Stabilisation of SWNTs by alkyl-sulfate chitosan derivatives of different molecular weight: towards the preparation of hybrids with anticoagulant properties (original) (raw)
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Nanoscale, 2009
A non-covalent approach to debundle single wall carbon nanotubes using a biocompatible chitosan-derivative, namely N-octyl-O-sulfate chitosan (NOSC), was investigated. The resulting stable dispersions were characterised by Raman spectroscopy, UV-Vis spectroscopy, atomic force microscopy (AFM), transmission electron microscopy (TEM) and z-potential measurements. Both AFM and TEM studies revealed the presence of individual carbon nanotubes wrapped with the polymer (diameters up to 7 nm). Raman spectra showed radial breathing mode frequency shifts, after the addition of NOSC, due to the wrapping of the biomolecules onto the graphitic sidewalls. Molecular modelling studies were employed to investigate the mode of binding of the NOSC chains to the surface of the nanotubes. In agreement with the experiments, modelling studies predicted that the wrapped tube has a maximum thickness of approximately 7 nm. Studies on the anticoagulant properties of these complexes revealed that NOSC coated SWCNTs exhibit similar activity to the polymer alone, this property would eliminate the risk for SWCNTs to induce coagulation as a host reaction process when used in vivo.
Low-molecular-weight sulfonated chitosan as template for anticoagulant nanoparticles
International journal of nanomedicine, 2018
In this work, low-molecular-weight sulfoethyl chitosan (SECS) was used as a model template for the generation of silver core-shell nanoparticles with high potential as anticoagulants for medical applications. SECS were synthesized by two reaction pathways, namely Michael addition and a nucleophilic substitution with sodium vinylsulfonate or sodium 2-bromoethanesulfonate (NaBES). Subsequently, these derivatives were used as reducing and capping agents for silver nanoparticles in a microwave-assisted reaction. The formed silver-chitosan core-shell particles were further surveyed in terms of their anticoagulant action by different coagulation assays focusing on the inhibition of either thrombin or cofactor Xa. In-depth characterization revealed a sulfoalkylation of chitosan mainly on its sterically favored 6-position. Moreover, comparably high average degrees of substitution with sulfoethyl groups (DS) of up to 1.05 were realized in reactions with NaBES. The harsh reaction conditions l...
Physical Chemistry Chemical Physics, 2010
Dimitris and Roldo, Marta (2010) Novel biocompatible chitosan decorated single-walled carbon nanotubes (SWNTs) for biomedical applications: theoretical and experimental investigations. Physical Chemistry Chemical Physics, 12 (48). Molecular mechanics and molecular dynamics simulations have been employed to characterise the interactions between SWNTs and biocompatible amphililic derivatives of chitosan, namely N-butyl-O-sulfate chitosan (NBSC), N-octyl-O-sulfate chitosan (NOSC) and N-palmitoyl-Osulfate chitosan (NPSC). The computational simulations have shown that the affinity of the polymer for the hydrophobic surface of the nanotubes depends on the length of the chitosan hydrophobic pendant chain. Longer chains have a higher flexibility and therefore a better ability to wrap around the nanotubes.
