Radical Precipitation Polymerization Research Articles

Magnetic and hydrophilic imprinted particles via ATRP at room temperature for selective separation of sulfamethazine

In this work, a facile route to prepare hydrophilic molecularly imprinted particles with magnetic susceptibility (MMIPs) was first reported via atom transfer radical precipitation polymerization (ATRPP) in a methanol/water solvent at low temperature (298 K), which can be considered as an environment-friendly system. During the process, 2-hydroxyethyl methacrylate and N, N-methylenebisacrylamide monomers were added to improve the hydrophilicity of the polymers. The obtained materials were characterized in detail by X-ray diffraction, transform infrared spectroscopy, thermogravimetric analysis, vibrating sample magnetometer, scanning electron microscopy and transmission electron microscopy, and then used for the selective separation of sulfamethazine (SMZ) from aqueous medium. The images showed Fe3O4 nanoparticles that were successfully embedded into the polymer particles with the size ranging from 450 to 650 nm, which exhibited great superparamagnetic susceptivity and high thermal stability. Batch adsorption experiments were performed to determine specific adsorption equilibrium, kinetics, and selective recognition and separation. The effect of the ratio of the double monomers used in the adsorption property was also studied. The equilibrium data of MMIPs toward SMZ was well fitted by the Langmuir isotherm model, and the maximum adsorption capacity estimated was 66.67 μmol g−1. The adsorption kinetics rapidly achieved equilibrium within 1.0 h and was well described by the pseudo-second-order model. The MMIPs synthesized showed outstanding affinity and selectivity toward SMZ over structurally analogous antibiotics and easily achieved magnetic separation under an external magnetic field. In addition, the adsorption performance of the resulting MMIPs was no obviously decreased at least six repeated cycles.

Multilayered Composite Microgels Synthesized by Surfactant-Free Seeded Polymerization

We report on a simple and rapid method to produce multilayered composite microgels. Thermosensitive microgels were synthesized by aqueous free radical precipitation polymerization using N-isopropylacrylamide (NIPAm) as a monomer. Using the microgels as cores, surfactant-free seeded polymerization of an oil-soluble monomer, glycidyl methacrylate (GMA), was carried out at 70 °C, where the microgels were highly deswollen in water. All of the oil-soluble monomers were polymerized, and the resultant polymers were attached on the pre-existing microgel cores, resulting in hard shell formation. It is worth mentioning that secondary particles of oil-soluble monomers have never been formed during the polymerization. The composite microgels were characterized by electron microscopy and dynamic light scattering. In particular, X-ray photoelectron spectroscopy (XPS) measurements revealed that the surface of the composite microgels was composed of a hydrogel layer, although microgel cores were covered by polyGMA shell. The mechanism of the trilayered composite microgel formation will be discussed.

Efficient synthesis of monodisperse, highly crosslinked, and “living” functional polymer microspheres by the ambient temperature iniferter‐induced “living” radical precipitation polymerization

AbstractThe facile and efficient one‐pot synthesis of monodisperse, highly crosslinked, and “living” functional copolymer microspheres by the ambient temperature iniferter‐induced “living” radical precipitation polymerization (ILRPP) is described for the first time. The simple introduction of iniferter‐induced “living” radical polymerization (ILRP) mechanism into precipitation polymerization system, together with the use of ethanol solvent, allows the direct generation of such uniform functional copolymer microspheres. The polymerization parameters (including monomer loading, iniferter concentration, molar ratio of crosslinker to monovinyl comonomer, and polymerization time and scale) showed much influence on the morphologies of the resulting copolymer microspheres, thus permitting the convenient tailoring of the particle sizes by easily tuning the reaction conditions. In particular, monodisperse poly(4‐vinylpyridine‐co‐ethylene glycol dimethacrylate) microspheres were prepared by the ambient temperature ILRPP even at a high monomer loading of 18 vol %. The general applicability of the ambient temperature ILRPP was confirmed by the preparation of uniform copolymer microspheres with incorporated glycidyl methacrylate. Moreover, the “livingness” of the resulting polymer microspheres was verified by their direct grafting of hydrophilic polymer brushes via surface‐initiated ILRP. Furthermore, a “grafting from” particle growth mechanism was proposed for ILRPP, which is considerably different from the “grafting to” particle growth mechanism in the traditional precipitation polymerization. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

