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Well-defined boronic acid block copolymers were demonstrated to exhibit glucose-responsive disassembly at physiological pH. A boronic acid-containing acrylamide monomer with an electron-withdrawing substituent on the pendant phenylboronic acid moiety was polymerized by reversible addition–fragmentation chain transfer (RAFT) polymerization to yield a polymer with a boronic acid pKa = 8.2. Below this value, a block copolymer of this monomer with poly(N,N-dimethylacrylamide) self-assembled into aggregates. Addition of base to yield a pH > pKa or addition of glucose at pH = 7.4 resulted in aggregate dissociation that may prove promising for controlled delivery applications under physiological relevant conditions.

Highly efficient polymer-antibody conjugations were demonstrated via a tetrafluorophenyl active ester. A well-defined diblock copolymer was synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization with a temperature-responsive block, poly(N-isopropylacrylamide), and a block of N,N-dimethylacrylamide and 2,3,5,6-tetrafluorophenyl acrylate active ester. The polymer was conjugated to anti-p24 IgG antibody with about 100% efficiency in as little as 2 h at room temperature in a pH 10.8 buffer. The temperature-responsiveness of the polymer was conferred to the polymer–antibody conjugates after conjugation. The conjugates bound p24 antigen specifically and with binding efficiency comparable to native antibodies. Thus, the active ester diblock copolymer can facilitate the synthesis of temperature-responsive bioconjugates, which may be promising reagents for immunoassays, bioseparations, and specimen-enrichment applications.

This study demonstrates a novel application of nitrogen-doped carbon dots (NCDs) to enable the separation of different lengths of single-stranded DNA (ssDNA) by eletrokinetic means. Carbon dots have recently found widespread application in the fields of sensing, diagnostics, and healthcare due to their biocompatibility and low toxicity. In light of growing interest in the use of ssDNA aptamers over antibodies in the fields of biosensor development and drug delivery, it is important to establish a simple and effective method for aptamer separation. In this study, we employed NCDs as buffer additives in a capillary electrophoresis (CE)-based method, giving rise to the separation of FAM-labeled ssDNA samples ranging from 32 to 100 bases in length, with resolutions ranging from 1.30 – 1.77. In particular, we adopted a capillary transient isotachophoresis (ctITP) system with laser-induced fluorescence (LIF) detection, with both the separation and sample buffers modified by the addition of 30 μg/mL NCDs. These nanomaterials were prepared by a simple hydrothermal method from a mixture of citric acid and ethylenediamine. The NCDs themselves are highly fluorescent and photostable. As components in the background electrolyte, they did not interfere with the fluorescence emission of the FAM-labeled DNA samples. Under the conditions employed, no separation could be achieved in the absence of the NCDs nor with undoped CDs. The results show that NCDs function as buffer additives capable of enhancing electrokinetic-based separations of ssDNA, and hence, provide a new application for these carbon nanomaterials.

The synthesis and characterization of a novel natural-synthetic hybrid material based on cellulose is reported. The reversible addition-fragmentation chain-transfer (RAFT) process was used to graft poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) onto a cellulosic substrate. The weight ratio was increased with an increase in monomer concentration, polymerization time and degree of polymerization (DP). We found that the addition of free chain-transfer agent has a pronounced effect on the weight ratio, chain length of grafted polymer, monomer conversion and homopolymer formation in solution. The cellulose-graft-poly(2-(dimethylamino)ethyl methacrylate) copolymers were characterized by gravimetry, elemental analysis, attenuated total reflectance Fourier transform infrared spectroscopy, scanning electron microscopy, thermal analysis and atomic force microscopy. The dithioester end-group present at the chain end of PDMAEMA was removed via aminolysis. The livingness of the process was utilized to block-copolymerize styrene from the grafted PDMAEMA chains. The hydrophilic/hydrophobic properties of the novel cellulose-g-(PDMAEMA-b-polystyrene) material were illustrated by contact-angle measurements.

