The ROMP toolbox upgraded

The present article comprehensively reviews the macromolecular synthesis using enzymes as catalysts. Among the six main classes of enzymes, the three classes, oxidoreductases, transferases, and hydrolases, have been employed as catalysts for the in vitro macromolecular synthesis and modification reactions. Appropriate design of reaction including monomer and enzyme catalyst produces macromolecules with precisely controlled structure, similarly as in vivo enzymatic reactions. The reaction controls the product structure with respect to substrate selectivity, chemo-selectivity, regio-selectivity, stereoselectivity, and choro-selectivity. Oxidoreductases catalyze various oxidation polymerizations of aromatic compounds as well as vinyl polymerizations. Transferases are effective catalysts for producing polysaccharide having a variety of structure and polyesters. Hydrolases catalyzing the bond-cleaving of macromolecules in vivo, catalyze the reverse reaction for bond forming in vitro to give various polysacchar...

Enzymes as Green Catalysts for Precision Macromolecular Synthesis

Development of thermal and photochemical strategies for thiol-ene click polymer functionalization

A cytocompatible controlled radical polymerization method has now been developed that initiates polymer synthesis directly on the surface of living cells. This method achieves significantly enhanced polymer grafting and enables active manipulation of cellular phenotypes.

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Engineering live cell surfaces with functional polymers via cytocompatible controlled radical polymerization

The requirement for deoxygenation in controlled/living radical polymerisation (CLRP) places significant limitations on its widespread implementation by necessitating the use of large reaction volumes, sealed reaction vessels as well as requiring access to specialised equipment such as a glove box and/or inert gas source. As a result, in recent years there has been intense interest in developing strategies for overcoming the effects of oxygen inhibition in CLRP and therefore remove the necessity for deoxygenation. In this review, we highlight several strategies for achieving oxygen tolerant CLRP including: “polymerising through” oxygen, enzyme mediated deoxygenation and the continuous regeneration of a redox-active catalyst. In order to provide further clarity to the field, we also establish some basic parameters for evaluating the degree of “oxygen tolerance” that can be achieved using a given oxygen scrubbing strategy. Finally, we propose some applications that could most benefit from the implementation of oxygen tolerant CLRP and provide a perspective on the future direction of this field.

Up in the air: oxygen tolerance in controlled/living radical polymerisation

Plants and some types of bacteria demonstrate an elegant means to capitalize on the superabundance of solar energy that reaches our planet with their energy conversion process called photosynthesis. Seeking to harness Nature’s optimization of this process, we have devised a biomimetic photonic energy conversion system that makes use of the photoactive protein complex Photosystem I, immobilized on the surface of nanoporous gold leaf (NPGL) electrodes, to drive a photoinduced electric current through an electrochemical cell. The intent of this study is to further the understanding of how the useful functionality of these naturally mass-produced, biological light-harvesting complexes can be integrated with nonbiological materials. Here, we show that the protein complexes retain their photonic energy conversion functionality after attachment to the nanoporous electrode surface and, further, that the additional PSI/electrode interfacial area provided by the NPGL allows for an increase in PSI-mediated electron ...

Functionalized nanoporous gold leaf electrode films for the immobilization of photosystem I.

We report the first use of a polymerization-based ELISA substrate solution employing enzymatically mediated radical polymerization as a dual-mode amplification strategy. Enzymes are selectively coupled to surfaces to generate radicals that subsequently lead to polymerization-based amplification (PBA) and biodetection. Sensitivity and amplification of the polymerization-based detection system were optimized in a microwell strip format using a biotinylated microwell surface with a glucose oxidase (GOx)–avidin conjugate. The immobilized GOx is used to initiate polymerization, enabling the detection of the biorecognition event visually or through the use of a plate reader. Assay response is compared to that of an enzymatic substrate utilizing nitroblue tetrazolium in a simplified assay using biotinylated wells. The polymerization substrate exhibits equivalent sensitivity (2 µg/mL of GOx-avidin) and over three times greater signal amplification than this traditional enzymatic substrate since each radical that is enzymatically generated leads to a large number of polymerization events. Enzyme-mediated polymerization proceeds in an ambient atmosphere without the need for external energy sources, which is an improvement upon previous PBA platforms. Substrate formulations are highly sensitive to both glucose and iron concentrations at the lowest enzyme concentrations. Increases in amplification time correspond to higher assay sensitivities with no increase in non-specific signal. Finally, the polymerization substrate generated a signal to noise ratio of 14 at the detection limit (156 ng/mL) in an assay of transforming growth factor-beta. Biotechnol. Bioeng. 2011; 108:1521–1528. © 2011 Wiley Periodicals, Inc.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/bit.23101

