embolism in drug delivery. To avoid this, they are generally coated with polymers. In this investigation, magnetic nanoparticles (MNPs) were coated with chitosan through in situ co-precipitation process and their properties in addition to their cytotoxicity in MCF7 and fibroblast cells were analyzed. The results showed MNPs–chitosan nanoparticles would contain an average mean diameter of 32 nm and a saturation magnetization (M{sub S}) value of 38.87 emu/g. To characterize the synthesized nanoparticles in terms of structural, morphological and magnetic properties, Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA) and vibrating sample magnetometry (VSM) studies were used. Toxicity test was also done to investigate whether their presence would cause any toxicity in the body; in addition, antibacterial assay was done to analyze if nanoparticles could be used as an antimicrobial agent.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Design and analysis of graphene–MoS{sub 2} hybrid layer based SPR biosensor with TiO{sub 2}–SiO{sub 2} nano film for formalin detection: numerical approach

In this paper, a Surface Plasmon Resonance (SPR) biosensor has been numerically developed that used Graphene–MoS{sub 2}–Au–TiO{sub 2}–SiO{sub 2} hybrid structure for the detection of formalin. This developed sensor has been sensed the presence the formalin based on attenuated total reflection (ATR) method by observing the change of “surface plasmon resonance angle-the change of minimum reflectance attributor” and “the resonance frequency characteristics (RFC)-maximum transmittance attributor”. Chitosan has been used as probe sensing medium to accelerate particular reaction with the formalin. Here, graphene is used as biomolecular recognition element because of its high adsorption ability and optical characteristics which helps to improve sensor sensitivity, MoS{sub 2} used for it has larger band gap, high fluroscence quenching ability, higher optical absorption efficiency, TiO{sub 2}–SiO{sub 2} bilayer as the improvement of sensitivity and Gold (Au) as the sharp SPR curve. Numerical results give the impression that the variation of RFC and SPR angle for improper sensing of formalin is quiet negligible that confirms no formalin is detected whereas for proper sensing these change are considerably countable that confirms the detection of formalin. From the sensor sensitivity analysis, owing to add TiO{sub 2}–SiO{sub 2} bilayer with Graphene–MoS{sub 2} Hybrid layer, maximum sensitivity of 85.375% has been numerically resulted. This high sensor performance is for taking advantages of Graphene surface high selectively which detect bio molecular compounds through pi-stacking force, larger work function (5.1 eV) of MoS{sub 2} which allows the high sensitive detection of bio targets and Rich plasmon happens at the TiO{sub 2}–SiO{sub 2} interface.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Macromolecular systems and nanocomposites based on N-succinylchitosan and silver nanoparticles

A water-soluble chitosan derivative, namely, N-succinylchitosan (NS-Chit), was used as a matrix for the formation of silver nanoparticles (AgNP) by metal ion re duction under influence of microwave irradiation in the presence of D-glucose as a reducing agent. The electron plasmon resonance spectra (λ{sub max} = 410 nm) obtained for the irradiated solutions were typical of spherical silver nanoparticles. The in vitro tests confirmed a high bactericidal activity of the colloidal solution containing AgNP in a NS-Chit polymer matrix against strains of grampositive bacteria, namely, Bacillus subtillus (ATCC 6633), B. coagulans (429), and Staphylococcus aureus (ATCC 21027).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Thermal stability of the complex of pyrene–β-cyclodextrin dimer with aromatic amino acids

Using the method of adsorption spectroscopy, the temperature dependence of the electronic absorption spectra of the fluorescent chemosensor (CS), based on the supramolecular pyrene–2β-cyclodextrin complex (Pyr@2βCD, PCD), was studied in the absence and in the presence of phenylalanine (Phe). The application of CS, where pyrene serves as a fluorescent probe, is based on the ability of CS to form the inclusion complexes with small organic molecules as well as with aromatic amino acids (AA) such as Phe, tryptophan (Trp), tyrosine (Tyr), and histidine (His) in aqueous solutions. Upon heating to 55 °C, the PCD complex in the presence of Phe shows a higher stability as compared to that in the absence of Phe. The molecular dynamics simulation was applied to study the thermal stability of PCD and its complexes with the above AAs in water. The PCD complex exists in two configurations. In configuration 1 the planar Pyr molecule lies in the equatorial plane of the βCD dimer, the plane of Pyr is nearly perpendicular to the vertical axis of the dimer 2βCD, and water fills up the empty part of the cavity. In configuration 2, the plane of Pyr is inclined with respect to the axis of the 2βCD dimer by ~30°. The PCD complex initially prepared in state 1 is spontaneously transformed into state 2 and remains stable up to the boiling temperature. The transition of PCD from the form 1 to 2 is provided by fluctuations in water content in its cavities. The inclusion complexes of amino acids 2AA@PCD exist in a single conformation 1. Complexes of PCD with Trp and Phe are stable up to the boiling temperature, i.e., these AAs are preserved within the PCD cavities even at the elevated temperature. The complex with Tyr decays at 60 °C, and the complex with His is unstable at room temperature and above.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Chitosan based composite sorbents for arsenic removal

