Investigation of pH-Sensitive Swelling and Curcumin Release Behavior of Chitglc Hydrogel

Hydrogels are in use for encapsulation of curcumin for possible use in wound healing. Encapsulation helps in targeted delivery and enhanced activity of curcumin. We report here a pH sensitive hydrogel developed from chitosan. The hydrogel was prepared by reaction of chitosan and d-glucose, facilitated by the reducing agent Na-cyanoborohydride. The maximum yield of the hydrogel was obtained at pH 4.5 with the amount of chitosan, d-glucose and Na-cyanoborohydride as 0.3, 2.0 and 2.0 g respectively. A maximum curcumin loading efficiency of 74% was observed with curcumin amount in the feed at 0.15 g. The release study revealed a sustained release pattern over a period of 80 h with an initial burst release. Curcumin loaded hydrogel showed mild antibacterial activity against Proteus mirabilis and Enterobacter aerogenes.     

Synthesis,Characterization and Application of Biodegradable Crosslinked Carboxymethyl Chitosan/Poly(Ethylene Glycol) Clay Nanocomposites

Crosslinked carboxymethyl chitosan (CMCh)/poly(ethylene glycol) (PEG) nanocomposites were synthesized using terephthaloyl diisothiocyanate as a crosslinking agent, in presence of montmorillonite (MMT), in different weight ratios of the two matrices. Characterization of nanocomposites was performed using different analyses. Swelling behavior was studied in different buffered solutions. It was found that formation of crosslinked CMCh/PEG nanocomposites increased the swell ability. Metal ions adsorption had also been investigated. The results indicated that crosslinked CMCh adsorbs various metal ions much more than non-crosslinked CMCh. Antimicrobial activity was examined against Gram-positive bacteria (S. aureus (RCMB 010027) and S. Pyogens (RCMB 010015), Gram-negative bacteria (E. coli (RCMB 010056), and also against fungi (A. fumigates (RCMBA 02564, G. candidum (RCMB 05096) and C. albicans (RCMB 05035). Data indicated that most of these nanocomposites exhibited good antimicrobial potency. Degradation studies were carried out in simulated body fluid for different time periods in order to find out the degradation index. Results showed that weight loss (%) of most of the nanocomposites increased as a function of incubation time.     

Bioethanol production from enzymatically saccharified lawn clippings from a golf course

The utilization of bioethanol is being focused on as a fuel alternative to oil and or natural gas. Bioethanol production from cellulosic plant residues is one of the solutions proposed for the problems caused by usage of food crops that are also vital for human consumption, such as sugar cane and corn, as a source of bioethanol. However, to utilize these new sources for bioethanol production, conditions for saccharification in each different material have not been optimized. In this study, we reported some optimum conditions for the saccharification of Korean lawn grass (KL) and bent grass (BG) using acremonium cellulase and endoglucanase as saccharifying enzymes for ethanol fermentation. With respect to saccharification of KL and BG, 0.19 and 0.18 g of d-glucose per g-substrate at maximum were produced, respectively. Comminution with a ball mill was found to be effective in the saccharification of KL, while ball-milled BG showed no significant improvement in saccharification. Being incorporated with 99 % of d-glucose consumption, saccharified KL was incubated for 3 days with Saccharomyces cerevisiae and Zymomonas mobilis, respectively, and each mixture fermented to ethanol yielding approximately 100 % of theoretical values from d-glucose consumption, respectively.     

Biodegradation of Poly-ε-caprolactones and Poly-<Emphasis Type="SmallCaps">l</Emphasis>-lactides by Fungi

This work assessed biodegradation, by Aspergillus, Fusarium, Penicillium and Parengyodontium fungi, of four samples of poly-ε-caprolactone (PCL), three samples of poly-l-lactide (PLA) and one sample of poly-d,l-lactide (DL-PLA) produced by ring-opening polymerization initiated by aluminium complexes of corresponding lactones. Mesophilic fungal strains actively biodegrading PCL (F. solani) and PLA (Parengyodontium album and A. calidoustus) were selected. The rate of degradation by the selected fungi was found to depend on the physicochemical and mechanical properties of the polymers (molecular weight, polydispersity, crystallinity). The most degradable poly-ε-caprolactone sample was shown to have the lowest molecular weight; the most biodegradable polylactide DL-PLA had the lowest crystallinity. Mass spectral analysis of biodegraded polymer residues showed PCL to be degraded more intensively than PLA. It is established that in the case of Parengyodontium album the colonization of the films of polypropylene composites with DL-PLA is observed, which will undoubtedly contribute to their further destruction under the influence of abiotic factors in the environment.     

