Fabrication of Nanocomposites with High Elasticity and Strength for the Load-Bearing Layer of Small-Diameter Vascular Grafts.

Compliance mismatch of commercially available artificial grafts, where the artificial graft and the native vessel are subject to different radial expansions, is a major issue that results in graft occlusion after implantation. A human artery possesses a nonlinear mechanical response to pulsatile pressure due to its nonlinear viscoelastic nature, which is difficult to replicate in artificial graft fabrication. Here, we fabricated nanocomposites with nonlinear mechanical responses for potential application as the load-bearing layer of vascular grafts, based on a poly(dimethylsiloxane) (PDMS)-casted nanofibrous film. The nanofibers consisted of a core-sheath structure with a PDMS elastomer reinforced with poly(methyl methacrylate) (PMMA) nanofibers as the sheath and thermoplastic polyurethane (TPU) elastomer as the core. The surface morphology and chemical composition together with the crystalline structure of the nanocomposites were characterized, and dynamic mechanical analysis was performed to select the graft with the most suitable properties as the load-bearing layer of a small-diameter vascular graft. The presence of the stiff polymer PMMA and elastic polymer TPU in the PMMA/PDMS/TPU combination resulted in a delayed dissipation of energy after exposure to a force corresponding to 180 mm Hg. Casting the PDMS/PMMA/TPU nanofibrous mat into a nanocomposite film improved the ultimate tensile strength of PDMS without compromising its elasticity. The compliance values of the nanocomposites were also found to be a close match to those of the greater saphenous vein, demonstrating a great potential of the nanocomposites as the load-bearing layer in a biostable vascular graft.

Fast and Effective Removal of Congo Red by Doped ZnO Nanoparticles.

ZnO nanoparticles (NPs) show remarkable efficiency in removing various contaminants from aqueous systems. Doping ZnO NPs with a second metal element can dramatically change the physicochemical properties of the pristine nanoparticles. However, there have been limited reports on the absorption of doped ZnO NPs, especially comparing the performance of ZnO NPs with different doping elements. Herein, ZnO NPs were doped with three transitional metals (Co, Fe, and Mn) at a nominal 2 wt.%. The particle surface had a higher dopant concentration than the interior for all NPs, implying the migration of the dopants to the surface. Because doping atoms inhibited grain growth, the doped ZnO NPs had a small particle size and a large surface area. The adsorption performance followed the order of Fe-doped < undoped < Mn-doped < Co-doped ZnO. Co-doped ZnO had an increased surface area and less tendency to agglomerate in an aqueous solution, showing the best adsorption performance. The adsorption of Congo red (CR) on Co-doped ZnO followed the pseudo-second-order model and the Langmuir isotherm. The adsorption process was spontaneous through monolayer chemisorption, and the maximum adsorption capacity was 230 mg/g. Finally, the Co-doped ZnO was successfully incorporated into an alginate membrane by electrospinning. The membrane demonstrated excellent adsorption performance and had great potential as an innovative and low-cost adsorbent (inexpensive raw materials and simple processing) for wastewater purification.

Advanced flexible transvaginal mesh with high visibility under computerized tomography (CT) scan.

Pelvic floor disorders, including pelvic organ prolapse (POP) and stress urinary incontinence (SUI), are serious and very common. Surgery is commonly undertaken to restore the strength of the vaginal wall using transvaginal surgical mesh (TVM). However, up to 15% of TVM implants result in long-term complications, including pain, recurrent symptoms, and infection.Clinical Relevance- In this study, a new bioengineered TVM has been developed to address these issues. The TVM is visible using noninvasive imaging techniques such as computed tomography (CT); it has a highly similar structural profile to human tissue and potential to reduce pain and inflammation. These combined technological advances have the potential to revolutionize women's health.

Review of Polymeric Biomimetic Small-Diameter Vascular Grafts to Tackle Intimal Hyperplasia.

Small-diameter artificial vascular grafts (SDAVG) are used to bypass blood flow in arterial occlusive diseases such as coronary heart or peripheral arterial disease. However, SDAVGs are plagued by restenosis after a short while due to thrombosis and the thickening of the neointimal wall known as intimal hyperplasia (IH). The specific causes of IH have not yet been deduced; however, thrombosis formation due to bioincompatibility as well as a mismatch between the biomechanical properties of the SDAVG and the native artery has been attributed to its initiation. The main challenges that have been faced in fabricating SDAVGs are facilitating rapid re-endothelialization of the luminal surface of the SDAVG and replicating the complex viscoelastic behavior of the arteries. Recent strategies to combat IH formation have been mostly based on imitating the natural structure and function of the native artery (biomimicry). Thus, most recently, developed grafts contain a multilayered structure with a designated function for each layer. This paper reviews the current polymeric, biomimetic SDAVGs in preventing the formation of IH. The materials used in fabrication, challenges, and strategies employed to tackle IH are summarized and discussed, and we focus on the multilayered structure of current SDAVGs. Additionally, the future aspects in this area are pointed out for researchers to consider in their endeavor.

Liquid metal polymer composite: Flexible, conductive, biocompatible, and antimicrobial scaffold.

Gallium and its alloys, such as eutectic gallium indium alloy (EGaIn), a form of liquid metal, have recently attracted the attention of researchers due to their low toxicity and electrical and thermal conductivity for biomedical application. However, further research is required to harness EGaIn-composites advantages and address their application as a biomedical scaffold. In this research, EGaIn-polylactic acid/polycaprolactone composites with and without a second conductive filler, MXene, were prepared and characterized. The addition of MXene, into the EGaIn-composite, can improve the composite's electrochemical properties by connecting the liquid metal droplets resulting in electrically conductive continuous pathways within the polymeric matrix. The results showed that the composite with 50% EGaIn and 4% MXene, displayed optimal electrochemical properties and enhanced mechanical and radiopacity properties. Furthermore, the composite showed good biocompatibility, examined through interactions with fibroblast cells, and antibacterial properties against methicillin-resistant Staphylococcus aureus. Therefore, the liquid metal (EGaIn) polymer composite with MXene provides a first proof-of-concept engineering scaffold strategy with low toxicity, functional electrochemical properties, and promising antimicrobial properties.