Which Sites React First? Functional Site Distribution and Kinetics on Solid Supports Investigated Using Confocal Raman and Fluorescence Microscopy

Abstract

Fluorescence microscopy is a powerful technique for analyzing beads with very low loadings of fluorophores; however, the method is flawed when looking at more highly loaded beads as a result of severe problems with absorption. To probe distributions at higher loading levels, Raman spectroscopy avoids many of these issues. These studies show that there is a uniform distribution of reactive sites throughout the beads but that the spatial distribution of reacted sites depends on the polymer type, with a fine balance between reaction and diffusion rate.

Hydrogels for the Detection and Management of Protease Levels

“…PEGA hydrogel particles were chosen as the matrix for the sensing system due to high PEG content, ease of chemical functionalisation and well documented compatibility with enzyme catalysis 34–40. Amine groups present throughout the cross‐linked structure allow for chemical coupling of peptide sequences via SPPS 29, 41.…”

A Recyclable, Metal-Free Mechanochemical Approach for the Oxidation of Alcohols to Carboxylic Acids

“…When Merrifield resins are swollen by a solvent, it allows the substrate greater accessibility to the active sites inside the polymer support. However, this mode of reactivity can be dependent on the size of the substrate, often requiring longer reaction times for larger substrates [50][51][52][53][54]. Under mechanochemical conditions, the polymer resin is pulverized; thus, the active sites of the polymer should be completely exposed to the substrate.…”

Raman and Infrared Imaging of Dynamic Polymer Systems

“…Accordingly, the identity of a catalyst support can impact the reaction rate in catalyst support resins. Raman imaging has allowed the simultaneous observation of both reagent uptake and conversion of 1,3‐diisopropyl carbodiimide by supported 4‐cyanobenzoic acid resins 65. The reagent's diffusion rate was faster than the conversion rate in a PS‐supported bead, which led to a homogeneous distribution of reagents across the bead profile.…”