IRGD-coupled responsive fluorescent nanogel for targeted drug delivery

In this investigation, we have designed and synthesized a multifunctional nanogel for anti-tumor drug delivery. Thermo- and pH-responsive poly (N-isopropyl acrylamide-co-acrylic acid) nanogels (NGs) were synthesized by free radical precipitation polymerization. Positive charged chemotherapeutic drug doxorubicin (DOX) was introduced into the negatively charged swollen NGs by electrostatic adsorption at pH 7.4. Fluorescent bovine serum albumin (BSA) encapsulated gold nanoclusters (AuNCs) were conjugated onto the surface of NGs, followed by functionalization of tumor targeting peptide iRGD onto the BSA for tumor targeting. Interestingly, the DOX-encapsulated iRGD-decorated NGs maintain both thermo- and pH-responsive properties, which are favorable for achieving a controlled drug release in tumor tissues. Stable red fluorescent emission, derived from AuNCs, was used to detect and track the NGs in vitro. As expected, the iRGD motif mediated specific targeting to tumor and endothelial cells and enhanced cellular uptake of the NGs, as demonstrated by flow cytometry and confocal microscopy assays. In vitro cytotoxicity studies proved that the presence of iRGD enhanced the cytotoxic efficiency of DOX to the targeted cells. All together, our current study indicates that the NGs drug-carriers can deliver chemotherapeutic drug specifically to the tumor and endothelial cells with enhanced anti-tumor efficacy and controlled drug release.

Interventional radionuclide therapy of hepatocellular carcinoma: Assessment of intratumoral retention of HPMA copolymers

To develop new radiopharmaceuticals for the interventional radionuclide therapy of recurrent hepatocellular carcinoma, poly(HPMA)-APMA-DTPA[HPMA=N-(2-hydroxypropyl) methacrylamide; APMA=N-(3-aminopropyl)methacrylamide; DTPA=diethylenetriaminepentaacetic acid] was synthesized by free radical precipitation polymerization in acetone/dimethylsulfoxide with N,N′-azobis(isobutyronitrile) as the initiator. The copolymers were characterized with nuclear magnetic resonance(NMR) spectroscopy and gel permeation chromatography(GPC, M n=2.2×104, M w/M n=1.38). Subsequently, poly(HPMA)-APMA-DTPA was conjugated with 99mTc radionuclide. Prolonged retention of poly(HPMA)-APMA-DTPA conjugate within the tumor tissues was demonstrated by single-photon emission computed tomography computed tomography(SPECT-CT) at 1, 2, 4 and 24 h following intra-tumoral injection of the conjugate to hepatocellular carcinoma xenografts in mice. DTPA-99mTc was also synthesized and characterized for comparison. The data suggest that the poly(HPMA)-APMA-DTPA conjugates might be useful for the interventional radionuclide therapy of recurrent hepatocellular carcinoma in humans.

Synthesis and NMR investigation of styrene glycopolymers containingd-galactose units functionalized with 4-(4-hydroxybutoxy)benzylamine residues

As a part of a work aimed at the synthesis of properly functionalized nanostructured glycopolymers suitable for interaction studies with copper amine oxidases, D-galactose was transformed through a six step sequence into the monomer N-(4-vinylbenzoyl)-6-amino-6-deoxy-D-galactose (1) which was converted into nanostructured crosslinked polymers (R1) by radical precipitation polymerization and into linear polymers (P1) by solution polymerization. The linear polymers were useful models for setting up glycosylation reactions to introduce N-trifluoroacetyl-4-(4-hydroxybutoxy)benzylamine residues in the presence of camphor sulfonic acid as the catalyst and to extend them to the nanostructured systems. The advancement of the glycosylation reaction was performed through the synthesis and glycosylation of N-benzoyl-6-amino-6-deoxy-D-galactose (9) as the model molecule for accurate NMR investigations. The removal of the trifluoroacetyl protecting group, unexpectedly stable, in glycosylated P1 and R1 was achieved with sodium borohydride.

An investigation into novel multifunctional cross-linkers effect on microgel prepared by precipitation polymerization

Novel microgels composed of acrylaic acid and multifunctional cross-linkers, acrylate/methacrylate cross-linkers, were synthesized via thermal initiated free radical precipitation polymerization in organic solvents. The effect of cross-linker functionality on the properties of microgels was investigated. Results showed both the solvent absorbency and apparent viscosity depend on the network structure, the cross-linker functionality and number of hydrophobic groups. Gel content indicated more reactivity of acrylate than methacrylate cross-linkers. A linear relation exists between elastic modulus (G′) and functionality (f). Also the results suggested an equation that confirmed a direct relationship between glass transition temperature (Tg) and (f). The rotational and apparent viscosity results supported the thickening properties of the microgels. Based on the observations, it is concluded that trifunctional AC cross-linker (TMPTA) choose as an improvement of thickening properties over another cross-linkers.

