查看更多>>摘要：Hydrogen bonds(H-bonds)are the most essential non-covalent interactions in nature,playing a crucial role in stabilizing the sec-ondary structures of proteins.Taking inspiration from nature,researchers have developed several multiple H-bonds crosslinked supramolecular polymer materials through the incorporation of H-bond side-chain units into the polymer chains.N-acryloyl glycinamide(NAGA)is a monomer with dual amides in the side group,which facilitates the formation of multiple dense intermolecular H-bonds within poly(N-acryloyl glycinamide)(PNAGA),thereby exhibiting diverse properties dependent on concentration and meeting various requirements across different applications.Moreover,numerous attempts have been undertaken to synthesize diverse NAGA-derived units through meticulous chemical structure regula-tion and fabricate corresponding H-bonding crosslinked supramolecular polymer materials.Despite this,the systematic clarification of the im-pact of chemical structures of side moieties on intermolecular associations and material performances remains lacking.The present review will fo-cus on the design principle for synthesizing NAGA-derived H-bond side-chain units and provide an overview of the recent advancements in mul-tiple H-bonds crosslinked PNAGA-derived supramolecular polymer materials,which can be categorized into three groups based on the chemical structure of H-bonds units:(1)monomers with solely cooperative H-bonds;(2)monomers with synergistic H-bonds and other physical interac-tions;and(3)diol chain extenders with cooperative H-bonds.The significance of subtle structural variations in these NAGA-derived units,en-abling the fabrication of hydrogen-bonded supramolecular polymer materials with significantly diverse performances,will be emphasized.More-over,the extensive applications of multiple H-bonds crosslinked supramolecular polymer materials will be elucidated.
查看更多>>摘要：Polymer aging under environmental conditions causes deterioration of service properties.Understanding the aging behavior and mechanism is important not only for lifetime prediction,but also for material improvement and development.Therefore,comprehensive charac-terization of polymer materials during aging is crucial.In this review,various analytical methods for characterization of chemical changes,physi-cal changes and service properties are introduced.Based on that,methods for stabilization evaluation and lifetime prediction,especially sensi-tive evaluation methods are reviewed.Chemical changes include molecular weight changes by chain scission and crosslinking,functional group changes on the surface and in the bulk,formation of free radicals,formation of small molecular species as the degradation products,and chemi-cal distribution by heterogeneous aging and additives migration.Physical changes include crystallization changes(post-or chemi-crystallization)and morphology changes(cracking,debonding,etc.).Service property changes include deterioration of processability,mechanical properties,electrical properties and appearance.In the end,existing problems and future research perspective are proposed,including relationship be-tween chemical/physical changes and service properties,introduction of modern mathematical and computer tools.
查看更多>>摘要：Tumor-associated carbohydrate antigens(TACAs)provide a special class of tumor-specific antigens that show promising applications in cancer immunotherapy.However,the weak immunogenicity and structural complexity of TACAs are obstacles to their clinical application.Here,based on a fast and low-cost purification strategy for oligosaccharide synthesis,the synthesis of tumour-associated carbohydrate antigens Globo H and mannobiose which resembles repeat unit of mannan was achieved.To enhance the immunogenicity and multivalent effect,Globo H and mannobiose were covalently attached to degradable polymer backbones.2D spindle-like lamellar micelle and globular micelle were ob-tained from glycopolymer through a solvent-exchange method of self-assembly.The glyconanoparticle showed good biocompatibility and degradability.Immunological functions of these glyconanoparticles such as stimulation of BMDC to cause upregulation of inflammatory factors were preliminarily explored.
