Anti‐AIDS active polyrotaxane‐AZT conjugates with bioactive bulky stoppers and their nanoparticles

New anti‐HIV active agents, polyrotaxane‐AZT conjugates with various bioactive bulky stoppers such as 3′‐azido‐3′‐deoxythymidine (AZT) and tocopherol and their nanoparticles were synthesized and characterized. The degree of AZT substitution of the conjugates was calculated from ELEM . ANAL and ranged from 1.8 to 5.9, respectively. The in vitro antiviral activity of these conjugates was determined and used to evaluate their potential applications in anti‐AIDS drugs. The in vitro anti‐HIV activities indicate that the synthesized polyrotaxane‐AZT conjugates and their nanoparticles against HIV‐1 and HIV‐2 strains were more potent inhibitors than free AZT, with reduced cytotoxicities against uninfected MT‐4 cells. The effect of the conjugates against HIV‐1 and HIV‐2 strains increased with decreasing particle size. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

C‐Glycosyl Amino Acids through Hydroboration–Cross‐Coupling of exo‐Glycals and Their Application in Automated Solid‐Phase Synthesis

O‐Glycosylation is one of the most important post‐translational modifications of proteins. The attachment of carbohydrates to the peptide backbone influences the conformation as well as the solubility of the conjugates and can even be essential for binding to specific ligands in cell–cell interactions or for active transport over membranes. This makes glycopeptides an interesting class of compounds for medical applications. To enhance the long‐term availability of these molecules in vivo, the stabilization of the glycosidic bond between the amino acid residue and the carbohydrate is of interest. The described modular approach affords β‐linked C‐glycosyl amino acids by a sequence of Petasis olefination of glyconolactones, stereoselective hydroboration and a mild B‐alkyl‐Suzuki coupling reaction. The coupling products were transformed to C‐glycosyl amino acid building‐blocks suitable for solid‐phase synthesis and successfully incorporated into a partial sequence of the tumor‐associated MUC1‐glycopeptide. The resulting C‐glycopeptides are candidates for the development of long‐term stable mimics of O‐glycopeptide vaccines.     

Imprinted silica nanoparticles coated with N‐propylsilylmorpholine‐4‐carboxamide for the determination of m‐cresol in synthetic and real samples

m‐Cresol‐imprinted silica nanoparticles coated with N‐propylsilylmorpholine‐4‐carboxamide have been developed that contain specific pockets for the selective uptake of m‐cresol. Silica nanoparticles were synthesized by a sol–gel process followed by functionalization of their surface with N‐propylsilylmorpholine‐4‐carboxamide. The formation of m‐cresol‐imprinted silica nanoparticles was confirmed by UV‐Vis spectrophotometry, infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. Electron microscopic studies revealed the formation of monodispersed imprinted silica nanoparticles with spherical shape and an average size of 83 nm. The developed nanoparticles were filled in a syringe and used for the extraction of m‐cresol from aqueous samples followed by quantification using high‐performance liquid chromatography with diode array detection. Various adsorption experiments showed that developed m‐cresol‐imprinted silica nanoparticles exhibited a high adsorption capacity and selectivity and offered a fast kinetics for rebinding m‐cresol. The chromatographic quantification was achieved using mobile phase consisting of acetonitrile/water (70:30 v/v) at an isocratic flow rate of 1.0 mL/min using a reversed‐phase C₁₈ column and detection at λ_max = 275 nm. The limits of detection and quantification were 1.86 and 22.32 ng/mL, respectively, for the developed method. The percent recoveries ranged from 96.66–103.33% in the spiked samples. This combination of this nanotechnique with molecular imprinting was proved as a reliable, sensitive and selective method for determining the target from synthetic and real samples.     

