Principles for Controlling the Shape Recovery and Degradation Behavior of Biodegradable Shape-Memory Polymers in Biomedical Applications

Abstract

Polymers with the shape memory effect possess tremendous potential for application in diverse fields, including aerospace, textiles, robotics, and biomedicine, because of their mechanical properties (softness and flexibility) and chemical tunability. Biodegradable shape memory polymers (BSMPs) have unique benefits of long-term biocompatibility and formation of zero-waste byproducts as the final degradable products are resorbed or absorbed via metabolism or enzyme digestion processes. In addition to their application toward the prevention of biofilm formation or internal tissue damage caused by permanent implant materials and the subsequent need for secondary surgery, which causes secondary infections and complications, BSMPs have been highlighted for minimally invasive medical applications. The properties of BSMPs, including high tunability, thermomechanical properties, shape memory performance, and degradation rate, can be achieved by controlling the combination and content of the comonomer and crystallinity. In addition, the biodegradable chemistry and kinetics of BSMPs, which can be controlled by combining several biodegradable polymers with different hydrolysis chemistry products, such as anhydrides, esters, and carbonates, strongly affect the hydrolytic activity and erosion property. A wide range of applications including self-expending stents, wound closure, drug release systems, and tissue repair, suggests that the BSMPs can be applied as actuators on the basis of their shape recovery and degradation ability.

Biomechanical Behaviors and Degradation Properties of Multilayered Polymer Scaffolds: The Phase Space Method for Bile Duct Design and Bioengineering

“…The surgical implantation of the graft in the patient’s body causes an injury with the occurrence of an inflammatory and reparative reaction [ 72 , 73 ]. Then, the activated macrophages start to move to the injury site, penetrate into the structure of the biocompatible material, and release the oxidative degradation products (oxygen free radicals) [ 74 , 75 ]. The chemical bonds of macromolecules break down during oxidative degradation, resulting in a gradual decrease in the molecular weight of the polymer.…”

Supplementation of Polymeric Reservoirs with Redox-Responsive Metallic Nanoparticles as a New Concept for the Smart Delivery of Insulin in Diabetes

“…In the drug delivery field, this terminological umbrella has encompassed materials capable of releasing their pharmaceutical loads only upon experiencing a specific physical or chemical stimulus from the environment. Common examples include materials comprising disulfide bonds cleaving in response to the reductive intracellular thiol, glutathione [ 1 , 2 ], which cancer cells contain in greater abundance than normal ones [ 3 ]; polythiols swelling due to a sulfoxide → sulfone transition promoted under oxidative stress mediated by reactive oxygen radical scavengers and releasing entrapped drugs accordingly [ 4 , 5 ]; particles binding a drug through a hydrazone bond, which is stable under neutral conditions but breaks at an acidic pH [ 6 , 7 ]; thermosensitive hydrogels undergoing sol–gel transition at a critical temperature that is the function of the monomer ratio, molecular weight and its distribution, terminal functional groups and copolymer concentration [ 8 ]; endosomal escape of the drug load achieved by the selective dissolution of calcium phosphate nanoparticles as drug carriers inside acidic lysosomes [ 9 , 10 , 11 ]; alterations in the compactness and drug binding strength of chitosan particles as a function of pH due to the protonation/deprotonation of constitutive amine groups [ 12 , 13 ]; the shape memory effect, where the material revives its prior structure after severe deformation [ 14 , 15 ]; and others.…”

Azo‐Functionalized Thermoplastic Polyurethane for Light‐Driven Shape Memory Materials

“…Materials with shape memory properties have also garnered significant attention in applications such as space satellite, [ 1 ] implantable biomedical devices, [ 2 ] 4D printing, [ 3–7 ] and soft robotics. [ 8–10 ] Owing to their versatility, enhanced biocompatibility, and potential biodegradability, [ 11 ] soft materials or polymers with shape memory properties are particularly of importance. To date, diverse types of soft matters, such as liquid crystalline (LC), [ 12–17 ] thermoplastic polyurethane (TPU), [ 18–20 ] polyethylene, [ 21–26 ] poly(cyclooctene), [ 27 ] and their blends or composites, have been discussed.…”

“…Materials with shape memory properties have also garnered significant attention in applications such as space satellite, [1] implantable biomedical devices, [2] 4D printing, [3][4][5][6][7] and soft robotics. [8][9][10] Owing to their versatility, enhanced biocompatibility, and potential biodegradability, [11] soft materials or polymers with shape memory properties are particularly of…”