Effect of Varying Filler Concentration on Zinc Oxide Nanoparticle Embedded Chitosan Films as Potential Food Packaging Material

Prevailing scenario of non-biodegradable food packaging materials worldwide was the motivation for this research. More than half of the packaging materials used today are non-biodegradable and lack one or the other feature that keeps it from being an ideal food packaging material. Based on the current need of food grade packaging materials, the present study illustrates the amelioration of the properties of biodegradable chitosan films with the incorporation of zinc oxide (ZnO) nanoparticles in varying concentration. The ZnO nanoparticles (ZnONPs) used as fillers in the chitosan films were synthesized by supersaturation method. They were characterized using UV–visible spectrophotometry, X-ray diffraction and field emission scanning electron microscopy (FE-SEM). The particles were observed to be around 100–200 nm in size. The chitosan films with varying concentration of ZnONPs were synthesized and characterized using Fourier transform infrared spectroscopy and FE-SEM. The films were studied for their thermal stability, water vapor transmission rate (WVTR) and mechanical properties. The thermal stability, as determined by Thermo Gravimetric Analysis and Differential Scanning Calorimetry increased slightly with increasing percentage of embedded ZnONPs while a substantial decrease in WVTR was observed. Mechanical properties also showed improvements with 77% increment in tensile modulus and 67% increment in tensile strength. The antimicrobial activity of the films was also studied on gram positive bacterium Bacillus subtilis (B. subtilis) and gram negative bacterium Escherichia coli (E. coli) by serial dilution method. A twofold and 1.5-fold increment in the antimicrobial activity was observed for B. subtilis and E. coli, respectively, with increased ZnONPs concentration in the films from 0(w/w) to 2%(w/w). Films thus prepared can prove to be of immense potential in the near future for antimicrobial food packaging applications.     

Preparation and Characterization of Polyaniline and Ag/ Polyaniline Composite Nanoporous Particles and Their Antimicrobial Activities

Polyaniline (PANI) and Ag/PANI nanoporous composite were prepared by an oxidative polymerization method. The oxidation process of PANI nanoparticles was occurred using (NH₄)₂S₂O₈ while the oxidation process of Ag/PANI nanoporous composite was occurred using AgNO₃ under the effect of artificial radiation. The structural, morphological, and optical properties of the PANI and Ag/PANI nanoporous structures were studied using different characterization tools. The results confirm the formation of polycrystalline nanoporous PANI and spherical nanoporous composite of Ag/PANI particles. Antibacterial activity tests against gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus, and gram-negative bacteria, Escherichia coli, and Salmonella species were carried out using different concentrations of PANI nanoparticles and Ag/PANI nanoporous composites. PANI has not antibacterial effect against all studied pathogens. In contrast, Ag/PANI nanoporous composites possessed antibacterial activity that is identified by the zone of inhibition. The inhibition zones of bacteria are in order; Salmonella species?>?S. aureus?>?B. subtilis?>?E. coli. The inhibition zones of all bacteria increased with increasing concentrations of Ag/PANI nanoporous composites from 200 to 400 ppm then decreased with further increasing of the dose concentrations to 600 ppm. Finally, a simplified mechanism based on the electrostatic attraction is presented to describe the antimicrobial activity of Ag/PANI nanoporous composite.     

