Structural origin of stress and shape recovery in shape memory starch

Shape-changing polymers for biomedical applications

Smart polymers that are capable of controlled shape transformations under external stimuli have attracted significant attention in the recent years due to the resemblance of this behavior to the biological intelligence observed in nature. In this review, we focus on the recent progress in the field of shape-morphing polymers, highlighting their most promising applications in the biomedical field.

Design, fabrication, and implantation of tube-shaped devices for the treatment of salivary duct diseases

Introduction: Starch-based materials were designed using a special extrusion die in order to obtain a tube-shaped device for application to salivary duct treatment in the field of endoscopy, i.e., sialendoscopy . Methods: Extrusion process was used to produce starch tubes. Mechanical properties of the dry tube before implantation were determined using an axial compression test. A finite element study was carried out to simulate the behavior of the hydrated tube under external axial pressure. Hydrolysis of these devices in a simulated salivary solution was studied, as well as its glycerol kinetics release. An animal short-term implantation model for salivary ducts was proposed as a feasibility study for starch tube-shaped devices. Results: A continuous production of regular and size-controlled tubes was obtained. The very small diameter obtained, less than 2 mm, corresponds to the requirement of being insertable in a human salivary duct using sialendoscopy guidewire. Finite element analysis showed that the starch tube can still support an external pressure higher than 0.2 MPa without irreversible damage. After 4 days of implantation, the host response is encouraging and the inflammatory response for this type of procedure remains normal. Conclusion: These devices were adapted to sialendoscopic guidewires and able to be implanted in the salivary ducts of pigs. If a longer lasting tube is required, the crystallinity of the starch material should be improved.