Search results for: conjugated dienes

Authors: Marina Nisnevitch, Anton Valkov, Faina Nakonechny, Kate Adar Raik, Yamit Mualem

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Photosensitizers are dye compounds belonging to various chemical groups that in all the cases have a developed structure of conjugated double bonds. Under illumination with visible light, the photosensitizers are excited and transfer the absorbed energy to the oxygen dissolved in an aqueous phase, leading to production of a reactive oxygen species which cause irreversible damage to bacterial cells. When immobilized onto a solid phase, photosensitizers preserve their antibacterial properties. In the present study, photosensitizers were immobilized in polyethylene or propylene and tested for antimicrobial activity against Gram-positive S. aureus, S. epidermidis and Streptococcus sp. For this purpose, water-soluble photosensitizers, Rose Bengal sodium salt, and methylene blue as well as water-insoluble hematoporphyrin and Rose Bengal lactone, were immobilized by dissolution in melted polymers to yield 3 mm diameter rods and 3-5 mm beads. All four photosensitizers were found to be effective in the eradication of Gram-positive bacteria under illumination by a white luminescent lamp or sunlight. The immobilized photosensitizers can be applied for continuous water disinfection; they can be easily removed at the end of the treatment and reused.

Keywords: antimicrobial polymers, gram-positive bacteria, immobilization of photosensitizers, photodynamic antibacterial activity

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Authors: Yung-Chih Kuo, Che-Yu Lin, Jay-Shake Li, Yung-I Lou

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Curcumin (CRM) and nerve growth factor (NGF) were entrapped in liposomes (LIP) with cardiolipin (CL) to downregulate the phosphorylation of mitogen-activated protein kinases for Alzheimer’s disease (AD) management. AD belongs to neurodegenerative disorder with a gradual loss of memory, yielding irreversible dementia. CL-conjugated LIP loaded with CRM (CRM-CL/LIP) and that with NGF (NGF-CL/LIP) were applied to AD models of SK-N-MC cells and Wistar rats with an insult of β-amyloid peptide (Aβ). Lipids comprising 1,2-dipalmitoyl-sn-glycero-3- phosphocholine (Avanti Polar Lipids, Alabaster, AL), 1',3'-bis[1,2- dimyristoyl-sn-glycero-3-phospho]-sn-glycerol (CL; Avanti Polar Lipids), 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N- [methoxy(polyethylene glycol)-2000] (Avanti Polar Lipids), 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[carboxy(polyethylene glycol)-2000] (Avanti Polar Lipids) and CRM (Sigma–Aldrich, St. Louis, MO) were dissolved in chloroform (J. T. Baker, Phillipsburg, NJ) and condensed using a rotary evaporator (Panchum, Kaohsiung, Taiwan). Human β-NGF (Alomone Lab, Jerusalem, Israel) was added in the aqueous phase. Wheat germ agglutinin (WGA; Medicago AB, Uppsala, Sweden) was grafted on LIP loaded with CRM for (WGA-CRM-LIP) and CL-conjugated LIP loaded with CRM (WGA-CRM-CL/LIP) using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (Sigma–Aldrich) and N-hydroxysuccinimide (Alfa Aesar, Ward Hill, MA). The protein samples of SK-N-MC cells (American Type Tissue Collection, Rockville, MD) were used for sodium dodecyl sulfate (Sigma–Aldrich) polyacrylamide gel (Sigma–Aldrich) electrophoresis. In animal study, the LIP formulations were administered by intravenous injection via a tail vein of male Wistar rats (250–280 g, 8 weeks, BioLasco, Taipei, Taiwan), which were housed in the Animal Laboratory of National Chung Cheng University in accordance with the institutional guidelines and the guidelines of Animal Protection Committee under the Council of Agriculture of the Republic of China. We found that CRM-CL/LIP could inhibit the expressions of phosphorylated p38 (p-p38), p-Jun N-terminal kinase (p-JNK), and p-tau protein at serine 202 (p-Ser202) to retard the neuronal apoptosis. Free CRM and released CRM from CRM-LIP and CRM-CL/LIP were not in a straightforward manner to effectively inhibit the expression of p-p38 and p-JNK in the cytoplasm. In addition, NGF-CL/LIP enhanced the quantities of p-neurotrophic tyrosine kinase receptor type 1 (p-TrkA) and p-extracellular-signal-regulated kinase 5 (p-ERK5), preventing the Aβ-induced degeneration of neurons. The membrane fusion of NGF-LIP activated the ERK5 pathway and the targeting capacity of NGF-CL/LIP enhanced the possibility of released NGF to affect the TrkA level. Moreover, WGA-CRM-LIP improved the permeation of CRM across the blood–brain barrier (BBB) and significantly reduced the Aβ plaque deposition and malondialdehyde level and increased the percentage of normal neurons and cholinergic function in the hippocampus of AD rats. This was mainly because the encapsulated CRM was protected by LIP against a rapid degradation in the blood. Furthermore, WGA on LIP could target N-acetylglucosamine on endothelia and increased the quantity of CRM transported across the BBB. In addition, WGA-CRM-CL/LIP could be effective in suppressing the synthesis of acetylcholinesterase and reduced the decomposition of acetylcholine for better neurotransmission. Based on the in vitro and in vivo evidences, WGA-CRM-CL/LIP can rescue neurons from apoptosis in the brain and can be a promising drug delivery system for clinical AD therapy.

Keywords: Alzheimer’s disease, β-amyloid, liposome, mitogen-activated protein kinase

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Authors: Ho-Wa Li, Sai-Wing Tsang

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The excitonic effect in organic semiconductors plays a key role in determining the electronic devices performance. Strong exciton binding energy has been regarded as the detrimental factor limiting the further improvement in organic photovoltaic cells. To the best of our knowledge, only limited reported can be found in measuring the exciton binding energy in organic photovoltaic materials. Conventional sophisticated approach using photoemission spectroscopy (UPS and IPES) would limit the wide access of the investigation. Here, we demonstrate a facile approach to study the electrical and optical quantum efficiencies of a series of conjugated photovoltaic polymer, fullerene and non-fullerene materials. Quantitative values of the exciton binding energy in those prototypical materials were obtained with concise photovoltaic device structure. And the extracted binding energies have excellent agreement with those determined by the conventional photoemission technique. More importantly, our findings can provide valuable information on the excitonic dissociation in the first excited state. Particularly, we find that the high binding energy of some non-fullerene acceptors limits the combination of polymer acceptors for efficiency exciton dissociation. The results bring insight into the engineering of excitonic effect for the development of efficient organic photovoltaic cells.

