最新刊期
卷 ， 期 8 ， 2011
- 摘要：Peptides and polypeptides have been widely used for gene and drug delivery due to their inherent bioactivity,biodegradability and well biocompatibility.Due to the specific bioactivity of peptides,peptide-based gene and drug delivery systems could achieve improved gene transfection efficiency,enhanced drug targeting property and reduced side-effect.This article reviews the recent progress in peptides and polypeptides as gene and drug carriers.The mechanism and characteristics of some bioactive peptides were also introduced.Finally,the prospect of bioactive peptides in cancer treatments was proposed.关键词：Peptide;Polypeptide;Gene vector;Drug delivery;Cancer therapy
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发布时间：2021-03-19
Reviews
- 摘要：Poly(methacrylic acid) (PMAA) modified silicon surface (Si-PMAA) was prepared via surface-initiated atom transfer radical polymerization (ATRP) of tert-butyl methacrylate (tBMA) on initiator-immobilized silicon followed by the hydrolysis of PtBMA to PMAA,The successful graft process was confirmed by X-ray photoelectron spectroscopy (XPS),ellipsometry and water contact angle characterization,The PMAA modified surface exhibited pH responsibility of both surface wettability and protein adsorption,At lower pH (pH=4),the Si-PMAA surface was relative hydrophobic (with a water contact angle (WCA) value ca.48.9),With an increasing pH,the surface turned more hydrophilic and at pH=9 the WCA value was ca.12.1,This pH-responsive surface wettability can be explained by the conformational transition of polymer chains,The addition of base will deprotonate the pendant carboxylic acidic groups,resulting in swollen polymer chains with many ionized COO-,which are favorable for the entrance of water molecules and make the surface more hydrophilic,This pH-sensitive wettability of the Si-PMAA surface was reversible for repeated cycles of alternating treatment by solution with different pH,Fibrinogen adsorption on the Si-PMAA and unmodified silicon surface was evaluated by radio-labeling method,The results indicated that fibrinogen adsorption on unmodified silicon surface at pH 9 was slightly lower than that at pH 4,while after modification with PMAA,the effect of pH was greater,The adsorption at pH 4 was ca.39 times higher than that at pH 9,suggesting that control over the adsorption of proteins through adjusting the pH value could be achieved on the PMAA modified surface.关键词：Poly(methacrylic acid);pH responsibility;Wettability;Protein adsorption
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发布时间：2021-03-19 - 摘要：Glycyrrhetinic acid modified alginate (GA-ALG) was prepared by covalent attachment of hydrophobic liver targeting ligand glycyrrhetinic acid (GA) onto the nature polysaccharide alginate (ALG).The resulting amphiphilic GA-ALG could form self-assembled nanoparticles (GA-ALG NPs) in an aqueous medium as liver targeting drug delivery carrier.Broad spectrum antitumor drug-doxorubicin (DOX) loaded GA-ALG NPs (DOX/GA-ALG NPs) were obtained by emulsification method for liver targeting drug delivery.Single photon emission computed tomography (SPECT) and some mathematical relationships were used to qualitatively and quantitatively evaluate the targeting efficiency of GA-ALG drug delivery systems in vivo .The SPECT image confirmed that 99mTc labeled GA-ALG nanoparticles mainly accumulated in the liver of Wistar rats after intravenous injection,and the accumulation of 99mTc labeled GA-ALG nanoparticles in the liver was about 40.2% at 3 h after injection.The biodistribution data showed that the concentration of DOX in the liver reached (67.8 4.9) g/g after intravenous administration of DOX/GA-ALG NPs,which was 4.7-fold higher than that of DOXHCl solution at 3 h post-injection.And the data of relative tissue exposure (re),targeting efficiency (te) and weighted-average targeting efficiency (te*) showed that liver targeting efficiency was enhanced by GA-ALG drug delivery systems.These results revealed the potential of GA-ALG nanoparticles as liver targeting drug delivery carriers.关键词：Glycyrrhetinic acid;Alginate;Drug delivery systems;Targeting efficiency
