Chemical Modifications of Porous Shape Memory Polymers for Enhanced X-ray and MRI Visibility.

Grace K Fletcher,Tyler J Touchet,Matthew D Wilcox,Scott M Herting,Lance M Graul,Mary P Mcdougall,Steven M Wright,Lindy K Jang,Ana Katarina Sweatt,Duncan J Maitland,Landon D Nash

doi:10.3390/molecules25204660

Abstract

The goal of this work was to develop a shape memory polymer (SMP) foam with visibility under both X-ray and magnetic resonance imaging (MRI) modalities. A porous polymeric material with these properties is desirable in medical device development for applications requiring thermoresponsive tissue scaffolds with clinical imaging capabilities. Dual modality visibility was achieved by chemically incorporating monomers with X-ray visible iodine-motifs and MRI visible monomers with gadolinium content. Physical and thermomechanical characterization showed the effect of increased gadopentetic acid (GPA) on shape memory behavior. Multiple compositions showed brightening effects in pilot, T1-weighted MR imaging. There was a correlation between the polymeric density and X-ray visibility on expanded and compressed SMP foams. Additionally, extractions and indirect cytocompatibility studies were performed to address toxicity concerns of gadolinium-based contrast agents (GBCAs). This material platform has the potential to be used in a variety of medical devices.

Highlights

Shape memory polymers (SMPs) are a class of polymeric materials with an ability to change geometry in response to external stimuli
The shape memory polymer (SMP) foam compositions synthesized for the studies were named according to the convention
The compositional names arise from the amounts of ATIPA

Summary

Introduction

Shape memory polymers (SMPs) are a class of polymeric materials with an ability to change geometry in response to external stimuli. Thermoresponsive SMP materials actuate across a characteristic transition temperature (Ttrans ) that is based on polymeric structure. Temperature elevation above the polymer’s Ttrans enables deformation into a secondary geometry. Maintaining the deformation while cooling below Ttrans temporarily programs this secondary shape. The unconstrained material will return to the primary geometry when heated back above the Ttrans. This behavior enables a variety of biomedical applications such as conformal bone defect grafts, self-tightening sutures, and devices for minimally-invasive procedures [1,2,3]

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