Keywords: organic photovoltaics, quantum efficiency, exciton binding energy, device physics

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Authors: Madhu Gupta, G. P. Agrawa, Suresh P. Vyas

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Certain tumor cells overexpress a membrane-spanning molecule aminopeptidase N (CD13) isoform, which is the receptor for peptides containing the NGR motif. NGR-modified Docetaxel (DTX)-loaded PEG-b-PLGA polymeric nanoparticles (cNGR-DNB-NPs) were developed and evaluated for their in vitro potential in HT-1080 cell line. The cNGR-DNB-NPs containing particles were about 148 nm in diameter with spherical shape and high encapsulation efficiency. Cellular uptake was confirmed both qualitatively and quantitatively by Confocal Laser Scanning Microscopy (CLSM) and flow cytometry. Both quantitatively and qualitatively results confirmed the NGR conjugated nanoparticles revealed the higher uptake of nanoparticles by CD13-overexpressed tumor cells. Free NGR inhibited the cellular uptake of cNGR-DNB-NPs, revealing the mechanism of receptor mediated endocytosis. In vitro cytotoxicity studies demonstrated that cNGR-DNB-NPs, formulation was more cytotoxic than unconjugated one, which were consistent well with the observation of cellular uptake. Hence, the selective delivery of cNGR-DNB-NPs formulation in CD13-overexpressing tumors represents a potential approach for the design of nanocarrier-based dual targeted delivery systems for targeting the tumor cells and vasculature.

Keywords: solid Tumor, docetaxel, targeting, NGR ligand

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Authors: Michelle C. S. Azevedo, Priscila M. Colavite, Carolina F. Francisconi, Ana P. Trombone, Gustavo P. Garlet

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VIP (vasoactive intestinal peptide) know as a potential protective factor in the view of its marked immunosuppressive properties. In this work, we investigated a possible association of VIP with the clinical status of experimental periapical granulomas and the association with expression markers in the lesions potentially associated with periapical lesions pathogenesis. C57BL/6WT mice were treated or not with recombinant VIP. Animals with active/progressive (N=40), inactive/stable (N=70) periapical granulomas and controls (N=50) were anesthetized and the right mandibular first molar was surgically opened, allowing exposure of dental pulp. Endodontic pathogenic bacterial strains were inoculated: Porphyromonas gingivalis, Prevotella nigrescens, Actinomyces viscosus, and Fusobacterium nucleatum subsp. polymorphum. The cavity was not sealed after bacterial inoculation. During lesion development, animals were treated or not with recombinant VIP 3 days post infection. Animals were killed after 3, 7, 14, and 21 days of infection and the jaws were dissected. The extraction of total RNA from periodontal tissues was performed and the integrity of samples was checked. qPCR reaction using TaqMan chemistry with inventoried primers were performed in ViiA7 equipment. The results, depicted as the relative levels of gene expression, were calculated in reference to GAPDH and β-actin expression. Periodontal tissues from upper molars were vested and incubated supplemented RPMI, followed by processing with 0.05% DNase. Cell viability and couting were determined by Neubauer chamber analysis. For flow cytometry analysis, after cell counting the cells were stained with the optimal dilution of each antibody; (PE)-conjugated and (FITC)-conjugated antibodies against CD4, CD25, FOXP3, IL-4, IL-17 and IFN-γ antibodies, as well their respective isotype controls. Cells were analyzed by FACScan and CellQuest software. Results are presented as the number of cells in the periodontal tissues or the number of positive cells for each marker in the CD4+FOXp3+, CD4+IL-4+, CD4+IFNg+ and CD4+IL-17+ subpopulations. The levels mRNA were measured by qPCR. The VIP expression was predominated in inactive lesions, as well part of the clusters of cytokine/Th markers identified as protective factors and a negative correlation between VIP expression and lesion evolution was observed. A quantitative analysis of IL1β, IL17, TNF, IFN, MMP2, RANKL, OPG, IL10, TGFβ, CTLA4, COL5A1, CTGF, CXCL11, FGF7, ITGA4, ITGA5, SERP1 and VTN expression was measured in experimental periapical lesions treated with VIP 7 and 14 days after lesion induction and healthy animals. After 7 days, all targets presented a significate increase in comparison to untreated animals. About migration kinetics, profile of chemokine receptors expression of TCD4+ subsets and phenotypic analysis of Tregs, Th1, Th2 and Th17 cells during the course of experimental periodontal disease evaluated by flow cytometry and depicted as the number of positive cells for each marker. CD4+IFNg+ and CD4+FOXp3+ cells migration were significate increased 7 days post VIP treatment. CD4+IL17+ cells migration were significate increased 7 and 14 days post VIP treatment, CD4+IL4+ cells migration were significate increased 14 and 21 days post VIP treatment compared to the control group. In conclusion, our experimental data support VIP involvement in determining the inactivity of periapical lesions. Financial support: FAPESP #2015/25618-2.

Keywords: chronic inflammation, cytokines, osteolytic lesions, VIP (Vasoactive Intestinal Peptide)

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Authors: Farhad Alizadeh, Alireza Faregh Gharamaleki, Mojtaba Jalilzadeh, Houshang Gholami, Ali Akhoundzadeh

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This study presented hybrid pre-processing approach along with a conceptual model to enhance the accuracy of river discharge prediction. In order to achieve this goal, Ensemble Empirical Mode Decomposition algorithm (EEMD), Discrete Wavelet Transform (DWT) and Mutual Information (MI) were employed as a hybrid pre-processing approach conjugated to Least Square Support Vector Machine (LSSVM). A conceptual strategy namely multi-station model was developed to forecast the Souris River discharge more accurately. The strategy used herein was capable of covering uncertainties and complexities of river discharge modeling. DWT and EEMD was coupled, and the feature selection was performed for decomposed sub-series using MI to be employed in multi-station model. In the proposed feature selection method, some useless sub-series were omitted to achieve better performance. Results approved efficiency of the proposed DWT-EEMD-MI approach to improve accuracy of multi-station modeling strategies.

Keywords: river stage-discharge process, LSSVM, discrete wavelet transform, Ensemble Empirical Decomposition Mode, multi-station modeling

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Authors: Hyehyeon Lee, Juwon Yu, Juwon Kim, Raquel Kristina Leoni Tumiar, Taewon Kim, Juae Kim, Hongsuk Suh

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Recently, the development of photovoltaics is rapidly accelerating as one of green energy sources. So we designed pyrimidine-based polymers with 2-{3-[4,6-bis-(4-hexyl-thiophen-2-yl)-pyrimidin-2-yl]-phenyl}-thiazolo[5,4-b]pyridine (mPTP), as active layer substances for polymer solar cells. Polymers with push-pull types, mPTPBDT-12, mPTPBDT-EH, mPTPBDTT-EH and mPTPTTI, are comprised of electron pushing unit using benzo[1,2-b;3,4-b’]dithiophene (BDT) or 4,8-bis(5-thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene (BDTT) or 6-(2-thienyl)-4H-thieno[3,2-b]indole(TTI) and electron pulling unit using mPTP. The device including mPTPTTI-12 indicated a VOC of 0.67 V, a JSC of 2.16 mA/cm², and a fill factor (FF) of 0.30, giving a power conversion efficiency (PCE) of 0.43%. The device including mPTPBDT-EH indicated a VOC of 0.56 V, a JSC of 2.64 mA/cm², and an FF of 0.30, giving a PCE of 0.44%. The device including mPTPBDTT-EH indicated a VOC of 0.44 V, a JSC of 2.45 mA/cm², and an FF of 0.29, giving a PCE of 0.31%. The device including mPTPTTI indicated a VOC of 0.72 V, a JSC of 4.95 mA/cm², and an FF of 0.32, giving a PCE of 1.15%. Therefore, mPTPBDT-12, mPTPBDT-EH, mPTPBDTT-EH and mPTPTTI were fabricated by Stille polymerization. Their optical properties were measured and the results show that pyrimidine-based polymers have a great promise to act as donor of active layer.