Reversible non-covalent derivatisation of carbon nanotubes with glycosides
Soft Matter, 2009
Financial support from the Swedish Research Council (VR) the Magn. Bergvall foundation and the Uppsala university KoF program. General Thin-layer chromatography analyses were performed on pre-coated Merck silica gel plates (60F254) and visualized by with UV light. Melting points were determined on a Bibby Stuart Scientific SMP10 apparatus and are reported without correction. 1 H and 13 C NMR spectra were recorded on a Varian 400 MHz or 500 MHz spectrometer and chemical shifts are given in ppm (δ) using CDCl 3 , CD 3 OD or D 2 O as internal standard. LC-MS analyses were performed on a Gilson reverse phase HPLC equipped with a Finnigan mass spectrometer (MeCN/H 2 O and 0.1% formic acid as mobile phase). Preparative HPLC was performed with a Supplementary Material (ESI) for Soft Matter This journal is (c) The Royal Society of Chemistry 2009-2-Gilson 333 pump, a Gilson 231 XL sampling injector, a Gilson FC 204 fraction collector and a Gilson 118/119 UV/Vis detector. MeCN/H 2 O (with 0.1% formic acid) was used as mobile phase and the chromatography was carried out with a YMC 150x20 mm C8 column. Centrifugation-assisted filtration was performed using an Eppendorf minispin centrifuge together with Vectaspin microvials equipped with a 0.45 μm polypropylene filter-membrane (Whatman Schleicher & Schuell). Raman spectra were recorded on a Renishaw Raman spectrometer using a 514 nm Argon laser, with a 50x lens and a laser power of 10 mW. IR spectra were recorded on a PerkinElmer Spectrum-100 FT-IR spectrometer with an ATR accessory. The samples were analyzed by placing neat samples directly on the ATR crystal. Fluorescence spectra were recorded on a Varian Cary Eclipse fluorescence spectrometer and UV spectra were recorded on a Varian Cary 3 Bio UV/Vis spectrometer. Acid-oxidized MWNTs (Shenzhen Nanotech Port, PRC, diameter range 10-30 nm) was prepared by literature procedure 1. The reported special surface area for these MWNTs is 40-300 m 2 /g. 2 Preparation of acid-oxidized SWNTs SWNTs (CNI HiPCO, lot p0332) (66 mg) was added to a 100 ml round bottomed flask together with HNO 3 (8M, 12.5 ml). The mixture was ultrasonicated for 10 minutes and then refluxed for 1 hour. The mixture was allowed to cool and the acidic solution was then separated from the SWNTs by centrifugation. The solid SWNT material was washed with aqueous KOH and with water and was then transferred to a vectaspin microvial equipped with a 0.45 μm polypropylene filter membrane. The SWNTs were washed with deionized water until the filtrate was neutral and the SWNTs was then dried in a vacuum oven at 160°C for 24 hours. The acid-oxidized SWNTs was analyzed by Raman and IR spectroscopy which
Chemical Communications, 2012
Materials: Cytochrome c (oxidized), all amino acids, palmitic acid, dicyclohexylcarbodiimide (DCC), 4-N,N-(dimethyl)aminopyridine (DMAP), 1hydroxybenzotriazole (HOBT) and all solvents were purchased from SRL India. 1,1´carbonyl diimidazole (CDI), thionyl chloride, sodium hydroxide were purchased from Spectrochem, India. Pyrogallol was obtained from Qualigens Fine chemical Company, India. Hydrogen peroxide (30%, w/v solution) was purchased from Ranbaxy, India. Single walled carbon nanotubes (SWNT, 1-2 nm diameter) and all deuteriated solvents for NMR experiments were obtained from Aldrich Chemical Co. Milli-Q Water was used throughout the study. Thin layer chromatography was performed on Merck precoated silica gel 60-F 254 plates. 1 H NMR spectra were recorded in AVANCE 300 MHz (Bruker) spectrometer. Mass spectrometric data were acquired by electron spray ionization (ESI) technique on a Q-tofmicro quadruple mass spectrometer (Micromass). Elemental analyses were performed on Perkin Elmer 2400 CHN analyzer. Probe sonication was done using Omni Sonic Ruptor 250. Bath sonication was performed with a Telsonic Ultrasonics bath sonicator. Sorvall RC 6 was used for centrifugation respectively. Synthetic procedure: All dipeptide amphiphiles were synthesized following the reaction conditions as reported previously. 1 Briefly, methyl ester of protected L-amino acid was
Soft Matter, 2015
