Browsing by Author "Hu, Zhonglue"
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Item 3D printed agar/ calcium alginate hydrogels with high shape fidelity and tailorable mechanical properties(2021) Wang, Jilong; Liu, Yan; Zhang, Xintian; Rahman, Syed Ehsanur; Su, Siheng; Wei, Junhua; Ning, Fuda; Hu, Zhonglue; Martínez-Zaguilán, Raul; Sennoune, Souad R.; Cong, Weilong; Christopher, Gordon; Zhang, KunIn this study, calcium alginate/agar (CA/Ag) 3D structures were printed as strip assembles with high resolution and tailorable mechanical properties by a thermal-assisted 3D printing method. Specifically, alginate and agar were combined to minimize the Barus effect, and further improved the printing resolution. The introduction of agar altered the rheological properties of the ink, such as increasing its viscosity to obtain a 3D printing structure with higher precision. The alginate chains were crosslinked by calcium ions, which connected different layers together and had good interface adhesion among layers in 3D printing constructs. In addition, after printing, the crosslinking of calcium alginate affected the swelling behavior and mechanical properties of printing gels. The width of extrusion gel stripes was close to the diameter of needle, demonstrating that the printing resolution is well controlled by minimizing the Barus effect of concentrated solution. Furthermore, the printed gel structures showed low cytotoxicity, indicating that these biocompatible 3D printed structures are promising substitutes for tissue engineering. Most importantly, soft polyacrylamide (PAAm) network was introduced into 3D printed CA/Ag hydrogels to toughen interfacial surfaces between adjacent stripes by combination of rigid calcium alginate network and soft PAAm network. These 3D printed hydrogels with excellent mechanical properties, high compatibility and high shape fidelity can be regarded as a potential candidate in bio-medical field.Item Controllable nanoshaping of metallic glass through thermoplastic drawing(2018-11-20) Hu, Zhonglue; Kumar, Golden; Aksak, Burak; Yeo, Changdong; Li, WeiMetallic nanostructures such as tips, rods, tubes, and wires are important in nanoscale devices and characterization of size-effects in metals. However, these technological and scientific advancements are hampered by the complex and expensive lithography-based fabrication approach. The lack of a cost-effective and scalable nanofabrication venue for metallic material is in direct contrast to the various nanoshaping approaches available for polymeric materials. The origin of this disparity in processing ability is because the polymers exhibit tunable rheological and interfacial properties, which are absent in conventional metals. Unlike conventional metals, amorphous metals (metallic glasses) exhibit supercooled liquid state which mimics rheology of plastics at moderate temperatures. Here we manipulate the supercooled liquid state of metallic glasses to develop a lithography-free nanomanufacturing scheme through elongation and rupture. The metallic glass supercooled liquids confined in a macroscopic cavity and subsequently downsized to nanoscale by stretching. The extent of size-reduction can be controlled by tuning the active volume of liquid and the viscous and capillary stresses. Structures in sub-micron length scales, such as nanowires and nanotips, can be predictably fabricated without using lithography or expensive molds. A systematic study is performed using glass forming Pt-Cu-Ni-P alloy to understand the effects of viscosity, surface tension, pulling velocity, and initial size on the evolution of cylindrical liquid column under tension. The results are quantitatively described by combining the lubrication theory with the capillary induced breakup of liquid filaments. A new manufacturing approach based on variable pulling velocity and/or spinning of metallic liquid is proposed for fabrication of complex geometries. The potential applications of metallic glass geometries fabricated through drawing are discussed.Item Thermal-recoverable tough hydrogels enhanced by porphyrin decorated graphene oxide(2019) Wang, Jilong; Wei, Junhua (TTU); Su, Siheng; Qiu, Jingjing (TTU); Hu, Zhonglue; Hasan, Molla; Vargas, Evan (TTU); Pantoya, Michelle (TTU); Wang, ShirenArtificial tissue materials usually suffer properties and structure loss over time. As a usual strategy, a new substitution is required to replace the worn one to maintain the functions. Although several approaches have been developed to restore the mechanical properties of hydrogels, they require direct heating or touching, which cannot be processed within the body. In this manuscript, a photothermal method was developed to restore the mechanical properties of the tough hydrogels by using near infrared (NIR) laser irradiation. By adding the porphyrin decorated graphene oxide (PGO) as the nanoreinforcer and photothermal agent into carrageenan/polyacrylamide double network hydrogels (PDN), the compressive strength of the PDN was greatly improved by 104%. Under a short time of NIR laser irradiation, the PGO effectively converts light energy to thermal energy to heat the PDN hydrogels. The damaged carrageenan network was rebuilt, and a 90% compressive strength recovery was achieved. The PGO not only significantly improves the mechanical performance of PDN, but also restores the compressive property of PDN via a photothermal method. These tough hydrogels with superior photothermal recovery may work as promising substitutes for load-bearing tissues.