Keywords: polymer solar cells, photovoltaics, thiazolopyridine, conjugated polymer

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Authors: Clarinda V. Nhangumbe, Ercília Sousa

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Weather Derivatives are financial instruments used to cover non-catastrophic weather events and can be expressed in the form of standard or plain vanilla products, structured or exotics products. The underlying asset, in this case, is the weather index, such as temperature, rainfall, humidity, wind, and snowfall. The complexity of the Weather Derivatives structure shows the weakness of the Black Scholes framework. Therefore, under the risk-neutral probability measure, the option price of a weather contract can be given as a unique solution of a two-dimensional partial differential equation (parabolic in one direction and hyperbolic in other directions), with an initial condition and subjected to adequate boundary conditions. To calculate the price of the option, one can use numerical methods such as the Monte Carlo simulations and implicit finite difference schemes conjugated with Semi-Lagrangian methods. This paper is proposed two explicit methods, namely, first-order upwind in the hyperbolic direction combined with Lax-Wendroff in the parabolic direction and first-order upwind in the hyperbolic direction combined with second-order upwind in the parabolic direction. One of the advantages of these methods is the fact that they take into consideration the boundary conditions obtained from the financial interpretation and deal efficiently with the different choices of the convection coefficients.

Keywords: incomplete markets, numerical methods, partial differential equations, stochastic process, weather derivatives

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Authors: Kasi Viswanadh Matte, Abhisheh Kumar Mehata, M.S. Muthu

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Brest cancer, up-regulated with human epidermal growth factor receptor type-2 (HER-2) led to the concept of developing HER-2 targeted anticancer therapeutics. Docetaxel-loaded D-α-tocopherol polyethylene glycol succinate 1000 conjugated chitosan (TPGS-g-chitosan) nanoparticles were prepared with or without Trastuzumab decoration. The particle size and entrapment efficiency of conventional, non-targeted and targeted nanoparticles were found to be in the range of 126-186 nm and 74-78% respectively. In-vitro, MDA-MB-231 cells showed that docetaxel-loaded non-targeted and HER-2 receptor targeted TPGS-g-chitosan nanoparticles have enhanced the cellular uptake and cytotoxicity with a promising bioadhesion property, in comparison to conventional nanoparticles. The IC50 values of non-targeted and targeted nanoparticles from cytotoxic assay were found to be 43 and 223 folds higher than DocelTM. The in-vivo pharmacokinetic study showed 2.33, and 2.82-fold enhancement in relative bioavailability of docetaxel for non-targeted and HER-2 receptor targeted nanoparticles, respectively than DocelTM, and after i.v administration, non-targeted and targeted nanoparticle achieved 3.48 and 5.94 times prolonged half-life in comparison to DocelTM. The area under the curve (AUC), relative bioavailability (FR) and mean residence time (MRT) were found to be higher for non-targeted and targeted nanoparticles compared to DocelTM. Further, histopathology results of non-targeted and targeted nanoparticles showed less toxicity on vital organs such as lungs, liver, and kidney compared to DocelTM.

Keywords: breast cancer, HER-2 receptor, targeted nanomedicine, chitosan, TPGS

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Authors: Syue-Liang Lin, C. Allen Chang

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Luminescence imaging is an important technique used in biomedical research and clinical diagnostic applications in recent years. Concurrently, the development of NIR luminescence probes / imaging contrast agents has helped the understanding of the structural and functional properties of cells and animals. Photodynamic therapy (PDT) is used clinically to treat a wide range of medical conditions, but the therapeutic efficacy of general PDT for deeper tumor was limited by the penetration of excitation source. The tumor targeting biomedical nanomaterials UCNP@PS (upconversion nanoparticle conjugated with photosensitizer) for photodynamic therapy and near-infrared imaging of cancer will be developed in our study. Synthesis and characterization of biomedical nanomaterials were completed in this studies. The spectrum of UCNP was characterized by photoluminescence spectroscopy and the morphology was characterized by Transmission Electron Microscope (TEM). TEM and XRD analyses indicated that these nanoparticles are about 20~50 nm with hexagonal phase. NaYF₄:Ln³⁺ (Ln= Yb, Nd, Er) upconversion nanoparticles (UCNPs) with core / shell structure, synthesized by thermal decomposition method in 300°C, have the ability to emit visible light (upconversion: 540 nm, 660 nm) and near-infrared with longer wavelength (downconversion: NIR: 980 nm, 1525 nm) by absorbing 800 nm NIR laser. The information obtained from these studies would be very useful for applications of these nanomaterials for bio-luminescence imaging and photodynamic therapy of deep tumor tissue in the future.

Keywords: Near Infrared (NIR), lanthanide, core-shell structure, upconversion, theranostics

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Authors: Syeda Kiran Shahzadi, Nasir Mahmood, Muhammad Abdul Qadir

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In the current research, three recombinant human interferon alpha-2b proteins (two modified and one normal form) were produced and Pegylated with an aim to produce more effective drugs against viral infections and cancers. The modified recombinant human interferon alpha-2b proteins were produced by site-directed modifications of interferon alpha 2b gene, targeting the amino acids at positions ‘R23’ and ‘H34’. The resulting chemically modified and unmodified forms of human interferon alpha 2b were conjugated with methoxy-polyethylene glycol propanealdehyde (400 KDa) and methoxy-polyethylene glycol succinimidyl succinate (400 KDa). Pegylation of normal and modified forms of Interferon alpha-2b prolong their release time and enhance their efficacy. The conjugation of PEG with modified and unmodified human interferon alpha 2b protein drugs was also characterized with 1H-NMR, HPLC, and SDS-PAGE. Antiproliferative assays of modified and unmodified forms of drugs were performed in cell based bioassays using MDBK cell lines. The results indicated that experimentally produced recombinant human interferon alpha-2b proteins were biologically active and resulted in significant inhibition of cell growth.

