最新刊期
卷 ， 期 4 ， 2010
- 摘要：A new terpyridine-functionalized dithioester was synthesized as a chain transfer agent in the reversible addition fragmentation chain transfer polymerization (RAFT) of N-isopropylacyamide (NIPAAm).The polymerization showed an first-order kinetics and the molecular weight increased linearly with conversion, indicating that the terpyridine-functionalized dithioester is an efficient chain transfer agent for the RAFT polymerization of NIPAAm.The terpyridine-functionalized poly(N-isopropylacyamide) (tpy-PNIPAAm) not only displays similar phase transition as PNIPAAm,but also have the coordination ability via terpyridine,which were further used to construct macromolecularmetal complex with ferrous ions as model metal ions.The appearance of a strong absorption at 555 nm in UV-Vis spectrum revealed the formation of macromolecular-metal complex,indicating the strong coordination ability of tpy-PNIPAAm to metal.Cloud point method and dynamic light scattering (DLS) were used to characterize the thermosensitivity of tpy-PNIPAAm and macromolecular-metal complex.The results showed that the macromolecularmetal complex could self-assemble into nanoparticles in aqueous solution due to the amphiphilic property The macromolecular-metal complex solution showed a similar phase transition as PNIPAAm.In addition,the nanoparticles of the macromolecular-metal complex in aqueous solution were stable even at temperature above the lower critical solution temperature(LCST) due to electrostatic repulsion.This work indicated the great potentials of tpyPNIPAAm as carriers for the delivery of therapeutic radioisotopes.
- 21
- |
- 13
- |
- 1
发布时间：2021-03-19 - 摘要：Aiming at the synergistic effects between cellulose ethers and other polysaccharides,hydroxypropylmethyl cellulose (HPMC) and konjac glucomannan (KGM) mixed systems in aqueous medium were studied.Dynamic mechanical analysis (DMA),viscosity and oscillatory measurements were employed to analyze the mechanism of interactions with a molecular structure model proposed.Viscosity measurements revealed the negative synergistic viscosity effects of HPMC-KGM systems,by reason of brokenness of inter and intra- hydrogen bonds of KGM.DMA tests were carried out from 30℃ to 95℃.The results showed when the mass ratio of KGM was no less than 1∶1,the thermal gelation of HPMC around 76~77℃ with a sharp drop in G′ was replaced by a steady decrease during a broad temperature range,and G′ of the mixed solutions stayed at relatively higher values compared with the single ones for the whole available temperatures.The degradation of KGM caused by the break of β1,4 glycosidic bonds especially (MM) glycosidic bonds approaching to 90℃ was to a great extent weakened in mixed systems.It was interpreted that in HPMC-KGM systems,the unsubstituted mannan regions of KGM and hydrophobic groups of HPMC formed weak junction zones through hydrophobic interactions,and the structure of HPMC as main network with KGM combined was finally formed,resulting in retardation or partial prevention to the thermal gelation of HPMC and degradation of KGM.Viscoelastic behavior characteristics and loss tangent values obtained from oscillatory measurements combined with thermal hysteresis observed from DMA tests showed that the hydrophobic association effects were more stable than hydrogen bonds,and more pronounced with HPMC/KGM mass ratios from 3∶1 to 1∶1 (W/W).
