最新刊期
卷 ， 期 4 ， 2015
- 摘要：The infectious behavior of polypropylene (PP) by other polymers during photo-oxidation was investigated in a sealed silica chamber.It is the first time to demonstrate that the photo-oxidation of one polymer (in this case PP,poly(methyl methacrylate) (PMMA),polyamide 6 (PA6) and styrene-butyl acrylate copolymer (PSB)) could infect another polymer (in this case PP).PP presented various sensitivities when it acted as the infected object.The carbonyl index of PP increased by 32.3%,8.7%,1.8% and 215.2%,respectively when PP was irradiated with PP,PMMA,PA6 and PSB as the neighbors compared to the isolated sample.The light stability of the neighbor polymers showed great effect on the acceleration.PSB,which is easy to be photo-oxidized and its volatile degradation products propagated easily in the chamber,showed the most significant acceleration effect on the photo-oxidation of PP.The concentration of the degradation products was also a key factor.When the aged PP and aged PMMA were used as the infective agents,the carbonyl index of PP increased more than that with the unaged PP as the infective agent.This interesting finding transferred a message that the photo-oxidation was propagated not only among adjacent polymer chains but also in relatively large space.It drove researchers to think more about the interaction of polymers at service conditions,especially when these polymers are in a closed atmosphere.In addition,the lifetime prediction should be more careful when there is such an interaction existed.关键词：Polypropylene;Photo-oxidation;Infectious behavior
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发布时间：2021-03-19
Rapid Communications
- 摘要：The sodium alginate/gelatin interpenetrating polymeric network (IPN) films were prepared by incorporating gelatin crosslinked with oxidized starch as a crosslinking agent into sodium alginate crosslinked with calcium chloride as a crosslinking agent.The structures of oxidized starch and sodium alginate/gelatin IPN films were investigated by Fourier transform infrared spectroscopy (FTIR).The effects of the oxidation degree of oxidized starch on the mechanical properties,thermal stabilities,micromorphologies,crosslinking degree,and water absorption and retaining rates of IPN films were investigated in details.The results indicated that tensile strength,elongation at break and crosslinking degree of IPN films first increased and then decreased with increasing oxidation degree of oxidized starch,and the above properties of the IPN films were optimized when the oxidation degree of oxidized starch increased to 60%.However,the water absorption and retaining rates first decreased and then increased with increasing oxidation degree of oxidized starch,and the reason was that the abundant hydroxyl and carboxyl groups of both macromolecular chains,which were hydrophilic,were trapped when uniform and dense network structures were formed in the two phases with increasing oxidation degree of oxidized starch,which decreased the water absorption and retaining rates of IPN films.And the results also indicated that there existed an optimal crosslinking degree of oxidized starch for crosslinking alginate/gelatin system.关键词：Oxidized starch;Sodium alginate;Gelatin;IPNs;Preparation;Properties
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发布时间：2021-03-19 - 摘要：Graphene oxide (GO) was prepared via Hummers' method,and its micromorphology was detected by scanning electron microscopy (SEM) and atomic force microscopy (AFM).The synergetic effects of GO and Si-P oligomer (DMS-DOPO) on flame retardant and mechanical properties of EP were studied in detail.Universal testing results showed that GO and DMS-DOPO had good effect on tensile strength and elongation at break,respectively.Tensile strength and elongation at break of EP were enhanced by 17.1% and 42.2% synergistically effected by GO and DMS-DOPO.Thermal and flame properties of EP and its composites were measured through thermal gravimetric analysis (TG),limiting oxygen index (LOI),vertical burning test (UL-94) and cone calorimeter (CONE).The micromorphology of char residual was observed by SEM.The char residual amount of EP/DMS-DOPO/GO was 5.2 times that of EP at 600 ℃,and 4.4% higher than that of EP/DMS-DOPO,208% for EP/GO.EP/DMS-DOPO/GO could pass UL-94 V-0 level,and its LOI value was over 30.Intumescent char layer with polyphorous inner structure and compact outside surface was formed during the combustion of EP/DMS-DOPO/GO.The heat release rate (HRR) of EP reduced from 1154 kW m-2 to 710 kW m-2 due to synergistical flame retard and effect of DMS-DOPO and GO.Total smoke production (TSP) of EP/DMS-DOPO/GO was 30% lower than that of EP.关键词：Graphene oxide;Synergetic flame retardant effect;Epoxy;Cone calorimeter