Keywords: protein refolding, antiproliferative activities, biomedical applications, human interferon alpha-2b, pegylation, mPEG-propionaldehyde, site directed mutagenesis, E. coli expression

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Authors: Madhu Gupta, Vikas Sharma, Suresh P. Vyas

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CD13 receptors are abundantly overexpressed in tumor cells as well as in neovasculature. The CD13 receptors were selected as a targeted site and polymeric nanoparticles (NPs) as a targeted delivery system. By combining these, a cyclic NGR (cNGR) peptide ligand was coupled on the terminal end of polyethylene glycol-b-poly(lactic-co-glycolic acid) (PEG-b-PLGA) and prepared the dual targeted-NPs (cNGR-PEG-PTX-NPs) to enhance the intracellular delivery of anticancer drug to tumor cells and tumor endothelial cells via ligand-receptor interaction. In-vitro cytotoxicity studies confirmed that the presence of cNGR enhanced the cytotoxic efficiency by 2.8 folds in Human Umbilical Vein Endothelial (HUVEC) cells, while cytotoxicity was improved by 2.6 folds in human fibrosarcoma (HT-1080) cells as compared to non-specific stealth NPs. Compared with other tested NPs, cNGR-PEG-PTX-NPs revealed more cytotoxicity by inducing more apoptosis and higher intracellular uptake. The tumor volume inhibition rate was 59.7% in case of cNGR-PEG-PTX-NPs that was comparatively more with other formulations, indicating that cNGR-PEG-PTX-NPs could more effectively inhibit tumor growth. As a consequence, the cNGR-PEG-PTX-NPs play a key role in enhancing tumor therapeutic efficiency for treatment of CD13 receptor specific solid tumor.

Keywords: cyclic NGR, CD13 receptor, targeted polymeric NPs, solid tumor, intracellular delivery

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Authors: Ivanor Zardo, Fernanda Walper Da Cunha, Júlia Sarkis, Ligia Damasceno Ferreira Marczak

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Lipid oxidation is one of the most important deteriorating processes in oil industry, resulting in the losses of nutritional value of oils as well as changes in color, flavor and other physiological properties. Autoxidation of lipids occurs naturally between molecular oxygen and the unsaturation of fatty acids, forming fat-free radicals, peroxide free radicals and hydroperoxides. In order to avoid the lipid oxidation in vegetable oils, synthetic antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tertiary butyl hydro-quinone (TBHQ) are commonly used. However, the use of synthetic antioxidants has been associated with several health side effects and toxicity. The use of natural antioxidants as stabilizers of vegetable oils is being suggested as a sustainable alternative to synthetic antioxidants. The alternative that has been studied is the use of natural extracts obtained mainly from fruits, vegetables and seeds, which have a well-known antioxidant activity related mainly to the presence of phenolic compounds. The sunflower seed cake is rich in phenolic compounds (1 4% of the total mass), being the chlorogenic acid the major constituent. The aim of this study was to evaluate the in vitro application of the phenolic extract obtained from the sunflower seed cake as a retarder of the lipid oxidation reaction in soybean oil and to compare the results with a synthetic antioxidant. For this, the soybean oil, provided from the industry without any addition of antioxidants, was subjected to an accelerated storage test for 17 days at 65 °C. Six samples with different treatments were submitted to the test: control sample, without any addition of antioxidants; 100 ppm of synthetic antioxidant BHT; mixture of 50 ppm of BHT and 50 ppm of phenolic compounds; and 100, 500 and 1200 ppm of phenolic compounds. The phenolic compounds concentration in the extract was expressed in gallic acid equivalents. To evaluate the oxidative changes of the samples, aliquots were collected after 0, 3, 6, 10 and 17 days and analyzed for the peroxide, diene and triene conjugate values. The soybean oil sample initially had a peroxide content of 2.01 ± 0.27 meq of oxygen/kg of oil. On the third day of the treatment, only the samples treated with 100, 500 and 1200 ppm of phenolic compounds showed a considerable oxidation retard compared to the control sample. On the sixth day of the treatment, the samples presented a considerable increase in the peroxide value (higher than 13.57 meq/kg), and the higher the concentration of phenolic compounds, the lower the peroxide value verified. From the tenth day on, the samples had a very high peroxide value (higher than 55.39 meq/kg), where only the sample containing 1200 ppm of phenolic compounds presented significant oxidation retard. The samples containing the phenolic extract were more efficient to avoid the formation of the primary oxidation products, indicating effectiveness to retard the reaction. Similar results were observed for dienes and trienes. Based on the results, phenolic compounds, especially chlorogenic acid (the major phenolic compound of sunflower seed cake), can be considered as a potential partial or even total substitute for synthetic antioxidants.

Keywords: chlorogenic acid, natural antioxidant, vegetables oil deterioration, waste valorization

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Authors: L. Malic, X. Zhang, D. Brassard, L. Clime, J. Daoud, C. Luebbert, V. Barrere, A. Boutin, S. Bidawid, N. Corneau, J. Farber, T. Veres

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The incidence of infections caused by foodborne pathogens such as Listeria monocytogenes (L. monocytogenes) poses a great potential threat to public health and safety. These issues are further exacerbated by legal repercussions due to “zero tolerance” food safety standards adopted in developed countries. Unfortunately, a large number of related disease outbreaks are caused by pathogens present in extremely low counts currently undetectable by available techniques. The development of highly sensitive and rapid detection of foodborne pathogens is therefore crucial, and requires robust and efficient pre-analytical sample preparation. Immunomagnetic separation is a popular approach to sample preparation. Microfluidic chips combined with external magnets have emerged as viable high throughput methods. However, external magnets alone are not suitable for the capture of nanoparticles, as very strong magnetic fields are required. Devices that incorporate externally applied magnetic field and microstructures of a soft magnetic material have thus been used for local field amplification. Unfortunately, very complex and costly fabrication processes used for integration of soft magnetic materials in the reported proof-of-concept devices would prohibit their use as disposable tools for food and water safety or diagnostic applications. We present a sample preparation magnetic microfluidic device implemented in low-cost thermoplastic polymers using fabrication techniques suitable for mass-production. The developed magnetic capture chip (M-chip) was employed for rapid capture and release of L. monocytogenes conjugated to immunomagnetic nanoparticles (IMNs) in buffer and beef filtrate. The M-chip relies on a dense array of Nickel-coated high-aspect ratio pillars for capture with controlled magnetic field distribution and a microfluidic channel network for sample delivery, waste, wash and recovery. The developed Nickel-coating process and passivation allows generation of switchable local perturbations within the uniform magnetic field generated with a pair of permanent magnets placed at the opposite edges of the chip. This leads to strong and reversible trapping force, wherein high local magnetic field gradients allow efficient capture of IMNs conjugated to L. monocytogenes flowing through the microfluidic chamber. The experimental optimization of the M-chip was performed using commercially available magnetic microparticles and fabricated silica-coated iron-oxide nanoparticles. The fabricated nanoparticles were optimized to achieve the desired magnetic moment and surface functionalization was tailored to allow efficient capture antibody immobilization. The integration, validation and further optimization of the capture and release protocol is demonstrated using both, dead and live L. monocytogenes through fluorescence microscopy and plate- culture method. The capture efficiency of the chip was found to vary as function of listeria to nanoparticle concentration ratio. The maximum capture efficiency of 30% was obtained and the 24-hour plate-culture method allowed the detection of initial sample concentration of only 16 cfu/ml. The device was also very efficient in concentrating the sample from a 10 ml initial volume. Specifically, 280% concentration efficiency was achieved in 17 minutes only, demonstrating the suitability of the system for food safety applications. In addition, flexible design and low-cost fabrication process will allow rapid sample preparation for applications beyond food and water safety, including point-of-care diagnosis.