- 39
- |
- 17
- |
- 7
发布时间：2021-03-19 - 摘要：The poly(styrene-co-maleic anhydride)/montmorillonite（SMA/MMT） nanocomposites prepared by in situ intercalation were applied as compatibilizers for polyamide 6 (PA6)/acrylonitrile-butadiene\|styrene terpolymer(ABS) blends.The compatibization effect of SMA/MMT nanocomposites on PA6/ABS blends was compared with that of SMA and MMT.The compatibization mechanism of SMA/MMT and MMT was investigated by TEM,SEM,DSC and XRD.The results show that compalibilizer SMA reduces the mechanical performance of blends; although compalibilizer MMT can improve the tensile strength of blends,the impact strength is decreased. Application of SMA/MMTnanocomposites as compalibilizer can improve the tensile strength and toughness of PA6/SMA blends.The results of TEM,SEM,DSC and XRD show that for the blends of PA6/ABS/(SMA-MMT),MMT is located at interphase of ABS and PA6.The decresed domain size of disperse phase and improvement of the interphase interaction are attributed to the fact that polymer chains of ABS and PA6 can coexist between the intercalated MMT platelets,forming the silimar structure of copolymers,playing the role of compalibilizer to increase the mechanical strength.For the blends of PA6/ABS/MMT,the MMT is located in the PA6 continuous phase.Although MMT can not reduce the size of disperse phase greatly,it can improve the PA6 phase strength,resulting in the increase of tensile shrength of PA6/ABS blends.
- 18
- |
- 13
- |
- 8
发布时间：2021-03-19 - 摘要：The thermo-stability of acrylate based holographic polymer dispersed liquid crystal(H\|PDLC) gratings has been evaluated with regard to their morphology,diffraction efficiency,remained almost unchanged up to Bragg angle and electro-optical tunable performance.These experimental results showed that the morphology,diffraction efficiency,Bragg angle and electrooptical tunable performance of two H\|PDLC gratings containing rigid rings in the polymer structure remained almost unchanged up to 200℃.The studies indicate that the chemical structure of the monomers plays an important role in the thermo-stability performance of H-PDLC gratings.Normally,a rigid molecular structure forms a hard polymer network which is very stable at high temperatures,subsequently,enhances the thermo-stability of H-PDLC gratings.Thermo-gravimetry (TG) was used to analyze the decomposition temperature of three kinds of polymer materials.The decomposition activation energies and the corresponding reaction orders of the polymers have been calculated by the Freeman-Carroll differential method.The tested results showed that the decomposition temperature,the decomposition activation energy and the corresponding reaction order of polymers which contained rigid ring structure were all higher than those of a polymer with flexible chain structure.In addition,the ring rigidity increases interactions between molecules and restricts the motion between them,thus enhances the thermostability.
- 43
- |
- 17
- |
- 1
发布时间：2021-03-19 - 摘要：The main objective of this work is the preparation and recognition of naringin(NG) molecularly imprinted membranes in aqueous media.The chatosan(CS) -NG molecularly imprinted membrane (MIM) was prepared in aqueous phase using CS as a functional polymer, NG as an imprinting molecule,polyethylene glycol(PEG) as a porogen.The CS-NG MIM was used to separate NG from neohesperidin in aqueous media.The effects of linkage reagent,porogen and imprinting molecule on membrane structure and properties were discussed.The MIM morphologies before and after modification of the porogen were observed by SEM.The imprinted membrane showed a good performance when sulfuric acid was used as the cross-linking agent and the mass ratio of CS and NG was 15∶1. The measurments of UV-Vis,FTIR and solubilities of naringin in acetic acid (HAc)-H2O and CS-HAc-H2O confirmed the formation of hydrogen bonds between bulk polymer CS and template molecule NG.The permeation rate of NG was 11.16%.
- 27
- |
- 12
- |
- 10
发布时间：2021-03-19 - 摘要：Comb-like hydroxyl functionalized atactic polystyrene was synthesized using the catalytic system (n-BuCp)2TiCl2/Sn/Is via living radical polymerization with Sn as the reducing agent and poly\|［(phenylglycidyl ether)-co-formaldehyde］ (Is) as the initiator.The effect of polymerization conditions,such as temperature,time,as well as the ratio of initiator to monomer on the polymerization performance was investigated.The catalytic active center was stable at the temperature range of 65～95℃,and the propagation rate increased with temperature.The structure and the properties of the obtained polymer were characterized by GPC,13C-NMR,WAXD and 1H-NMR.The GPC result indicated that a linear dependence of Mn on the monomer conversion was observed in each case,and the resulting polymer exhibited a rather low polydispersity (Mw/Mn=1.6～1.9) even the polymerization time (6,8,12,16,18 h) or the ratio of initiator to monomer (［Is］/［St］ = 1/250,1/500,1/750) had been changed,which confirmed that living radical polymerization characters prevailed in the polymerization process.The results of 13C-NMR and WAXD suggested that the polymer is featured by an atactic structure.The 1H-NMR results showed that the polymer molecules possessed hydroxyl groups,and the number of arms in each polymer molecule was in good agreement with the number of epoxy functional groups in the initiator (Is),which indicated the radicals derived from ring opening reaction of epoxide were the active species for living radical polymerization of styrene.