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发布时间：2021-03-19 - 摘要：The negatively charged heparin and heparin-biotin were complexed with the positively charged PAMAM/DNA via electrostatic interactions to prepare PAMAM/DNA/heparin and PAMAM/DNA/heparin-biotin complexes,respectively.By using a fast degrading cholic acid functionalized star poly(DL-lactide) as a matrix and a water soluble polymer,,-poly(N-2-hydroxyethyl)-L-aspartamide (PHEA) as an additive,thin films loaded with PAMAM/DNA,PAMAM/DNA/heparin or PAMAM/DNA/heparin-biotin complexes were prepared.The in vitro substrate-mediated gene transfections were carried out in HeLa cells and 293T cells.The results indicated that the complexes loaded polymer films could effectively mediate sustained transfections.The PAMAM/DNA/heparin-biotin complexes loaded polymer films exhibited improved transfection efficiency because the existence of heparin-biotin on the complex surface resulted in an enhanced cellular uptake for HeLa cells due to the specific interaction between the biotin moiety and the biotin-specific receptors on HeLa cells.By adding the water soluble polymer PHEA,which could keep the bioactivity of DNA during the film fabrication,the gene expression levels could be significantly improved.During the cellular transfection,the degradation of the polymer films did not show any negative effects on the gene transfection.关键词：Substrate-mediated gene delivery;Heparin;Biotin;Self-assembly;Biodegradation
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发布时间：2021-03-19 - 摘要：A stable concentrated inverse polymer emulsion (CIPE) was prepared using ternary monomers of acrylic acid,acrylamide and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS),with Span-80 and Tween-60 as complex emulsifiers in the presence of a redox initiator system at room temperature.As a control,a common emulsion with a low volume fraction of dispersed phase and a pseudo CIPE obtained from the centrifuge of the common emulsion were also prepared.The morphology of latex particles was observed under an optic microscope and the size and its distribution were statistically figured out.Images show CIPE has smaller particles entrapped among the larger ones,and the characteristic analysis of CIPE exhibits a dual peak distribution of latex sizes,as sharp contrast to the single peak distribution for both the other emulsions.It was proposed that these small particles functioned as a wedge,effectively reducing the stress exerted on the large particles and enhancing the CIPE stability.A series of experiments testified the wedge effect.The apparent complex modulus of CIPE is 3-fold higher than that of the pseudo CIPE in terms of a dynamic rheological technique though both the emulsions have the same volume fractions.Furthermore,CIPE demonstrates high stability under hyperacoustic and thermal treatment compared with both the pseudo CIPE and the common emulsion.These observations provide a proof that CIPE displays a high stability with the characteristic structure of dual peak and the wedge effect thereof.关键词：Concentrated inverse polymer emulsion;Emulsion stability;Structure model;Dynamic rheology
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发布时间：2021-03-19 - 摘要：In order to obtain the gradient fluorinated/non-fluorinated polyacrylate latex blend films as cheap as possible,the fluorinated polyacrylate emulsion with small particle size was synthesized by bulk emulsion polymerization method,the acrylate copolymer emulsion with big particle size was synthesized by semicontinuous emulsion polymerization method,and then the fluorinated polyacrylate emulsion and the acrylate copolymer emulsion were mixed with a series of ratios (1/9,2/8,3/7,4/6,5/5).The blend latices were dried on clean glass at 20℃ and then annealled at 110℃/210℃ for some time (2~6 h).The effects of the fluorinated polyacrylate content on the gradient structure and surface property of the blend films were discussed.The content of fluorine on the film surface and the film section was analyzed by XPS,SEM-EDX.The surface properties and morphology were characterized by contact angle measurements and AFM.It was found that,while the content of fluorinated polyacrylate latex in the blend system