Primaquine and tafenoquine are the two 8-aminoquinoline (8-AQ) antimalarial drugs approved for malarial radical cure - the elimination of liver stage hypnozoites after infection with Plasmodium vivax. A single oral dose of tafenoquine leads to high efficacy against intra-hepatocyte hypnozoites after efficient first pass liver uptake and metabolism. Unfortunately, both drugs cause hemolytic anemia in G6PD-deficient humans. This toxicity prevents their mass administration without G6PD testing given the approximately 400 million G6PD deficient people across malarial endemic regions of the world. We hypothesized that liver-targeted delivery of 8-AQ prodrugs could maximize liver exposure and minimize erythrocyte exposure to increase their therapeutic window. Primaquine and tafenoquine were first synthesized as prodrug vinyl monomers with self-immolative hydrolytic linkers or cathepsin-cleavable valine-citrulline peptide linkers. RAFT polymerization was exploited to copolymerize these prodrug monomers with hepatocyte-targeting GalNAc monomers. Pharmacokinetic studies of released drugs after intravenous administration showed that the liver-to-plasma AUC ratios could be significantly improved, compared to parent drug administered orally. Single doses of the liver-targeted, enzyme-cleavable tafenoquine polymer were found to be as efficacious as an equivalent dose of the oral parent drug in the P. berghei causal prophylaxis model. They also elicited significantly milder hemotoxicity in the humanized NOD/SCID mouse model engrafted with red blood cells from G6PD deficient donors. The clinical application is envisioned as a single subcutaneous administration, and the lead tafenoquine polymer also showed excellent bioavailability and liver-to-blood ratios exceeding the IV administered polymer. The liver-targeted tafenoquine polymers warrant further development as a single-dose therapeutic via the subcutaneous route with the potential for broader patient administration without a requirement for G6PD diagnosis.

Clinical studies have validated that antiretroviral (ARV) drugs can serve as an HIV pre-exposure prophylactic (PrEP) strategy. Dosing adherence remains a crucial factor determining the final efficacy outcomes, and both long-acting implants and injectable depot systems are being developed to improve patient adherence. Here, we describe an injectable depot platform that exploits a new mechanism for both formation and controlled release. The depot is a polymeric prodrug synthesized from monomers that incorporate an ARV drug tenofovir alafenamide (TAF) with degradable linkers that can be designed to control release rates. The prodrug monomers are synthetically incorporated into homopolymer or block designs that exhibit high drug weight percent (wt%) and also are hydrophobized in these prodrug segments to drive depot formation upon injection. Drug release converts those monomers to more hydrophilic pendant groups via linker cleavage, and as this drug release proceeds, the polymer chains losing hydrophobicity are then disassociated from the depot and released over time to provide a depot dissolution mechanism. We show that long-acting TAF depots can be designed as block copolymers or as homopolymers. They can also be designed with different linkers, for example with faster or slower degrading p-hydroxybenzyloxycarbonyl (Benzyl) and ethyloxycarbonyl (Alkyl) linkers, respectively. Diblock designs of p(glycerol monomethacrylate)-b-p(Alkyl-TAF-methacrylate) and p(glycerol monomethacrylate)-b-p(Benzyl-TAF-methacrylate) were first characterized in a mouse subcutaneous injection model. The alkylcarbamate linker design (TAF 51 wt%) showed excellent sustained release profiles of the key metabolite tenofovir (TFV) in skin and plasma over a 50-day period. Next, the homopolymer design with a high TAF drug wt% of 73% was characterized in the same model. The homopolymer depots with p(Alkyl-TAFMA) exhibited sustained TFV and TAF release profiles in skin and blood over 60 days, and TFV-DP concentrations in peripheral blood mononuclear cells (PBMC) were found to be at least 10-fold higher than the clinically suggested minimally EC90 protective concentration of 24 fmol/106 cells. These are the first reports of sustained parent TAF dosing observed in mouse and TFV-DP in mouse PBMC. IVIS imaging of rhodamine labeled homopolymer depots showed that degradation and release of the depot coincided with the sustained TAF release. Finally, these polymers showed excellent stability in accelerated stability studies over a six-month time period, and exceptional solubility of over 700 mg/mL in the DMSO formulation solvent. The homopolymer designs have a drug reservoir potential of well over a year at mg/day dosing and may not require cold chain storage for global health and developed world long-acting drug delivery applications.

