New-generation biomaterials for bone regenerations should be highly bioactive, resorbable and mechanically strong. Mesoporous bioactive glass (MBG), as a novel bioactive material, has been used for the study of bone regeneration due to its excellent bioactivity, degradation and drug-delivery ability; however, how to construct a 3D MBG scaffold (including other bioactive inorganic scaffolds) for bone regeneration still maintains a significant challenge due to its/their inherit brittleness and low strength. In this brief communication, we reported a new facile method to prepare hierarchical and multifunctional MBG scaffolds with controllable pore architecture, excellent mechanical strength and mineralization ability for bone regeneration application by a modified 3D-printing technique using polyvinylalcohol (PVA), as a binder. The method provides a new way to solve the commonly existing issues for inorganic scaffold materials, for example, uncontrollable pore architecture, low strength, high brittleness and the requirement for the second sintering at high temperature. The obtained 3D-printing MBG scaffolds possess a high mechanical strength which is about 200 times for that of traditional polyurethane foam template-resulted MBG scaffolds. They have highly controllable pore architecture, excellent apatite-mineralization ability and sustained drug-delivery property. Our study indicates that the 3D-printed MBG scaffolds may be an excellent candidate for bone regeneration.

Three-dimensional printing of hierarchical and tough mesoporous bioactive glass scaffolds with a controllable pore architecture, excellent mechanical strength and mineralization ability

Architected hydrogels are widely used in biomedicine, soft robots, and flexible electronics while still possess big challenges in strong toughness, and shape modeling. Here, inspired with the universal hydrogen bonding interactions in biological systems, a strain‐induced microphase separation path toward achieving the printable, tough supramolecular polymer hydrogels by hydrogen bond engineering is developed. Specifically, it subtly designs and fabricates the poly (N‐acryloylsemicarbazide‐co‐acrylic acid) hydrogels with high hydrogen bond energy by phase conversion induced hydrogen bond reconstruction. The resultant hydrogels exhibited the unique strain‐induced microphase separation behavior, resulting in the excellent strong toughness with, for example, an ultimate stress of 9.1 ± 0.3 MPa, strain levels of 1020 ± 126%, toughness of 33.7 ± 6.6 MJ m−3, and fracture energy of 171.1 ± 34.3 kJ m−2. More importantly, the hydrogen bond engineered supramolecular hydrogels possess dynamic shape memory character, i.e shape fixing at low temperature while recovery after heating. As the proof of concept, the tailored hydrogel stents are readily manufactured by 3D printing, which showed good biocompatibility, load‐bearing and drug elution, being beneficial for the biomedical applications. It is believed that the present 3D printing of the architected dynamic hydrogels with ultrahigh toughness can broaden their applications.

Strong and Ultra‐Tough Supramolecular Hydrogel Enabled by Strain‐Induced Microphase Separation

Zirconia-toughened alumina (ZTA) ceramic has potential dental restoration and repair applications due to its high mechanical strength, toughness, wear resistance, chemical durability, and biocompatibility. Nevertheless, there is a great deal of crack initiation caused by stress accumulation and also material wastage after computer-aided design/computer-aided manufacturing of ZTA ceramics in conventional clinical processing. In this study, we prepared a ZTA green compact using Stereolithography (SLA) technology followed by sintering at high temperatures ranging between 1450 °C and 1650 °C. The microstructures, mechanical properties, friction and wear performance, and cytotoxicity of the ZTA ceramic were investigated. The results indicate that all ZTA samples were composed of α-Al2O3, m-ZrO2, and t-ZrO2 phases before and after sintering. With increasing sintering temperatures from 1450 °C to 1650 °C, the density, mechanical properties, hardness, and wear performance of the ZTA samples were gradually improved. The ZTA sample sintered at 1650 °C with a relative density of 96.65% showed the best mechanical performance, with a flexural strength of 572.0 MPa, a Vickers hardness of 16.2 GPa, and a fracture toughness of 7.4 MPa m1/2. The sintered ZTA sample exhibited a good cell viability toward MC3T3-E1 cells. 

