查看更多>>摘要：Efficient intracellular delivery of protein drugs is critical for protein therapy.The combination of protein drugs with chemotherapeu-tics represents a promising strategy in enhancing anti-cancer effect.However,co-delivery systems for efficient delivery of these two kinds of drugs are still lacking because of their different properties.Herein,we show a well-designed delivery system based on dynamic covalent bond for efficient intracellular co-delivery of ribonuclease A(RNase A)and doxorubicin(DOX).Two polymers,PEG-b-P(Asp-co-AspDA)and PAE-b-P(Asp-co-AspPBA),and two 2-acetylphenylboronic acid(2-APBA)-functionalized drugs,2-APBA-RNase A and 2-APBA-DOX,self-assemble into mixed-shell nanoparticles(RNase A/DOX@MNPs)via dynamic phenylboronic acid(PBA)-catechol bond between PBA and dopamine(DA)moieties.The PBA-catechol bond endows the nanoparticles with high stability and excellent stimulus-responsive drug release behavior.Under the slight acidic envi-ronment at tumor tissue,RNase A/DOX@MNPs are positively charged,promoting their endocytosis.Upon cellular uptake into endosome,further protonation of PAE chains leads to the rupture of endosomes because of the proton sponge effect and the cleavage of PBA-catechol bond pro-motes the release of two drugs.In cytoplasm,the high level of GSH removed the modification of 2-APBA on drugs.The restored RNase A and DOX show a synergistic and enhanced antic-cancer effect.This system may be a promising platform for intracellular co-delivery of protein drugs and chemotherapeutics.
查看更多>>摘要：L-glutamic acid(LA)is a bio-based,non-toxic,environmentally friendly material derived from biomass.The present study reports the application of Passerini three-component polymerization(P-3CP)for the straightforward preparation of LA-based light-responsive polyesters(PLTDs)under mild conditions.PLTDs with molar masses up to 8500 g/mol and high yields exceeding 90％are obtained.The chemical structures and light-responsive self-immolative behavior of PLTDs are comprehensively characterized by employing ultraviolet-visible(UV-Vis)spec-troscopy,size exclusion chromatography(SEC),nuclear magnetic resonance(NMR)spectroscopy,and liquid chromatography mass spectrometry(LC-MS).Meanwhile,monodisperse PLTD-based doxorubicin-loaded nanoparticles(PLTD-DOX-NP)(size=193 nm,PDI=0.018)are formulated by nanoprecipitation method.Upon light-induced depolymerization,the PLTD-DOX-NP undergoes rapid decomposition,resulting in a burst re-lease of 80％cargo within 13 s.Furthermore,according to biological toxicity tests,the PLTD-NP possesses adequate biosafety,both before and af-ter irradiation.Overall,the incorporation of P-3CP with biorenewable LA-based monomer adheres to the principles of green chemistry,signifi-cantly simplifying the synthetic pathway of light-responsive polymers.
查看更多>>摘要：Owing to their high significance in fundamental study and diverse applications,stimuli-responsive and fluorescent polymers,particu-larly those with cluster-triggered emission(CTE)featured by non-conjugated chromophores,have drawn tremendous attention in recent years.In this work,fluorescent and multi-responsive polysiloxane(FRPS)was synthesized by hydrolytic condensation polymerization of 3-aminopropyl methyl diethoxysilane(APMS)with 3-(N-isopropyl propionamide)iminopropyl methyl diethoxysilane(APMS-NIP),which was formed in situ through aza-Michael addition between APMS and N-isopropyl acrylamide.FRPS was not only highly sensitive to temperature,pH and CO2 in wa-ter,but also showed an enhanced and stimuli-adjustable fluorescence emission.The effects of monomer feeding,pH and CO2 on its lower critical solution temperature and fluorescent property were investigated.FRPS fluorescence emission was ascribed to CTE mechanism.In addition,FRPS was shown to be highly potential as physiological indicator for cell imaging,and for controlled release and trace detection of doxorubicin.This study provides therefore a type of stimuli-responsive and fluorescent material for potential applications in biomedical fields,and it is also of great significance for understanding of the fluorescence mechanism of polysiloxane-based stimuli-responsive polymers.