We describe a novel, two-nanoparticle mRNA delivery system and show that it is highly effective as a means of intracellular enzyme replacement therapy (i-ERT) using a murine model of ornithine transcarbamylase deficiency (OTCD). Our Hybrid mRNA Technology delivery system (HMT) comprises an inert lipid nanoparticle that protects the mRNA from nucleases in the blood as it distributes to the liver and a polymer micelle that targets hepatocytes and triggers endosomal release of mRNA. This results in high-level synthesis of the desired protein specifically in the liver. HMT delivery of human OTC mRNA normalizes plasma ammonia and urinary orotic acid levels, and leads to a prolonged survival benefit in the murine OTCD model. HMT represents a unique, non-viral mRNA delivery method that allows multi-dose, systemic administration for treatment of single-gene inherited metabolic diseases.

The macrostructures of synthetic polymers are essentially the complete molecular chain architectures, including the types and amounts of constituent short-range microstructures, such as the regio- and stereosequences of the inserted monomers, the amounts and sequences of monomers found in co-, ter-, and tetra-polymers, branching, inadvertent, and otherwise, etc. Currently, the best method for characterizing polymer microstructures uses high field, high resolution 13C-nuclear magnetic resonance (NMR) spectroscopy observed in solution. However, even 13C-NMR is incapable of determining the locations or positions of resident polymer microstructures, which are required to elucidate their complete macrostructures. The sequences of amino acid residues in proteins, or their primary structures, cannot be characterized by NMR or other short-range spectroscopic methods, but only by decoding the DNA used in their syntheses or, if available, X-ray analysis of their single crystals. Similarly, there are currently no experimental means to determine the sequences or locations of constituent microstructures along the chains of synthetic macromolecules. Thus, we are presently unable to determine their macrostructures. As protein tertiary and quaternary structures and their resulting ultimate functions are determined by their primary sequence of amino acids, so too are the behaviors and properties of synthetic polymers critically dependent on their macrostructures. We seek to raise the consciousness of both synthetic and physical polymer scientists and engineers to the importance of characterizing polymer macrostructures when attempting to develop structure–property relations. To help achieve this task, we suggest using the electrical birefringence or Kerr effects observed in their dilute solutions. The molar Kerr constants of polymer solutes contributing to the birefringence of their solutions, under the application of a strong electric field, are highly sensitive to both the types and locations of their constituent microstructures. As a consequence, we may begin to characterize the macrostructures of synthetic polymers by means of the Kerr effect. To simplify implementation of the Kerr effect to characterize polymer macrostructures, we suggest that NMR first be used to determine the types and amounts of constituent microstructures present. Subsequent comparison of observed Kerr effects with those predicted for different microstructural locations along the polymer chains can then be used to identify the most likely macrostructures. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 155–166

Polymeric nanoparticles are prepared by selectively cross-linking a photo-sensitive dimethylmaleimide-containing block of a diblock copolymer via UV irradiation. A well-defined photo-cross-linkable block copolymer is prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization of a dimethylmaleimide-functional acrylamido monomer containing photoreactive pendant groups with a poly(N,N-dimethylacrylamide) (PDMA) macro-chain transfer agent. The resulting amphiphilic block copolymers form micelles in water with a hydrophilic PDMA shell and a hydrophobic photo-cross-linkable dimethylmaleimide-containing core. UV irradiation results in photodimerization of the dimethylmaleimide groups within the micelle cores to yield core-cross-linked aggregates. Alternatively, UV irradiation of homogeneous solutions of the block copolymer in a non-selective solvent leads to in situ nanoparticle formation.

In this brief report, we demonstrate that Kerr effect measurements, which determine the excess birefringence con- tributed by polymer solutes in dilute solutions observed under a strong electric field, are highly sensitive to and capable of determining their microstructures, as well as their locations along the macromolecular backbone. Specifically, using atactic triblock copolymers with the same overall composition of sty- rene (S) and p-bromostyrene (pBrS) units, but with two differ- ent block arrangements, that is, pBrS90-b-S120-b-pBrS90 (I) and S60-b-pBrS180-b-S60 (II), which are indistinguishable by NMR, we detected a dramatic difference in their molar Kerr constants (mK), in agreement with those previously estimated. Although similar in magnitude, their Kerr constants differ in sign, with mK(II) positive and mK(I) negative. In addition, S/pBrS random and gradient copolymers synthesized by reversible addition- fragmentation chain-transfer (RAFT) polymerization exhibit a heretofore unexpected enhanced enchainment of racemic (r) pBrS-pBrS diads. Comparison of their observed and calculated mKs suggests that the gradient S/pBrS copolymers possess an unanticipated additional gradient in stereosequence that paral- lels their comonomer gradient, that is, as the concentration of pBrs units decreases from one end of the copolymer chain to the other, so does the content of r diads. This conclusion could only be reached by comparison of observed and calculated Kerr effects, which access the global properties of macromole- cules, and not NMR, which is only sensitive to local polymer structural environments, but not to their locations on the co- polymer chains. Molar Kerr constants are characteristic of entire polymer chains and are highly sensitive to their constitu- ent microstructures and their distribution along the chain. They may be used to both identify constituent microstructures and locate them along the polymer chain, thereby enabling, for the first time, characterization of their complete macrostructures. V C 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 735-741

