Elastic modulus distribution in poly(N-isopopylacrylamide) and oligo(ethylene glycol methacrylate)-based microgels studied by AFM

Abstract

The spatial elastic modulus distribution of microgel networks in presence and absence of bifunctional crosslinkers is studied by AFM. Thermoresponsive poly(N-isopopylacrylamide) (PNIPAM) and poly(2-(2-methoxyethoxy)ethyl methacrylate-co-oligo(ethylene glycol) methacrylate)) (P(MEO2MA-co-OEGMA)) microgel are...

Microgels react to force: mechanical properties, syntheses, and force-activated functions

“…While E was highest in the center, it decreased laterally towards the periphery by one order of magnitude. 68 This trend has even been observed in the collapsed state above VPTT, where microgels in solution are actually homogeneous. 45,52 Stiffness tomography measurements have revealed that the stiffness is an intricate function of the position within the network (Fig.…”

Specific Binding of Ligand-Functionalized Thermoresponsive Microgels: Effect of Architecture, Ligand Density, and Hydrophobicity

“…This is due to the lower diffusion and lower reactivity of the bulkier OEGMA monomers compared to the smaller comonomers MEO 2 MA and ManEAM. 16 Furthermore, the proposed POEGMA-rich segments have a higher LCST compared to segments where MEO 2 MA is present in larger amounts. 48 Therefore, these microgels are not fully collapsed at 37 °C as seen from the swelling curve (Figure 1).…”

“…This is to be expected since the addition of a crosslinker leads to more compact networks, and previous work showed that P(OEGMA-co-MEO2MA) microgels are stiffer and denser compared to PNIPAM microgels for similar crosslinker concentrations. 16 When increasing the temperature above the VPTT, the increased deformability of self-crosslinked microgels enables a large increase in Man density, up to 50-fold, whereas the microgels with an additional crosslinker showed only a 4-fold increase in Man density. This explains the E. coli release for the self-crosslinked microgels below VPTT, which was not seen for PNIPAM BIS -Man.…”

“…binding receptor FimH at their fimbriae, which enables their attachment to cells. 14,16,29,30,40 Here, we studied the E. colimicrogel aggregation via optical microscopy and visual inspection as a measure of specific microgel interactions (Figure 2). To study the effect of microgel collapse and the concurrent increase in Man density in the network, the experiments were conducted below and above the VPTT, at 20 and 37 °C.…”

“…15,29,30 We suggest that an increased shift in ligand density upon crossing the VPTT via reduced crosslinking could solve this problem. 16,31,32 Therefore, E. coli binding to Man presenting microgels with-and without a dedicated crosslinker (selfcrosslinked) will be compared here. In addition, the effect of different polymer backbones (PNIPAM and POEGMA) for specific E. coli binding will be tested and the distribution of Man units in the network will be assessed using superresolution microscopy.…”