Keywords: array of pillars, bacteria isolation, immunomagnetic sample preparation, polymer microfluidic device

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Authors: Shirin Jalili, Sadegh Hasannia, Hadi Shirzad, Afshin Khara

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Morphine is one of the most medicinally important analgesics and narcotics. Structurally, it is classified as an alkaloid because of the presence of nitrogen. Its structure is similar to that of codeine, thebaine, and heroin. An immunoassay to accurately discriminate between these analogous alkaloids would be highly beneficial. A key factor for such an assay is specificity with high sensitivity, which is totally dependent on the antibody employed. However, most antibodies against haptens are polyclonal serum antibodies that exhibit significant cross-reactivities with closely related compounds. The camel-derived single-chain antibody fragments (VHH) are the smallest molecules with antigen-binding capacity, possessing unique properties compared to other conventional antibodies. In this study, a library containing the VHH genes of a camel immunized with with morphine conjugated BSA following phage display technology was generated. By screening the camel-derived variable region of the heavy chain cDNA phage display library with the ability to bind the desired hapten, we obtained some nanobodies that recognize this hapten. Phage display expression of the Nbs from this library and pannings against this hapten resulted in a clear enrichment of four distinct Nb-displaying phages with specificity for morphine that could be a potential target site for the development of new strategies for the development of a biosensor for detecting illicit drug.

Keywords: phage display, nanobody, Morphine-3, glucuronide, ELISA, biosensor

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Authors: Adrian Ionut Nicoara, Denisa Ionela Ene, Alina Maria Holban, Cristina Busuioc

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At present, the development of materials with biomedical applications is a domain of interest that will produce a full series of benefits in engineering and medicine. In this sense, it is required to use a natural material, and this paper is focused on the development of a composite material based on bacterial cellulose – hydroxyapatite and silver nanoparticles with applications in hard tissue. Bacterial cellulose own features like biocompatibility, non-toxicity character and flexibility. Moreover, the bacterial cellulose can be conjugated with different forms of active silver to possess antimicrobial activity. Hydroxyapatite is well known that can mimic at a significant level the activity of the initial bone. The material was synthesized by using an ultrasound probe and finally characterized by several methods. Thereby, the morphological properties were analyzed by using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Because the synthesized material has medical application in restore the tissue and to fight against microbial invasion, the samples were tested from the biological point of view by evaluating the biodegradability in phosphate-buffered saline (PBS) and simulated body fluid (SBF) and moreover the antimicrobial effect was performed on Gram-positive bacterium Staphylococcus aureus, Gram-negative bacterium Escherichia coli, and fungi Candida albicans. The results reveal that the obtained material has specific characteristics for bone regeneration.

Keywords: bacterial cellulose, biomaterials, hydroxyapatite, scaffolds materials

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Authors: Chakrit Thapphan, Suteeraporn Chaowattanapanit, Sorutsiri Chareonsudjai, Wisitsak Phoksawat, Supranee Phantanawiboon, Kiatichai Faksri, Steve W. Edwards, Kanin Salao

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Background: Psoriasis is a chronic inflammatory disease of the skin that is mediated by crosstalk between keratinocytes and immune cells, especially CD4+ T helper (Th) cells. To date, psoriasis is established as a T helper 17 (Th17) cell-mediated inflammatory process driven by the over-expression of Th17. However, the role of other CD4+T helper cells is rather controversial. Objective: Our study, thereby, aimed to characterize and analyze T cell subsets in the circulating blood of psoriasis patients and compare them to healthy controls. Methods: Peripheral blood mononuclear cells were isolated from the participants and stained with fluorescent dye-conjugated monoclonal antibodies specific for intracellular cytokines, including interferon-gamma (IFN- γ), interleukin (IL-4), IL-17 and forkhead box P3 (FOXP3), that can be used to define T helper 1 (Th1) cells, T helper 2 (Th2), T helper 17 (Th17) and regulatory T cells (Treg) respectively. Results: We found that the numbers of Th2 (59.6% ± 17.0) and Th17 (4.0% ± 2.0) cells in the circulating blood of psoriasis patients were significantly higher than those of the healthy controls (p= 0.0007 and 0.0013 respectively). In contrast, the numbers of Th1 and Treg cells were not significantly different between psoriasis patients and healthy controls (p= 0.0593 and 0.8518, respectively). Additionally, when adjusting these numbers of Th cells to Treg, we observed a similar trend that the ratio of Th2/Treg and Th17/Treg also elevated (p = 0.0007 and 0.0047, respectively). Conclusion: Taken together, our results suggest an imbalanced T exhibit toward the Th2 and Th17 skewed-immune responses in psoriasis patients.

Keywords: psoriasis, Th cell subsets, Th2 cells, Th17 cells, Treg cells

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Authors: Yves Lacroix, Van Van Than, Didier Léandri, Pierre Liardet

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The western Tombolo of the Giens peninsula in southern France, known as Almanarre beach, is subject to coastal erosion. We are trying to use computer simulation in order to propose solutions to stop this erosion. Our aim was first to determine the main factors for this erosion and successfully apply a coupled hydro-sedimentological numerical model based on observations and measurements that have been performed on the site for decades. We have gathered all available information and data about waves, winds, currents, tides, bathymetry, coastal line, and sediments concerning the site. These have been divided into two sets: one devoted to calibrating a numerical model using Mike 21 software, the other to serve as a reference in order to numerically compare the present situation to what it could be if we implemented different types of underwater constructions. This paper presents the first part of the study: selecting and melting different sources into a coherent data basis, identifying the main erosion factors, and calibrating the coupled software model against the selected reference period. Our results bring calibration of the numerical model with good fitting coefficients. They also show that the winter South-Western storm events conjugated to depressive weather conditions constitute a major factor of erosion, mainly due to wave impact in the northern part of the Almanarre beach. Together, current and wind impact is shown negligible.