We report the successful conjugation of a bioactive thiolated α(1,2)-trimannoside to a copolymer of allyl methacrylate (AMA) and N-(2-hydroxypropyl) methacrylamide (HPMA) via photo-mediated thiol–ene chemistry. Well-defined copolymers of AMA and HPMA were synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. Trimannose conjugation was carried out using near stoichiometric ratios of thiolated trimannoside to pendant alkene functional groups contained within the copolymer. About 87% disappearance of the alkene groups was observed in 2 h by proton NMR spectroscopy with approximately 9 trimannose units grafted per polymer chain. The glycan-modified polymer showed binding activity against the mannose-specific lectin concanavalin A, as observed by UV-Vis spectroscopy agglutination and surface plasmon resonance imaging (SPRi) analysis. These results demonstrate the facile addition of multivalent glycan targeting moieties to polymeric carrier segments.

A detailed study of the pH- and sugar-responsive behavior of poly(3-acrylamidophenylboronic acid pinacol ester)-b-poly(N,N-dimethylacrylamide) (PAPBAE-b-PDMA) block copolymers is presented. Reversible addition-fragmentation chain transfer (RAFT) polymerization of the pinacol ester of 3- acrylamidophenylboronic acid resulted in homopolymers with molecular weights between 12,000 and 37,000 g/mol. The resulting homopolymers were employed as macro-chain trans- fer agents during the polymerization of N,N-dimethylacryla- mide (DMA). Successful chain extension and removal of the pinacol protecting groups to yield poly(3-acrylamidophenylbor- onic acid)-b-PDMA (PAPBA-b-PDMA) with free boronic acid moieties resulted in pH- and sugar-responsive block copoly- mers that were subsequently investigated for their behavior in aqueous solution. The PAPBA-b-PDMA block copolymers were capable of solution self-assembly due to the PAPBA block being water-insoluble below its pKa. The resulting aggregates were demonstrated to solubilize and release model hydropho- bic compounds, as demonstrated by fluorescence studies. Dis- sociation of the aggregates was induced by raising the pH above the pKa of the boronic acid residues or by adding sugars capable of forming boronate esters. Aggregate size, dissocia- tion kinetics, and the effect of various sugars were considered. The critical sugar concentration needed to induce aggregate dissociation was tuned by incorporation of hydrophilic DMA units within the PAPBA responsive segment to yield PDMA-b- poly(3-acrylamidophenylboronic acid-co-DMA) block copoly- mers. V C 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 3373-3382, 2012

Macromolecular stars containing reversible boronic ester linkages were prepared by an arm-first approach by reacting well-defined boronic acid-containing block copolymers with multifunctional 1,2/1,3-diols. Homopolymers of 3-acrylamidophenylboronic acid (APBA) formed macroscopic dynamic-covalent networks when cross-linked with multifunctional diols. On the other hand, adding the diol cross-linkers to block copolymers of poly(N,N-dimethylacrylamide (PDMA))-b-poly(APBA) led to nanosized multiarm stars with boronic ester cores and PDMA coronas. The assembly of the stars under a variety of conditions was considered. The dynamic-covalent nature of the boronic ester cross-links allowed the stars to reconfigure their covalent structure in the presence of monofunctional diols that competed for bonding with the boronic acid component. Therefore, the stars could be induced to dissociate via competitive exchange reactions. The star formation-dissociation process was shown to be repeatable over multiple cycles.