查看更多>>摘要：The self-consistent field theory(SCFT)was employed to numerically study the interaction and interpenetration between two oppos-ing weak polyelectrolyte(PE)brushes formed by grafting weak PE chains onto the surfaces of two long and parallel columns with rectangular-shaped cross-section immersed in a salty aqueous solution.The dependences of the brush heights and the average degree of ionization on vari-ous system parameters were also investigated.When the brush separation is relatively large compared with the unperturbed brush height,the degree of interpenetration between the two opposing PE brushes was found to increase with increasing grafting density and bulk degree of ion-ization.The degree of interpenetration also increases with the bulk salt concentration in the osmotic brush regime.Numerical results further re-vealed that,at a brush separation comparable to the unperturbed brush height,the degree of interpenetration does not increase further with in-creasing bulk degree of ionization,bulk salt concentration in the osmotic regime and grafting density.The saturation of the degree of interpene-tration with these system parameters indicates that the grafted PE chains in the gap between the two columns retract and tilt in order to reduce the unfavorable electrostatic and steric repulsions between the two opposing PE brushes.Based on salt ion concentrations at the midpoint be-tween the two opposing brushes,a quantitative criterion in terms of the unperturbed brush height and Debye screening length was established to determine the threshold value of the brush separation beyond which they are truly independent from each other.
查看更多>>摘要：Nonconventional luminescent materials(NLMs)are a type of organic luminescent materials that does not contain aromatic units.Due to the simplicity of the synthesis process,mild reaction conditions,good hydrophilicity and biological compatibility,NLMs have attracted much attention.Nevertheless,numerous reports indicate that NLMs can only effectively luminesce at high concentrations and in solid state,which lim-its their applicability in the field of cell imaging.This study addresses this limitation by designing and synthesizing oligomers P1,P2 and P3 using ethylene glycol diglycidyl ether and amine compounds containing ethylene groups.These oligomers exhibit remarkable luminescence efficiency reaching as high as 9.2％in dilute solutions(0.1 mg/mL),making them among the best NLMs in this category.Furthermore,the synthesized oligomers exhibit excitation wavelength-dependent and concentration-dependent luminescence intensity,fluorescence response to tempera-ture and pH changes,as well as the ability to identify Fe3+,Cu2+and Mo5+in dilute solutions.These characteristics render them potentially useful in the for cell imaging.
查看更多>>摘要：Photodynamic therapy(PDT)has been emerged as a promising modality for cancer treatment.However,the development of drug de-livery system enabling continuous release of photosensitizers(PSs)for long-term PDT treatment still remains challenges.Herein,a H2O2-respon-sive injectable hydrogel,covalently crosslinked by N1-(4-boronobenzyl)-N3-(4-boronophenyl)-N1,N1,N3,N3-tetramethylpropane-1,3-diaminium(TSPBA)with PVA containing polythiophene quaternary ammonium salt(PT2)polymer dots(PDots)as a photosensitizer was fabricated.Under the stimulation of H2O2,the obtained injectable hydrogel gradually degrades and releases PDots.In vitro experiments suggested that the re-leased PDots could realize efficient tumor cells inhibition through its robust singlet oxygen generation capability upon 577 nm laser irradiation.In vivo studies demonstrated a sustained retention of PDots for at least 7 days following single-dose administration,facilitating efficient tumor inhi-bition with light treatments for 3 times without apparent biotoxicity.This work presents an innovative polymer dots-based composite local drug delivery system for long-term PDT in cancer treatment.
查看更多>>摘要：Polyethyleneimine(PEI),as a widely used polymer material in the field of gene delivery,has been extensively studied for modification and shielding to reduce its cytotoxicity.However,research aimed at preparing degradable PEI is scarce.In this work,the hydrogen peroxide(H2O2)oxidation method was used to introduce degradable amide groups in the PEI and a series of oxidized PEI22k(oxPEI22k)with different de-grees of oxidation were synthesized by regulating the dosage of H2O2.The relationship between the oxidation degree of oxPEI22k and the gene transfection efficiency of oxPEI22k was studied in detail,confirming that the oxPEI22k with oxidation degrees of 16.7％and 28.6％achieved im-proved transfection efficiency compared to unmodified PEI.These oxPEI22k also proved reduced cytotoxicity and improved degradability.Fur-ther,this strategy was extended to the synthesis of low-molecular-weight oxPEI1.8k.The oxPEI1.8k with suitable oxidation degree also achieved improved transfection efficiency and reduced cytotoxicity.In brief,this work provided high-efficiency and low-cytotoxicity degradable gene de-livery carriers by regulating the oxidation degree of PEI,which was of great significance for promoting clinical applications of PEI.