- 19
- |
- 10
- |
- 1
发布时间：2021-03-19 - 摘要：The casting solution was obtained by blending polyethersulfone (PES) and cellulose crystal in dimethylacetamide(DMAC).PES/cellulose crystal blend membranes were prepared by the immersion precipitation phase inversion process.The effects of cellulose crystal content on the properties of blend membranes were discussed.The pure water flux,rejection ratio,porosity,mean pore size and anti-fouling property were tested in the ultrafiltration equipments.Also,the mechanical properties,thermal stability and morphology were characterized by tensile testing,thermogravimetric analysis (TGA) and atomic force microscopy (AFM).The results showed that at first,the pure water flux of blend membranes was greatly improved with the increasing of cellulose crystal content,but then it decreased to some extent.All the rejection ratios remained at 91%~95%.The tendencies of tensile strength and elongation curses were the same as the one of pure water flux curve.The anti-fouling property of blend membrane had been improved.When the mass fraction of cellulose crystal was 1%,the pure water flux got to a maximum,813.3 L#12539;m-2#12539;h-1; porosity was 88.8% and mean pore size was 70.9 nm.At the same condition,tensile strength was 7.25 MPa and elongation was 11.6%.In addition,fouling degree (FR value) and attenuation coefficient of fouling (m value) were 22.0% and 35.8%,respectively.There were two weight loss stages in the blend membrane,due to thermal degradation of PES and cellulose crystal,respectively.The typical asymmetric membrane structure was displayed in the blend membrane.The surface layer of the blend membrane was dense,and the support layer had larger size pores.Both of them composed the typical asymmetric membrane structure.
- 19
- |
- 10
- |
- 5
发布时间：2021-03-19 - 摘要：The surface activity of cationic DMBAC (dimethyl methacryloyloxyethyl benzyl ammonium chloride) was revealed by measuring surface tension and estimating of critical micelle concentration (CMC).The copolymerization of acrylamide (AM) and DMBAC was studied in aqueous solution at above and below CMC of DMBAC,respectively.The reactivity ratios r1 and r2 were determined by the Fineman\|Ross method.IR and 1H\|NMR spectra afford information about polymer structure.The compositions of copolymers were calculated by UV spectrophotometer.The intrinsic viscosity values of the copolymers were measured by the Ubbelohde\|type Viscometer.Molecular weight (Mw) and polydispersity index (PDI) of the copolymers were measured by gel permeation chromatography (GPC).The effect of DMBAC concentration on the microstructure of the copolymers was analyzed by 13C\|NMR and DSC spectra.The property of hydrophobic association of the copolymers was characterized by using pyrene fluorescence probe technique.The experimental results of copolymerization showed that the reactivity ratios of monomers were different at above and below CMC of DMBAC,r1(AM)=0.65,r2(DMBAC)=1.41 and r1(AM)=0.74,r2(DMBAC)=0.91,respectively.These results suggested that DMBAC monomers may distribute in a microblock sequence in the copolymer chain at above CMC of DMBAC,and in a random sequence at below CMC of DMBAC.The structures of copolymers were proved again by 13C-NMR and DSC spectra.The copolymer CP-1 with microblock sequences showed stronger hydrophobically associating than the copolymer CP-2 with random sequences.
