Natural materials employ many elegant strategies to achieve mechanical properties required for survival under varying environmental conditions. Thus these remarkable biopolymers and nanocomposites often not only have a combination of mechanical properties such as high modulus, toughness, and elasticity, but also exhibit adaptive and stimuli-responsive properties. Inspired by skeletal muscle protein titin, we have synthesized a biomimetic modular polymer that not only closely mimics the modular multi-domain structure of titin, but also manifests an exciting combination of mechanical properties, as well as adaptive properties such as self-healing and temperature-responsive shape-memory properties.Whereas man-made polymers can be prepared to meet particular parameters one at a time, it remains a challenge to design synthetic polymers with a combination of mechanical properties such as high modulus, toughness, and resilience. A further challenge is to introduce adaptive properties into polymers. In contrast, many smart strategies have evolved in nature to achieve biopolymers possessing excellent combinations of mechanical properties. 1 To survive in often variable environments, natural materials have also evolved to be adaptive, maintaining functions across a range of stress or strain, or changing properties in response to stimuli such as temperature or moisture level. 2 In recent years, the elucidation of molecular mechanisms for natural materials has prompted many biomimetic materials designs. 3 Herein, we report a Supporting Information Available: Synthesis and characterization of monomers and polymers, stress-strain, DMA, X-ray, AFM, and molecular modeling experiments. This material is available free of charge at http//:pubs.acs.org. biomimetic design of a modular polymer that has a combination of high modulus, toughness, and resilience, while possessing adaptive mechanical properties. NIH Public AccessOur biomimetic concept is based on the modular domain design observed in the skeletal muscle protein titin, which possesses a remarkable combination of strength, toughness, and elasticity. 4 The ability of titin to absorb energy by the reversible rupture of intramolecular secondary interactions, followed by re-folding induced recovery, makes it an intriguing model for the design of adaptive materials. Following titin's modular design, our group first synthesized polymers incorporating the quadruple hydrogen bonding 2-ureido-4[1H]-pyrimidone (UPy) motif 5 as the modular domain-forming mimic of the Ig domains in titin. 6 To overcome issues such as structural heterogeneity and inter-chain cross-linking, we further developed a cyclic modular polymer using a peptidomimetic β-sheet dimer. 7 Despite the well-defined single molecule unfolding properties, the synthesis of the second generation polymers is tedious, and the rupture forces of the H-bonded modules are much lower than the UPy dimer. To simplify synthesis and improve mechanical strength, the cyclic modular concept was applied to the UPy core. In our pre...

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Pain from traumatic rib fractures presents a source of major morbidity and mortality. Prior studies have reported 59% of patients continue to have persistent pain at 2 months post injury. Most modern analgesia modalities have short duration of effect (<72 h) and require repeated doses to achieve adequate effect. There are few studies that address long-term analgesia treatment for these injuries. Intercostal cryoneurolysis (IC) is a technique of long-term chest wall analgesia previously studied in thoracic surgery and pediatric chest wall reconstruction. This technique may also be an effective treatment for rib fracture pain. Presented is a case of successful control of rib fracture pain with IC used as an adjunct to surgical stabilization of rib fractures (SSRF). This is followed by a discussion of IC's role in the treatment of traumatic rib fracture pain.

The long term efficacy of tissue based heart valve grafts may be limited by progressive degeneration characterized by immune mediated inflammation and calcification. To avoid this degeneration, decellularized heart valves with functionalized surfaces capable of rapid in vivo endothelialization have been developed. The aim of this study is to examine the capacity of CD133 antibody-conjugated valve tissue to capture circulating endothelial progenitor cells (EPCs). Decellularized human pulmonary valve tissue was conjugated with CD133 antibody at varying concentrations and exposed to CD133 expressing NTERA-2 cl.D1 (NT2) cells in a microflow chamber. The amount of CD133 antibody conjugated on the valve tissue surface and the number of NT2 cells captured in the presence of shear stress was measured. Both the amount of CD133 antibody conjugated to the valve leaflet surface and the number of adherent NT2 cells increased as the concentration of CD133 antibody present in the surface immobilization procedure increased. The data presented in this study support the hypothesis that the rate of CD133+ cell adhesion in the presence of shear stress to decellularized heart valve tissue functionalized by CD133 antibody conjugation increases as the quantity of CD133 antibody conjugated to the tissue surface increases.

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