was up to 30 wt%,the small and hard fluorinated polyacrylate particles were selectively gathered on the film-air interface after film-formation at room temperature,and the fluorine content increased from the film-glass interface to the film-air interface gradually in the blend films annealled 2 h at 110℃.The obtained gradient film has low surface free energy as the pure fluorinated polyacrylate and strong adhesion as the pure polyacrylate.The further increasing of fluorinated polyacrylate in the blend system helped the formation and enlargement of gradient structure,but the adhesion of film was decreased a little.The emulsion system with the content of fluorinated polyacrylate latex under 30 wt% was hard to form gradient structure.关键词：Fluorinated polyacrylate;Self-organization;Gradient;Latex blend;Emulsion particle
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发布时间：2021-03-19 - 摘要：A redox-sensitive drug delivery system was fabricated.Dendritic poly(L-glutamic acid) was synthesized.Anti-tumor drug methotrexate (MTX) was immobilized on the dendritic poly(L-glutamic acid) via disulfide bonds using cystines as linkers.The disulfide bond was sensitive to glutathione in intracellular environment,thus to release the MTX from the dendritic poly(L-glutamic acid) backbones.The dendritic poly(L-glutamic acid) backbones and drug loaded conjugates were characterized by nuclear magnetic resonance (NMR).The release profiles of the conjugates were investigated in phosphate buffer saline (PBS) with dithiothreitol (DTT) to simulate the intracellular environment; the results showed that the release rates were closely dependant on the concentration of DTT.Higher DTT concentration resulted in faster release.When the DTT concentration was lower than 0.2 mmol/L,MTX was not released from dendritic backbones.The conjugates were incubated with HepG2 cells to evaluate their anti-tumor effect in vitro.The dendritic poly(L-glutamic acid) was nontoxic to cells even when its concentration was as high as 20 g/mL.The inhibition effect of the conjugates on tumor cells was better than that of free MTX after incubation for 72 h.Fluorescein isothiocyanate (FITC) was immobilized on the dendrmers and conjugates to trace the endocytosis.The MTX could promote the cell uptake for its folic acid mimetic structure.关键词：Dendritic poly(L-glutamic acid);Methotrexate (MTX);Redox-sensitive;Drug delivery system
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发布时间：2021-03-19 - 摘要：A series of block copolymers of methoxy poly(ethylene glycol) and poly(2-methoxyethyl ethylene phosphate) (MPEG-b-PMOEEP) were synthesized using methoxy poly(ethylene glycol) (MPEG) as the initiator and tin (II) 2-ethylhexanoate as the catalyst.The polymers were characterized by gel permeation chromatograph (GPC) and nuclear magnetic resonance (NMR).After dissolved in water directly,the block polymers self-assembled into polymeric micelles with PMOEEP as the hydrophobic core and MPEG as the hydrophilic shell.They were used for hydrophobic anticancer drug paclitaxel (PTX) solubilization.It was found that the solubility of PTX in aqueous solutions was greatly enhanced after addition of the polymers,and was significantly affected by polymer composition and concentrations.Increasing weight ratio of PMOEEP block of the polymer resulted in enhanced PTX solubility,and PTX solubility was increased with the increase of polymer concentration that was correlative to the micellization process of the block polymer in aqueous solutions.The polymers were proved to be biodegradable and biocompatible.1H-NMR spectra were used to demonstrate the degradability of PMOEEP by phosphodiesterase (I).MTT assay revealed these block copolymers were nontoxic to breast cancer cells MCF-7 up to a concentration of 10 mg mL-1,while the activity of PTX solubilized by MPEG-b-PMOEEP polymer against MCF-7 cells was comparable to free PTX dissolved in dimethyl sulfone,indicating these polymers are potential materials for enhanced PTX solubility.关键词：Polyphosphate;Block polymer;Paclitaxel;Solubilization;Micelle