Glucose Oxidase-Mediated Polymerization as a Platform for Dual-Mode Signal Amplification and Biodetection

We report the sulfonation of surface-initiated polynorbornene with acetyl sulfate to produce ultrathin ionomer films. The complete process consists of exposure of a hydroxyl-terminated self-assembled monolayer (SAM) on gold to a norbornenyl diacid chloride, attachment of Grubbs first generation catalyst, ring-opening metathesis polymerization (ROMP), and sulfonation. Structural and chemical changes in the film upon sulfonation are confirmed by RAIRS, contact angle goniometry, ellipsometry, optical microscopy, and electrochemical impedance spectroscopy. Sulfonation of surface-initiated polynorbornene results in a highly nonuniform surface morphology which can be relaxed to a more uniform film through exposure to dimethyl sulfoxide at room temperature. The sulfonated polynorbornene films have an intermediate surface energy (θA(H2O) ≈ 75°) and a low resistance against proton transport (Rf ≈ 1.6 Ω·cm2), which is 6 orders of magnitude lower than that of the original polynorbornene film. The sulfonated films ar...

Sulfonation of Surface-Initiated Polynorbornene Films

We report the preparation of loosely packed hydroxyl-terminated self-assembled monolayers (SAMs) on gold by the adsorption of bis(11,11‘-dithioundecyl)perfluoroheptanoate and base-mediated cleavage of the fluorocarbon terminal group. As shown through complementary characterization methods, the partially fluorinated SAM exhibits a structure in which the outer surface contains mostly −CF3 groups, the fluorocarbon groups are slightly canted on average, and the hydrocarbon chains underneath are in a fluidlike state. Upon cleavage of the fluorocarbon group, the hydroxyl-terminated alkyl chains relax into an increasingly canted, fluidlike state. The resulting monolayer packing exposes both methylene and hydroxyl functionalities, yielding an intermediate surface energy (θa(H2O) ≈ 68°). As compared to a densely packed hydroxyl-terminated SAM prepared from bis(11-hydroxyundecyl)disulfide, the cleaved films are thinner because of the greater average chain cant and exhibit a ∼50% higher capacitance and a factor of 5...

Loosely packed hydroxyl-terminated SAMs on gold.

We report the surface-initiated growth of poly(alkylnorbornene) films via ring-opening metathesis polymerization (ROMP). The films are grown by exposure of a vinyl-terminated self-assembled monolayer (SAM) on gold to Grubbs first-generation catalyst and the subsequent exposure to an alkylnorbornene monomer. We investigate the influence of alkyl side chains on the structure, barrier, surface properties, and the growth kinetics of surface-initiated ROMP-type poly(norbornene) films. Rate constants for film growth are estimated for the comparison of monomer reactivity. The rate constant for film growth decreases by 3 orders of magnitude from norbornene to decylnorbornene, indicating a strong effect of chain length on initiation and/or propagation rates. Reflectance−absorption infrared spectroscopy is used to show the molecular level packing within the poly(alkylnorbornene) films is disrupted by the alkyl side chains. Tapping-mode atomic force microscopy is used to show that norbornene, butylnorbornene, and he...

Brad J. Berron

Papers

Functionalized nanoporous gold leaf electrode films for the immobilization of photosystem I.

Glucose Oxidase-Mediated Polymerization as a Platform for Dual-Mode Signal Amplification and Biodetection

Sulfonation of Surface-Initiated Polynorbornene Films

Loosely packed hydroxyl-terminated SAMs on gold.

Growth and Structure of Surface-Initiated Poly(n-alkylnorbornene) Films