Preparation and Stability Evaluation of Size‐Controllable PDHCA‐β‐CD Nanoparticles as Drug Carrier

A novel biocompatible polymer was prepared by grafting the derivate of β ‐cyclodextrin (6‐SH ‐β ‐CD ) onto poly(3,4‐dihydroxycinnamic acid) (PDHCA ) via Michael addition. PDHCA ‐β ‐CD nanoparticles were prepared by the self‐assembly of amphiphilic PDHCA ‐β ‐CD polymer with N,N ‐dimethylformamide (DMF ) as good solvent and water as poor solvent. The PDHCA ‐β ‐CD nanoparticles were monodispersed with spherical morphology as shown in the scanning electron microscopic (SEM ) images in accord with the result of dynamic light scattering (DLS ) measurement. The size of the nanoparticles could be controlled from 60 to 180 nm by tuning the grafting degree (GD ) of PDHCA ‐β ‐CD polymer and also significantly influenced by the amount of water used during the process. These as‐prepared nanoparticles were stable without any significant change in the particle size after six‐months’ storage and even after being irradiated by UV at λ >280 nm for hours. The formation mechanism of PDHCA ‐β ‐CD nanoparticles was explored. The content of doxorubicin (DOX ) loaded onto the nanoparticles was up to 39% with relatively high loading efficiency (approximately 78.8% of initial DOX introduced was loaded). In vitro release studies suggested that DOX released slowly from PDHCA ‐β ‐CD nanoparticles. These features strongly support the potential of developing PDHCA ‐β ‐CD nanoparticles as carriers for the controlled delivery of drug.     

5-氟尿嘧啶的三元环类化合物的缀合物的合成及其抗肿瘤活性

基于具有三元环状结构的化合物的广泛生理活性和氟尿嘧啶的抗癌作用机制,本文设计、合成并表征了一系列新型5-氟尿嘧啶（5-FU）的三元碳环缀合物及三元氧杂环缀合物。并对5-FU 的N-1和N-3位的选择性烷基化方法进行了系统研究,发现苄氧甲酰氧甲基保护基具有稳定性高、有效保护性好、制备方便、易于脱除等特点,适宜于在本类反应中应用。测试了所合成的新型5-FU三元环缀合物的体外抗肿瘤活性,化合物7、8、12、13显示了对人食管癌细胞Ec9706不同程度的抑制活性。     

Photocatalytic Hydrogen Evolution Based on Efficient Energy and Electron Transfers in Donor–Bridge–Acceptor Multibranched‐Porphyrin‐Functionalized Platinum Nanocomposites

Two donor–bridge–acceptor conjugates (5,10,15,20‐tetrakis[4‐(N,N‐diphenylaminobenzoate)phenyl] porphyrin (TPPZ) and 5,10,15,20‐tetrakis[4‐(N,N‐diphenylaminostyryl)phenyl] porphyrin (TPPX)) were covalently linked to triphenylamine (TPA) at the meso‐position of porphyrin ring. The triphenylamine entities were expected to act as energy donors and the porphyrins to act as an energy acceptor. In this paper, we report on the synthesis of these multibranched‐porphyrin‐functionalized Pt nanocomposites. The conjugates used here not only served as a stabilizer to prevent agglomeration of Pt nanoparticles, but also as a light‐harvesting photosensitizer. The occurrence of photoinduced electron‐transfer processes was confirmed by time‐resolved fluorescence and photoelectrochemical spectral measurements. The different efficiencies for energy and electron transfer in the two multibranched porphyrins and the functionalized Pt nanocomposites were attributed to diverse covalent linkages. Moreover, in the reduction of water to produce H₂, the photocatalytic activity of the Pt nanocomposite functionalized by TPPX, in which the triphenylamine and porphyrin moieties are bonded through an ethylene bridge, was much higher than that of the platinum nanocomposite functionalized by TPPZ, in which the two moieties are bonded through an ester. This investigation demonstrates the fundamental advantages of constructing donor–bridge–acceptor conjugates as highly efficient photosensitizers based on efficient energy and electron transfer.     

Facile synthesis,characterisation and anti‐inflammatory activities of ferrocenyl ester derivatives of 4‐arylidene‐5‐imidazolinones

This article describes the synthesis, optoelectronic properties and anti‐inflammatory activities of a series of seven ferrocenyl ester‐linked 4‐arylidene‐5‐imidazolinone conjugates. Three different types of ortho‐, meta‐ and para‐substituted ferrocenyl esters have been prepared. Their UV–Vis spectra and electrochemical studies are described. The structure of one of the conjugates was confirmed by single‐crystal X‐ray diffraction study. These conjugates exhibited moderate anti‐inflammatory activities.     