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发布时间：2021-03-19 - 摘要：A kind of aromatic diamine,4',4-(2,2-diphenylethene-1,1-diyl)dibiphenyl-4-amine (TPEDA) containing nonplanar rigid twisted moieties in the molecular structure was used as curing agent to prepare epoxy resins cured composites with commercial epoxy resins (E51).Comparing with conventional diamines (4,4'-diaminodiphenylmethane,DDM and 4,4'-diaminodiphenylsulfone,DDS),the properties of system E51/TPEDA,such as glass transition temperature,elastic modulus,stress relaxation and creep,thermal expansion,the dielectric constant and dielectric loss,were roundly studied by dynamic mechanic analysis (DMA),thermal mechanic analysis (TMA),impedance analyzer,et al.The results show that the structure of rigid non-specific coplanar diamine TPEDA as epoxy curing agent,can significantly improve the glass transition temperature (258 ℃),elastic modulus (23.7 MPa) and dimensional stability,while reduce the thermal expansion coefficient of the cured product (CTE1:61.9612 10-6,CTE2:138.3265 10-6),dielectric constant (4.76 at 1 kHz) and the dielectric loss (1.93 10-2 at 1 MHz).When TPEDA which contains a special twisted steric structure is introduced into the epoxy resin main chain,it minimizes the strong interaction and tight stacking of the molecular chains and then increases the free volume of the polymers.Furthermore,the abundant rigid moieties in TPEDA used as curing agent can also improve the thermal stability of epoxy resins.Therefore E51/TPEDA can be used for high-density integrated circuit device package.关键词：Electronic packaging;Epoxy resin;Rigid nonplanar moieties;Curing agent
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发布时间：2021-03-19 - 摘要：Based on the modified flow induced crystallization model taking into account the effect of shear flow on the crystal growth,a compared study was made on the influence of shear flow on the crystallization kinetics of isotactic polypropylene in nucleation and crystal growth processes.It was theoretically confirmed that shear flow could also accelerate the spherulite growth rate of polypropylene though this effect was small and limited compared with that on the nucleation rate.However,in order to understand and predict the whole crystallization kinetics more accurately and practically,it is essentially necessary to consider the effect of shear flow on the spherulite growth rate especially at high shear rates and low crystallization temperatures.Our theoretic results showed that the shearing effect on the crystal growth rate was relatively large at a high supercooling degree in comparison with that at a low supercooling degree.This could be attributed to the relaxation behavior of macromolecule chains,which vanishes shear history quickly at high crystallization temperatures.The theoretically predicted curves are in good agreement with the experimental data indicating the validity of the modified model.关键词：Isotactic polypropylene;Conformation tensor;Half crystallization time;Crystallization kinetics;Flow;Theoretical model
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发布时间：2021-03-19 - 摘要：Polypropylene microporous membranes were prepared by melt-extrusion and cold-stretching (MSCS) method.The structure changes of microporous membrane during cold stretching,heat setting and hot stretching were studied in suit to reduce the effect of other factors on cold-stretching samples,such as natural retraction induced by cold stretch and the need of cool detection after heat setting.The influences of cold-stretching ratio on micro-lamellae and micropore structure of polypropylene microporous membranes were investigated by in situ small angle X-ray scattering (SAXS),scanning electron microscope (SEM) and differential scanning calorimeter (DSC).The results show that different cold-stretching ratios lead to the different hole formation mechanism.Long-period SAXS signals of the meridian direction at the cold-stretching ratio 15% indicate a slight change of macroscopic strain.Thus the corresponding pore formation mechanism is that cold stretching induces micro defects while hot stretching transforms them into micropores.At the cold stretching ratio 30%,small lamellae transform into unstable bridges and part of the bridges break after heat setting.Besides,noticeable signals of streak emerge in the vertical direction.When the cold-stretching ratio is increased to 40%,signals in stretching direction demonstrate that the growth rate of actual lamellar long period is lower than that of macroscopic strain.This phenomenon can be attributed to that partial skeleton lamellae are destroyed by stretching and transformed into bridging crystal fibers.Macro statistics and micro calculations show that the larger the stretching radio,the shorter the length of bridges and the smaller the aperture.Thus the S30 is the most appropriate cold-stretching radio to prepare microporous membranes.关键词：Polypropylene;Microporous membrane;SAXS;cold stretching;Heat-setting;Pore forming mechanism