- 16
- |
- 10
- |
- 3
发布时间：2021-03-19 - 摘要：A study of the mean-square radius of gyration and mean-square dipole moment of the symmetric di-substituted polymers is presented basing on the improved rotational-isomeric-state method.The deduced formulas are used to investigate the conformation-dependent properties of poly(tetrafluoroethylene) (PTFE), poly(dimethylsilylene) (PDMS) and polyethylene (PE) chains.Here, the configuration parameters of the PTFE4 (PTFE of the 4state model) chain and PDMS chain are calculated to be about 0.44 .mol0.5 . g-0.5 and 0.43 . mol 0.5. g-0.5 respectively for large polymerization degree x.However,the temperature coefficient of PDMS chain -7.32×10-3 K-1 is different obviously from that of PTFE and PE chains (about -1.00×10-3 K-1).The calculated characteristic ratios of meansquare dipole moment for long PTFE and PDMS chains are rather small,such as the ratio of PDMS is 0.27.The results show that PTFE and PDMS are non-polar polymers，good dielectric and poor in induction,even though the dipole moments of C—F and Si—C are large in PTFE and PDMS chains.Therefore,the polar and dielectric properties of polymers are also affected by the conformation and structure of chains.In addition,the chain end effect of short PTFE and PDMS chains (repeat unit x 10) results in obvious change of the ratios with x,which is in agreement with the results of Flory et al.
- 21
- |
- 12
- |
- 3
发布时间：2021-03-19 - 摘要：A simple spray approach to fabricate superhydrophobic coatings on tile and glass substrates is presented.Commercial available polyphenylene sulfide (PPS) and hydrophobic silica (H—SiO2) powder were suspended in ethanol and the mixed suspensions were spray on substrates.After dried at different temperatures,surface coatings with different hydrophobicity were obtained.By observing the surface morphologies with scanning electron microscope (SEM) and atomic force microscope (AFM),and measuring water contact angles with a contact angle system,factors affecting the morphology,roughness and contact angle of the surface coatings,such as thermal treatment temperature and the weight ratio of H—SiO2 to PPS,were investigated in detail.With the increase of the thermal treatment temperature,both the surface roughness and the contact angle increased when the temperature was lower than 280℃.As the weight ratio of H—SiO2 to PPS rose from 1∶10 to 1∶1,more H—SiO2 powders accumulated on the surface,leading to a significant increase of hydrophobicity.The surface coating obtained at 280℃ with the weight ratio of H—SiO2 to PPS 1∶1 showed a water contact angle higher than 150° and a sliding angle lower than 4°,exhibiting fascinating superhydrophobic properties.The surface coating could remain superhydrophobicity upon a further increase in thermal treatment temperature or the amount of H—SiO2 powder.Moreover,the surface coatings showed high contact angles,larger than 150°,for all the solutions with pH ranging from 1 to 14. The abrasion resistant property of the asprepared superhydrophobic surface coating was tested using a homemade setup.Being scraped by freely-falling sands,the superhydrophobic coating could keep its high hydrophobicity,while a commercial hydrophobic coating transformed from hydrophobicity to hydrophilicity.This result implied our superhydrophobic surface coating was very stable.Moreover,chalk powders on the superhydrophobic surface coatings could easily be washed off with water,indicating good self-cleaning properties.The presented approach is convenient and can be potentially applied in fabrication of superhydrophobic surfaces in large scale.