Cationic polymers have recently attracted attention due to their proven potential for nonviral gene delivery. In this study, we report novel biocompatible nanocomplexes produced using chemically functionalized N,N,N-trimethyl chitosan (TMC) with different N-acyl chain lengths (C5-C18) associated with single-stranded oligonucleotides. The TMC derivatives were synthesized by covalent coupling reactions of quaternized chitosan with n-pentanoic (C5), n-decanoic (C10), and noctadecanoic (C18) fatty acids, which were extensively characterized by Fourier transform-infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance (1 H NMR). These N-acylated TMC derivatives (TMCn) were used as cationic polymeric matrices for encapsulating anionic 18-base singlestranded thiophosphorylated oligonucleotides (ssONs), leading to the formation of polyplexes further characterized by zeta potential (ZP), dynamic light scattering (DLS), binding affinity, transfection efficiency and in vitro cytotoxicity assays. The results demonstrated that the length of Version: Postprint (identical content as published paper) This is a self-archived document from i3S-Instituto de Investigação e Inovação em Saúde in the University of Porto Open Repository For Open Access to more of our publications, please visit http://repositorio-aberto.up.pt/ A01/00 the grafted hydrophobic N-acyl chain and the relative amino:phosphate groups ratio (N/P ratio) between the TMC derivatives and ssON played crucial roles in determining the physicochemical properties of the obtained nanocomplexes. While none of the tested derivatives showed appreciable cytotoxicity, the type of acyl chain had a remarkable influence on the cell transfection capacity of TMC-ssON nanocomplexes with the derivatives based on stearic acid showing the best performance based on the results of in vitro assays using a model cell line expressing luciferase (HeLa/Luc705). Version: Postprint (identical content as published paper) This is a self-archived document from i3S-Instituto de Investigação e Inovação em Saúde in the University of Porto Open Repository For Open Access to more of our publications, please visit http://repositorio-aberto.up.pt/ A01/00 fluorescence. Cells treated with TMC-C18-based nanoparticles showed the highest fluorescence intensity for all N/P ratios in comparison to all other TMC nanoparticles and control free ON, but below L2k. The higher hydrophobicity imparted by the C18 chains seems to play an important role in the initial interaction of the nanocomplexes with the cells. Still, in general, an increase in hydrophobicity improves cellular interactions of the TMC/ssON nanocomplexes as verified for the TMC-C5s and TMC-C18. The nanocomplexes formed with TMC-C10 did not follow this rule, which, however, goes in line with the overall instability of such nanocomplexes demonstrated in the previous experiments. 3.8. Cell toxicity (metabolic activity) Cell viability was evaluated by measuring metabolic activity after incubation with the TMC/ssON nanocomplexes at different N/P ratios (Fig. 9). Independently of the nanocomplexes tested no significant alterations of the metabolic activity of the cells have been observed indicating absence of cytotoxicity by the TMC/ssON nanocomplexes.
Carbohydrate Polymers, 2011
The aim of this study was to investigate three kinds of methylated chitosan containing different aromatic moieties; methylated N-(4-N,N-dimethylaminobenzyl) chitosan (TM-Bz-CS), methylated N-(4-N,N-dimethylaminocinnamyl) chitosan (TM-CM-CS) and methylated N-(4-pyridylmethyl) chitosan (TM-Py-CS), on the paracellular permeability of Caco-2 cell monolayers and their toxicity towards the cell lines. The factors affecting epithelial permeability were evaluated in intestinal cell monolayers of Caco-2 cells using the transepithelial electrical resistance (TEER) and permeability of Caco-2 cell monolayers, with fluorescein isothiocyanate dextran 4400 (FD-4) as a model compound for paracellular tight junction transport. The results revealed that methylated chitosan containing different aromatic moieties showed the different absorption enhancing ability. The rank of enhancing paracellular permeability was TM 65 CM 50 CS > TM 56 Bz 42 CS > TM 65 CS > TM 53 Py 40 CS. The cytotoxicity of these modified chitosans on Caco-2 cells was also studied by MTT assay where the TM 53 Py 40 CS exhibited less toxicity than other derivatives. These studies demonstrated that the chemical structure and the positive charge location play an important role for absorption enhancement and cytotoxicity.