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发布时间：2021-03-19 - 摘要：A simple,effective,green and economic approach of lipase immobilization is provided in this article.Single-crystal,hydrophilic,biocompatible Fe3O4magnetic nanoparticles as good carriers were prepared via a solvothermal reduction method.Microsphere diameters were observed to be about 200 nm by transmission electron microscopy (TEM).Superior monodispersity was demonstrated,and saturation magnetization was found to be 83.7 emug-1.The resulting products were modified directly with -aminopropyltriethoxysilane (APTS).Porcine pancreas lipase (PPL) was covalently immobilized on the obtained particles using glutaraldehyde as a coupling reagent.The enzymatic activities of free and immobilized PPL were measured by titration of fatty acid which came from the hydrolysis of olive oil and the amount of protein was determined by the Bradford method using bovine serum albumin (BSA) as a standard.The factors related with the activity of the immobilized lipase on prior carriers,such as the pH value of the immobilized reaction,the concentration of glutaraldehyde and the amount of enzyme were investigated.The immobilized lipase exhibited excellent thermal stability and reusability in comparison with free enzyme.High activity recovery (54.8%) of the immobilized lipase was achieved and the amount of protein was up to 120 mg/g.This immobilized lipase can be reused 10 times with the enzymatic activity remained above 90%.关键词：Fe3O4;Monodisperse;Solvothermal reduction;Immobilization;Lipase
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发布时间：2021-03-19 - 摘要：Porous polylactide (PLA) microspheres were prepared by means of the modified double emulsion solvent evaporation. The organic solvents with different boiling points and aqueous solubility were used to prepare PLA microspheres with different porous structures. Microspheres prepared with methylene chloride, chloroform and toluene as solvents had the similar homogeneous porous structure, while those microspheres with ethyl acetate as solvent showed a hollow structure with a porous thin shell. The effects of solvent types on porous structure of microspheres were discussed. It was concluded that the removal rate of solvent plays the decisive role in determining the porous structure of microspheres. Accordingly, a formation mechanism of porous microspheres fabricated with different solvents was proposed.关键词：Polylactide;Porous microspheres;Solvent removal rate
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发布时间：2021-03-19 - 摘要：Polyaspartamides containing pendant imidazolyl propyl groups and amino ethyl groups were synthesized via ring-opening of polysuccinimide (PSI) reacting with N-Boc protected ethylenediamine and 1-(3-aminopropyl)imidazole.Polyaspartamides ( P1~P5 ) with different grafting ratios were characterized by FTIR and 1H-NMR spectra,which were well in accordance with the expected chemical structures.The cytotoxicity of polymers was evaluated by MTT assay.Compared to the commercial branched polyethyleneimine(PEI) (25 kDa) with an IC50 of 15 g/mL, P1~P5 showed no significant cytotoxicity against both 293T cells and COS-7 cells.More than 90% cells still retained their metabolic ability even at the polymer concentration up to 0.8 mg/mL.The introduction of imidazolyl group into polymer side chains make them possess high buffer capacity between pH 5 and pH 7,which was 2~5 times higher than that of PEI.Gel electrophoresis assay and dynamic light scattering measurements were performed to characterize the polycation/DNA complexes.At an N/P ratio of above 5,all of the five polyaspartamide-based polycations can condense plasmid DNA to form nanosized (100 nm) polyelectrolyte complexes with positive surface charge (+20 mV).The transfection assay demonstrated that the transfection efficiencies of foreign DNA in 293T cells and COS-7 cells increased with increasing the contents of imidazolyl graft of polyaspartamides. P4 with a grafting ratio of 1/3.7 (amino ethylene group to imidazolyl propyl group) showed the highest ability to deliver pGL-3 and pEGFP-C1 into both 293T cells and COS-7 cells.At the optimal N/P ratios,the gene expression efficiencies mediated by P4 were comparable to or even 2~3 times higher than that of PEI.The results suggest that imidazole-containing polyaspartamides are a very promising class of novel polycations for highly efficient and less toxic gene delivery.The structure-gene delivery ability relationship of imidazole-grafted polyaspartamides will provide valuable insight into the development of novel nonviral gene carrier.关键词：Gene delivery;Polycation;Polyaspartamide;Imidazole;Less toxic
