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Yoshio Okamoto - One of the best experts on this subject based on the ideXlab platform.

  • improved preparation of chiral stationary phases via immobilization of Polysaccharide Derivative based selectors using diisocyanates
    IEEE Journal of Solid-state Circuits, 2011
    Co-Authors: Shouwan Tang, Yoshio Okamoto, Xiaofang Li, Fang Wang
    Abstract:

    : The classical method for the preparation of immobilized Polysaccharide-based chiral stationary phases (CSPs) with a diisocyanate was improved. Cellulose or amylose was directly coated onto 3-aminopropyl silica gel after it was dissolved in a mixture of N,N-dimethylacetamide, LiCl, and pyridine, then immobilized onto silica gel with a diisocyanate, and finally allowed to react with an excess of corresponding isocyanate. Four Polysaccharide Derivatives, 3,5-dimethylphenylcarbamate and 3,5-dichlorophenylcarbamate of cellulose, and 3,5-dimethylphenylcarbamate and 5-chloro-2-methylphenylcarbamate of amylose, were immobilized onto silica gel utilizing this method. Compared with the classical diisocyanate method, the improved procedure avoided the derivatization and regeneration of 6-hydroxyl groups of cellulose and amylose, and thus showed an advantage for simple and economical preparation. The relationships among the amount of diisocyanate used, immobilization efficiency, and enantioseparation on the cellulose-based CSPs were investigated. Also, the solvent durability of the obtained CSPs was examined with eluents containing chloroform or THF. By utilizing these eluents, the chiral recognition abilities of the obtained CSPs for some of the tested racemates were improved.

  • direct enantiomeric separations of tris 2 phenylpyridine iridium iii complexes on Polysaccharide Derivative based chiral stationary phases
    Journal of Separation Science, 2007
    Co-Authors: Xiaoming Chen, Yoshio Okamoto, Tomohiro Yano, Joe Otsuki
    Abstract:

    A convenient method is presented for the first time for the direct separation of enantiomers of a tris(2-phenylpyridine) iridium (III) and an analog substituted with long alkoxy chains on Polysaccharide Derivative-based chiral stationary phases by HPLC. Tris(2-phenylpyridine) iridium (III) was separated on the immobilized amylose 3,5-dimethylphenylcarbamate (Chiralpak IA) using hexane/CHCl3/CH2Cl2 (75:20:5) as an eluent, and the analog could be separated on the coated cellulose 3,5-dimethylphenylcarbamate (Chiralcel OD) and cellulose 4-methylbenzoate (Chiralcel OJ) using hexane/2-propanol (96:4) as the eluent. CD spectra of the eluted HPLC fractions were also recorded, and the observed mirror image patterns confirm their enantioseparations.

  • Immobilized Polysaccharide-Based Chiral Stationary Phases for HPLC
    Polymer Journal, 2006
    Co-Authors: Tomoyuki Ikai, Chiyo Yamamoto, Masami Kamigaito, Yoshio Okamoto
    Abstract:

    Polysaccharide Derivatives, such as phenylcarbamates and benzoates of cellulose and amylose, are known to show high chiral recognition abilities for many racemates when used as chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC). This type of CSPs has usually been prepared by coating the Polysaccharide Derivatives onto a macroporous silica gel without a chemical bond. Therefore, rather limited numbers of solvents can be used as eluents, and solvents, such as chloroform and tetrahydrofuran (THF), which swell or dissolve the Polysaccharide Derivatives cannot be used. The selection of a suitable eluent is very important for both analytical and preparative separations. In order to enhance the versatility of the Polysaccharide Derivative-based CSPs, the Derivatives have to be immobilized. Here we review the immobilization methods of the Polysaccharide Derivatives mainly onto silica gel.