查看更多>>摘要：Semi-interpenetrating(semi-IPN)hydrogels formed by the continuous interpenetration of cross-linked polymer network and linear non-crosslinked polymer with multifunctionality are widely used in biomedical and other fields.However,the negative impact of linear polymer on the homogeneity of the cross-linked network often leads to a decrease in the mechanical properties of semi-IPN hydrogels and severely limits their applications.Herein,a bioinspired hydrogen-bonding induced phase separation strategy is presented to construct the tough semi-IPN polyvinylpyrrolidone/polyacrylamide hydrogels(named PVPx/PAM hydrogels),including the linear polymer polyvinylpyrrolidone(PVP)and cross-linked polyacrylamide(PAM)network.The resultant PVPx/PAM hydrogels exhibit unique phase separation induced by the hydrogen bond-ing between PVP and PAM and affected by the amount of substance of PVP.Meanwhile,the phase separation of PVPx/PAM hydrogels results in excellent mechanical properties with a strain of 2590％,tensile strength of 0.28 MPa and toughness of 2.17 MJ/m3.More importantly,the hydro-gen bonding between PVP and PAM firstly disrupts to dissipate energy under external forces,so the PVPx/PAM hydrogels exhibit good self-recov-ery properties and outperform chemically cross-linked PAM hydrogels in impact resistance and damping applications.It is believed that the PVPx/PAM hydrogels with hydrogen-bonding induced phase separation possess more potential application prospects.
查看更多>>摘要：Water-soluble copolymers of p-methacrylamidobenzoic acid(MABA)with neutral comonomers(N-vinylpyrrolidone(VP),N-methyl-N-vinylacetamide(MVAA),N-methacryloyl glucosamine(MAG))and anionic comononer sodium styrene sulfonate(NaSS)were synthesized by radi-cal copolymerization.The interactions between the prepared copolymers and Tb3+ions in aqueous solutions were studied;the significant influ-ence of chemical structure of a comonomer on luminescence intensity of Tb3+complexes with the copolymers was revealed.The luminescence intensity of Tb3+complexes with the copolymers containing N-vinylamide units(VP,MVAA)is three times more intense than that observed for the complexes between Tb3+and MAG-containing copolymers.In the case of NaSS-containing copolymers,the luminescence intensity is controlled by the values of binding constants between Tb3+and MABA and the content of MABA units in a copolymer.The studied copolymers and their complexes with Tb3+have low cytotoxicity and a pronounced antiviral activity against human respiratory syncytial virus.
查看更多>>摘要：In this study,a novel iron-based catalyst system,Fe(acac)3/(isocyanoimino)triptenylphosphorane(IITP)/AIR3,was employed for the synthesis of syndiotactic 1,2-polybutadiene in hexane.This catalyst system exhibits remarkably high catalytic activity,achieving a polymerization activity of 762 kgpolymer·molcatalyst-1·-h-1 at 50 ℃ with a[BD]/[Fe]molar ratio of 20000.Furthermore,living polymerization characteristic were ob-served during the investigation of the polymerization kinetics of 1,3-butadiene polymerization.These characteristics were well demonstrated by a narrow molecular weight distribution(PDI≈2.0)of the resulting polybutadiene and a linear relationship between-In(1-c)and polymerization time as well as number average molecular weight and polymer yield.The resultant polymer showed a 1,2-selectivity of approximately 76％and stereoregularity ranging from 62％to 73％(rrrr).Additionally,through kinetic studies on polymerization reaction,an apparent activation energy Ea value of this catalytic system was calculated to be 84.98 kJ.mol-1,which suggests that high polymerization temperature favors efficient polymer-ization.