Well-defined homopolymers and block copolymers of vinyl esters were synthesized under microwave irradiation via reversible addition-fragmentation chain transfer (RAFT)/macromolecular design via interchange of xanthates (MADIX) polymerization without the significant inhibition or retardation often observed under conventional heating conditions. Poly(vinyl acetate) (PVAc) with molecular weights of 1000−10 000 g/mol was prepared in less than 15 min under microwave irradiation at an apparent temperature of 70 °C in the presence of the commercially available chain transfer agent ethylxanthogenacetic acid. The polymerizations were well-controlled, leading to polymers with narrow molecular weight distributions and excellent agreement between theoretical and experimental number average molecular weights. Despite the high rates of polymerization, the resulting PVAc homopolymers retained a high degree of thiocarbonylthio end group functionality that allowed the synthesis of block copolymers by chain extension with vinyl benzoate and vinyl pivalate. The rates of polymerization during the addition of the second blocks were also high, and the resulting block copolymers were obtained in good yield with excellent blocking efficiencies.

We developed multi-scale, live-time interactive visualization of color image data, including microscopic whole-mouse cryo-images serving many biomedical applications. Using true-color volume rendering, we interactively, selectively enhanced anatomy using feature detection. For example, to enhance red organs (vessels, liver, etc.) and internal surfaces, we computed a red feature from R /( R + G + B ) and surface features from color/gray-scale gradients, respectively. For >70GB cryo-image volumes, we developed multi-resolution visualization, which provided low-resolution rendering of an entire mouse and zooming to organs, tissues, and cells. Fusions of fluorescence and color cryo-volumes uniquely showed biodistribution of metastatic and stem cells within an anatomical context.

A facile approach to prepare thiol-terminated poly(styrene-ran-vinyl phenol) (PSVPh) copolymers and PSVPh-coated gold nanoparticles is reported with the goal of creating stabilizing ligands for nanoparticles with controlled hydrophilicity. Dithioester-terminated poly(styrene-ran-acetoxystyrene) copolymers were synthesized via RAFT polymerization using cumyl dithiobenzoate as a chain transfer agent. These copolymers were converted to thiol-terminated PSVPh copolymers by a one step hydrazinolysis reaction using hydrazine hydrate to simultaneously convert dithioester-terminal and acetoxy-pendant groups to thiol-terminal and hydroxyl-pendant groups, respectively. Spectroscopic observations including NMR and IR confirm end- and pendant-group conversion. PSVPh-coated gold nanoparticles were synthesized in the presence of a mixture of thiol-terminated PSVPh and PSVPh copolymers containing disulfides as stabilizing ligands in a water/toluene, two-phase system. The size and size distribution of core gold nanoparticles were determined by TEM and image analysis. The hydrodynamic radius of PSVPh-coated gold nanoparticles was also determined by dynamic light scattering experiment, which confirms the particle analysis by TEM. This procedure provides a facile technique to control the polarity and hydrophilicity of metal nanoparticle surfaces and could prove critical in advancing the control of nanoparticle placement in biological and hierarchically ordered systems, such as diblock copolymers.

A single-mode microwave reactor was employed for the synthesis of well-defined homopolymers and block copolymers of acrylamido and acrylate monomers via reversible addition−fragmentation chain transfer (RAFT) polymerization. The rates of polymerization of N,N-dimethylacrylamide and N-isopropylacrylamide were significantly higher than those observed under conventional heating conditions, yet the resulting homopolymers retained thiocarbonylthio end group functionality, as evidenced by efficient extension during block copolymerizations. Moreover, the dramatically enhanced rates of polymerization observed under microwave conditions did not negatively affect molecular weight control during homopolymerization or block copolymerization. In all cases, low polydispersity indices were observed, and the agreement between theoretical and experimental molecular weights was excellent. Rate enhancement may ultimately be the result of thermal effects not easily duplicated under conventional heating conditions. The method...

Well-defined homopolymers and block copolymers with boronic acid-functional end groups were prepared by reversible addition−fragmentation chain transfer (RAFT) polymerization and subsequently investigated for the potential to undergo model supramolecular and dynamic covalent self-assembly in aqueous and organic media. By employing a boronic acid-functionalized RAFT chain transfer agent, end-functional polymers were prepared without recourse to postpolymerization functionalization. The polymerizations of styrene, N,N-dimethylacrylamide, and N-isopropylacrylamide all led to homopolymers of controlled molecular weight that were capable of subsequent chain extension to form well-defined block copolymers. The amphiphilic and stimuli-responsive block copolymers were capable of self-assembly into micellar aggregates. Quantitative retention of the boronic acid chain termini during polymerization was spectroscopically demonstrated, and two types of dynamic covalent transformations involving these moieties were inv...

