Surface Crystal and Degradability of Shape Memory Scaffold Essentialize Osteochondral Regeneration.

The minimally invasive deployment of scaffolds is a key safety factor for the regeneration of cartilage and bone defects. Osteogenesis relies primarily on cell-matrix interactions, whereas chondrogenesis relies on cell-cell aggregation. Bone matrix expansion requires osteoconductive scaffold degradation. However, chondrogenic cell aggregation is promoted on the repellent scaffold surface, and minimal scaffold degradation supports the avascular nature of cartilage regeneration. Here, a material satisfying these requirements for osteochondral regeneration is developed by integrating osteoconductive hydroxyapatite (HAp) with a chondroconductive shape memory polymer (SMP). The shape memory function-derived fixity and recovery of the scaffold enabled minimally invasive deployment and expansion to fill irregular defects. The crystalline phases on the SMP surface inhibited cell aggregation by suppressing water penetration and subsequent protein adsorption. However, HAp conjugation SMP (H-SMP) enhanced surface roughness and consequent cell-matrix interactions by limiting cell aggregation using crystal peaks. After mouse subcutaneous implantation, hydrolytic H-SMP accelerated scaffold degradation compared to that by the minimal degradation observed for SMP alone for two months. H-SMP and SMP are found to promote osteogenesis and chondrogenesis, respectively, in vitro and in vivo, including the regeneration of rat osteochondral defects using the binary scaffold form, suggesting that this material is promising for osteochondral regeneration.

Shape-Configurable Mesh for Hernia Repair by Synchronizing Anisotropic Body Motion.

Continuous progress has been made in elucidating the relationship between material property, device design, and body function to develop surgical meshes. However, an unmet need still exists wherein the surgical mesh can handle the body motion and thereby promote the repair process. Here, the hernia mesh design and the advanced polymer properties are tailored to synchronize with the anisotropic abdominal motion through shape configuration. The thermomechanical property of shape configurable polymer enables molding of mesh shape to fit onto the abdominal structure upon temperature shift, followed by shape fixing with the release of the heat energy. The microstructural design of mesh is produced through finite element modeling to handle the abdominal motion efficiently through the anisotropic longitudinal and transverse directions. The design effects are validated through in vitro, ex vivo, and in vivo mechanical analyses using a self-configurable, body motion responsive (BMR) mesh. The regenerative function of BMR mesh leads to effective repair in a rat hernioplasty model by effectively handling the anisotropic abdomen motion. Subsequently, the device-tissue integration is promoted by promoting healthy collagen synthesis with fibroblast-to-myofibroblast differentiation. This study suggests a potential solution to promote hernia repair by fine-tuning the relationship between material property and mesh design.

Vascular Cast to Program Antistenotic Hemodynamics and Remodeling of Vein Graft.

The structural stability of medical devices is established by managing stress distribution in response to organ movement. Veins abruptly dilate upon arterial grafting due to the mismatched tissue property, resulting in flow disturbances and consequently stenosis. Vascular cast is designed to wrap the vein-artery grafts, thereby adjusting the diameter and property mismatches by relying on the elastic fixity. Here, a small bridge connection in the cast structure serves as an essential element to prevent stress concentrations due to the improved elastic fixity. Consequently, the vein dilation is efficiently suppressed, healthy (laminar and helical) flow is induced effectively, and the heathy functions of vein grafting are promoted, as indicated by the flow directional alignment of endothelial cells with arterialization, muscle expansion, and improved contractility. Finally, collaborative effects of the bridge drastically suppress stenosis with patency improvement. As a key technical point, the advantages of the bridge addition are validated via the computational modeling of fluid-structure interaction, followed by a customized ex vivo set-up and analyses. The calculated effects are verified using a series of cell, rat, and canine models towards translation. The bridge acted like "Little Dutch boy" who saved the big mass using one finger by supporting the cast function.

Surface property change of C doped TiO2 nano-pillars by O2 plasma treatment.

TiO2 surface is led to super-hydrophilic surface by modifying to hydroxyl group. The super-hydrophilic surface can be applied to anti-fogging, because of preventing formation of water droplet on the surface. Super-hydrophilic coatings are made of metal oxides, polymers, or their mixtures. In this study, columnar-structured C doped TiO2 nano-pillars were grown on glass substrates by MOCVD method. For change of surface properties, grown columnar-structured C-TiO2 nano-pillars were treated by oxygen plasma. After oxygen plasma treatment, the surface property of grown columnar structured C-TiO2 nano-pillars changed from hydrophobic surface to super hydrophilic surface. For determination of this mechanism, scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), FT-IR spectroscopy, and contact angle analyzer were employed.

Growth of TiO2 nanorods on a Ta substrate by metal-organic chemical vapor deposition.

TiO2 nanorods were successfully grown on Tantalum (Ta) substrates using titanium tetra isopropoxide (TTIP) as a single precursor without any carriers or bubbling gases. For characterization of the TiO2 structures, scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were employed. For substrate temperatures below 800 degrees C, a rough film structure without nanorods could be found. However, at a sample temperature of 800 degrees C, nanorod structures with a respective diameter and length of 0.1 approximately 0.2 microm and 0.7 approximately 1.5 microm, respectively, could be synthesized. The nanorods exhibited a rutile phase with a 2:1 stoichiometry of O:Ti, identified using XRD and XPS. When the growth temperature exceeded 800 degrees C, agglomeration of the nanorods was identified.