查看更多>>摘要：For practicable elastomeric polyethylene,achieving high catalyst thermal stability and activity,along with precise control of polymer properties such as branching density,molecular weights,and distribution,is crucial but challenging.In this study,two sets of symmetrical a-diimine nickel complexes,each comprising four nickel bromide or chloride complexes,were synthesized and investigated their performance for ethylene polymerization under various reaction conditions.Upon activation with either Et2AlCl or MMAO cocatalysts,these complexes displayed not only high activity but also generated high molecular weight polyethylenes with controlled polydispersity and a substantial number of branches.The catalyst with the least steric hindrance displayed the remarkable high activity(up to 1.2×107 g·mol-1·h-1).Notably,nickel bromides demonstrated higher activity compared to their chloride counterparts.The investigation into the effect of reaction temperature on catalytic per-formance revealed that NiBrMe-MMAO system displayed high thermal stability(activity up to 2.51 ×106 g·mol-1·h-1 at 100 ℃)and consistently yielded high polymer molecular weights with narrow polydispersity over a broad temperature range of 30-100 ℃.Of significant note,mechani-cal analysis of the resulting polyethylene demonstrated excellent ultimate tensile strength and high strain at break.Particularly,the polyethylene sample prepared at 100 ℃ exhibited ultimate tensile strength up to 10 MPa with 1863％maximum strain at break and a strain recovery of up to 54.9％after ten cycles at a fixed strain of 300％,indicating excellent material properties of prepared thermoplastic polyethylene elastomers(TPE).
查看更多>>摘要：The rich phase behavior of block copolymers(BCPs)has drawn great attention in recent years.However,the double diamond(DD)phase is rarely obtained because of the competition between the minimization of interfacial energy and packing frustration.Here,a rod-coil BCP containing mesogen-jacketed liquid crystalline polymer is designed to acquire ordered bicontinuous network nanostructures.The reduction of internal energy originating from the orientational interaction among the rod blocks can compensate for the free energy penalty of packing frus-tration to stabilize the DD structure.The resulting BCP can also experience lamellae-to-DD and double gyroid-to-lamellae transitions by chang-ing the annealing temperature.These results make the rod-coil BCP an excellent candidate for the self-assembly of ordered network structures,demonstrating great potential in nanopatterning and metamaterials.
查看更多>>摘要：To simultaneously endow thermal conductivity,high glass transition temperature(Tg)and healing capability to glass fiber/epoxy(GFREP)composite,dynamic crosslinked epoxy resin bearing reversible β-hydroxyl ester bonds was reinforced with boron nitride nanosheets modified glass fiber cloth(GFC@BNNSs).The in-plane heat conduction paths were constructed by electrostatic self-assembly of polyacrylic acid treated GFC and polyethyleneimine decorated BNNSs.Then,the GFC@BNNSs were impregnated with the mixture of lower concentration(3-glycidyloxypropyl)trimethoxysilane grafted BN micron sheets,3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate and hexahydro-4-methylphthalic anhydride,which accounted for establishing the through-plane heat transport pathways and avoiding serious deterioration of mechanical performances.The resultant GFREP composite containing less boron nitride particles(17.6 wt％)exhibited superior in-plane(3.29 W·m-1·K-1)and through-plane(1.16 W·m-1·K-1)thermal conductivities,as well as high Tg of 204 ℃(Tg of the unfilled epoxy=177 ℃).The re-versible transesterification reaction enabled closure of interlaminar cracks within the composite,achieving decent healing efficiencies estimated by means of tensile strength(71.2％),electrical breakdown strength(83.6％)and thermal conductivity(69.1％).The present work overcame the disadvantages of conventional thermally conductive composites,and provided an efficient approach to prolong the life span of thermally con-ductive GFREP laminate for high-temperature resistant integrated circuit application.
查看更多>>摘要：In this study,we proposed a novel method that integrates density functional theory(DFT)with the finite field method to accurately es-timate the polarizability and dielectric constant of polymers.Our approach effectively accounts for the influence of electronic and geometric con-formation changed on the dielectric constant.We validated our method using polyethylene(PE)and polytetrafluoroethylene(PTFE)as bench-mark materials,and found that it reliably predicted their dielectric constants.Furthermore,we explored the impact of conformation variations in poly(vinylidene fluoride)(PVDF)on its dielectric constant and polarizability.The resulting dielectric constants of α-and γ-PVDF(3.0)showed ex-cellent agreement with crystalline PVDF in experiments.Our findings illuminate the relationship between PVDF's structural properties and its electrical behavior,offering valuable insights for material design and applications.
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