Novel Glycopolymers Based on d-Mannose and Methacrylates: Synthesis, Thermal Stability and Biodegradability Testing

This paper presents the synthesis, thermal stability and biodegradability of new d-mannose glycopolymers. These glycopolymers have been obtained by free radical bulk copolymerization of d-mannose based glycomonomer, 1-O-(2′-hydroxy-3′-methacryloyloxypropyl)-2,3:5,6-di-O-isopropylidene-d-mannofuranose (Mm), and respectively d-mannose derived oligomer (Mo) with methyl methacrylate and respectively 2-hydroxypropyl methacrylate. The chemical structures of Mm and Mo have been confirmed via FTIR, ¹H-NMR and HPLC–MS spectroscopy. The copolymerization process has been investigated using differential scanning calorimetry, which allowed calculating the activation energies by applying Kissinger–Akahira–Sunose method. The glycopolymers are thermally stable, fact assessed by TG analysis; their glass transition temperature exceeds 50 °C, so they are part of the glassy class of polymers. The biodegradability of these glycopolymers has been investigated in vitro, using pure cultures of Zymomonas mobilis and Trichoderma reesei. The glycopolymers lose up to 55 % weight in just 14 days of incubation as their surface and composition is altered by colonies of microorganisms that grow on/into them, fact demonstrated using SEM/EDX.     

Antibacterial and Drug Elution Performance of Thermoplastic Blends

Food preservatives or drug compounds can be eluted from polymer substrates to prevent the occurrence of hospital-acquired infections and food spoilage. We investigated the antimicrobial and drug-elution properties of the albumin and zein thermoplastic blends plasticized with glycerol and mixed with varying amounts of low-density polyethylene (LDPE), food preservatives (sodium benzoate or sodium nitrite), and drugs (ampicillin or ciprofloxacin). Bacillus subtilis and Escherichia coli were utilized as Gram (+) and Gram (?) species, respectively, for antimicrobial and drug-elution analyses, since these species are common in the human body and in food environments. The amount of contamination occurring in food and medical applications could be limited with usage of plastic blends made from thermomechanical molding of proteins (albumin from hen egg white and zein from corn), drug eluting compounds, and low-density polyethylene.     

Biopolymer (Chitin) from Various Marine Seashell Wastes: Isolation and Characterization

Chitin has been produced from different sea waste sources including, molluscs (mussel and oyster shell), crustacean (prawn and crab) and fish scale (pang and silver scales) using deproteinization and demineralization as chemical methods. The conditions of chemical extraction process determine the quality of chitin. The obtained results revealed that, about 1 and 10% HCl and NaOH were adequate concentrations for deproteinization and demineralization process respectively. Chitin from oyster and crab shell waste had the highest yield of 69.65 and 60.00% while prawn, mussel shell, pang and silver scales had the lowest yield of 40.89, 35.03, 35.07 and 31.11% respectively. Chitin solubility is controlled by the quantity of protonated acetyl groups within the polymeric chain of the chitin backbone, thus on the percentage of acetylated and non-acetylated d-glucos-acetamide unit. Good solubility results were obtained in mussel, oyster and crab shells respectively. The chitin molecular weight characteristics and activity are controlled by the degree of acetylation (DA) and the distribution of acetyl group extending in the polymer chain. DA is determined by acid-base titration methods and molecular weight determined by Brookfield viscometry. Both methods are found to be effective.     

Chelating Ability and Microbial Stability of an <Emphasis Type="SmallCaps">l</Emphasis>-Arginine-Modified Chitosan-Based Environmental Remediation Material

To improve the heavy metal ion chelating ability and the microbiological stability of chitosan (CS), l-arginine (l-Arg) was grafted on CS polymer in the presence of the condensing agent 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC) and the coupling reagent N-hydroxysuccinimide (NHS) to prepare a natural polymer-based environmental rehabilitation material: l-arginine-grafted chitosan (CA). The graft mechanism is discussed, and the reaction conditions were optimized. The product was characterized using elemental analysis, infrared spectroscopy (FT-IR) and ¹³C-NMR spectroscopy (¹³C-NMR). The optimal reaction conditions were a reactant molar ratio nCS:nArg:nEDC:nNHS of 3:3:3:1, a reaction time of 12 h, and a reaction system pH?=?5. Under these conditions, the grafting ratio (GR) was 16.85%, while the product yield (PY) was 90.48%. The results of the adsorption experiments showed that the CA (GR?=?16.85%) had a better removal capacity for highly concentrated Cu²⁺ and Ni²⁺ ions than CS. The antibacterial activity of the CA was also enhanced. When the GR reached 16.85%, the CA almost completely inhibited the growth of colibacillus and Staphylococcus aureus. Due to its high chelating ability and microbiological stability, this novel metal-ion adsorption material, CA, can be considered to have broad application potential in heavy metal ion-polluted water and soil remediation.     