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发布时间：2021-03-19 - 摘要：MgCl2/TiCl4 catalyst with 9,9-bis(methoxymethyl)fluorine (BMMF) as internal electron donor has been paired with triethylaluminum (TEA) and used to catalyze propylene polymerization in bulk,to which tiny amounts of 1,4-pentadiene (PD) are added and their influence on the polymerization behavior and polymer properties are investigated.Gel permeation chromatography (GPC),differential scanning calorimetry (DSC) and dynamic shear rheology are used as the main polymer characterization tools.The results indicate that,within a very low [PD]/[propylene] molar ratio range ([PD]/[propylene]0.1%),the catalyst activity decreases sharply following PD concentration increasing.At a [PD]/[propylene] of 0.08%,the activity is barely a quarter of that when PD is absent.However,it is found that PD does not cause a monotonous decrease in viscosity-average molecular weight (Mv) as its concentration increases.Matter-of-factly,at the lowest PD concentration an abrupt increase in Mv is observed for the copolymer as compared to the homopolymer.GPC results further confirm that increase and indicate no branching has occurred to the PP chains due to PD.Results from dynamic shear rheology tests reveal that tiny amounts of PD raise polymer shear viscosity and modulus and prolong the relaxation time,so does the tensile viscosity in extensional flow tests.We argue that a synergism may exist between PD and H2 that is used in the polymerizations as a polymer molecular weight controller (chain transfer agent),of which a too low concentration of PD may presume chain extension for polymer chain growth,while higher PD concentrations will inevitably slow down the rate of chain growth and cause reduction in polymer molecular weight.关键词：Ziegler-Natta catalyst;Propylene;1;4-Pentadiene;Copolymerization
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发布时间：2021-03-19 - 摘要：A series of sulfonated polyimides (SPI) which had different degrees of sulfonation were synthesized by high-temperature one-step method with 2,2'-benzidinedisulfonic (BDSA),oxydiphthalic dianhydride (ODPA) and 4,4'-diaminodiphenyl methane (MDA) monomer.The molar ratio of BDSA and MDA was controlled to get the different SPIs.The SPIs were characterized by Fourier transform infrared spectroscopy,nuclear magnetic resonance analysis and thermogravimetry.The results show that the sulfonated polyimides were successfully synthesized and have good thermal stability with three-step degradation patterns.Then,a series of sulfonated polyimide/polyvinylpyrrolidone (SPI/PVP) acid-base blend membranes were prepared at the mass ratio of 9:1 and applied in vanadium redox flow battery (VRB).SEM images of the membranes show that the phase separation of the blend membrane is more obvious with the increase of the degree of sulfonation.The parameters of the blend membranes were obtained and reported,such as water uptake,ion exchange capacity (IEC),area resistance and vanadium ion permeability.The blend membranes have lower water uptake and vanadium ion permeability than those of Nafion117.The IEC,water uptake,proton conductivity and the vanadium ion permeability of SPI/PVP acid-base blend membranes increased with increasing the degrees of sulfonation.The selectivity of the membranes is much better than that of Nafion117,Especially SPI/PVP-3,its selectivity is 10 times higher than that of Nafion117 membrane.In the charge-discharge tests the VRB single cell of the SPI/PVP blend membrane shows higher columbic efficiency (CE) and similar energy efficiency (EE) compared with that of Nafion117.And the VE and EE were increased with the increasing of degree of sulfonation,as CE on the contrary.CE and EE of the SPI/PVP-3 membrane are higher than those of Nafion117 membrane.The performance of SPI/PVP-3 in the charge-discharge test of VRB single cell showed good stablilty.All these results demonstrate that the SPI/PVP acid-base blend membrane is a new promising material for VRB application.关键词：SPI;Acid-base composite membrane;VRB;Vanadium ion permeability;Battery efficiency