Keywords: Almanarre beach, coastal erosion, hydro-sedimentological, numerical model

Procedia PDF Downloads 308

Authors: Suhas Pednekar, Prashant Chavan, Ramesh Chaughule, Deepak Patkar

Abstract:

Iron oxide (Fe3O4) magnetic nanoparticles (MNPs) are one of the most attractive nanomaterials for various biomedical applications. An important potential medical application of polymer-coated iron oxide nanoparticles (NPs) is as imaging agents. Composition, size, morphology and surface chemistry of these nanoparticles can now be tailored by various processes to not only improve magnetic properties but also affect the behavior of nanoparticles in vivo. MNPs are being actively investigated as the next generation of magnetic resonance imaging (MRI) contrast agents. Also, there is considerable interest in developing magnetic nanoparticles and their surface modifications with therapeutic agents. Our study involves the synthesis of biocompatible cancer drug coated with iron oxide nanoparticles and to evaluate their efficacy as MRI contrast agents. A simple and rapid microwave method to prepare Fe3O4 nanoparticles has been developed. The drug was successfully conjugated to the Fe3O4 nanoparticles which can be used for various applications. The relaxivity R2 (reciprocal of the spin-spin relaxation time T2) is an important factor to determine the efficacy of Fe nanoparticles as contrast agents for MRI experiments. R2 values of the coated magnetic nanoparticles were also measured using MRI technique and the results showed that R2 of the Fe complex consisting of Fe3O4, polymer and drug was higher than that of bare Fe nanoparticles and polymer coated nanoparticles. This is due to the increase in hydrodynamic sizes of Fe NPs. The results with various amounts of iron molar concentrations are also discussed. Using MRI, it is seen that the R2 relaxivity increases linearly with increase in concentration of Fe NPs in water.

Keywords: cancer drug, hydrodynamic size, magnetic nanoparticles, MRI

Procedia PDF Downloads 475

Authors: Homa Torabizadeh, Mohaddeseh Mikani

Abstract:

Inulinase from Aspergillus niger was covalently immobilized on magnetic nanoparticles (MNPs/Fe₃O₄) covered with soy protein isolate (SPI/Fe₃O₄) functionalized by bovine serum albumin (BSA) nanoparticles. MNPs are promising enzyme carriers because they separate easily under external magnetic fields and have enhanced immobilized enzyme reusability. As MNPs aggregate simply, surface coating strategy was employed. SPI functionalized by BSA was a suitable candidate for nanomagnetite coating due to its superior biocompatibility and hydrophilicity. Fe₃O₄@SPI-BSA nanoparticles were synthesized as a novel carrier with narrow particle size distribution. Step by step fabrication monitoring of Fe₃O₄@SPI-BSA nanoparticles was performed using field emission scanning electron microscopy and dynamic light scattering. The results illustrated that nanomagnetite with the spherical morphology was well monodispersed with the diameter of about 35 nm. The average size of the SPI-BSA nanoparticles was 80 to 90 nm, and their zeta potential was around −34 mV. Finally, the mean diameter of fabricated Fe₃O₄@SPI-BSA NPs was less than 120 nm. Inulinase enzyme from Aspergillus niger was covalently immobilized through gluteraldehyde on Fe₃O₄@SPI-BSA nanoparticles successfully. Fourier transform infrared spectra and field emission scanning electron microscopy images provided sufficient proof for the enzyme immobilization on the nanoparticles with 80% enzyme loading.

Keywords: high fructose syrup, inulinase immobilization, functionalized magnetic nanoparticles, soy protein isolate

Procedia PDF Downloads 281

Authors: Yves Lacroix, Van Van Than, Didier Léandri, Pierre Liardet

Abstract:

The western Tombolo of the Giens peninsula in southern France, known as Almanarre beach, is subject to coastal erosion. We are trying to use computer simulation in order to propose solutions to stop this erosion. Our aim was first to determine the main factors for this erosion and successfully apply a coupled hydro-sedimentological numerical model based on observations and measurements that have been performed on the site for decades. We have gathered all available information and data about waves, winds, currents, tides, bathymetry, coastal line, and sediments concerning the site. These have been divided into two sets: one devoted to calibrating a numerical model using Mike 21 software, the other to serve as a reference in order to numerically compare the present situation to what it could be if we implemented different types of underwater constructions. This paper presents the first part of the study: selecting and melting different sources into a coherent data basis, identifying the main erosion factors, and calibrating the coupled software model against the selected reference period. Our results bring calibration of the numerical model with good fitting coefficients. They also show that the winter South-Western storm events conjugated to depressive weather conditions constitute a major factor of erosion, mainly due to wave impact in the northern part of the Almanarre beach. Together, current and wind impact is shown negligible.

Keywords: Almanarre beach, coastal erosion, hydro-sedimentological, numerical model

Procedia PDF Downloads 368

Authors: Dinesh Pathaka, Tomas Wagnera, J. M. Nunzib

Abstract:

We investigated blends of MdPVV.PCBM.AIS for photovoltaic application. AgInSe2 powder was synthesized by sealing and heating the stoichiometric constituents in evacuated quartz tube ampule. Fine grinded AIS powder was dispersed in MD-MOPVV and PCBM with and without surfactant. Different concentrations of these particles were suspended in the polymer solutions and spin casted onto ITO glass. Morphological studies have been performed by atomic force microscopy and optical microscopy. The blend layers were also investigated by various techniques like XRD, UV-VIS optical spectroscopy, AFM, PL, after a series of various optimizations with polymers/concentration/deposition/ suspension/surfactants etc. XRD investigation of blend layers shows clear evidence of AIS dispersion in polymers. Diode behavior and cell parameters also revealed it. Bulk heterojunction hybrid photovoltaic device Ag/MoO3/MdPVV.PCBM.AIS/ZnO/ITO was fabricated and tested with standard solar simulator and device characterization system. The best performance and photovoltaic parameters we obtained was an open-circuit voltage of about Voc 0.54 V and a photocurrent of Isc 117 micro A and an efficiency of 0.2 percent using a white light illumination intensity of 23 mW/cm2. Our results are encouraging for further research on the fourth generation inorganic organic hybrid bulk heterojunction photovoltaics for energy. More optimization with spinning rate/thickness/solvents/deposition rates for active layers etc. need to be explored for improved photovoltaic response of these bulk heterojunction devices.