Green Synthesis and Antioxidant Study of Silver Nanoparticles of Root Extract of <Emphasis Type="Italic">Sageretia thea</Emphasis> and Its Role in Oxidation Protection Technology

Development of environmentally friendly synthesis of nanoparticles is one of the important areas of research in nanotechnology. In present study silver naopartticles (AgNPs) of root extract of Sageretia thea (S. thea) were synthesized at room temperature. The synthesized AgNPs were characterized by UV. Visible spectroscopy (UV), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDX), transmission electron microscopy (TEM), dynamic light scattering (DLS) and Fourier transform infrared (FT-IR) spectroscopy. Formation of AgNPs was confirmed by visual examination the colour change from yellow to brick red due to surface Plasmon resonance band at 435 nm. SEM and TEM analysis of synthesized AgNPs revealed spherical morphology with average particle size 25 nm. Crystalline nature of the AgNPs in face centered cubic structure is evident from the selected area electron diffraction (SAED) and XRD pattern. The presence of elemental Ag was confirmed by EDX analysis at 3kv. Different functional groups which responsible for reduction and stabilization of reaction medium was confirmed by FTIR spectroscopy. The biosynthesized AgNPs showed strong DPPH and dye protection radical scavenging assay while modest hydrogen peroxide radical scavenging assay as compare to crude extract. The present investigations suggest that biosynthesized nanoparticles have a high potential for use in the preparation of drugs used against various diseases and also a promising candidate for many medical applications.     

Biodegradable Compatibilized Poly(<Emphasis Type="SmallCaps">l</Emphasis>-lactide)/Thermoplastic Polyurethane Blends: Design,Preparation and Property Testing

Biodegradable blends of poly(l-lactide) (PLL) toughened with a polycaprolactone-based thermoplastic polyurethane (TPU) elastomer and compatibilized with a purpose-designed poly(l-lactide-co-caprolactone) (PLLCL) copolymer were prepared. Both 2-component (PLL/TPU) and 3-component (PLL/TPU/PLLCL) blends of various compositions were prepared by melt mixing, hot-pressed into thin films and their properties tested. The results showed that, although the TPU could toughen the PLL, the blends were immiscible leading to phase separation with the TPU domains distributed in the PLL matrix. However, addition of the PLLCL copolymer could partially compatibilize the blend by improving the interfacial adhesion between the two phases. Biodegradability testing showed that the blends were biodegradable and that the PLLCL copolymer could increase the rate of biodegradation under controlled composting conditions. The 3-component blend of composition PLL/TPU/PLLCL?=?90/10/10 parts by weight was found to exhibit the best all-round properties.     

Experimental Investigation of Cellulose/Silver Nanocomposites Using In Situ Generation Method

Cellulose gel films were prepared by regeneration process using pre-cooled aq.(8 wt% LiOH + 15 wt% urea) mixture as solvent and ethyl alcohol as non solvent. The Terminus cattapa leaf extract diffused wet cellulose films were then dipped in 1–5 mM aq.AgNO₃ solutions to allow in situ generation of silver nanoparticles (AgNPs). Besides the in situ generation, some AgNPs were also formed outside the wet films in the solution. The AgNPs formed outside the films were observed under transmission electron microscope and scanning electron microscope. The nanocomposite films were also characterized by Fourier transform infrared spectroscopy, X-ray diffraction and thermogravimetric analysis and tensile test. The thermal stability of the composite films was lower than that of the matrix up to a temperature of ~300 °C and afterwards showed a reverse trend. The tensile strength of the nanocomposite films was found to be higher than the matrix but decreased with increasing concentration of aq.AgNO₃. The cellulose/AgNPs composite films showed good antibacterial activity against E. coli (gram positive) and Bacillus sp. (gram negative). Based on the aforementioned properties, the cellulose/AgNPs composite films can be considered for antibacterial packaging and medical applications.     