Synthesis and Characterization of Thermally and Glucose-Sensitive Poly <I>N</I>-Vinylcaprolactam-Based Microgels

Temperature and glucose sensitive microgels were prepared via radical precipitation polymerization, using N-vinylcaprolactam (NVCL) as the main monomer, N,N-methylenebisacrylamide (MBA) as a crosslinker, V50 as initiator and 4-vinylphenylboronic acid (VPBA) as a functional monomer. The LCST of homopoly (NVCL) was first determined and found to be around 33 degrees C. The preparation of microgels was examined as a function of crosslinker (MBA) and VPBA amount in the polymerization recipe. Each polymerization was examined by considering the polymerization conversion and water-soluble polymer formation. Transmission electron microscopy, dynamic light scattering (DLS) and FT-IR characterizations show that the prepared microgels are monodisperse submicron particles, thermally sensitive and containing boronic acid functions. The effect of glucose on the swelling ability of boronic acid containing microgel was particularly examined and revealed the presence of specific interaction.

Drying Mechanism of Poly(N-isopropylacrylamide) Microgel Dispersions

The drying mechanism of poly(N-isopropylacrylamide) (pNIPAm) microgel dispersions was investigated. The microgels were synthesized by temperature-programmed aqueous free radical precipitation polymerization using NIPAm, N,N'-methylenebis(acrylamide), and water-soluble initiator. Drying processes of the microgel dispersions were observed with a digital camera and an optical microscope, and the resultant dried structures were observed by scanning electron microscopy. We found that the presence of the microgels changed the behavior of the drying process of water. In particular, the microgels were adsorbed at the air/water interface selectively within a few minutes irrespective of the microgel concentration. The relationship between the drying mechanism and structure of the resultant microgel thin film has been clarified by changing the microgel concentration of the dispersions.

Characterizations of Modified Silica Nanoparticles(II) ; Preparation and Application of Silica Nanoparticles as a Environmentally Filler

A chemical process involves polymerization within microspheres, whereas a physical process involves the dispersion of polymer in a nonsolvent. Nano-sized monodisperse microspheres are usually prepared by chemical processes such as water-based emulsions, seed suspension polymerization, nonaqueous dispersion polymerization, and precipitation polymerizations. Polymerization was performed in a four-necked, separate-type flask equipped with a stirrer, a condenser, a nitrogen inlet, and a rubber stopper for adding the initiator with a syringe. Nitrogen was bubbled through the mixture of reagents for 1 hr. before elevating the temperature. Functional silane (3-mercaptopropyl)trimethoxysilane (MPTMS) was used for the modification of silica nanoparticles and the self-assembled monolayers obtained were characterized by X-ray photoelectron spectroscopy (XPS), laser scattering system (LSS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), elemental analysis (EA), and thermogravimetric analysis (TGA). In addition, polymer microspheres were polymerized by radical polymerization of <TEX>${\gamma}$</TEX>-mercaptopropyl modified silica nanoparticles (MPSN) and acrylamide monomer via precipitation polymerization; then, their characteristics were investigated. From the elemental analysis results, it can be concluded that the conversion rate of acrylamide monomer was 93% and that polyacrylamide grafted to MPSN nanospheres via the radical precipitation polymerization with AAm in ethanol solvent. The microspheres were successfully polymerized by the 'graft from' method.

Azobenzene-Containing Molecularly Imprinted Polymer Microspheres with Photo- and Thermoresponsive Template Binding Properties in Pure Aqueous Media by Atom Transfer Radical Polymerization

A facile, general, and highly efficient approach to obtain azobenzene (azo)-containing molecularly imprinted polymer (MIP) microspheres with both photo- and thermoresponsive template binding properties in pure aqueous media is described for the first time, which involves the first synthesis of "living" azo-containing MIP microspheres with surface-immobilized alkyl halide groups via atom transfer radical precipitation polymerization (ATRPP) and their subsequent modification via surface-initiated atom transfer radical polymerization (ATRP) of N-isopropylacrylamide (NIPAAm). The successful grafting of poly(NIPAAm) (PNIPAAm) brushes onto the obtained MIP microspheres was confirmed by FT-IR, SEM, water dispersion stability and static contact angle studies, and template binding experiments. The introduction of PNIPAAm brushes onto the azo-containing MIP microspheres significantly improved their surface hydrophilicity and imparted thermoresponsive properties to them, leading to their pure water-compatible and thermoresponsive template binding properties. In addition, the binding affinity of the imprinted sites in the grafted azo-containing MIP microspheres was found to be photoresponsive toward the template in pure water, and this photoregulation process proved to be highly repeatable under photoswitching conditions.