A Novel Synthesis of 2-Amino-2-deoxy-D-gluconic Acid and Its Complexation with Cu（Ⅱ） in Alkaline Medium

A novel synthesis of the functional carbohydrate 2-amino-2-deoxy-D-gluconic acid was introduced and itscomplex formation with Cu(Ⅱ)was investigated to obtain the stability constant for its further applications to thefood and pharmaceutical industries.The equilibrium was investigated by spectrophotometric measurements andprocessed by dual-series linear regression method.Results:the yield of 2-amino-2-deoxy-D-gluconic acid is 70%.The complexation molar ratio is 1:2,the molar apsorptivity of the complex is 39.906 L·mol~(-1)·cm~(-1) at 630 nm,and the stability constant β_n is 6.24×10~5.     

Construction of Polycation‐Based Non‐Viral DNA Nanoparticles and Polyanion Multilayers via Layer‐by‐Layer Self‐Assembly

Summary: The multilayers of polycation‐based non‐viral DNA nanoparticles and biodegradable poly(L ‐glutamic acid) (PGA) were constructed by a layer‐by‐layer (LbL) technique. Poly(ethyleneimine) (PEI) was used to condense DNA to develop non‐viral DNA nanoparticles. AFM, UV‐visible spectrometry, and TEM measurements revealed that the PEI‐DNA nanoparticles were successfully incorporated into the multilayers. The well‐structured, easily processed multilayers with the non‐viral DNA nanoparticles may provide a novel approach to precisely control the delivery of DNA, which may have great potential for gene therapy applications in tissue engineering, medical implants, etc.

A TEM image of the cross section of a (PGA/PEI‐DNA nanoparticle)₂₀ multilayer.     

Biocompatible and pH‐responsive triblock copolymer mPEG‐b‐PCL‐b‐PDMAEMA: Synthesis,self‐assembly,and application

A series of well‐defined amphiphilic triblock copolymers [polyethylene glycol monomethyl ether]‐block‐poly(ε‐caprolactone)‐block‐poly[2‐(dimethylamino)ethyl methacrylate] (mPEG‐b‐PCL‐b‐PDMAEMA or abbreviated as mPEG‐b‐PCL‐b‐PDMA) were prepared by a combination of ring‐opening polymerization and atom transfer radical polymerization. The chemical structures and compositions of these copolymers have been characterized by Fourier transform infrared spectroscopy, ¹H NMR, and thermogravimetric analysis. The molecular weights of the triblock copolymers were obtained by calculating from ¹H NMR spectra and gel permeation chromatography measurements. Subsequently, the self‐assembly behavior of these copolymers was investigated by fluorescence probe method and transmission electron microscopy, which indicated that these amphiphilic triblock copolymers possess distinct pH‐dependent critical aggregation concentrations and can self‐assemble into micelles or vesicles in PBS buffer solution, depending on the length of PDMA in the copolymer. Agarose gel retardation assays demonstrated that these cationic nanoparticles can effectively condense plasmid DNA. Cell toxicity tests indicated that these triblock copolymers displayed lower cytotoxicity than that of branched polyethylenimine with molecular weight of 25 kDa. In addition, in vitro release of Naproxen from these nanoparticles in pH buffer solutions was conducted, demonstrating that higher PCL content would result in the higher drug loading content and lower release rate. These biodegradable and biocompatible cationic copolymers have potential applications in drug and gene delivery. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1079–1091, 2010     

Effect of incorporated CdS nanoparticles on the crystallinity and morphology of poly(styrene‐b‐ethylene oxide) diblock copolymers

Surface‐modified CdS nanoparticles selectively dispersed in hexagonally packed poly(ethylene oxide) (PEO) cylinders of poly(styrene‐b‐ethylene oxide) (PSEO) block copolymers were prepared. The photoluminescence and ultraviolet–visible characteristics of the presynthesized CdS nanoparticles in N,N‐dimethylformamide and in PEO domains of the PSEO block copolymers were determined. Because of strong interactions between the CdS nanoparticles and PEO chains, as shown by Fourier transform infrared spectroscopy, the incorporation of the CdS nanoparticles prevented the PEO cylinders from properly crystallizing; this was confirmed by differential scanning calorimetry and wide‐angle X‐ray diffraction measurements. The intercylinder distance between the swollen and reduced‐crystallinity CdS/PEO cylinders in turn increased, as confirmed by small‐angle X‐ray scattering and transmission electron microscopy. At a high CdS concentration (43 wt % or 8.3 vol % with respect to PEO), however, the hexagonally packed cylindrical nanostructure of the PSEO diblock copolymers was destroyed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1220–1229, 2005     