Characteristic Properties of Novel Organosolv Lignin/Polylactide/Delta-Valerolactone Terpolymers

Compostable terpolymers of l-lactide (LLA), delta-valerolactone (DVL), and switchgrass organosolv lignin (OSL) were synthesized via ring-opening polymerization to improve on polylactide homopolymer properties for commercial applications. OSL has properties that improve some of the deficiencies of polylactide, including polylactide’s limitations for use in food, beverage and medical applications due to its high water permeability and low ultraviolet light (UV) blocking capabilities. DVL was incorporated into these polymers to add flexibility. The addition of DVL to the polymer had a positive effect on the tensile strain properties of the resultant terpolymer, resulting in a more flexible polymer with a reduced Young’s modulus. Water vapor transmission rate calculations confirmed that water vapor was transported more slowly through terpolymer films than through the PLLA homopolymer under varying hygrostatic conditions. While the addition of DVL increased UV permeability, the addition of even a small amount of lignin can effectively counteract this effect.     

Kinetic Analysis of the Temperature Effect on Polyhydroxyalkanoate Production by <Emphasis Type="Italic">Haloferax mediterranei</Emphasis> in Synthetic Molasses Wastewater

Haloferax mediterranei is an extremely halophilic archaeon that is able to synthesize polyhydroxyalkanoate (PHA) in high salt environment with low sterility demand. In this study, a mathematical model was validated and calibrated for describing the kinetic behavior of H. mediterranei at 15, 20, 25, and 35 °C in synthetic molasses wastewater. Results showed that the production of PHA by H. mediterranei, ranging from 390 to 620 mg h^?1 L^?1, was strongly dependent on the temperature. The specific growth rate (µ _max), specific substrate utilization rate (q _max), and specific decay rate (k _d) of H. mediterranei increased with temperature following Arrhenius equation prediction. The estimated activation energy was 58.31, 25.59, and 22.38 kJ mol^?1 for the process of cell growth, substrate utilization, and cell decay of H. mediterranei, respectively. The high temperature triggered the increased PHA storage even without nitrogen limitation. Thus, working at high temperatures seems a good strategy for improving the PHA productivity of H. mediterranei.     

Ecotoxicity Evaluation of the Biodegradable Polymers PLA,PBAT and its Blends Using <Emphasis Type="Italic">Allium cepa</Emphasis> as Test Organism

Biodegradable polymers are considered a feasible option to minimize the environment impacts of high disposal of solid waste. Nevertheless, environmental safety of these materials is a few explored issue. In this context, this study evaluated ecotoxicological effects in soil of the biodegradable materials poly(lactic acid)-PLA, poly(butylene adipate co-terephthalate)-PBAT and their blends compatibilized with a chain extender. The tool used for this analysis was the bioassay with Allium cepa as test organism. The studied materials were not phytotoxic, cytotoxic, genotoxic nor mutagenic for meristematic cells of A. cepa.     

Technical and environmental long-term properties of industrial residues--summary of field and laboratory investigations

In Sweden, use of industrial residues is still hindered by concern for their long-term properties. A three-year research project was therefore initiated aiming to (1) identify the crucial processes of ageing related to the usefulness of residues in roads; (2) investigate the consequences of these processes for technical and environmental properties of the residues, and (3) propose a method for accelerated ageing to predict the long-term properties. This paper gives an overview of the project methodology, a summary of the test results and references to papers where further details are given.The project, running through 2006-2008, compared naturally aged samples of two residues used as sub-bases in existing asphalt paved roads with samples of fresh residues from producers’ piles. Steel slag of electric arc furnace (EAF) type and municipal solid waste incinerator (MSWI) bottom ash were chosen. The samples were thoroughly characterised in order to identify which ageing processes had been crucial.The results showed that:

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Bottom ash from the pavement edge was more aged than bottom ash from the road centre. However, no difference in pH was found, instead the differences were caused by differences in water exposure.

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Steel slag from the pavement edge showed traces of carbonation and leaching processes, whereas slag from the road centre was identical to fresh slag.

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Water exposure to the subbase materials after ten years in an asphalt paved road was calculated to less than 0.1-0.5 litres per kg.

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Ageing reactions in steel slag and MSWI bottom ash, ready for use, were too small to be verified by laboratory measurement of deformation properties under loaded conditions.

An accelerated ageing test for steel slag was set up to achieve the carbonation (decrease in pH) and leaching that was observed in the pavement edge material.An accelerated ageing test for bottom ash was set up to achieve the pozzolan reactions that were observed in SEM analyses of in situ specimens.It is recommended to use uncrushed particles when properties of aged material are studied, in order to preserve the original particle surfaces.