Superparamagnetic and fluorescent thermo-responsive core–shell–corona hybrid nanogels with a protective silica shell

We present the preparation and the characterization of the solution behavior and functional properties of superparamagnetic and/or fluorescent, thermo-responsive inorganic/organic hybrid particles with an intermediate protective silica shell and a smart polymer corona. These well-defined multifunctional nanogels were prepared via two consecutive encapsulation processes of superparamagnetic Fe2O3 nanoparticles (NPs) and/or fluorescent CdSe(ZnS) semiconductor nanocrystals with a silica layer and a crosslinked poly(N-isopropylacrylamide) (PNIPAAm) polymer shell. First, the different NPs were entrapped into a silica shell using a microemulsion process. Therein, the precise adjustment of the conditions allows to entrap either several particles or single ones and to tailor the thickness of the silica shell in the range of 20–60nm. In a second step, a polymer coating, i.e. thermosensitive PNIPAAm, was attached onto the surface of the multifunctional core–shell particles via free radical precipitation polymerization, furnishing multifunctional core–shell–corona hybrid nanogels. Analyses of the functional properties, i.e. optical brightness and magnetic moments, along with transmission electron microscopy reveal near monodisperse hybrid nanoparticles that retain the intrinsic properties of the original nanocrystals. Additionally, we demonstrate the drastically increased chemical stability due to the barrier properties of the intermediate silica layer that protects and shields the inner functional nanocrystals and the responsive character of the smart PNIPAAm shell.

Ambient temperature synthesis of narrow or monodisperse, highly cross-linked, and “living” polymer microspheres by atom transfer radical precipitation polymerization

A facile ambient temperature atom transfer radical precipitation polymerization (ATRPP) approach is developed for the efficient one-pot synthesis of narrow or monodisperse, highly cross-linked, and “living” polymer microspheres under mild reaction conditions. The simple introduction of an atom transfer radical polymerization (ATRP) mechanism into a precipitation polymerization system, together with the rational use of polar alcoholic solvents, allows the direct ambient temperature preparation of uniform “living” polymer microspheres with their number-average diameters ranging from 0.36–1.95 μm and their particle size distributions being typically less than 1.01. The polymerization parameters (including the monomer loading, polymerization time, and kind of alcoholic solvent) proved to have a pronounced influence on the yields and morphologies of the polymer microspheres, which makes it very convenient to tailor the particle sizes by tuning the polymerization conditions. The general applicability of ambient temperature ATRPP was demonstrated by its successful application in a range of alcoholic solvents as well as its versatility in the synthesis of a series of uniform copolymer microspheres of different monovinyl functional monomers (4-vinylpyridine, glycidyl methacrylate, methyl methacrylate, and 2-hydroxyethyl methacrylate) with ethylene glycol dimethacrylate. In addition, the “livingness” of the resulting polymer microspheres was confirmed by their direct grafting of hydrophilic polymer brushes via surface-initiated ambient temperature ATRP, leading to advanced functional polymer microspheres with significantly improved surface hydrophilicity.

Binary Mixtures of Cationic and Anionic Microgels

Colloidal behaviors of binary mixtures composed of cationic and anionic microgels are reported. Both microgels were synthesized by aqueous free radical precipitation polymerization using N-isopropylacrylamide and N,N'-methylenebisacrylamide but using different types of water-soluble initiators and comonomer. Effects of temperature and salt concentration on phase behaviors of binary mixtures of cationic and anionic microgels were investigated as well as single-species microgels by UV-vis spectroscopy. We found that the presence of a small amount of NaCl altered the dispersing behavior of the binary mixtures of cationic and anionic microgels when they were in hydrated and swollen states. In particular, scanning electron microscope observation clarified that the binary mixtures containing a small amount of NaCl were not flocculated, and microgels showed non-close-packed structures on a planar substrate in the dry state. Furthermore, flocculations formed when both microgels were in the swollen states could be redispersed by adding a small amount of NaCl and gently stirring. These tunable properties have not been observed in mixtures of hard particles, and are due to the coexistence of electrostatic interactions and steric hindrance of highly hydrated soft particles.