Poly(L‐Glutamic Acid)‐Drug Conjugates for Chemo‐ and Photodynamic Combination Therapy

Despite the polymeric vascular disrupting agent (poly(_L‐glutamic acid)‐graft‐methoxy poly(ethylene glycol)/combretastatin A4) nanoparticles can efficiently inhibit cancer growth, their further application is still a challenge owing to the tumor recurrence and metastasis after treatment. In this study, two poly(_L‐glutamic acid)‐drug conjugates for chemo‐and photodynamic combination therapy are fabricated. PLG‐g‐mPEG‐CA4 nanoparticles are prepared by combretastatin A4 (CA4) and poly(_L‐glutamic acid)‐graft‐methoxy poly(ethylene glycol) (PLG‐g‐mPEG) using the Yamaguchi esterification reaction. PLG‐g‐mPEG‐TPP (TPP: 5, 10, 15, 20‐tetraphenylporphyrin) nanoparticles are constructed using PLG‐g‐mPEG and amine porphyrin through condensation reaction between carboxyl group of PLG‐g‐mPEG and amino group of porphyrin. The results showed that PLG‐g‐mPEG‐CA4 nanoparticles have good antitumor ability. PLG‐g‐mPEG‐TPP nanoparticles can produce singlet oxygen under the laser irradiation. Moreover, the combined therapy of PLG‐g‐mPEG‐CA4 and PLG‐g‐mPEG‐TPP nanoparticles has higher antitumor effect than the single chemotherapy or the single photodynamic therapy in vitro. The combination of CA4 nondrug and photodynamic therapy provides a new insight for enhancing the tumor therapeutic effect with vascular disrupting agents and other therapy.     

Synthesis of chitosan‐based thermo‐ and pH‐responsive porous nanoparticles by temperature‐dependent self‐assembly method and their application in drug release

In this research, thermo‐ and pH‐responsive chitosan‐based porous nanoparticles were prepared by the temperature‐dependent self assembly method. The chitosan‐graft‐poly(N‐isopropylacrylamide) (CS‐g‐PNIPAAm) copolymer solution was prepared through polymerization of N‐isopropylacrylamide (NIPAAm) monomer in the presence of chitosan (CS) solution using cerium ammounium nitrate as the initiator. Then, CS‐g‐PNIPAAm solution was diluted by deionized water and heated to 40 °C for CS‐g‐PNIPAAm self‐assembly. After that, CS‐g‐PNIPAAm assembled to form micelles in which shell layer was CS. Crosslinking agent was used to reinforce the micelle structure to form nanoparticle. The molar ratio of CS/NIPAAm in the feed mixture was changed to investigate its effect on structure, morphology, thermal‐ and pH‐responsive properties of the nanoparticles. TEM images showed that a porous structure of nanoparticles was developed. The synthesized nanoparticles carried positive charges on the surface and exhibited stimuli‐responsive properties, and their mean diameter thus could be manipulated by changing pH value and temperature of the environment. The nanoparticles showed a continuous release of the encapsulated doxycycline hyclate up to 10 days during an in‐vitro release experiment. These porous particles with environmentally sensitive properties are expected to be utilized in hydrophilic drug delivery system. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5126–5136, 2009     

Well‐Defined Amphiphilic C60‐PEG Conjugates: Water‐Soluble and Thermoresponsive Materials

For the preparation of well‐defined H₂O‐soluble C₆₀ polymers, several C₆₀‐PEG conjugates were prepared from a C₆₀ biscarboxylic acid derivative and monodisperse NH₂‐PEGs (NH₂‐EG_n, n = 4 – 36) via amide conjugation. When the relatively long PEGs (EG_n, n ≥ 12) were employed, the C₆₀‐PEG conjugates became completely H₂O‐soluble by forming micelle‐like structure shown by the data of surface tension, DLS, and cryo‐TEM. Interestingly, these H₂O‐soluble C₆₀‐PEG conjugates (C₆₀(EG_n)₂, n = 12 – 36) showed reversible thermoresponse to form larger aggregates (ca. 1 μm by DLS) at higher temperatures. The temperature for the aggregation was related to the lengths of PEGs attached to C₆₀; 29 °C (C₆₀(EG_n)₂, n = 12), 51 °C (n = 20), and 72 °C (n = 36). This thermoresponse was speculated to occur by dehydration of well‐organized PEG chains in the micelle‐type structure of monodisperse C₆₀‐PEG caused by gauche‐to‐anti conformational change of PEG anchors. This thermoresponse of well‐defined amphiphilic C₆₀‐PEG conjugates indicates potential applications in areas such as temperature sensors and thermoresponsive materials.     