Keywords: thin films, photovoltaic, hybrid systems, heterojunction

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Authors: Elad Arad, Raz Jelinek, Hanna Rapaport

Abstract:

Amyloidoses are a family of diseases characterized by abnormal protein folding that leads to aggregation. They accumulate to form fibrillar plaques which are implicated in the pathogenesis of Alzheimer, prion, diabetes type II and other diseases. To the best of our knowledge, despite extensive research efforts devoted to plaque aggregates inhibition, there is yet no cure for this phenomenon. Titanium and its alloys are found in growing interest for biomedical applications. Variety of surface modifications enable porous, adhesive, bioactive coatings for its surface. Titanium oxides (titania) are also being developed for photothermal and photodynamic treatments. Inspired by this, we set to explore the effect of functionalized titania nanoparticles in combination with external stimuli, as potential photothermal ablating agents against amyloids. Titania nanoparticles were coated with bi-functional catechol derivatives (dihydroxy-phenylalanine propanoic acid, noted DPA) to gain targeting properties. In conjunction with UV-radiation, these nanoparticles may selectively destroy the vicinity of their target. Titania modified 5 nm nanoparticles coated with DPA were further conjugated to the amyloid-targeting Congo Red (CR). These Titania-DPA-CR nanoparticles were found to target mature amyloid fibril of both amyloid-β (Aβ 1-42 a.a). Moreover, irradiation of the peptides in presence of the modified nanoparticles decreased the aggregate content and oligomer fraction. This work provides insights into the use of modified titania nanoparticles for amyloid plaque targeting and photothermal destruction. It may shed light on future modifications and functionalization of titania nanoparticles for different applications.

Keywords: titanium dioxide, amyloids, photothermal treatment, catechol, Congo-red

Procedia PDF Downloads 138

Authors: Sanghamitra Acharya, Suwarna Datar

Abstract:

Extensive use of digital and smart communication createsprolong expose of unwanted electromagnetic (EM) radiations. This harmful radiation creates not only malfunctioning of nearby electronic gadgets but also severely affects a human being. So, a suitable microwave absorbing material (MAM) becomes a necessary urge in the field of stealth and radar technology. Initially, Aluminum based hexa ferrite was prepared by sol-gel technique and for carbon derived composite was prepared by the simple one port chemical reduction method. Finally, composite films of Poly (Vinylidene) Fluoride (PVDF) are prepared by simple gel casting technique. Present work demands that aluminum-based hexaferrite phase conjugated with graphene in PVDF matrix becomes a suitable candidate both in commercially important X and Ku band. The structural and morphological nature was characterized by X-Ray diffraction (XRD), Field emission-scanning electron microscope (FESEM) and Raman spectra which conforms that 30-40 nm particles are well decorated over graphene sheet. Magnetic force microscopy (MFM) and conducting force microscopy (CFM) study further conforms the magnetic and conducting nature of composite. Finally, shielding effectiveness (SE) of the composite film was studied by using Vector network analyzer (VNA) both in X band and Ku band frequency range and found to be more than 30 dB and 40 dB, respectively. As prepared composite films are excellent microwave absorbers.

Keywords: carbon nanocomposite, microwave absorbing material, electromagnetic shielding, hexaferrite

Procedia PDF Downloads 164

Authors: Manal Kamel, Sara Maher, Hanan El Baz, Faten Salah, Omar Sayyouh, Zeinab Demerdash

Abstract:

In the recent COVID 19 pandemic, experts of public health have emphasized testing, tracking infected people, and tracing their contacts as an effective strategy to reduce the spread of the virus. Development of rapid and sensitive diagnostic assays to replace reverse transcription polymerase chain reaction (RT-PCR) is mandatory..Our innovative test strip relying on the application of nanoparticles conjugated to recombinant nanobodies for SARS-COV-2 spike protein (S1) & angiotensin-converting enzyme 2 (that is responsible for the virus entry into host cells) for rapid detection of SARS-COV-2 spike protein (S1) in saliva or sputum specimens. Comparative tests with RT-PCR will be held to estimate the significant effect of using COVID 19 nanobodies for the first time in the development of lateral flow test strip. The SARS-CoV-2 S1 (3 ng of recombinant proteins) was detected by our developed LFIA in saliva specimen of COVID-19 Patients No cross-reaction was detected with Middle East respiratory syndrome coronavirus (MERS-CoV) or SARS- CoV antigens..Our developed system revealed 96 % sensitivity and 100% specificity for saliva samples compared to 89 % and 100% sensitivity and specificity for nasopharyngeal swabs. providing a reliable alternative for the painful and uncomfortable nasopharyngeal swab process and the complexes, time consuming PCR test. An increase in testing compliances to be expected.

Keywords: COVID 19, diagnosis, LFIA, nanobodies, ACE2

Procedia PDF Downloads 118

Authors: Kanchan Yadav, Ai-Chuan Chou, Rajesh Kumar Ulaganathan, Hua-De Gao, Hsien-Ming Lee, Chien-Yuan Pan, Yit-Tsong Chen

Abstract:

Optogenetics is an innovative technology now widely adopted by researchers in different fields of the biological sciences. However, due to the weak tissue penetration capability of the short wavelengths used to activate light-sensitive proteins, an invasive light guide has been used in animal studies for photoexcitation of target tissues. Upconverting nanoparticles (UCNPs), which transform near-infrared (NIR) light to short-wavelength emissions, can help address this issue. To improve optogenetic performance, we enhance the target selectivity for optogenetic controls by specifically conjugating the UCNPs with light-sensitive proteins at a molecular level, which shortens the distance as well as enhances the efficiency of energy transfer. We tagged V5 and Lumio epitopes to the extracellular N-terminal of channelrhodopsin-2 with an mCherry conjugated at the intracellular C-terminal (VL-ChR2m) and then bound NeutrAvidin-functionalized UCNPs (NAv-UCNPs) to the VL-ChR2m via a biotinylated antibody against V5 (bV5-Ab). We observed an apparent energy transfer from the excited UCNP (donor) to the bound VL-ChR2m (receptor) by measuring emission-intensity changes at the donor-receptor complex. The successful patch-clamp electrophysiological test and an intracellular Ca2+ elevation observed in the designed UCNP-ChR2 system under optogenetic manipulation confirmed the practical employment of UCNP-assisted NIR-optogenetic functionality. This work represents a significant step toward improving therapeutic optogenetics.

Keywords: Channelrhodopsin-2, near infrared, optogenetics, upconverting nanoparticles

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Authors: Zeynep Dikmen, Vural Bütün

Abstract:

Electron donor or acceptor capability to participate in electron conjugation is the requirement for an electroactive material. Conjugated molecules and polymers bearing heterocyclic units have potential as optically electroactive materials. Thiazolo thiazole based compounds have attention for last two decades, because they have attractive electronic and optical properties, these compounds are useful for electronic application areas such as dye sentisized solar cells (DSSCs), organic light emitting diodes (OLEDs) and field effect transistors (FETs). Thiazolo[5,4-d]thiazole is bicyclic aromatic structure contains N and S atoms which act as electron donor. A new electron accepting or donating group bound to thiazolo [5,4-d] thiazole fused ring can change the electronic, spectroscopic, stability and dyeing properties of the new material. Polyphenylene(thiazolo [5,4-d] thiazole) (p-PhTT) compound was synthesized via condensation reaction of terephthalaldehyde with dithiooxamide. The chemical structure was determined with solid state 13C NMR spectroscopy. Optical properties (i.e. absorbance and band gap) was determined via solid UV-vis spectroscopy. The insoluble polymer was quarternized with 4-vinylbenzyl chloride (VBC). Colorless VBC changed into a yellow liquid. AgNO3 complex were prepared and optical properties were investigated with UV-Vis, fluorescence spectroscopy and X-ray spectroscopy and cyclic voltammetry studies were examined in this research. This structure exhibits good absorbance and fluorescence in UV-vis region. Synthesis scheme of PyTT and preparation of metal complexes are given. PyTT has absorbance at ~360 nm and fluorescence at ~420 nm.