2-(dimethylamino)ethyl methacrylate (DMAEMA) was polymerized from cellulosic filter paper via reversible addition-fragmentation chain transfer (RAFT) polymerization. The tertiary amino groups of the grafted PDMAEMA chains were subsequently quaternized with alkyl bromides of different chain lengths (C8-C16) to provide a large concentration of quaternary ammonium groups on the cellulose surface. The antibacterial activity of the quaternized and nonquaternized PDMAEMA-grafted cellulosic fibers was tested against Escherichia coli. The antibacterial activity was found to depend on the alkyl chain length and on the degree of quaternization, i.e., the amount of quaternary amino groups present in the cellulose graft copolymers. The PDMAEMA-grafted cellulose fiber with the highest degree of quaternization and quaternized with the shortest alkyl chains was found to exhibit particularly high activity against E. coli.

Tinospora cordifolia also known as Giloy or Guduchi, is an indigenous climber plant indigenous to tropical areas of India, Myanmar and Sri Lanka. Its stem is used for treatment of fever, jaundice, emaciation, skin ailments, diabetes, anaemia and various infectious diseases. The study was undertaken to evaluate the proximate and elemental analysis of the stems of Tinospora cordifolia. The proximate analyses were carried out using standard methods, while mineral elements were analyzed using Atomic Absorption Spectrophotometer, equipped with air acetylene flame. The proximate analysis of the stems of Tinospora cordifolia showed that it contained moisture 34.39%, ether extract 0.912%, crude protein 7.74%, crude fibre 56.42%, total ash 7.96%, nitrogen free extract 26.97%, cellulose 23.02% and hemicellulose 3.70%. The mineral analysis of the stems showed that they contain the following essential minerals: Calcium (102.23 ppm), phosphorous (24.81 ppm), iron (26.058 ppm), copper (3.733 ppm), zinc (7.342 ppm) and manganese (12.242 ppm). The study revealed that Tinospora cordifolia stems to be a potential source of nutrition and minerals for man as well as animals.

Antibodies armed with biologic drugs could greatly expand the therapeutic potential of antibody–drug conjugates for cancer therapy, broadening their application to disease targets currently limited by intracellular delivery barriers. Additional selectivity and new therapeutic approaches could be realized with intracellular protein drugs that more specifically target dysregulated pathways in hematologic cancers and other malignancies. A multifunctional polymeric delivery system for enhanced cytosolic delivery of protein drugs has been developed that incorporates endosomal-releasing activity, antibody targeting, and a biocompatible long-chain ethylene glycol component for optimized safety, pharmacokinetics, and tumor biodistribution. The pH-responsive polymeric micelle carrier, with an internalizing anti-CD22 monoclonal targeting antibody, effectively delivered a proapoptotic Bcl-2 interacting mediator (BIM) peptide drug that suppressed tumor growth for the duration of treatment and prolonged survival in a xenograft mouse model of human B-cell lymphoma. Antitumor drug activity was correlated with a mechanistic induction of the Bcl-2 pathway biomarker cleaved caspase-3 and a marked decrease in the Ki-67 proliferation biomarker. Broadening the intracellular target space by more effective delivery of protein/peptide drugs could expand the repertoire of antibody–drug conjugates to currently undruggable disease-specific targets and permit tailored drug strategies to stratified subpopulations and personalized medicines.

RAFT polymerization was used to prepare PMMA-b-PNIPAM copolymers. Two different chain transfer agents, tBDB and MCPDB, were used to mediate the sequential polymerizations. Micellar solutions and gels were prepared from the resulting copolymers in aqueous solution. When heated above T-c of PNIPAM (about 31 degrees C), DLS revealed that PNIPAM coronas collapsed, resulting in aggregation of the original micelles. The micellar gels underwent syneresis above T-c as water was expelled from the ordered gel structure, the lattice periodicity of which was determined by SANS. A large decrease in lattice spacing was observed above T-c. The gel became more viscoelastic at high temperature, as revealed by shear rheometry which showed a large increase in G".

Reversible addition−fragmentation chain transfer (RAFT) polymerization was used to control the grafting of styrene from a cellulose substrate. The hydroxyl groups of the cellulose fiber were conver...