- 23
- |
- 18
- |
- 4
发布时间：2021-03-19 - 摘要：Hollow polyelectrolyte microcapsules with size around 4～5 μm,have been prepared by layer-by-layer (LbL) adsorption technique,based on template of weakly crosslinked melamine formaldehyde (MF) latex microspheres.In the presence of aqueous HCl solution (pH=1.0),the MF cores are decomposed and hollow polyelectrolyte microcapsules are acquired.This kind of microcapsules can be utilized in many fields such as biosensor,drug release.Therefore,understandings on loading,penetrability of biomelocules on cell size microcapsules and their interaction with capsules are important,which are definitely favorable to their employment in real industry.In this study,Rphycoerythrins(R-PE) are used as a model to examine protein load behaviors and protein-capsules interaction.The R-PE is a kind of phycobiliprotein,which is found in red algae.It plays a crucial role in efficiently harvesting sunlight and then transfers this energy via a series of energy transfer mechanisms to chrolophyll in the membranes of photosynthetic organisms.The fluorescent intensity of R-phycoerythrin is compared before and after mixing with microcapsules where the pH value ranges at 3～10.It shows a maximum protein loading at pH 4～5.Moreover,the pH dependent protein loading of microcapsules is analyzed on laser scanning confocal microscope.The further results indicate some R-phycoerythrin is entrapped into capsules at pH 4～5.However,the R-phycoerythrin mainly adsorbs at the surface of the microspheres at a pH range of 6～10 and has a constant amount.It attributes microcapsules to have porous structure and high surface free energy.The capsules have a very poor protein loading amount at pH 3.
- 15
- |
- 11
- |
- 1
发布时间：2021-03-19 - 摘要：A branched gelator synthesized from 1,2,4-benzene tricarboxylic acid and 4hydroxy pyridine was characterized by 1H\|NMR,IR and elemental analysis.Supramolecular fiber with length of several centimeters was formed by pulling up the melting sample of the gelator,indicating a strong interaction of the molecules.Three supramolecular hydrogels were obtained via cooling the gelator aqueous solutions at 25℃,0℃ and at 25℃ under ultrasonic treatment,respectively.The results indicated that the gelator molecules assembled into fibrillar networks during forming the gels with the network density and gel stability increased by the order of the above formation methods.The electron spectroscopic spectrum of the xerogel surface reveals that the nitrogen atom locates mainly within the fiber,indicating the molecular assembling in water is affected by the amphiphilic gelator molecule.The assembling fashion of the gelator was further investigated by analyzing the single crystal structures of the complex formed from 4-hydroxypyridine and ophthalic acid,and 1,2,4-benzene tricarboxylic acid,which shows that the molecules assembled into branched fiber via different hydrogen bonding.Moreover,the powder X-ray diffraction diagram of the xerogel indicates that the gelator molecules assembled in a preferred direction during forming the gel.
- 16
- |
- 11
- |
- 1
发布时间：2021-03-19 - 摘要：The rheological behavior of loach surface mucus was investigated in this paper.The steady shear curves of loach surface mucus can be divided into three regions.The initial shear\|independent value attained in the low shear horizontal region of such plots is known as the zero shear or Newtonian viscosity (η0),which is called as the first Newtonian region.Subsequent decrease in viscosity with increasing shear rate (γ) maybe attributed to progressive breakdown of intermolecular network character,which is called as shear thinning phenomenon.With increasing further,viscosity of loach surface mucus becomes shear\|independent again.This region is the second Newtonian region.The relationship between apparent viscosity (ηa) of loach surface mucus and can be well described by the Carreau model.The relationship between specific viscosity (ηsp) and concentration (c) follows ηsp ∝ c 1.5,which is in excellent agreement with that of semidilute entangled polyelectrolyte aqueous solution without salt,suggests it is in the semidilute entangled regime.In the tested angle frequency (ω) region,the storage modulus (G′) and the loss modulus (G″) neither changes a lot with ω. G′G″ suggests the loach surface mucus exhibits more elasticity than viscidity.There is a critical temperature,35℃,for loach surface mucus.Below 35℃,ηa of loach surface mucus changes little with temperature.Above 35℃,the loach surface mucus appears heat\|denature and exhibits thoroughly different rheological responses.