  • high performance liquid chromatographic enantioseparations on monolithic silica columns containing a covalently attached 3 5 dimethylphenylcarbamate Derivative of cellulose
    Journal of Chromatography A, 2004
    Co-Authors: Bezhan Chankvetadze, Tomoyuki Ikai, Chiyo Yamamoto, Yoshio Okamoto
    Abstract:

    Covalent immobilization of 3,5-dimethylphenylcarbamate Derivative of cellulose was performed in situ onto native silica monoliths cladded in a 50 mm x 4.6 mm polyether ether ketone high-performance liquid chromatographic (HPLC) column. The covalent attachment of cellulose Derivative in the range of 16-19% (w/w) was performed via an epoxide moiety. The column obtained by this technique combines the high enantiomer-resolving ability of the Polysaccharide Derivative with favourable dynamic properties of monolithic HPLC columns. The covalent attachment of the cellulose Derivative enables this column to be used in combination with the mobile phases which are incompatible with coated-type Polysaccharide columns due to solubility of chiral selector in some organic solvents.

  • effect of organic solvent electrolyte salt and a loading of cellulose tris 3 5 dichlorophenyl carbamate on silica gel on enantioseparation characteristics in capillary electrochromatography
    Electrophoresis, 2001
    Co-Authors: Bezhan Chankvetadze, Yoshio Okamoto, Irma Kartozia, Jorg Breitkreutz, Gottfried Blaschke
    Abstract:

    The effect of the amount of the chiral selector, cellulose tris(3,5-dichlorophenylcarbamate) (CDCPC) on the separation characteristics of enantiomers of some charged and neutral analytes was studied in capillary electrochromatography (CEC). For better understanding of the effect of the loading of the chiral selector on the particles and pore size of the packing material, laser-beam particle size analyzer and scanning electron microscopy (SEM) were used. As shown in this study, CDCPC can be used for CEC enantioseparations of a wide range of chiral charged and neutral analytes with high efficiency. The loading of the Polysaccharide Derivative on the surface of silica materials even in high amounts does not markedly affect the particle size and porous structure of the packing material. The separation characteristics are strongly affected by the loading of CDCPC onto silica gel in both CEC and capillary liquid chromatography (CLC).

Liming Zhang - One of the best experts on this subject based on the ideXlab platform.

  • naturally occurring bacterial cellulose hyperbranched cationic Polysaccharide Derivative mmp 9 sirna composite dressing for wound healing enhancement in diabetic rats
    Acta Biomaterialia, 2020
    Co-Authors: Liqun Yang, Liming Zhang, Chenglin Pan, Phei Er Saw, Meng Ren, Biyun Lan, Xiaoyi Wang, Tingting Zeng, Liyan Zhou, Chuan Yang
    Abstract:

    The anomalous high expression of matrix metalloproteinase 9 (MMP-9) is one important factor that impedes diabetic wound healing. Therefore, inhibition of MMP-9 expression in a diabetic wound could be a feasible method to promote wound healing. In this study, we studied the possibility of self-therapy using wound dressings that contain bacterial cellulose-hyperbranched cationic Polysaccharide (BC-HCP) Derivatives that encapsulate siRNA (BC-HCP/siMMP-9) and have controlled release properties. Herein, we used four HCPs (Gly-DMAPA, Gly-D4, Amyp-DMAPA, Amyp-D4) as gene carriers. Our results showed that all HCP Derivatives were minimally toxic to cells in vitro, while the cationic properties of HCP could be used as a complexation agent for MMP-9 siRNA (siMMP-9). Upon exposure to bacterial cellulose (BC), the BC slowly released HCP/siMMP-9. The released siMMP-9 effectively reduced the gene expression and protein levels of MMP-9 in a human immortalized epithelial cell line (HaCAT) and in diabetic rat wounds. Inhibition of MMP-9 in the wounds of diabetic rats resulted in a significant enhancement of wound healing, suggesting that the BC-HCP/siMMP-9 composite dressing could be used as a safe and effective dressing to promote wound healing in diabetic rats. STATEMENT OF SIGNIFICANCE: In this work, we evaluated the possibility of using bacterial cellulose-hyperbranched cationic Polysaccharide Derivatives (BC-HCP) as a self-therapeutic wound dressing with siRNA encapsulated and controlled release properties. Our results showed that the BC-HCP/siMMP-9 composite dressing slowly released HCP/siMMP-9. The released siMMP-9 effectively reduced the gene expression and protein level of MMP-9 in human immortalized epithelial cell line and in the wound of diabetic rats. The BC-HCP/siMMP-9 composite dressing promoted diabetic wound healing by the unique nanostructure of BC and by releasing siMMP-9 for specific MMP-9 inhibition. Therefore, it could be used as a safe and effective dressing to promote wound healing in diabetic rats. This is the first evidence on the study of using BC as a dressing composite by encapsulating HCP/siRNA complexes for efficient RNAi gene silencing for better wound healing in diabetic rats.