Reversible addition–fragmentation chain transfer (RAFT) polymerization was employed to prepare a nanoparticulate drug delivery system for chemotherapeutics. The nanoparticles contain a PEG “stealth” corona as well as a reactive anhydride functionality designed for conjugating targeting proteins. The multifunctional carrier functionality was achieved by controlling the copolymerization of the hydrophobic monomer lauryl methacrylate (LMA), with a reactive anhydride functional methacrylate (TMA), and a large polyethylene glycol methacrylate monomer (Mn ∼ 950 Da) (O950). RAFT polymerization kinetics of O950 were evaluated as a function of target degrees of polymerization (DPs), initial chain transfer agent to initiator ratio ([CTA]o/[I]o), and solvent concentration. Excellent control over the polymerization was observed for target DPs of 25 and 50 at a [CTA]o/[I]o ratio of 10 as evidenced by narrow and symmetric molecular weight distributions and the ability to prepare block copolymers. The TMA-functional copolymers were conjugated to the tumor targeting protein transferrin (Tf). The targeted copolymer was shown to encapsulate docetaxel at concentrations comparable to the commercial single vial formulation of docetaxel (Taxotere). In vitro cytotoxicity studies conducted in HeLa cells show that the Tf targeting enhances the cancer killing properties relative to the polymer encapsulated docetaxel formulation.

We applied the Case cryo-imaging system to detect signals of developmental toxicity in transgenic mouse fetuses resulting from maternal exposure to a developmental environmental toxicant (2,3,7,8-tetrachlorodibenzo-p-dioxin, TCDD). We utilized a fluorescent transgenic mouse model that expresses Green Fluorescent Protein (GFP) exclusively in smooth muscles under the control of the smooth muscle gamma actin (SMGA) promoter (SMGA/EGFP mice kindly provided by J. Lessard, U. Cincinnati). Analysis of cryo-image data volumes, comprising of very high-resolution anatomical brightfield and molecular fluorescence block face images, revealed qualitative and quantitative morphological differences in control versus exposed fetuses. Fetuses randomly chosen from pregnant females euthanized on gestation day (GD) 18 were either manually examined or cryo-imaged. For cryo-imaging, fetuses were embedded, frozen and cryo-sectioned at 20 μm thickness and brightfield color and fluorescent block-face images were acquired with an in-plane resolution of ≈15 μm. Automated 3D volume visualization schemes segmented out the black embedding medium and blended fluorescence and brightfield data to produce 3D reconstructions of all fetuses. Comparison of Treatment groups TCDD GD13, TCDD GD14 and control through automated analysis tools highlighted differences not observable by prosectors performing traditional fresh dissection. For example, severe hydronephrosis, suggestive of irreversible kidney damage, was detected by cryoimaging in fetuses exposed to TCDD. Automated quantification of total fluorescence in smooth muscles revealed suppressed fluorescence in TCDD-exposed fetuses. This application demonstrated that cryo-imaging can be utilized as a routine high-throughput screening tool to assess the effects of potential toxins on the developmental biology of small animals.

This critical review is concerned with the recent advances in graft polymerisation techniques involving cellulose and its derivatives. It summarises some of the features of cellulose structure and cellulose reactivity. Also described are the various techniques for grafting synthetic polymers from the cellulosic substrate. In addition to the traditional grafting techniques, we highlight the recent developments in polymer synthesis that allow increased control over the grafting process and permit the production of functional celluloses that possess improved physical properties and chemical properties (189 references).