- 34
- |
- 13
- |
- 3
发布时间：2021-03-19
Research Article
- 摘要：Two model drugs,indomethacin and vitamin E(α\|tocopherol),which have different physical stae and similar hydrophobicity,were incorporated respectively into polymerc micelles in aqueous media by dialysis method. The micelles were formed from two types of biodegradable amphiphilic block copolymers based on methoxy poly(ethylene glycol)(mPEG) as a hydrophilic block and either crystalline poly(ε-caprolactone-b-L-lactide) (P(CL-b-LLA)) or amorphous poly(ε-caprolactone-b-D,L-lactide)(P(CL-b-DLLA)) as a hydrophobic block.The morphology and drug loading property of the polymeric micelles were characterized by transmission electron microscopy(TEM),laser light scattering(LLS),ultraviolet(UV) spectroscopy measureemnts.It was found that incorporating drugs into the micelles resulted in significant changes of the micellar morphologies.The different behaviors of the morphological change depended mainly on the crystalline property of the core\|forming blocks.The morphology of micelles formed with P(CL-b-LLA)-b-mPEG changed from short rod-like cylinders to wormike ones; whereas those formed with P(CL-b-DLLA)-b-mPEG changed from spheres to cylinders.In addition,the transformation of the micellar morphologies upon the drug entrapment was influenced by the hydrophobicity of the drugs more significantly than by the physical state of the drugs,while the drug loading amount was affected by the comatibility between carriers and drugs.Much more liquid\|like drugs were entrapped in the amphiphilic copolymers with non-crystalline core.
- 25
- |
- 12
- |
- 1
发布时间：2021-03-19
Rapid Communications
- 摘要：Linear and hyperbranched poly(ester amine)s (PEAs) were used as additives in electrospinning of low concentration poly(methyl methacrylate) solutions to eliminate beads and improve the fiber uniformity.With only 1 wt% PEA,no matter linear or hyperbranched,the electrospinnability was all improved,and uniform fibers without beads were obtained.Compared to linear PEA,hyperbrchched PEA has better ability in improving the fiber uniformity.The average fiber diameter decreases significantly (from 1.9 μm to 1.0 μm) compared to those obtained at high concentration without PEA.The principle of the improvement in electrospinnability was investigated by measuring the solution properties (viscosity,conductivity and surface tension),and it was attributed to the significant increase in solution conductivity.The solution viscosity and surface tension only change slightly,while solution conductivity increases greatly with the addition of 1 wt% PEA (including linear and hyperbranched).The hyperbranched PEAs have higher conductivity than the linear PEA because they have more polar endgroups resulted from the multiple branches,and therefore the hyperbranched PEAs have better performance than the linear PEA in improving the electrospinnability of low concentration PMMA solutions.The method reported in this paper could be generalized and provides a good alternative to the existing methods.
- 18
- |
- 10
- |
- 4
发布时间：2021-03-19 - 摘要：An endothelial preferential PTFE was developed via polydopamineassisted self\|assembly monolayer(SAM) technique.XPS,ellipsometer,QCMD and contact angle data confirmed the selfpolymerization process of DOPA and subsequently selfassembly monolayer formation of CGREDVDY.In cell adhesion experiments,both endothelial cells （ECs） and smooth muscle cells （SMCs） exhibited improved attachment on DOPA modified PTFE surfaces,but the surfaces did not have noticeable preference between the two cell types.However,after further SAM formation,those surfaces containing bioactive peptides CGREDVDY showed significant selection toward ECs.ECs preferential surface based on such approaches might open another window towards in situ endothelialization in those complex physiological environments in vivo.