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发布时间：2021-03-19 - 摘要：A biodegradable pH-sensitive hydrogel composed of poly(acrylic acid) (PAA) and poly (L-glutamic acid) (PGA) was synthesized.The swelling behavior of the hydrogel samples was studied.PGA is both biodegradable and pH-sensitive,with the pKa at 4.51. The hydrogels showed different swelling ratios (SR) in buffers at different pH values,indicating the pH-sensitivity.The hydrogels exhibited lower swelling ratios in an acidic medium because of the deprotonation of both PAA and PGA.While in a basic medium (pH 8.3),the highest swelling ratios were 5 to 10 times higher than those in the acidic medium.The SR increased sharply when the pH was increased from 4,which was consistent to the pKa of PAA and PGA.In neutral medium,the sample with the lowest SR was the one composed of 50% PGA and 50% PAA,of which the SR was only about 30. In contrast,with either more PGA or more PAA,the SR got higher.The SR of the sample with 70% of PAA was 66.3,while the SR of hydrogel composed of 70% PGA was 121.4. The swelling kinetics studies showed that all the hydrogel samples underwent a rapid swelling process in 20 min,followed by gradual decrease of the swelling rate.The samples reached swelling balance at 2 h.Because of the pH-sensitivity of the hydrogels,drugs can be protected at acidic pH,and released at neutral pH.Therefore,the hydrogels may have potential applications as oral drug delivery systems.关键词：Intelligent hydrogels;Poly(L-glutamic acid);Poly(acrylic acid);pH-Sensitive;Swelling kinetics
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发布时间：2021-03-19 -
CATIONIC POLYCARBONATES PREPARED VIA MICHAEL ADDITION OF AMINES ON THE PENDANT METHACRYLAMIDO GROUPS
摘要：This paper reports the preparation and pDNA complexation characteristics of cationic polycarbonates with pendant ethylenediamino groups or low molecular PEI side chains.The polyamino pendant groups or side chains were introduced on the polycarbonate backbone via Michael addition with methacrylamido pendant groups.First,cyclic carbonate monomer,2-(methacrylamido)trimethylene carbonate (MATC) was prepared from 2-amino-1,3-prapanediol by a two-step reaction.Ring-opening polymerization of MATC using 1,8-diazabicyclo[5.4.0[undec-7-ene (DBU) as a catalyst afforded poly(2-metacrylamidotrimethylene carbonate) (PMATC).Then,cationic polycarbonates PTMC-EDA and PTMC-PEI were prepared by Michael addition of ethylenediamine and 600 Da PEI,respectively,on the methacrylamido pedant groups.The weight average molecular weights measured by GPC of polymers PMATC,PTMC-EDA,and PTMC-PEI were 6300,7400,and 15100,and the polydispersity indexes were 1.21,1.83 and 2.17,respectively.Cationic polycarbonates could form stable complexes with plasmid DNA at low polymer/pDNA weight ratios.The average diameters of the complexes were around 200 nm.The zeta potentials of cationic polycarbonates and DNA complexes were about 30 mV.The characteristics of the cationic polycarbonates of forming polyplexes with pDNA were very similar to those of 25 kDa PEI.Their cytotoxicity measured by MTT assay,however,was very low.The excellent ability for DNA complexation and low toxicity suggest that the cationic polycarbonates might have a good potential for use as gene vectors.关键词：Polycarbonate;Polyethyleneimine;Polycation;Ring-openning polymerization;Michael addition- 46