We developed a cryo-imaging system to provide single-cell detection of fluorescently labeled cells in mouse, with particular applicability to stem cells and metastatic cancer. The Case cryoimaging system consists of a fluorescence microscope, robotic imaging positioner, customized cryostat, PC-based control system, and visualization/analysis software. The system alternates between sectioning (10-40 μm) and imaging, collecting color brightfield and fluorescent blockface image volumes >60GB. In mouse experiments, we imaged quantum-dot labeled stem cells, GFP-labeled cancer and stem cells, and cell-size fluorescent microspheres. To remove subsurface fluorescence, we used a simplified model of light-tissue interaction whereby the next image was scaled, blurred, and subtracted from the current image. We estimated scaling and blurring parameters by minimizing entropy of subtracted images. Tissue specific attenuation parameters were found [uT : heart (267 ± 47.6 μm), liver (218 ± 27.1 μm), brain (161 ± 27.4 μm)] to be within the range of estimates in the literature. "Next image" processing removed subsurface fluorescence equally well across multiple tissues (brain, kidney, liver, adipose tissue, etc.), and analysis of 200 microsphere images in the brain gave 97±2% reduction of subsurface fluorescence. Fluorescent signals were determined to arise from single cells based upon geometric and integrated intensity measurements. Next image processing greatly improved axial resolution, enabled high quality 3D volume renderings, and improved enumeration of single cells with connected component analysis by up to 24%. Analysis of image volumes identified metastatic cancer sites, found homing of stem cells to injury sites, and showed microsphere distribution correlated with blood flow patterns. We developed and evaluated cryo-imaging to provide single-cell detection of fluorescently labeled cells in mouse. Our cryo-imaging system provides extreme (>60GB), micron-scale, fluorescence, and bright field image data. Here we describe our image preprocessing, analysis, and visualization techniques. Processing improves axial resolution, reduces subsurface fluorescence by 97%, and enables single cell detection and counting. High quality 3D volume renderings enable us to evaluate cell distribution patterns. Applications include the myriad of biomedical experiments using fluorescent reporter gene and exogenous fluorophore labeling of cells in applications such as stem cell regenerative medicine, cancer, tissue engineering, etc.

This critical review is concerned with the recent advances in graft polymerisation techniques involving cellulose and its derivatives. It summarises some of the features of cellulose structure and cellulose reactivity. Also described are the various techniques for grafting synthetic polymers from the cellulosic substrate. In addition to the traditional grafting techniques, we highlight the recent developments in polymer synthesis that allow increased control over the grafting process and permit the production of functional celluloses that possess improved physical properties and chemical properties (189 references).

A facile route to well-defined boronic acid (co)polymers from stable and easily manipulated boronic ester monomers is presented. The polymerization of 4-pinacolatoborylstyrene by reversible addition−fragmentation chain transfer (RAFT) yielded polymeric boronic acid precursors. Selection of stoichiometry allowed tuning of polymerization kinetics and targeting specific molecular weights in the range of Mn = 17000−32000 g/mol. The resulting low polydispersity poly(4-pinacolatoborylstyrene) homopolymers were employed as macro-chain transfer agents for block copolymerization with N,N-dimethylacrylamide to yield amphiphilic block copolymers that formed micelles in aqueous media. The pinacol ester derivatized (co)polymers were easily deprotected by a mild and convenient strategy to yield free boronic acid polymers

Boronic acid-containing block copolymers capable of solution self-assembly into micelles and reverse micelles in response to changes in temperature, pH, and sugar concentration were prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization.

Novel sugar-responsive block copolymers were prepared by RAFT block copolymerization of unprotected boronic acid monomers, providing a direct route to supramolecular assemblies that dissociate upon the addition of glucose.

Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) was grafted from cellulose by reversible addition–fragmentation chain transfer (RAFT) polymerization. The use of a free chain transfer agent in solution allowed for a better control over graft ratio, chain length of grafted polymer, monomer conversion, and homopolymer formation in solution. An increase in polymerization time or degree of polymerization led to an increase in graft ratio, as expected from a living system.

Background The surface modification of the cellulose fibres through graft polymerization is of great interest to the researcher due to their wide range of potential applications. Living radical polymerization methods have been used to achieve well defined and living polymer grafts from the cellulose surface. [1] RAFT polymerization is a versatile method that allows the synthesis of polymers with complex molecular architectures, low polydispersity, and functionalizable end groups. [2] The controlled surface modification of different solid substrates (such as poly(propylene) lanterns, core-shell microspheres, silica, gold nanoparticles, carbon nanotubes, and the Merrifield resin system) via RAFT has already been reported. [3-7] RAFT graft polymerization from a solid support can be performed using both the R-group approach (the leaving and reinitiating R-group attached to the backbone) and the Z-group approach (the stabilizing group attached to the backbone).The R-group approach follows the 'grafting from' mechanism and higher graft densities can be achieved relative to that achieved using the 'grafting onto' (Z-group) approach due to fewer steric hindrance problems. [7,8] The use of a solid-supported chain transfer agent (the R-group approach) to mediate the controlled graft polymerization from the different cellulosic surfaces such as cotton fabric and filter paper has been the focus of recent studies. [9-11] Current research into RAFT polymerization is covered by two reviews. [12,13] .