Back Cover: Macromol. Biosci. 2/2015

Abstract

Back Cover: Liquid crystal elastomers (LCE) for the use as three‐dimensional cell culture scaffolds are prepared by E. Hegmann and co‐workers by cross‐linking of star blockco‐polymers with pendant cholesterol units resulting in the formation of smectic‐A LCEs. http://doi.wiley.com/10.1002/mabi.201400325 these biodegradable materials prove to be compatible with growth, survival, and expansion of cultured neuroblastomas and myoblasts for extended time periods (about a month) and are also excellent candidates for testing on several other cell lines.

Effects of Structural Variations on the Cellular Response and Mechanical Properties of Biocompatible, Biodegradable, and Porous Smectic Liquid Crystal Elastomers

“…Table summarizes the X‐ray diffraction data for the γ‐LCEs. For the α‐series, SAXD pattern for 3‐LCE‐α were reported earlier and provided clear evidence for the formation of a smectic‐A phase with interdigitated cholesterol moieties . 4‐LCE‐α and 6‐LCE‐α were too weak (less elastic, explained later in section ) and the films broke during stretching to prepare thin films for SAXD measurement.…”

“…With the LC pendants in the sterically more demanding α‐position to the ε‐CL carbonyl groups, less elastic but more porous structures are expected considering thermal expansion and contraction during cross‐linking. The absence of LC pendant units leads to smooth materials for the nonmodified elastomers, and sterically more flexible LC pendants in the γ‐position elastomers should lead to elastomers with lower porosity but higher elasticity . We will see later that the mechanical properties of the α‐ and γ‐series corroborate this to some extent.…”

“…Displacement of the bromo (Br) by the azide (N 3 ) was confirmed by the appearance of the 2099 cm −1 band in the ATR FT‐IR spectrum (Figure S1, Supporting Information) and higher chemical shifts of specific protons in the 1 H NMR spectra. The chosen LC pendant, cholesterylhexynoate, was covalently attached to the star block‐copolymer using alkyne‐azide Huisgen's cycloadditon reaction (“click” reaction) obtaining 3SBCα‐CLC. The disappearance of the 2100 cm −1 band and the appearance of a new band at 3263 cm −1 in the FT‐IR spectra confirmed success of reaction (Figure S1, Supporting Information).…”

“…Elastomers were prepared using a modified, previously reported method . For the synthesis of 3LCE‐α, LC‐modified poly­mer (3‐SBC 1 ‐CLC), ε‐caprolactone (ε‐CL), and cross‐linker 2,2‐bis(1‐caprolactone‐4‐yl) propane (BCP) at a ratio of 3:1:1 were used.…”

“…Recent research has shown that the orientational ordering of nematic LCs can influence cell attachment and proliferation . Previous work from our group has shown that both nematic and smectic biodegradable, biocompatible and porous LCEs with “Swiss‐cheese” like morphology, 3D channel or foam‐like as well as globular morphology are viable candidates for active cell scaffolds that support the attachment and proliferation of cells, further expanding possibilities toward tissue regeneration …”