Narrow or Monodisperse, Highly Cross-Linked, and “Living” Polymer Microspheres by Atom Transfer Radical Precipitation Polymerization

A facile, general, and efficient one-pot approach to obtaining narrow or monodisperse, highly cross-linked, surface-functionalized, and “living” polymer microspheres with uniformly cross-linked structures by atom transfer radical precipitation polymerization (ATRPP) is described for the first time. The simple introduction of atom transfer radical polymerization (ATRP) mechanism into precipitation polymerization system allows the direct generation of uniformly cross-linked “living” polymer microspheres with their number-average diameters ranging from 0.73 to 3.25 μm and their polydispersity indices being typically lower than 1.01. The polymerization parameters (including stirring rate, monomer loading, initiator and catalyst concentrations, molar ratio of cross-linker to monovinyl functional comonomer, and polymerization scale and time) have proven to show significant influence on the morphologies of the resulting polymer microspheres, which makes it very convenient to control the particle sizes by easily tuning the reaction conditions. The general applicability of ATRPP was demonstrated by synthesizing a series of uniform functional copolymer microspheres with different incorporated functional comonomers (i.e, 4-vinylpyridine, acrylamide, and 2-hydroxyethyl methacrylate). Moreover, the “livingness” of the resulting polymer microspheres was confirmed by their direct grafting of hydrophilic polymer brushes via surface-initiated ATRP under mild reaction conditions. Furthermore, a “grafting from” particle growth mechanism is proposed for ATRPP, which is considerably different from the “grafting to” particle growth mechanism in the traditional precipitation polymerization.

Well defined hybrid PNIPAM core-shell microgels: size variation of the silica nanoparticle core

Thermoresponsive core-shell hybrid microgels with different core sizes were prepared by radical precipitation polymerization of the monomer N-isopropylacrylamide (NIPAM) in the presence of functionalized silica cores. The size of the cores was varied in a range of 70–170 nm in diameter. Characterization of the hybrid microgels was done by means of imaging techniques such as transmission electron microscopy (TEM) and atomic force microscopy (AFM). In addition, scattering techniques were used to study the swelling behavior and network structure of the responsive polymer shells. While dynamic light scattering (DLS) was employed to investigate the overall particle dimensions, SANS allowed to determine the correlation length ξ of the polymer network. Additionally, SANS also provides the average core size and the polydispersity of the cores in-situ using the method of contrast variation.

Responsive Hybrid Polymeric/Metallic Nanoparticles for Catalytic Applications

AbstractThe aims of the current study were to synthesize new responsive polymeric microgels with embedded silver nanoparticles and then to employ these particles as catalyst for reduction reactions. To these ends, stimuli‐responsive microgels from PNIPAAm and the chitosan derivative were firstly synthesized by free radical precipitation polymerization. Then, silver nanoparticles were synthesized inside these microgel networks by in situ reduction of AgNO3. These microgels were temperature/pH sensitive with a phase transition temperature of 32–35 °C in water at pH = 3 and 8, respectively. The catalytic activity of the Ag nanoparticles for the reduction of 4‐nitrophenol can be tuned through the swelling or collapse of the responsive microgel network hosting the active nanoparticles. magnified image

One‐pot synthesis of surface‐functionalized molecularly imprinted polymer microspheres by iniferter‐induced “living” radical precipitation polymerization

AbstractThis article describes for the first time the development of a new polymerization technique by introducing iniferter‐induced “living” radical polymerization mechanism into precipitation polymerization and its application in the molecular imprinting field. The resulting iniferter‐induced “living” radical precipitation polymerization (ILRPP) has proven to be an effective approach for generating not only narrow disperse poly(ethylene glycol dimethacrylate) microspheres but also molecularly imprinted polymer (MIP) microspheres with obvious molecular imprinting effects towards the template (a herbicide 2,4‐dichlorophenoxyacetic acid (2,4‐D)), rather fast template rebinding kinetics, and appreciable selectivity over structurally related compounds. The binding association constant Ka and apparent maximum number Nmax for the high‐affinity sites of the 2,4‐D imprinted polymer were determined by Scatchard analysis and found to be 1.18 × 104 M−1 and 4.37 μmol/g, respectively. In addition, the general applicability of ILRPP in molecular imprinting was also confirmed by the successful preparation of MIP microspheres with another template (2‐chloromandelic acid). In particular, the living nature of ILRPP makes it highly useful for the facile one‐pot synthesis of functional polymer/MIP microspheres with surface‐bound iniferter groups, which allows their direct controlled surface modification via surface‐initiated iniferter polymerization and is thus of great potential in preparing advanced polymer/MIP materials. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3217–3228, 2010

Synthesis and Characterization of Her-2 Targetable N-(2-Hydroxypropyl)methacrylamide Copolymer Conjugates.