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发布时间：2021-03-19 - 摘要：One-pot chain walking copolymerization of ethylene and polyhedral oligomeric silsesquioxane (POSS) monomer was first performed at 0.1 MPa/35℃ with a Pd-diimine catalyst to synthesize hyperbranched polyethylene covalently tethered with multiple POSS nanoparticles (HBPE@POSS).The resulting HBPE@POSS was then used to functionalize multi-walled carbon nanotubes (MWCNTs) under the assistance of ultrasonication in tetrahydrofuran (THF) and chloroform,respectively.The structure and POSS portion of the HBPE@POSS were characterized via proton nuclear magnetic resonance (1H-NMR),gel permeation chromatography (GPC),thermogravimetric analysis (TGA) and wide-angled X-ray diffraction (WAXD) techniques,respectively.Further,the dispersibility,morphology and aggregate state of HBPE@POSS functionalized MWCNTs,and noncovant interactions between MWCNTs and HBPE@POSS as well,are investigated through UV-Vis absorbance spectroscopy,transmittance electron microscopy (TEM),WAXD,Fourier-transformed infrared (FTIR) spectroscopy and TGA techniques,respectively.It is testified that POSS can be covalently introduced into hyperbranched polyethylene with a portion of 39.0 wt% in the HBPE@POSS.The HBPE@POSS is found to effectively debundle/solubilize MWCNTs both in THF and chloroform,giving stable MWCNTs solutions with concentrations up to 987 mg/L in THF and 511 mg/L in chloroform.Also,it is found that POSS of certain portion can be irreversibly adsorbed onto MWCNTs by means of the noncovalent CH- interactions between MWCNTs and HBPE@POSS.It is expected that more inorganic nanoparticles (INPs) can be introduced onto CNTs through this method,thus leading to a novel strategy for surface functionalization of CNTs with INPs.关键词：Hyperbranched polyethylene;Polyhedral oligomeric silsesquioxane;Copolymer;Multi-walled carbon nanotubes;Noncovalent functionalization;CH- interactions
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发布时间：2021-03-19 - 摘要：The surface of attapulgite (ATP) was treated with the -mercaptopropyltrimethoxysilane coupling agent (MTS) to give thiol functionalized ATP (ATP-MTS),and then a thiol-caprolactam initiation system was constructed with the thiol groups on the surface of ATP-MTS and caprolactam (CL) in the sultion,surface-initiated living radical graft polymerization of styrene based on iniferter was realized to afford polystyrene grafted ATP hybrid particles (ATP-g-PS).The structure,composition and morphology of hybrid particles were characterized by Fourier transform infrared spectroscopy (FTIR),X-ray photoelectron spectroscopy (XPS),thermo gravimetric fanalyze (TGA) and transmission electron microscopy (TEM) methods.The polymerization kinetics of solution polymerization with different amounts of caprolactam was discussed in detail by model experiments.The results showed that MTS was bonded onto the surface of attapulgite successfully.Thiol-caprolactam initiation system can effectively initiated styrene to be graft-polymerized from the surface of ATP-MTS,and a high grafting degree of 33.3% was obtained according to TGA analysis.The diameter of ATP-g-PS hybrid particles was increased to about 60 nm.The kinetic results revealed the controllability of polymerization,and the conversion and molecular weight of PS increased with increasing polymerization time.Under the condition that the ratio value of [CL]/[SH] was 20/1,the Mn and PDI of PS obtained from slution plymerization were 1.1104 and 1.33 respectively when the conversion of monomer was 38.9%.关键词：Attapulgite;Styrene;Thiol-caprolactam initiation system;Surface-initiated living radical polymerization;Hybrid particles
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发布时间：2021-03-19 - 摘要：A novel polyurethane elastomer composite modified by polydimethylsiloxane and organic-montmorillonite was prepared by the following three steps:(1) grind the mixture of polyether triol N330 and organic-montmorillonite (OMMT) to obtain N330/OMMT compound, (2) mix the N330/OMMT compound with the polyurethane prepolymer modified by hydroxypropyl terminated polydimethylsiloxane (HTPDMS) and (3) cure the mixture of step two with dimethylthiotoluenediamine (DMTDA).The structures of the products were characterized by Fourier transform infrared (FTIR) spectrum.X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies showed that galleries of the clay were expanded and the silicate layers were dispersed in the polyurethane matrix.Scanning electron microscopy (SEM) demonstrated that OMMT promoted the compatibility of PU phase and PDMS phase.Thermo-gravimetric analysis (TGA) data indicated that the HTPDMS/OMMT/polyurethane nanocomposites have better thermal stability in comparison with the HTPDMS modified polyurethane,when the OMMT content was 5 wt%,the thermal stability of the nanocomposite reached its maximum.Differential scanning calorimetry (DSC) data revealed that the glass transition temperature (Tg) of the composite modified polyurethane showed significant increase upon using 5 wt% of OMMT.The nanocomposites also showed good surface properties and mechanical properties,and the maximal values of tensile strength,elongation at break and hardness occurred at 3 wt% OMMT concentration.关键词：Polyurethane;Polydimethylsiloxane;Montmorillonite;Composite modification;Intercalation