  • nanoscale Polysaccharide Derivative as an aeg 1 sirna carrier for effective osteosarcoma therapy
    International Journal of Nanomedicine, 2018
    Co-Authors: Fen Wang, Jiadong Pang, Leilei Huang, Ran Wang, Kang Sun, Liantang Wang, Liming Zhang
    Abstract:

    Background Nanomedicine, which is the application of nanotechnology in medicine to make medical diagnosis and treatment more accurate, has great potential for precision medicine. Despite some improvements in nanomedicine, the lack of efficient and low-toxic vectors remains a major obstacle. Objective The aim of this study was to prepare an efficient and low-toxic vector which could deliver astrocyte elevated gene-1 (AEG-1) small interfering RNA (siRNA; siAEG-1) into osteosarcoma cells effectively and silence the targeted gene both in vitro and in vivo. Materials and methods We prepared a novel Polysaccharide Derivative by click conjugation of azidized chitosan with propargyl focal point poly (L-lysine) dendrons (PLLD) and subsequent coupling with folic acid (FA; Cs-g-PLLD-FA). We confirmed the complexation of siAEG-1and Cs-g-PLLD or Cs-g-PLLD-FA by gel retardation assay. We examined the cell cytotoxicity, cell uptake, cell proliferation and invasion abilities of Cs-g-PLLD-FA/siAEG-1 in osteosarcoma cells. In osteosarcoma 143B cells tumor-bearing mice models, we established the therapeutic efficacy and safety of Cs-g-PLLD-FA/siAEG-1. Results Cs-g-PLLD-FA could completely encapsulate siAEG-1 and showed low cytotoxicity in osteosarcoma cells and tumour-bearing mice. The Cs-g-PLLD-FA/siAEG-1 nanocomplexes were capable of transferring siAEG-1 into osteosarcoma cells efficiently, and the knockdown of AEG-1 resulted in the inhibition of tumour cell proliferation and invasion. In addition, caudal vein injecting of Cs-g-PLLD-FA/siAEG-1 complexes inhibited tumor growth and lung metastasis in tumor-bearing mice by silencing AEG-1 and regulating MMP-2/9. Conclusion In summary, Cs-g-PLLD-FA nanoparticles are a promising system for the effective delivery of AEG-1 siRNA for treating osteosarcoma.

  • efficient delivery of nf κb sirna to human retinal pigment epithelial cells with hyperbranched cationic Polysaccharide Derivative based nanoparticles
    International Journal of Nanomedicine, 2015
    Co-Authors: Zhenzhen Liu, Liming Zhang, Haijun Gong, Rui Zeng, Xuan Liang, Liqun Yang, Yuqing Lan
    Abstract:

    A hyperbranched cationic Polysaccharide Derivative-mediated small interfering (si)RNA interference strategy was proposed to inhibit nuclear transcription factor-kappa B (NF-κB) activation in human retinal pigment epithelial (hRPE) cells for the gene therapy of diabetic retinopathy. Two hyperbranched cationic Polysaccharide Derivatives containing the same amount of cationic residues, but with different branching structures and molecular weights, including 3-(dimethylamino)-1-propylamine-conjugated glycogen (DMAPA-Glyp) and amylopectin (DMAPA-Amp) Derivatives, were developed for the efficient delivery of NF-κB siRNA into hRPE cells. The DMAPA-Glyp Derivative showed lower toxicity against hRPE cells. Furthermore, the DMAPA-Glyp Derivative more readily condensed siRNA and then formed the nanoparticles attributed to its higher branching architecture when compared to the DMAPA-Amp Derivative. Both DMAPA-Glyp/siRNA and DMAPA-Amp/siRNA nanoparticles were able to protect siRNA from degradation by nuclease in 25% fetal bovine serum. The particle sizes of the DMAPA-Glyp/siRNA nanoparticles (70-120 nm) were smaller than those of the DMAPA-Amp/siRNA nanoparticles (130-180 nm) due to the higher branching architecture and lower molecular weight of the DMAPA-Glyp Derivative. In addition, the zeta potentials of the DMAPA-Glyp/siRNA nanoparticles were higher than those of the DMAPA-Glyp/siRNA nanoparticles. As a result, siRNA was much more efficiently transferred into hRPE cells using the DMAPA-Glyp/siRNA nanoparticles rather than the DMAPA-Amp/siRNA nanoparticles. This led to significantly high levels of suppression on the expression levels of NF-κB p65 messenger RNA and protein in the cells transfected with DMAPA-Glyp/siRNA nanoparticles. This work provides a potential approach to promote hyperbranched Polysaccharide Derivatives as nonviral siRNA vectors for the inhibition of NF-κB activation in hRPE cells.

  • synthesis and characterization of in situ photogelable Polysaccharide Derivative for drug delivery
    International Journal of Pharmaceutics, 2010
    Co-Authors: Yuyun Chen, Liming Zhang
    Abstract:

    A novel Polysaccharide Derivative with photoreactivity was prepared by the conjugation of carboxymethylated chitosan with N-hydroxyl succinimide-activated nitrocinnamate in the presence of N,N-dicyclohexylcarbodiimide, and characterized by IR, 1H NMR, UV–vis and rheological analyses. It was found that such a modified Polysaccharide could exhibit an unique photogelation ability in the absence of potentially toxic photoinitiator or catalyst and be suitable particularly for the in situ preparation of photocrosslinked hydrogel biomaterials. By changing the photoirradiation time and incorporated nitrocinnamate content, its photogelation property could be modulated. For the resultant hydrogels incorporated with various nitrocinnamate contents, their properties such as swelling, viscoelasticity, in vitro biodegradation and drug release were investigated. In addition, the photogelation mechanism of this Polysaccharide Derivative was also discussed.

  • synthesis of an amphiphilic Polysaccharide Derivative and its micellization for drug release
    Journal of Bioactive and Compatible Polymers, 2008
    Co-Authors: Liming Zhang, Jiyan Liu, Rufu Chen
    Abstract:

    A new route for the synthesis of novel amphiphilic Polysaccharides was developed, in which a synthetic biodegradable poly(e-caprolactone) was capped with a phenylalanine group (PCL-phenylalanine). ...

Bezhan Chankvetadze - One of the best experts on this subject based on the ideXlab platform.

  • comparative high performance liquid chromatography enantioseparations on Polysaccharide based chiral stationary phases prepared by coating totally porous and core shell silica particles
    Journal of Chromatography A, 2012
    Co-Authors: Ketevan Lomsadze, George Jibuti, Tivadar Farkas, Bezhan Chankvetadze
    Abstract:

    Abstract This article reports comparative high-performance liquid chromatographic separations of enantiomers with chiral stationary phases (CSPs) prepared by coating cellulose tris(4-chloro-3-methylphenylcarbamate) on totally porous and on core–shell type silica of comparable particle diameter. Several interesting observations were made: (1) the selectivity of separation was higher on core–shell type CSP compared to totally porous CSP at comparable content of chiral selector (Polysaccharide Derivative); (2) much flatter dependence of plate height on the mobile phase flow rate was observed for columns packet with CSP prepared with core–shell silica compared to the ones packed with CSPs prepared with totally porous particles; (3) at low mobile phase flow rates core–shell CSP provided lower resolving ability compared to a commercially available CSP having four times higher content of chiral selector along with higher retention of chiral analytes. However, at high flow rates core–shell type CSP performed similarly or better than the commercial column in regards of plate count ( N ) and peak resolution ( R s ) per column length and within a given total analysis time. The advantage of CSP prepared with core–shell silica is obvious from the viewpoint of plate numbers and resolution calculated per unit time (i.e. speed of analysis).

  • high performance liquid chromatographic enantioseparations on monolithic silica columns containing a covalently attached 3 5 dimethylphenylcarbamate Derivative of cellulose
    Journal of Chromatography A, 2004
    Co-Authors: Bezhan Chankvetadze, Tomoyuki Ikai, Chiyo Yamamoto, Yoshio Okamoto
    Abstract:

    Covalent immobilization of 3,5-dimethylphenylcarbamate Derivative of cellulose was performed in situ onto native silica monoliths cladded in a 50 mm x 4.6 mm polyether ether ketone high-performance liquid chromatographic (HPLC) column. The covalent attachment of cellulose Derivative in the range of 16-19% (w/w) was performed via an epoxide moiety. The column obtained by this technique combines the high enantiomer-resolving ability of the Polysaccharide Derivative with favourable dynamic properties of monolithic HPLC columns. The covalent attachment of the cellulose Derivative enables this column to be used in combination with the mobile phases which are incompatible with coated-type Polysaccharide columns due to solubility of chiral selector in some organic solvents.

  • effect of organic solvent electrolyte salt and a loading of cellulose tris 3 5 dichlorophenyl carbamate on silica gel on enantioseparation characteristics in capillary electrochromatography
    Electrophoresis, 2001
    Co-Authors: Bezhan Chankvetadze, Yoshio Okamoto, Irma Kartozia, Jorg Breitkreutz, Gottfried Blaschke
    Abstract:

    The effect of the amount of the chiral selector, cellulose tris(3,5-dichlorophenylcarbamate) (CDCPC) on the separation characteristics of enantiomers of some charged and neutral analytes was studied in capillary electrochromatography (CEC). For better understanding of the effect of the loading of the chiral selector on the particles and pore size of the packing material, laser-beam particle size analyzer and scanning electron microscopy (SEM) were used. As shown in this study, CDCPC can be used for CEC enantioseparations of a wide range of chiral charged and neutral analytes with high efficiency. The loading of the Polysaccharide Derivative on the surface of silica materials even in high amounts does not markedly affect the particle size and porous structure of the packing material. The separation characteristics are strongly affected by the loading of CDCPC onto silica gel in both CEC and capillary liquid chromatography (CLC).

Roberto Cirilli - One of the best experts on this subject based on the ideXlab platform.

Roberto Fantozzi - One of the best experts on this subject based on the ideXlab platform.

  • the non anticoagulant heparin like k5 Polysaccharide Derivative k5 n osepi attenuates myocardial ischaemia reperfusion injury
    Journal of Cellular and Molecular Medicine, 2012
    Co-Authors: Massimo Collino, Alessandro Pini, Rosanna Mastroianni, Elisa Benetti, Cecilia Lanzi, Daniele Bani, Jacopo Chini, Marco Manoni, Roberto Fantozzi, Emanuela Masini
    Abstract:

    Heparin and low molecular weight heparins have been demonstrated to reduce myocardial ischaemia/reperfusion (I/R) injury, although their use is hampered by the risk of haemorrhagic and thrombotic complications. Chemical and enzymatic modifications of K5 Polysaccharide have shown the possibility of producing heparin-like compounds with low anticoagulant activity and strong anti-inflammatory effects. Using a rat model of regional myocardial I/R, we investigated the effects of an epimerized N-,O-sulphated K5 Polysaccharide Derivative, K5-N,OSepi, on infarct size and histological signs of myocardial injury caused by 30 min. ligature of the left anterior descending coronary artery followed by 1 or 24 h reperfusion. K5-N,OSepi (0.1–1 mg/kg given i.v. 15 min. before reperfusion) significantly reduced the extent of myocardial damage in a dose-dependent manner. Furthermore, we investigated the potential mechanism(s) of the cardioprotective effect(s) afforded by K5-N,OSepi. In left ventricular samples, I/R induced mast cell degranulation and a robust increase in lipid peroxidation, free radical-induced DNA damage and calcium overload. Markers of neutrophil infiltration and activation were also induced by I/R in rat hearts, specifically myeloperoxidase activity, intercellular-adhesion-molecule-1 expression, prostaglandin-E2 and tumour-necrosis-factor-α production. The robust increase in oxidative stress and inflammatory markers was blunted by K5-N,OSepi, in a dose-dependent manner, with maximum at 1 mg/kg. Furthermore, K5-N,OSepi administration attenuated the increase in caspase 3 activity, Bid and Bax activation and ameliorated the decrease in expression of Bcl-2 within the ischaemic myocardium. In conclusion, we demonstrate that the cardioprotective effect of the non-anticoagulant K5 Derivative K5-N,OSepi is secondary to a combination of anti-apoptotic and anti-inflammatory effects.

  • effects of a semi synthetic n o sulfated glycosaminoglycan k5 Polysaccharide Derivative in a rat model of cerebral ischaemia reperfusion injury
    Thrombosis and Haemostasis, 2009
    Co-Authors: Massimo Collino, Jacopo Chini, Marco Manoni, Emanuela Masini, Sara Castiglia, Liana Salsini, Roberto Fantozzi
    Abstract:

    Heparin and low molecular weight heparins may reduce brain damage evoked by ischaemia/reperfusion (I/R) injury, although their use is hampered by the risk of haemorrhage. Chemical and enzymatic modifications of K5 Polysaccharide have shown the possibility to produce heparin-like compounds with low anticoagulant activity and strong anti-inflammatory effects. Using a rat model of transient cerebral I/R, we investigated the effects of an epimerised N-,O-sulfated K5 Polysaccharide Derivative, K5-N,OSepi, on the infarct size, motor activity and injury caused by ischaemia (30 min) and reperfusion. Reperfusion was allowed for 60 min or 1–5 days. Rats reperfused for 5 days showed an infarct volume of 30.7 ± 3.1% and K5-N,OSepi (0.1–1 mg/kg) caused dose-dependent reduction in infarct size (maximum at 1 mg/kg: 13.1 ± 2.1% infarct volume). This effect was associated with a significant improvement in motor performance. In the rat hippocampus, one of the brain areas most sensitive to I/R injury, I/R induced a robust increase in myeloperoxidase (MPO) activity, a marker of neutrophil infiltration, that was halved by K5-N,OSepi administration (66.38 ± 7.75 μU MPO/tissue g, 30.78 ± 5.67 μU MPO/tissue g, respectively). K5-N,OSepi drastically reduced the expression of cyclooxygenase-2, inducible-nitric- oxide-synthase and intercellular-adhesion-molecule-1. I/R-induced activation of nuclear factor-kB was attenuated by drug treatment. Furthermore, K5-N,OSepi administration was associated with a significant modulation of apoptosis markers, such as Bid and Bcl-2. In conclusion, the results demonstrated that the sulfated semi-synthetic K5 Derivative K5-N,OSepi protects the brain against I/R injury by disrupting multiple levels of the apoptotic and inflammatory cascade, including inhibition of NF-κB activation.