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发布时间：2021-03-19 - 摘要：A series of poly(N-isopropylacrylamide) (PNIPAM)-blocked polycarbonates,P(MAC-co-DTC)-b-PNIPAM,were designed as thermosensitive micelles for drug delivery.The amphiphilic block copolymers were synthesized by enzymatic ring-opening copolymerization of HO-PNIPAM,5-methyl-5-allyloxycarbonyl-trimethylene carbonate (MAC) and 5,5-dimethyltrimethylene carbonate (DTC).The novel block copolymers were characterized by1H-NMR and GPC-MALLS analyses.All the amphiphilic copolymers were able to self-assemble into nano-sized micelles in aqueous solutions with hydrophilic PNIPAM shells and hydrophobic polycarbonates cores.The critical micelle concentration (CMC) determined by fluorescence spectroscopy using pyrene as a probe was around 20~60 mg/L.Transmission electron microscopy (TEM) measurements showed that the micelles presented even spherical shape and the diameters of them were about 20~70 nm.The micelles exhibited thermosensitivity at lower critical solution temperature (LCST) of around 38~43℃,which was related to the hydrophilic PNIPAM blocks.In vitro experiments demonstrated that the P(MAC-co-DTC)- b -PNIPAM showed low cytotoxicity.Furthermore,the micelles were loaded with hydrophobic drug of prednisone acetate (PA) and in vitro drug release investigation also displayed thermosensitivity.The results suggested that P(MAC-co-DTC)-b-PNIPAM copolymers would be a promising thermosensitive carrier for drug delivery.关键词：Amphiphilic thermosensitive micelles;PNIPAM;Biodegradable polycarbonates;Enzymatic polymerization;Drug delivery;Cytotoxicity
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发布时间：2021-03-19 - 摘要：Getting inspiration of excellent mechanical properties of double network hydrogels,we explored to prepare a free-standing multilayer film with double network structure.The diffusion of the monomer,crosslinker,especially the initiator into the multilayer with different outermost layer was investigated by quartz crystal microbalance (QCM).The positive charged outmost layer of polyethylenimine (PEI) was proved to be beneficial to the diffusion of negatively charged initiator into the multilayer.A free-standing film can be formed by immersing the (PEI/PAA)12-PEI multilayer film in a solution consisting of monomer,initiator and crosslinker,following with a double crosslink process via photo and thermal polymerization.XPS data show that the upper and bottom surfaces of multilayers have similar components.Instead of a top hydorgel coating on the multilayer surface,the data proved the formation of a double network multilayer.The Young's modulus and ultimate strain of the free-standing film were 0.04 MPa and 2.7%,respectively.This method provides a facile method to improve the resilience of the multilayer and fabricate the free-standing film without changing the thickness of the multilayers.关键词：Double network hydrogels;Layer-by-layer self assembled;Free-standing film;Exponential growth
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发布时间：2021-03-19
Research Article
- 摘要：The distribution of oxygen element in the cross section of polyacrylonitrile (PAN) precursor fibers and oxidized fibers has been investigated by using a scanning transmission X-ray microscope (STXM) with a spatial resolution of 30 nm,combined with dual-energy contrast imaging method.By using the optical density ratio of the corresponding pixels in the two STXM images,the STXM experimental results indicated that the oxygen is homogeneously distributed in the pristine PAN fibers.During stabilization process,two important reactions occur and change the chemistry of PAN structure.In the skin section of PAN fiber,oxidation converts it into a conjugated and hetero-aromatic structure in the presence of oxygen.While in the core section of PAN fiber,cyclization turns linear PAN into a six-member ring structure due to the absence of oxygen.After treatment,an increase in the oxygen concentration in the skin of the PAN fibers is clearly observed while it remains constant in the core of PAN fibers,clearly demonstrating the diffusion process in the treatment.The propagating velocity of oxygen along the radical direction is about 0.033m/min.This research shows that the STXM is a powerful technique to characterize the internal microstructure of the PAN pre-oxidized fibers,and therefore will help to rationally understand the evaluation mechanism of the skin-core structure.关键词：PAN fibers;Stabilization;Oxidation;Scanning transmission X-ray microscope
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发布时间：2021-03-19
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