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发布时间：2021-03-19 - 摘要：Polymer-coated gold nanoparticles (PNIPAM-AuNPs) with temperature sensitive and intelligent fluorescent properties were prepared by ligand exchange between dimethylaminochalcone-terminated poly(N-isopropylacrylamide) (PNIPAM-DMAC) and 4-dimethylaminopyridine-stabilized gold nanoparticles (DMAP-AuNPs) precursor,and the morphology and structure of the as-prepared AuNPs were analyzed by UV-Vis,TEM,1H-NMR,FTIR and TGA.The as-synthesized PNIPAM-AuNPs can be well dispersed not only in water but also in ethanol,acetone,chloroform and tetrahydrofuran,and the corresponding characteristic peak of the surface plasmon resonance (SPR) absorption of the PNIPAM-AuNPs is observed at 537 nm,527.6 nm,527.4 nm,532.2 nm and 530.4 nm respectively.The surface grafting density of PNIPAM-DMAC is 1-2 polymer chains/nm2.The results of thermosensitive properties show that PNIPAM-AuNPs have a lower critical solution temperature (LCST) 2.5 K lower than that of PNIPAM-DMAC,and the SPR absorption peak of PNIPAM-AuNPs blueshifts to 525 nm from 537 nm after the phase transition.With the increase of the solvent polarity,the fluorescence characteristic wavelength of PNIPAM-AuNPs redshifts,and the fluorescence intensity first increases then decreases,which indicates solvent polarity sensitive fluorescence properties of PNIPAM-AuNPs.There are no fluorescent emitting properties of PNIPAM-AuNPs aqueous solution at 25 ℃,while at 45 ℃ the fluorescence intensity of PNIPAM-AuNPs enhances obviously,which endows PNIPAM-AuNPs with temperature on/off fluorescent properties.关键词：Gold nanoparticles;Poly(N-isopropylacrylamide);Thermosensitivity;Intelligent fluorescence
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发布时间：2021-03-19 - 摘要：A well-defined degradable and aldehyde-functionalized amphiphilic block copolymer PEO-b-poly(VBA-co-BMDO) with narrow molecular weight distribution (Mw/Mn 1.20) was synthesized via reversible addition-fragmentation chain transfer (RAFT) copolymerization of 4-vinylbenzaldehyde (VBA) and 5,6-benzo-2-methylene-1,3-dioxepane (BMDO) using PEO-DDMAT as chain transfer agent and benzoyl peroxide (BPO) as initiator at 80 ℃ in 2-butanone.Copolymers with variable amounts of BMDO or VBA units could be obtained just by changing the feed composition.The obtained amphiphilic block copolymers were found to be hydrolytically degradable due to the main-chain polyester structure.Low cytotoxicity against L929 cells was observed at polymer concentration up to 1.0 mg mL-1,indicating that amphiphilic block copolymer PEO-b-poly(VBA-co-BMDO) exhibits good biocompatibility.The highly reactive aldehyde functions in the synthesized amphiphilic block copolymer could provide the key intermediates to conjugate biomolecules,and the availability of the amphiphilic block copolymer to conjugate bioactive molecules was confirmed via aldehyde-aminooy click reaction with an aminooxy model drug,aminooxy functionalized cholesterol (H2NO-Chol).The successful conjugate formation was demonstrated by GPC and 1H-NMR analyses.Self-assemblies in water of the amphiphilic block copolymer PEO-b-poly(VBA-co-BMDO) and its bioconjugate were also investigated by dynamic light scattering (DLS) and scanning electron microscopy (SEM) measurements.The conjugates of PEO-b-poly(VBA-co-BMDO) with cholesterol could self-assemble into spherical micelles in aqueous solution with size in the range of 70~110 nm.These results suggested that the amphiphilic copolymer PEO-b-poly(VBA-co-BMDO) would be useful as a versatile polymer scaffold for bioconjugating.关键词：Aldehyde;Degradable;RAFT;Bioconjugate
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发布时间：2021-03-19 - 摘要：This work demonstrated the combination of the self-assembly of a block copolymer with the well-established non-solvent induced phase separation process.Nanoporous films were obtained with well-ordered cylinder pores perpendicular to the film surfaces on top of a non-ordered bicontinous porous layer.Numerous parameters during the film formation process,including the concentration of casting solution,the solvent evaporation time,the temperature of precipitation bath,and the gate height of doctor blade,were systematically investigated to realize the effective control of surface morphology.Voronoi tessellation was first introduced to quantitatively describe the regularity of the surface pattern.It was found that the concentration of casting solution and the solvent evaporation time have synergetic influences on the porous structures.With the increase of concentration,the minimum evaporation time needed for a well-ordered porous surface decreases.If keep the concentration as a constant,the evolution of surface morphologies from non-ordered cylinder pores to ordered cylinder