Shape Memory RGD‐Containing Networks: Synthesis, Characterization, and Application in Cell Culture

Abstract

Hydrogels have found wide application in tissue engineering and cell mechanobiology research due to their tunable, and often biomimetic, biochemical and biomechanical properties. Although it has been known for more than a decade that hydrogels can be designed to exhibit shape memory functionality—the ability to change from one defined shape to another when triggered by a defined stimulus—shape memory hydrogels have not previously been exploited in tissue engineering or mechanobiology research. Here we report the development of a biodegradable and biocompatible hydrogel with tailored shape memory as well as desirable mechanical property for soft‐tissue applications. A shape memory hydrogel was synthesized by photopolymerization of PCL3k diacry‐lates together with acrylate‐PEG2k‐GRGDS in the presence of a crosslinker, tetrathiol, and photoinitiator, DMPA, through thiol‐ene chemistry. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were carried out to examine the thermal, mechanical and shape memory properties of the hydrogel in dry and wet states. Cell culture studies were performed to characterize material cytocompatibility. We found that the PCL phase was crystalline in the hydrogel, providing an excellent, reproducible shape memory effect. The transition temperature (shape memory “trigger”) was tuned to fall between room and body temperature. Both cell attachment and proliferation studies revealed that the presentation of GRGDS molecules in the hydrogel facilitated fibroblasts adhesion and spreading on the hydrogel surface. This hydrogel, tailored to exhibit shape memory behavior in the cell culture compatible temperature range, should provide new opportunities for “smart” shape‐changing scaffolds and substrates for application in tissue engineering and investigation of cell mechanobiology.

On-command on/off switching of progenitor cell and cancer cell polarized motility and aligned morphology via a cytocompatible shape memory polymer scaffold

“…SMPs achieve the shape memory effect by “memorizing” a permanent shape through chemical or physical cross-linking, then being manipulated and fixed to a temporary shape by an immobilizing transition, such as vitrification or crystallization, and then later recovering to the permanent shape by a triggering event, such as thermal, electrical or solvent activation [25–31]. A number of recent breakthroughs in the area of cytocompatible SMPs [32–39] have enabled application of SMP on-command functionality in cell culture application. Although SMPs have not previously been applied in the study of cell motility and polarity switching, we have recently demonstrated the feasibility of employing SMPs in the study of cell motility in a 2D system [40].…”

Pendant allyl crosslinking as a tunable shape memory actuator for vascular applications

“…The x%PCL-y%ACPCL copolymerization format offers a convenient, combinatorial approach to fine-tune material properties of SMPs. The pendant allyl carboxylate-based crosslinkers enable pendant conjugation to growth factors, therapeutics, and extracellular matrix-derivatives via thiol-ene click chemistry [44, 45] or photocrosslinking of modified peptides [46] to control cell and tissue responses. Allyl composition (y%) can be used to simultaneously control both the spacing of netpoints and crystallinity, offering an efficient means to tune thermomechanical, shape memory, and biological functions.…”

Scaffolds with shape memory behavior for the treatment of large bone defects

“…Also biocompatible gels obtained from acrylic derivatives or gelatin exhibiting cells stimulation effect have been reported . However, for formation of such types of the scaffolds, almost solely the cross‐linked polymers are used …”

“…12,13 Also biocompatible gels obtained from acrylic derivatives or gelatin exhibiting cells stimulation effect have been reported. [14][15][16][17] However, for formation of such types of the scaffolds, almost solely the cross-linked polymers are used. [18][19][20] Successful attempt to develop a scaffold with a memory shape behavior to fill a bone defect 20 related to thermoresponsive behavior of scaffolds prepared via photocrosslinking of poly(e-caprolactone) (PCL) diacrylate and exhibiting superior bioactivity is especially interesting.…”