Abstract Background: Current Her-2 overexpressing cancer therapies are limited by rapid drug resistance development from Trastuzumab (TRZ) treatment or low selectivity and non specific side effects of hepatotoxicity with small molecular tyrosine kinase inhibitors such as lapatinib. N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer-drug conjugates with tailored side-chain composition have demonstrated their clinical potential as tumor targetable chemotherapeutic delivery systems. The present study evaluates the potential of novel HPMA copolymer-TRZ conjugates to enhance the therapeutic index of Her-2 targeted therapy.Material and Methods: HPMA copolymer-TRZ conjugates were synthesized in two steps. In the first step, an HPMA copolymer precursor containing reactive p-nitrophenyl ester (ONp) side chains was synthesized by free radical precipitation polymerization. In the second step a series of polymer precursors were conjugated to varying amounts of TRZ by aminolysis. The feed ratio of TRZ to HPMA copolymer was calculated based on the number of primary amine groups available on TRZ surface as determined spectrophotometrically using the 2,3,6-Tri-nitrobenzenesulfonic acid (TNBS) assay. The copolymer conjugates were characterized by correlating the feed ratio with the degree of conjugation (TNBS assay) and molecular weight distribution (size exclusion chromatography). The antiproliferative action of HPMA copolymer-TRZ conjugates was evaluated on a Her-2 overexpressing BT474 breast cancer cell line. Cell proliferation was quantified by MTT assay. Activation of Her-2 after treatment with polymer conjugate was measured by western immunoblotting.Results and Discussion: A series of three HPMA copolymer-TRZ conjugates were successfully synthesized and characterized. It was observed that an increase in the feed ratio of HPMA copolymer precursor to TRZ resulted in a corresponding increase in the degree of TRZ conjugation. The size exclusion chromatography profile of the conjugates was also consistent with the degree of conjugation. As HPMA copolymer precursor contents increased, the elution time decreased suggesting an increase in the hydrodynamic volume of conjugates. The growth inhibition effects of all HPMA copolymer-TRZ conjugates were concentration dependant. The half maximal inhibitory concentrations (IC50) of the conjugates with TRZ/HPMA=1/1, 2/1 and 4/1 were 10, 29, and 20 nM respectively, which were comparable to that of free TRZ (8 nM) suggesting that the antibody retained bioactivity against Her-2 overexpressing cancer cells upon conjugation to the polymer. Western immunoblotting showed that polymer conjugated TRZ effectively downregulated activated Her-2 (phospho-Her2) to a greater extent than free TRZ.Conclusion: Here we report for the first time, the successful synthesis, characterization and in vitro evaluation of HPMA copolymer-anti-Her-2 drug (TRZ) conjugates for active targeting to Her-2 overexpressing breast cancer cells. The conjugate compositions were consistent with their molar feed ratios and inhibited model cancer cell growth comparable to the free drug. Preliminary studies indicate improved efficacy of TRZ against Her-2 positive breast cancer cells when administered as polymeric conjugate. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5065.

Preparation of molecularly imprinted polymer microspheres via atom transfer radical precipitation polymerization

AbstractThe first combined use of atom transfer radical polymerization (ATRP) and precipitation polymerization in the molecular imprinting field is described. The utilized polymerization technique, namely atom transfer radical precipitation polymerization (ATRPP), provides MIP microspheres with obvious molecular imprinting effects towards the template, fast template binding kinetics and an appreciable selectivity over structurally related compounds. The living chain propagation mechanism in ATRPP results in MIP spherical particles with diameters (number‐average diameter Dn ≈ 3 μm) much larger than those prepared via traditional radical precipitation polymerization (TRPP). In addition, the MIP microspheres prepared via ATRPP have also proven to show significantly higher high‐affinity binding site densities on their surfaces than the MIP generated via TRPP, while the binding association constants Ka and apparent maximum numbers Nmax of the high‐affinity sites as well as the specific template bindings are almost the same in the two cases. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3257–3270, 2009