pores,and then to lamellar pores,was observed with the increase of evaporation time.Although lots of combinations of these two parameters can be utilized for the well-ordered structure formation,the mean pore size of the film surface didn't change significantly with the change of film preparation conditions.Besides,the decrease of the temperature of precipitation bath also helped to improve surface pattern regularity.Further study revealed that once the gate height of casting solution was decreased,the evaporation of solvent induced more significant change of casting solution concentration and the solvent composition,resulting in the disappearance of well-ordered cylinder pores.Two ways,including decreasing the solvent evaporation time and applying the solvent annealing process,were proven to be very effective to prepare thinner films with well-ordered nanoporous structures.The above results greatly broaden the operation window and provide possibilities to fabricate films suitable for different applications.关键词：Block copolymer;Self-assembly;Non-solvent induced phase separation;Ordered nanoporous films
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发布时间：2021-03-19 - 摘要：Self-assembly of mixtures of amphiphilic AB diblock copolymers and solvophobic BC diblock copolymers in selective solvents was investigated by dissipative particle dynamics simulations.A series of aggregates such as multicompartment micelles were observed.Density profiles of the aggregates were plotted to gain insight into the details of the aggregates.It was found that the BC block copolymers mainly occupy the cores of the aggregates to increase the hierarchy of the structures.Effects of copolymer concentration and block length on the aggregates were studied.As the concentration of BC diblock copolymers increases,a morphological transformation from vesicles to cylindrical micelles and then to spherical multicompartment micelles occurs.At high concentration of BC diblock copolymers,the number of concentric layers within spherical micelles was found to be significantly dependent on the concentration of BC copolymers.By tuning the block length of C block length,both the concentric and nonconcentric multicompartment micelles were found.In addition to the morphological studies,the dynamic process was further analyzed with Minkowski functionals.The results show that the formation of multicompartment micelles is a hierarchical process of self-assembly.During the self-assembly,the large-length-scale structures are first formed,and then the small-length-scale structures within the cores gradually appears.The present simulation results could provide in-depth information about the mechanism behind the formation of multicompartment micelles from mixtures of amphiphilic and solvophobic copolymers,and also could provide guide for preparation of controllable structures for advanced functional nano-devices.关键词：Block copolymer;Mixture;Self-assembly;Multicompartment micelle;Dissipative particle dynamics
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发布时间：2021-03-19 - 摘要：The lack of effective siRNA delivery vector with low toxicity limited the development of siRNA therapy.The cationic molecule diethylenetriamine (DETA) with low molecular weight was grafted on the block copolymer (PEG-PAsp) of poly(aspartic)(PAsp) and poly(ethylene glycol)(PEG) to make a ternary copolymer PEG-PAsp(DETA)30.The MTT analytical results demonstrated that the PEG-PAsp(DETA)30-SPIONs have lower cytotoxicity.The biodegradable of PEG-PAsp and the low molecular weight of DETA endow the nanocarrier with good biocompatibility.Furthermore,the MR contrast imaging agent SPIO was introduced into copolymer via a ligand exchange method,yielding a MR-visible nanocarrier for imaging siRNA delivery and therapy simultaneously.The SPIONs didn't affect the loading of siRNA.Based on the data of zeta potential and diameter,the N/P=12 was used to prepare the PEG-PAsp(DETA)30-SPIONs@siRNA nanoparticle.The MRI-visible polyplexs of N/P=12 exhibited higher T2 relaxivity (r2=147 Fe (mmol/L)-1 s-1) than WSPIO (r2=46.4 Fe (mmol/L)-1 s-1),indicating high MRI T2-weighted imaging sensitivity.Using the laser confocal microscope and prussian blue staining,the efficient co-delivery of siRNA and SPIO was confirmed in the present study.Moreover,the luciferase gene-specific siRNA delivered with vector could effectively inhibit the firefly luciferase gene expression in cancer cells.SPIO co-delivered with siRNA provides a real-time and noninvasive approach to guide the optimization of the properties of siRNA delivery vector.关键词：Biodegradable cationic polymer;Co-delivery;siRNA;MR contrast imaging agent
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发布时间：2021-03-19
Research Article
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