- 16
- |
- 14
- |
- 5
发布时间：2021-03-19 - 摘要：A novel targeted carrier of drug loaded microcapsules with thermo- and magnetic-sensitivities was fabricated by the layer-by-layer self-assembly technique.Natural polyelectrolytes such as chitosan and sodium alginate,magnetic nanoparticles Fe3O4,and lipid dipalmitoyl-sn-glycero-3-phosphate (monosodium salt) (DPPA),(1,2-dipalmitoyl-sn-glycero-3-phosphocholine) (DPPC) or their composite 10%DPPA/90%DPPC were used as components of microcapsule.The structure,drug loading and thermo-sensitive drug release of the microcapsules were characterized by TEM,SEM,laser scanning confocal microscope and ultraviolet spectrophotometer.The results showed that positive Fe3O4 nanoparticles with superparamagnetic property were successfully assembled on the microcapsules,which could be effectively trapped by solid permanent magnet.The drug entrapment efficiency is affected by the drug concentration and the temperature.The highest drug loading amount could reach to 22.40% when the temperature reached 60℃.The drug release properties of microcapsules were measured at 37℃ and 40℃,which were lower and higher than the phase transition of DPPA lipid film respectively.The results showed that the microcapsules with lipid film were sensitive to temperature.The thermo-sensitive lipid film assembled on the surface of microcapsule could effectively prevent drug from being released at the lower temperature,which will favor the drug to reach the targeted site with less drug loss.
- 23
- |
- 14
- |
- 4
发布时间：2021-03-19 - 摘要：In order to study the crystal structure of polypropylene obtained by cooling melt near melting point under shear flow,samples were prepared by using a dynamic packing injection molding (DPIM) device which was designed by ourselves.With the aid of scanning electron microscopy (SEM),differential scanning calorimetry (DSC) and wide-angle x-ray diffraction (WAXD),crystal stuctures and morphologies were studied from skin to shear regions in these samples obtained by cooling melt near melting point under shear flow （DL）.Compared with the samples molded with traditional injection molding （SL）and the samples molded with high melt temperature（DH）,SEM results indicated that crystal structures and morphologies in DL had been greatly affected.Oriented crystal stuctureswere formed from skin to shear regions in DL,and no shish-kebabs could be found in these samples.DSC results showed that the dimension of lamellae in DL is bigger than that in SL and DH .WAXD test exhibited,compared with SL and DH,the dimension of crystal plane （110，040 and 130） is not greatly changed in DL.
- 20
- |
- 14
- |
- 1
发布时间：2021-03-19 - 摘要：The Cu (I)-catalyzed “click” reaction of azides and alkynes was selected as the coupling reaction to prepare a novel biocompatible polyrotaxane (PR) conjugate,which was composed of azidofunctionalized PR backbone (Mn=1.35×105) based on α-cyclodextrins (α-CDs)/poly(ethylene glycol) (PEG) inclusion complex and amino acids protected by tert-butyloxycarbonyl (Boc) groups,that is,Boc-Gly-OH,Boc-Lys(Boc)-OH,and Boc-Phe-OH.The alkynyl groups were introduced into the aforementioned amino acids via N,N-dicyclohexylcarbodiimide(DCC)/4-(dimethylamino)pyridine(DMAP) condensation with propargyl alcohol.The click coupling reaction was demonstrated to be extremely efficient,and high conversion of azido groups,approximate 100%,was achieved in a short reaction time (within several minutes) in the cases of Boc-Gly-OH and Boc-Lys(Boc)-OH.As to the bulky Boc-Phe-OH,only part of the azido groups of the backbone was converted though the coupling reaction time was prolonged (3 h).The corresponding amino acids-PR conjugates were soluble in a wide variety of organic solvents,such as N,Ndimethylformamide,acetone,ethanol and so forth.GPC was utilized to measure the molecular weight of Boc-Lys(Boc)-PR conjugates (PR-Lys),and the result was Mn = 1.66×105 (Mw/Mn = 1.57),much smaller than the theoretical ones.This might be resulted from the compactly packed conformation of PRLys.The warmlike morphology of PR-Lys was observed via AFM.Other alkyne-functionalized compounds involving 4-(2-azidoethoxy)-4-oxobutanoic acid and propargyl alcohol were also attached to the PR backbone successfully.This click strategy would be a promising general method for the functionalization of PRs.
- 34
- |
- 12
- |
- 0
发布时间：2021-03-19
Research Bulletin
- Postal code：100190
- Tel：010-62588927 Email：gfzxb@iccas.ac.cn
- Technical support is provided by Beijing Founder electronics co., LTD 京ICP备05002797号-8
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0