The possibilities of using chitosan and its composites with transition metal oxides for arsenic removal from solutions with low concentrations are discussed. Methods for the formation of composite sorbents based on chitosan and molybdenum in a composition with a carbon fiber providing improved physical and chemical properties with respect to the recovered component are considered. The sorption properties of the obtained materials under dynamic conditions for the purification of solutions from arsenic are compared. It is shown that the preliminary modification of the carbon fiber with chitosan by ionic gelation using sulfate ion and then by adsorption with molybdate ion leads to the production of an efficient sorption material that provides the purification of 1600 column volumes of an arsenic solution at an initial concentration of 105 μg L{sup –1} to a maximum permissible concentration of 50 μg L{sup –1}. The calculation methods show that the gel ability of sulfate and molybdate ions is approximately the same.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Inclusion complexes formed in lanthanide—amino acid—β-cyclodextrin systems

Interactions in lanthanide—amino acid—β-cyclodextrin systems (amino acid = tryptophan, phenylalanine; lanthanide = Eu{sup 3}+, Pr{sup 3}+) were studied in aqueous solution. An analysis of the chemical shifts observed in the {sup 1}H NMR spectra, as well as the ROESY data suggest the possibility for amino acid—lanthanide ion complexes encapsulated in the β-cyclodextrin cavity to form in solution. According to ROESY data, the indole ring of tryptophan and the phenyl group of phenylalanine enter the β-CD cavity from the wide rim side. Coordination with the metal ion occurs through the amino acid carboxyl group.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Therapeutic Potential of DNAzyme Loaded on Chitosan/Cyclodextrin Nanoparticle to Recovery of Chemosensitivity in the MCF-7 Cell Line

Commonly, acquired resistances to anticancer drug are mediated by overexpression of a membrane-associated protein that encode via multi-drug resistance gene-1 (MDR1). Herein, the mRNA-cleaving DNAzyme that targets the mRNA of MDR1 gene in doxorubicin-resistant breast cancer cell line (MCF-7/DR) loaded on the chitosan β-cyclodextrin complexes was used as a tropical agent. Chitosan/β-cyclodextrin complexes were used to deliver DNAzymes into cancer cells. Determination of the physicochemical characteristics of the particles was done by photon correlation spectroscopy and scanning electron microscopy. The encapsulation efficiency of the complexes was tested by using gel retardation assay. Positively charged nanoparticles interacted with DNAzyme that could perform as an efficient DNAzyme transfection system. The rationale usage of this platform is to sensitize MCF-7/DR to doxorubicin by downregulating the drug-resistance gene MDR1. Results demonstrated a downregulation of MDR1 mRNAs in MCF-7/DR/DNZ by real-time PCR, compared to the MCF-7/DR as control. WST1 assay showed the 22-fold decrease in drug resistance on treated cells 24 h after transfection. Results showed the intracellular accumulation of Rh123 increased in the treated cells with DNAzyme. Results suggested a potential platform in association with chemotherapy drug for cancer therapy and indicated extremely efficient at delivery of DNAzyme in restoring chemosensitivity.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Mechanism-based inhibition of cancer metastasis with (−)-epigallocatechin gallate