查看更多>>摘要：Amyloidosis is characterized by the deposition of fibrillar aggregates,with a specific peptide or protein as the primary component,in affected tissues or organs.Excessive proliferation and deposition of amyloid fibrils can cause organismal dysfunction and lethal pathological out-comes associated with amyloidosis.In this study,a nanochaperone(nChap-NA)was developed to inhibit protein misfolding and fibrillation by simulating the function of natural molecular chaperones.The nanochaperone was prepared by self-assembly of two block copolymers PEG-b-PCL and PCL-b-P(NIPAM-co-AANTA),which had a phase-separated surface consisting of hydrophobic PNIPAM microdomains with coordinative NTA(Zn)moieties and hydrophilic PEG chains.The hydrophobic interaction of the PNIPAM microdomain and the coordination of NTA(Zn)syner-gistically work together to effectively trap the amyloid monomer and block its fibrillation site.Insulin and human islet amyloid polypeptide(hIAPP)were used as model proteins to investigate the nanochaperone's inhibition of amyloid misfolding and fibrillation.It was proved that the nanochaperone could stabilize the natural conformation of the trapped insulin and hIAPP,and effectively inhibit their fibrillation.In vivo study demonstrated that the nanochaperone could effectively preserve the bioactivity of insulin and reduce the cytotoxicity caused by hIAPP aggrega-tion.This study may provide a promising strategy for the prophylactic treatment of amyloidosis.
查看更多>>摘要：Silicon-containing arylacetylene(PSA)resins have broad application prospects because of their excellent heat resistance.However,im-proving their mechanical properties and interfacial bonding with reinforcement fibers while maintaining heat resistance is a challenge in engi-neering applications.Here,poly(diethynylbenzene-methylsilyl-3-benzonitrile)(DEB-CN)and poly(diethynylbenzene-methylsilyl-3,6-diethynylcar-bazole-3-benzonitrile)(DEC-CN)were synthesized via an isopropylmagnesium chloride lithium-chloride complex(i-PrMgClLiCl),overcoming the compatibility problem between cyano groups and Grignard reagents.The cyano and alkyne groups in the resin underwent cyclization to form pyridine,catalyzed by the-NH-moiety in DEC-CN,resulting in extremely high thermal stability(5％weight loss temperature:669.3 ℃,glass transi-tion temperature＞650 ℃).The combination of cyano dipole-dipole pairing and hydrogen bonding greatly enhanced the resin-fiber interface properties,while the generated pyridine promoted stress relief in the crosslinked network,substantially improving the mechanical properties of the cyano-silicon-containing arylacetylene resin composites.The flexural strength of quartz fiber cloth/DEC-CN composites was 298.2 MPa at room temperature and 145.9 MPa at 500 ℃,corresponding to 84.0％and 127.6％enhancements,respectively,over the cyano-free counterpart.These cyano-silicon-containing arylacetylene resins exhibited a dual reinforcement mechanism involving physical interfacial interactions and chemical crosslinking,achieving a good balance between thermal stability and mechanical properties.
查看更多>>摘要：Nuclear magnetic resonance(NMR)is an advanced technique for the molecular weight(MW)determination of polymers at quantita-tive conditions.In this study,we investigate the effect of liquid 1H-NMR instrumental setting parameters on the MW determination of polyether diols,namely poly(ethylene glycol)(PEG)and poly(tetramethylene oxide)(PTMO)diols,using hydroxymethylene groups as chain-ends.Our re-sults show that the protons in chain-ends have larger spin-lattice relaxation time(T1)than those in main chains.To let most of the excited protons relax to the equilibrium state,the delay time(d1)should be much larger than T1 of end-groups.When 13C decoupling is inactive,the relative er-rors can be greater than 60％,due to the13C-coupled proton satellite peaks,which can overlap with chain-end groups or be misassigned as chain-ends.The optimal quantitative NMR conditions for the MW estimation of polyethers are revealed below:standard pulse with inverted gated 13C decoupling pulse sequence,32 scans,2.0 s acquisition time in 90 degree of flip angle and 30 s d1.The MWs determined from 1H quantitative NMR are all smaller than those from SEC which are relative to polystyrene(PS)standards,since the size of polyether chains is larger than that of PS with the same MW.In addition,the MW obtained from SEC for PTMOs shows larger overestimation than PEGs,suggesting PEG chains are more flexible than PTMO's.
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