Sugar‐Decorated Sugar Vesicles: Lectin–Carbohydrate Recognition at the Surface of Cyclodextrin Vesicles

An artificial glycocalix self‐assembles when unilamellar bilayer vesicles of amphiphilic β‐cyclodextrins are decorated with maltose and lactose by host–guest interactions. To this end, maltose and lactose were conjugated with adamantane through a tetra(ethyleneglycol) spacer. Both carbohydrate–adamantane conjugates strongly bind to β‐cyclodextrin (K_a≈4×10⁴ M ^?1). The maltose‐decorated vesicles readily agglutinate (aggregate) in the presence of the lectin concanavalin A, whereas the lactose‐decorated vesicles agglutinate in the presence of peanut agglutinin. The orthogonal multivalent interaction in the ternary system of host vesicles, guest carbohydrates, and lectins was investigated by using isothermal titration calorimetry, dynamic light scattering, UV/Vis spectroscopy, and cryogenic transmission electron microscopy. It was shown that agglutination is reversible, and the noncovalent interaction can be suppressed and eliminated by the addition of competitive inhibitors, such as D ‐glucose or β‐cyclodextrin. Also, it was shown that agglutination depends on the surface coverage of carbohydrates on the vesicles.     

Water‐soluble metalated and non‐metalated A2B‐ and A3‐corrole/amino acid conjugates: syntheses,characterization and properties

In this study, novel water‐soluble corrole amino acid conjugates were synthesized and characterized. The coupling reaction of A₂B‐ and A₃‐corroles with glycine ethyl ester and taurine under strong basic conditions proved to be successful and yielded di‐ and trifunctionalized corrole amino acid conjugates in good yields. The subsequent metalation of the corrole/amino acid conjugates broadens the scope for applications considerably. As examples, we herein show the catalytic activity of the Mn(III) A₃‐corrole towards O₂ evolution. First we employed tert‐butyl hydroperoxide (t‐BuOOH) as oxidant to obtain the Mn(V)oxo species and tetrabutyl ammonium hydroxide (TBAH) as hydroxide donor agent. Furthermore, the binding properties of the non‐metalated and the Mn(III) A₃‐corrole/amino sulfonic acid conjugates and transport of proteins were investigated and the conjugates exhibited binding to human serum albumin (HSA). Finally, a novel Ga(III) A₃‐corrole/amino sulfonic acid derivative was synthesized and we briefly describe the photophysical properties of this compound. Copyright © 2013 John Wiley & Sons, Ltd.     

Photoresponsive Switches at Surfaces Based on Supramolecular Functionalization with Azobenzene–Oligoglycerol Conjugates

The synthesis, supramolecular complexation, and switching of new bifunctional azobenzene–oligoglycerol conjugates in different environments is reported. Through the formation of host–guest complexes with surface immobilized β‐cyclodextrin receptors, the bifunctional switches were coupled to gold surfaces. The isomerization of the amphiphilic azobenzene derivatives was examined in solution, on gold nanoparticles, and on planar gold surfaces. The wettability of functionalized gold surfaces can be reversibly switched under light‐illumination with two different wavelengths. Besides the photoisomerization processes and concomitant effects on functionality, the thermal cis to trans isomerization of the conjugates and their complexes was monitored. Thermal half‐lives of the cis isomers were calculated for different environments. Surprisingly, the half‐lives on gold nanoparticles were significantly smaller compared to planar gold surfaces.     

