Preparation of dehydroabietyl polyethylene glycol aldehyde modified hydroxyethyl chitosans and their physicochemical properties
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A series of polymeric surfactants based on monodehydroabietyl polyoxyethylene(5) ether (DHA(EO)5H) and hydroxyethyl chitosan (HEC) were prepared through a three-step process. First, DHA(EO)5H was oxidized using activated MnO2 and transformed into dehydroabietyl polyethylene glycol(5) aldehyde (DHA(EO)4CH2CHO). Then, the DHA(EO)4CH2CHO was reacted with HEC and converted into Schiff-base. Finally, the polymeric surfactant, DHA(EO)4CH2CHO modified HEC (DHA(EO)4CH2CHO-m-HEC), was obtained by reducing the Schiff-base with sodium borohydride. The grafting degree (DG) of DHA(EO)4CH2CHO substitution onto HEC for DHA(EO)4CH2CHO-m-HECs was determined using elemental analysis (EA), and the surface activities and foam performance of DHA(EO)4CH2CHO-m-HECs in aqueous solution were investigated respectively. The emulsifying capacities of DHA(EO)4CH2CHO-m-HECs were evaluated according to the stability times of emulsion composed of water and liquid paraffin. The experimental results showed the DG could have significant influence on the critical micelle concentration (cmc) of DHA(EO)4CH2CHO-m-HECs and their surface tensions at cmc (γcmc), but nearly no effect on their minimum surface tensions (γmin) in aqueous solution. Among the synthetic polymeric surfactants in this investigation, DHA(EO)4CH2CHO-m-HEC with DG of 56.95% exhibited the best emulsification and foam properties.The objective of this study was to design lipopolymers for hydrophobic drug delivery. Poly(ethylene glycol)-block-poly(2-methyl-2-carboxyl-propylene carbonate-graft-dodecanol) (PEG-PCD) lipopolymers were synthesized and characterized by 1H NMR, FT-IR, GPC, and DSC. The critical micelle concentration (CMC) of PEG-PCD micelles was around 10−8 M and decreased with increasing length of hydrophobic block. PEG-PCD micelles could efficiently load a model drug embelin into its hydrophobic core and significantly improve its solubility. The loading capacity was dependent on the polymer core structure, but the length of hydrophobic core had little effect. PEG-PCD formed both spherical and cylindrical micelles, which were dependent on the copolymer structure and composition. PEG-PCD lipopolymers with various hydrophobic core lengths showed similar drug release profiles, which were slower than that of poly(ethylene glycol)-block-poly(2-methyl-2-benzoxycarbonyl-propylene carbonate) (PEG-PBC) micelles. Embelin loaded PEG-PCD micelles showed significant inhibition of C4-2 prostate cancer cell proliferation, while no obvious cellular toxicity was observed for blank micelles.
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Polypropylene glycol
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Abstract Reverse micelles are formed in apolar solvents by spontaneous aggregation of surfactants. Surfactant sodium bis (2‐ethylhexyl) sulfosuccinate (AOT) is most often used for the reverse micellar extraction of enzymes. However, the inactivation of enzyme due to strong interaction with AOT molecules is a severe problem. To overcome this problem, the AOT/water/isooctane reverse micellar system was modified by adding short chain polyethylene glycol 400 (PEG 400). The modified AOT reverse micellar system was used to extract Mucor javanicus lipase from the aqueous phase to the reverse micellar phase. The extraction efficiency (E) increased with the increase in PEG 400 addition and the maximum E in PEG 400 modified system was twofold higher than that in the PEG 400‐free system. Upon addition of PEG 400, the water activity (a w ) of aqueous phase decreased, whereas a w of reverse micellar phase increased. The circular dichroism spectroscopy analysis revealed that PEG 400 changes the secondary and tertiary structure of lipase. The maximum specific activity of lipase extracted in PEG 400‐modified reverse micellar system was threefold higher than that in the PEG‐free system.
Micellar solutions
Aqueous two-phase system
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A zwitterionic gemini surfactant, called 2,2′-(1,4-phenylenebis(oxy))bis(N ,N -dimethyl-N -carboxyethyl)-N -(alkylamide propyl) ammonium chloride(C14–B–C14), was synthesized successfully.
Thermodynamics of micellization
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Polyethylene glycol (PEG) grafted poly (γ-benzyl L-glutamate) (PBLG) was synthesized by the substitution reaction of PBLG and PEG having primary amino groups at both ends. PEG-g-PBLG films containing hydroxyl group were also prepared by the substitution reaction of PEG-g-PBLG film and ethanolamine (EA). Adhesion of platelets and activation of plasma proteins on the copolypeptide films were studied. The results showed that platelets are less adhered and activated on the PEG-g-PBLG than on other polypeptides and plasma recalcification time (PRT) on the PEG-g-PBLG was longer than that on other polypeptides. These results were consistent with those of blood clotting time and thrombus formation on the polypeptides. As a results, PEG-g-PBLG surfaces showed better blood compatibility than PBLG or PEG-g-PBLG-EA surfaces.
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Polyethylene glycol (PEG) grafted poly γ-benzyl L-glutamate (PBLG) were prepared from esterification or substitution reaction of PBLG with PEG having hydroxyl group at one end or primary amino groups at both ends. The viscosity of these polymer solution was decreased with decrease of polymer concentration. But in more dilute solution the viscosity was increased with decrease of polymer concentration. PEG-grafted PBLG polymers showed smaller water contact angles than PBLG homopolymer, and the water contact angles of the surface of PEG-grafted PBLG polymers were largely dropped by reacting with aminoethanol, resulting in hydrogel surfaces.
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Nanocarriers
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Chitosan is one of best non-viral gene carriers. Folic acid can specifically interact with folate receptor located on the plasma cell membrane.Poly(ethylene glycol) can improve the solubility of chitosan and prolong plasma circulation time of chitosan/DNA complexes.In this study,folic acid and methoxy-polyethylene glycol acetic acid were grafted onto chitosan with different molecular weigh through their primary amino groups for target gene delivery.The successful grafting were proved by FTIR,~1H NMR,UV-Vis and TEM.
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