Highlights: •EGCG reduced cell motility of highly metastatic human lung cancer cells. •EGCG increased cell stiffness of the cells, indicating the inhibition of phenotypes of EMT. •EGCG inhibited expression of vimentin and Slug in the cells at the leading edge of scratch. •Treatment of MβCD increased cell stiffness, and inhibited cell motility and vimentin expression. •Inhibition of EMT phenotypes with EGCG is a mechanism-based inhibition of cancer metastasis. -- Abstract: Cell motility and cell stiffness are closely related to metastatic activity of cancer cells. (−)-Epigallocatechin gallate (EGCG) has been shown to inhibit spontaneous metastasis of melanoma cell line into the lungs of mice, so we studied the effects of EGCG on cell motility, cell stiffness, and expression of vimentin and Slug, which are molecular phenotypes of epithelial–mesenchymal transition (EMT). Treatments of human non-small cell lung cancer cell lines H1299 and Lu99 with 50 and 100 μM EGCG reduced cell motility to 67.5% and 43.7% in H1299, and 71.7% and 31.5% in Lu99, respectively in in vitro wound healing assay. Studies on cell stiffness using atomic force microscope (AFM) revealed that treatment with 50 μM EGCG increased Young’s modulus of H1299 from 1.24 to 2.25 kPa and that of Lu99 from 1.29 to 2.28 kPa, showing a 2-fold increase in cell stiffness, i.e. rigid elasticity of cell membrane. Furthermore, treatment with 50 μM EGCG inhibited high expression of vimentin and Slug in the cells at a leading edge of scratch. Methyl-β-cyclodextrin, a reagent to deplete cholesterol in plasma membrane, showed inhibition of EMT phenotypes similar that by EGCG, suggesting that EGCG induces inhibition of EMT phenotypes by alteration of membrane organization.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Inhibition of protein kinase C affects on mode of synaptic vesicle exocytosis due to cholesterol depletion

Highlights: • We examine the involvement of PKC in MCD induced synaptic vesicle exocytosis. • PKC inhibitor does not decrease the effect MCD on MEPP frequency. • PKC inhibitor prevents MCD induced FM1-43 unloading. • PKC activation may switch MCD induced exocytosis from kiss-and-run to a full mode. • Inhibition of phospholipase C does not lead to similar change in exocytosis. - Abstract: Previous studies demonstrated that depletion of membrane cholesterol by 10 mM methyl-beta-cyclodextrin (MCD) results in increased spontaneous exocytosis at both peripheral and central synapses. Here, we investigated the role of protein kinase C in the enhancement of spontaneous exocytosis at frog motor nerve terminals after cholesterol depletion using electrophysiological and optical methods. Inhibition of the protein kinase C by myristoylated peptide and chelerythrine chloride prevented MCD-induced increases in FM1-43 unloading, whereas the frequency of spontaneous postsynaptic events remained enhanced. The increase in FM1-43 unloading still could be observed if sulforhodamine 101 (the water soluble FM1-43 quencher that can pass through the fusion pore) was added to the extracellular solution. This suggests a possibility that exocytosis of synaptic vesicles under these conditions could occur through the kiss-and-run mechanism with the formation of a transient fusion pore. Inhibition of phospholipase C did not lead to similar change in MCD-induced exocytosis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Delivery of human NKG2D-IL-15 fusion gene by chitosan nanoparticles to enhance antitumor immunity

Nanoparticles are becoming promising carriers for gene delivery because of their high capacity in gene loading and low cell cytotoxicity. In this study, a chitosan-based nanoparticle encapsulated within a recombinant pcDNA3.1-dsNKG2D-IL-15 plasmid was generated. The fused dsNKG2D-IL-15 gene fragment consisted of double extracellular domains of NKG2D with IL-15 gene at downstream. The average diameter of the gene nanoparticles ranged from 200 nm to 400 nm, with mean zeta potential value of 53.8 ± 6.56 mV. The nanoparticles which were loaded with the dsNKG2D-IL-15 gene were uptaken by tumor cells with low cytotoxicity. Tumor cells pre-transfected by gene nanopartilces stimulated NK and T cells in vitro. Intramuscular injection of gene nanoparticles suppressed tumor growth and prolonged survival of tumor-bearing mice through activation of NK and CD8{sup +} T cells. Thus, chitosan-based nanoparticle delivery of dsNKG2D-IL-15 gene vaccine can be potentially used for tumor therapy. - Highlights: • Generation of a nanoparticle for delivery of dsNKG2D-IL-15 gene. • Characterization of the gene nanoparticle. • Antitumor activity mediated by the gene nanoparticle.

60 APPLIED LIFE SCIENCES↗