Nanometrization of Lanthanide‐Based Coordination Polymers

Heteronuclear lanthanide‐based coordination polymers are microcrystalline powders, the luminescence properties of which can be precisely tuned by judicious choice of the rare‐earth ions. In this study, we demonstrate that such materials can also be obtained as stable solutions of nanoparticles in non‐toxic polyols. Bulk powders of the formula [Ln_2?2xLn′_2x(bdc)₃ ? 4 H₂O]_∞ (where H₂bdc denotes 1,4‐benzene‐dicarboxylic acid, 0≤x≤1, and Ln and Ln′ denote lanthanide ions of the series La to Tm plus Y) afford nanoparticles that have been characterized by dynamic light‐scattering (DLS) and transmission electron microscopy (TEM) measurements. Their luminescence properties are similar to those of the bulk materials. Stabilities versus time and versus dilution with another solvent have been studied. This study has revealed that it is possible to tune the size of the nanoparticles. This process offers a reliable means of synthesizing suspensions of nanoparticles with tunable luminescence properties and tunable size distributions in a green solvent (glycerol). The process is also extendable to other coordination polymers and other solvents (ethylene glycol, for example). It constitutes a new route for the facile solubilization of lanthanide‐based coordination polymers.     

Reduction‐responsive poly (ethylene glycol)‐dexamethasone biarm conjugate and its self‐assembled nanomicelles: Preparation,physicochemical characterization,and thiol‐triggered drug release

In this study, a reduction‐responsive poly (ethylene glycol)‐dexamethasone biarm conjugate was synthesized as intracellular targeted drug delivery carriers. The hydroxyl end group of methoxy poly (ethylene glycol) (mPEG) was modified to introduce a biarm structure with bioreducible disulfide bond and amine end groups. Dexamethasone (Dex) as a nuclear targeting moiety was conjugated to the amine end groups of mPEG biarm derivatives, mPEG‐(NH₂)₂ or mPEG‐(ss‐NH₂)₂, with or without bioreducible disulfide bonds. The bioreducible and nonreducible mPEG‐Dex biarm conjugates, R‐mPEG‐Dex and N‐mPEG‐Dex, were synthesized and characterized by various analytical methods, proton nuclear magnetic resonance (¹H‐NMR), Fourier transform infraredspectroscopy (FT‐IR), dynamic light scattering (DLS), and fluorescence measurements. Amphiphilic mPEG‐Dex conjugates self‐assembled in aqueous solutions to form nanoparticles (NPs) with a size range of 130 to 150 nm, and their critical micelle concentrations (CMCs) were determined to be 12.4 and 15.3 mg/L, respectively, for bioreducible and nonreducible ones. The R‐mPEG‐Dex NPs maintained good colloidal stability in the presence of bovine serum albumin (BSA) for more than 1 week but demonstrated a significant change in colloidal stability in the presence of dithiothreitol (DTT). In DTT‐containing phosphate‐buffered saline (PBS), the bioreducible NPs showed not only reduction‐responsive destabilization with PEG shedding but also thiol‐dependent drug release profile. Our observations indicated that the R‐mPEG‐Dex NPs have a promising prospective as an efficient nanocarrier for intracellular targeted delivery of various anticancer drugs.     

Novel organotin‐containing shell‐cross‐linked knedel and core‐cross‐linked knedel: Synthesis and application in catalysis

A series of novel organotin‐containing core‐cross‐linked knedels and shell‐cross‐linked knedels were first synthesized facilely from poly(styrene)‐b‐poly(acrylate acid) nanoparticles in different selective solvents [Tetrahydrofuran (THF)/H₂O or THF/n‐octane] by using organotin compound 1,3‐dichloro‐tetra‐n‐butyl‐distannoxane as a new cross‐linker. The formation of the 1‐chloro‐3‐carboxylato‐tetra‐n‐butyl‐distannoxane layer in our cross‐linking reaction was supported by Fourier transform infrared (FT‐IR) and inductive coupled plasma emission spectrometer (ICP) analysis of the resulting shell‐cross‐linked knedels and core‐cross‐linked knedels. Transmission electron microscopy (TEM) study showed the spherical morphology and the size of the core‐cross‐linked knedels and shell‐cross‐linked knedel. Especially, the layer structure of the core‐cross‐linked knedels was clearly displayed in TEM image. The increase of extent of cross‐linking lead to the increasing of diameter for the shell‐cross‐linked knedels, whereas there was no significant effect on the core‐cross‐linked knedels. Dynamic light scattering (DLS) measurements gave hydrodynamic diameters of the core‐cross‐linked knedels that were in agreement with the TEM diameters. Moreover, the wall thickness of the shell layer of the core‐cross‐linked knedels could be easily modified by varying the block copolymer composition. Notably, the organotin‐containing core‐cross‐linked knedel exhibited highly efficient catalytic activity for the aqueous esterification reaction under nearly neutral conditions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010