Keywords: thiazolo thiazole, quarternized polymers, polymeric ligands, Ag complexes

Procedia PDF Downloads 254

Authors: S. B. Bhandare, K. S. Laddha

Abstract:

Podphyllum hexandrum belonging to family berberidaceae has gained attention in phytochemical and pharmacological research as it shows excellent anticancer activity and has been used in treatment of skin diseases, sunburns and radioprotection. Chemically it contains lignans and flavonoids such as kaempferol, quercetin and their glycosides. Objective: To isolate and identify Kaempferol and Quercetin from Podophyllum rhizome. Method: The powdered rhizome of Podophyllum hexandrum was subjected to soxhlet extraction with methanol. This methanolic extract is used to obtain podophyllin. Podohyllin was extracted with ethyl acetate and this extract was then concentrated and subjected to column chromatography to obtain purified kaempferol and quercetin. Result: Isolated kaempferol, quercetin were light yellow and dark yellow in colour respectively. TLC of the isolated compounds was performed using chloroform: methanol (9:1) which showed single band on silica plate at Rf 0.6 and 0.4 for kaempferol and quercetin. UV spectrometric studies showed UV maxima (methanol) at 259, 360 nm and 260, 370 nm which are identical with standard kaempferol and quercetin respectively. Both IR spectra exhibited prominent absorption bands for free phenolic OH at 3277 and 3296.2 cm-1 and for conjugated C=O at 1597 and 1659.7 cm-1 respectively. The mass spectrum of kaempferol and quercetin showed (M+1) peak at m/z 287 and 303.09 respectively. 1H NMR analysis of both isolated compounds exhibited typical four-peak pattern of two doublets at δ 6.86 and δ 8.01 which was assigned to H-3’,5’ and H-2’,6’ respectively. Absence of signals less than δ 6.81 in the 1H NMR spectrum supported the aromatic nature of compound. Kaempferol and Quercetin showed 98.1% and 97% purity by HPLC at UV 370 nm. Conclusion: Easy and simple method for isolation of Kaempferol and Quercetin was developed and their structures were confirmed by UV, IR, NMR and mass studies. Method has shown good reproducibility, yield and purity.

Keywords: flavonoids, kaempferol, podophyllum rhizome, quercetin

Procedia PDF Downloads 294

Authors: Z. Okay, M. Kalkan Erdoğan, M. Şahin, M. Saçak

Abstract:

Polyacrylonitrile (PAN) is one of the most common and cheap fiber-forming polymers because of its high strength and high abrasion resistance properties. The result of alkaline hydrolysis of PAN fiber could be formed the products with conjugated sequences of –C=N–, acrylamide, sodium acrylate, and amidine. In this study, PAN fiber was hydrolyzed in a solution of sodium hydroxide, and this hydrolyzed PAN (HPAN) fiber was used to prepare conductive composite fiber by silver particles. The electrically conductive PAN fiber has the usage potential to produce variety of materials such as antistatic materials, life jackets and static charge reducing products. We monitored the change in the weight loss values of the PAN fiber with hydrolysis time. It was observed that a 60 % of weight loss was obtained in the fiber weight after 7h hydrolysis under the investigated conditions, but the fiber lost its fibrous structure. The hydrolysis time of 5h was found to be suitable in terms of preserving its fibrous structure. The change in the conductivity values of the composite with the preparation conditions such as hydrolysis time, silver ion concentration was studied. PAN fibers with different degrees of hydrolysis were treated with aqueous solutions containing different concentrations of silver ions by continuous stirring at 20 oC for 30 min, and the composite having the maximum conductivity of 2 S/cm could be prepared. The antibacterial property of the conductive HPAN fibers participated silver was also investigated. While the hydrolysis of the PAN fiber was characterized with FTIR and SEM techniques, the silver reduction process of the HPAN fiber was investigated with SEM and TGA-DTA techniques. The SEM micrographs showed that the surface of HPAN fiber was rougher and much more corroded than that of the PAN fiber. Composite, Conducting polymer, Fiber, Polyacrylonitrile.

Keywords: composite, conducting polymer, fiber, polyacrylonitrile

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Authors: Abbas Jafarizad, Duygu Ekinci

Abstract:

In this work targeted drug delivery is proposed to decrease adverse effect of drugs with concomitant reduces in consumption and treatment outgoings. Nanoparticles (NPs) can be prepared from a variety of materials such as lipid, biodegradable polymer that prevent the drugs cytotoxicity in healthy cells, etc. One of the most important drugs used in chemotherapy is mitoxantrone (MTX) which prevents cell proliferation by inhibition of topoisomerase II and DNA repair; however, it is not selective and has some serious side effects. In this study, mentioned aim is achieved by using several nanocarriers like magnetite (Fe3O4) and their composites with magnetic graphene oxide (Fe3O4@GO). Also, cytotoxic potential of Fe3O4, Fe3O4-MTX, and Fe3O4@GO-MTX nanocomposite were evaluated on mesenchymal stem cells (MSCs). In this study, we reported the synthesis of monodisperse Fe3O4 NPs and Fe3O4@GO nanocomposite and their structures were investigated by using field emission scanning electron microscope (FESEM), Fourier transform infrared (FTIR) spectra, atomic force microscopy (AFM), Brauneur Emmet Teller (BET) isotherm and contact angle studies. Moreover, we used 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay to evaluate cytotoxic effects of MTX, Fe3O4 NPs, Fe3O4-MTX and Fe3O4@GO-MTX nanocomposite on MSCs. The in-vitro MTT results indicated that all concentrations of MTX and Fe3O4@GO-MTX nanocomposites showed cytotoxic effects while all concentrations of Fe3O4 NPs and Fe3O4-MTX NPs did not show any cytotoxic effect on stem cells. The results from this study indicated that using Fe3O4 NPs as anticancer drug delivery systems could be a trustworthy method for cancer treatment. But for reaching excellent and accurate results, further investigation is necessary.

Keywords: mitoxantrone, magnetite, magnetic graphene oxide, MTT assay, mesenchymal stem cells

Procedia PDF Downloads 264