Gold Nanorods as Effective Modulators of Shape Memory Behavior in Physiological Conditions of PLA/PEG Blends

The shape memory effect (SME) in poly-(l-lactide) (PLA) has been widely studied for the development of smart bioabsorbable medical devices. Shape recovery in PLA occurs at its glass transition temperature (T _g) at 60 °C and hence, its safe application under physiological conditions remains challenging. In this study, we demonstrate the tunability of the T _g of PLA to a physiologically safe range of 32-42 °C by blending it with 6-10 wt % low-molecular weight poly-(ethylene glycol) (PEG). We characterize the blends using differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis and study their shape memory behavior. From three programming strain levels studied, 50, 75 and 100%, the 8 wt % PEG-containing blend showed the greatest recovery capabilities, reaching 75% shape recovery ratio at 37 °C, up to over 95% at 40 °C. This blend showed the overall optimal balance between mechanical properties and shape recovery performance. Finally, we explore the remote SME activation by incorporating plasmonic gold nanorods (AuNRs) as heat transducers to the blend and demonstrate selective near-infrared (NIR) light-triggered shape recovery. We demonstrate that incorporating plasmonic anisotropic nanoparticles as key modulators in these polymeric blends enables rapid and selective recovery under biologically safe conditions, making them suitable for biological applications. The study highlights the potential of developing shape memory medical devices based on PLA/PEG and AuNRs, to be safely activated by an external stimulus in physiological conditions.