Chemical and Biomolecular Engineering - Research Publications

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Author: McKenzie, Thomas × Author: Nothling, Mitchell × Author: Qiao, Greg × Author: Reyhani, Amin ×

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    Blood-Catalyzed RAFT Polymerization
    Reyhani, A ; Nothling, MD ; Ranji-Burachaloo, H ; McKenzie, TG ; Fu, Q ; Tan, S ; Bryant, G ; Qiao, GG (WILEY-V C H VERLAG GMBH, 2018-08-06)
    The use of hemoglobin (Hb) contained within red blood cells to drive a controlled radical polymerization via a reversible addition-fragmentation chain transfer (RAFT) process is reported for the first time. No pre-treatment of the Hb or cells was required prior to their use as polymerization catalysts, indicating the potential for synthetic engineering in complex biological microenvironments without the need for ex vivo techniques. Owing to the naturally occurring prevalence of the reagents employed in the catalytic system (Hb and hydrogen peroxide), this approach may facilitate the development of new strategies for in vivo cell engineering with synthetic macromolecules.
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    Tunable, Quantitative Fenton-RAFT Polymerization via Metered Reagent Addition
    Nothling, MD ; McKenzie, TG ; Reyhani, A ; Qiao, GG (WILEY-V C H VERLAG GMBH, 2018-10)
    A continuous supply of radical species is a key requirement for activating chain growth and accessing quantitative monomer conversions in reversible addition-fragmentation chain transfer (RAFT) polymerization. In Fenton-RAFT, activation is provided by hydroxyl radicals, whose indiscriminate reactivity and short-lived nature poses a challenge to accessing extended polymerization times and quantitative monomer conversions. Here, an alternative Fenton-RAFT procedure is presented, whereby radical generation can be finely controlled via metered dosing of a component of the Fenton redox reaction (H2 O2 ) using an external pumping system. By limiting the instantaneous flux of radicals and ensuring sustained radical generation over tunable time periods, metered reagent addition reduces unwanted radical "wasting" reactions and provides access to consistent quantitative monomer conversions with high chain-end fidelity. Fine tuning of radical concentration during polymerization is achieved simply via adjustment of reagent dose rate, offering significant potential for automation. This modular strategy holds promise for extending traditional RAFT initiation toward more tightly regulated radical concentration profiles and affords excellent prospects for the automation of Fenton-RAFT polymerization.