Reading<i>Utopia</i>in the Reformation of Punishment

Ritger, Matthew

doi:10.1017/rqx.2019.375

Cited by 1 publication

(1 citation statement)

References 34 publications

(17 reference statements)

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“…14 Briefly, the fluorescence intensity at each time point was compared to the equilibrium intensity measured after 48 h. Release rates were extracted from these data using the Ritger-Peppas equation. 31 Micelles prepared from polymer 5a (highest core T g ) exhibited the slowest release kinetics, with a release rate of 3.1% / h. An intermediate release rate was obtained for polymer assemblies prepared from polymer 5c (10% / h), while the fastest release rate of 17% / h was measured for assemblies prepared from polymer 5e. This observed trend in fluorescein release rates is related to the T g of the block copolymers utilized in the study, with the fastest release rates occurring from the polymer assemblies with the lowest T g cores.…”

Section: Effect Of Core Mobility On Diffusionmentioning

confidence: 92%

Tuning H₂S Release by Controlling Mobility in a Micelle Core

et al. 2019

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Drug delivery from polymer micelles has been widely studied, but methods to precisely tune rates of drug release from micelles are limited. Here, the mobility of hydrophobic micelle cores was varied to tune the rate at which a covalently bound drug was released. This concept was applied to cysteine-triggered release of hydrogen sulfide (H 2 S), a signaling gas with therapeutic potential. In this system, thiol-triggered H 2 S donor molecules were covalently linked to the hydrophobic blocks of self-assembled polymer amphiphiles. Because release of H 2 S is triggered by cysteine, diffusion of cysteine into the hydrophobic micelle core was hypothesized to control the rate of release. We confirmed this hypothesis by carrying out release experiments from H 2 S-releasing micelles in varying compositions of EtOH/H 2 O. Higher EtOH concentrations caused the micelles to swell, facilitating diffusion in and out of their hydrophobic cores and leading to faster H 2 S release from the micelles. To achieve a similar effect without addition of organic solvent, we prepared micelles with varying core mobility via incorporation of a plasticizing co-monomer in the core-forming block. The glass transition temperature (T g ) of the core block could therefore be precisely varied by changing the amount of the plasticizing co-monomer in the polymer. In aqueous solution under identical conditions, the release rate of H 2 S varied over 20-fold (t ½ = 0.18 -4.2 h), with the lowest T g hydrophobic block resulting in the fastest H 2 S release. This method of modulating release kinetics from polymer micelles by tuning core mobility may be applicable to many types of physically encapsulated and covalently linked small molecules in a variety of drug delivery systems.

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Section: Effect Of Core Mobility On Diffusionmentioning

confidence: 92%