Microstructure, mechanical properties, friction and wear performance, and cytotoxicity of additively manufactured zirconia-toughened alumina for dental applications

Additive manufacturing and 3D printing methods based on the extrusion of material have become very popular in recent years. There are many methods of printing ceramics, but the direct extrusion method gives the largest range of sizes of printed objects and enables scaling of processes also in large-scale applications. Additionally, the application of this method to ceramic materials is of particular importance due to its low cost, ease of use, and high material utilization. The paper presents the most important literature reports on ceramics printed by direct extrusion. The review includes articles written in English and published between 2017 and 2022. The aim of this literature review was to present the main groups of ceramic materials produced by extrusion-based 3D printing.

/pdf/3d-printing-ceramics-materials-for-direct-extrusion-process-2i3w4gmi.pdf

3D Printing Ceramics—Materials for Direct Extrusion Process

Efficient removal and sensing of copper(II) ions by alkaline earth metal-based metal–organic frameworks

Direct ink writing of aluminum-phosphate-bonded Al2O3 ceramic with ultra-low dimensional shrinkage

Bioprosthetic cardiac valves are efficient replacements to clinically treat the valvular heart diseases including stenosis and regurgitation, while these often suffer from the issues of mechanical mismatch, biocompatibility, thrombus, degradation, etc. Here, we report a big step toward the biomechanically compatible hydrogel heart valves by the reversible addition–fragmentation chain transfer polymerization compatible three-dimensional (RAFT-3D) printing tough hydrogels. The biocompatible hydrogel valves have favorable mechanical properties matching with native valves and long-term stability and durability owing to the wide and robust hydrogen-bonding networks, on which the heparin-like polymer with −SO3– is readily grafted through RAFT polymerization, endowing outstanding hemocompatibility including low hemolysis, anticoagulation, and acceptable inflammatory response. The proof-of-concept hydrogel aortic valve displayed a low transvalvular pressure gradient of 14–24 mmHg, which efficiently regulates the flow direction and regurgitation and, more importantly, endures a cyclic pressure of ∼80 mmHg for at least 1.8 × 105 cycles yet maintaining a stable transvalvular pressure gradient without any damage to the configuration and performance. It is believed that the engineered hydrogel cardiac valves pave a significant way toward addressing the complications of cardiovascular diseases. 

Biomechanically Compatible Hydrogel Bioprosthetic Valves

Direct ink writing of Pd-Decorated Al2O3 ceramic based catalytic reduction continuous flow reactor

Here, we report a novel 3D printed layered ordered mesoporous template that can encapsulate active Co-MOFs species in a confined way to achieve the goal of monolithic catalyst. The monolithic OM-Co3O4@SiO2-S catalyst can maintain a macroscopic porous layered structure and a microscopic ordered mesoporous structure. This monolithic OM-Co3O4@SiO2-S catalyst has excellent catalytic performance (T90 = 236 °C), water resistance, and thermal stability in the catalytic combustion of toluene. The catalytic performance of the monolithic OM-Co3O4@SiO2-S catalyst is much better than that of many monolithic catalysts reported in the former. Among them, the introduction of binder aluminum phosphate (AP) can effectively enhance the rheological properties of the printing ink, achieve the purpose of ink writing monolithic layered porous material, enrich the acidic point of the monolithic catalyst, and increase the number of reactive oxygen species. This work reveals a novel monolithic catalyst forming strategy that can combine the advantages of ordered mesoporous materials with active species to form macro-layered porous materials and provide ideas and an experimental basis for the elimination of VOCs in industrial applications.

Rational Design and Construction of Monolithic Ordered Mesoporous Co3O4@SiO2 Catalyst by a Novel 3D Printed Technology for Catalytic Oxidation of Toluene.

Xin Xu

Papers

Direct ink writing of aluminum-phosphate-bonded Al2O3 ceramic with ultra-low dimensional shrinkage

Biomechanically Compatible Hydrogel Bioprosthetic Valves

Direct ink writing of Pd-Decorated Al2O3 ceramic based catalytic reduction continuous flow reactor

Rational Design and Construction of Monolithic Ordered Mesoporous Co3O4@SiO2 Catalyst by a Novel 3D Printed Technology for Catalytic Oxidation of Toluene.

Strong and Ultra‐Tough Supramolecular Hydrogel Enabled by Strain‐Induced Microphase Separation