programmed, reshaping hydrogel architectures were fabricated from sugar/hydrogel inks via a threedimensional printing method involving a stimuli-responsive polymer. We developed a new hydrogel ink composed of monomers (acrylamide [AAm]) and n-isopropylacrylamide [nipAAm]), and sugar (mixture of glucose and sucrose) as a pore-generator, enabling to improve printability by increasing the ink's viscoelastic properties and induce the formation of macropores in the hydrogel architectures. this study demonstrated that creating macropores in such architectures enables rapid responses to stimuli that can facilitate four-dimensional printing. We printed bilayer structures from monomer inks to which we had added sugar, and we exposed them to processes that cross-linked the monomers and leached out the sugar to create macropores. in comparison with a conventional poly(n-isopropylacrylamide) hydrogel, the macroporous hydrogels prepared using polymerization in the presence of a high concentration of sugar showed higher swelling ratios and exhibited much faster response rates to temperature changes. We used rheometry and scanning electron microscopy to characterize the properties of these inks and hydrogels. the results suggest that this method may provide a readily available route to the rapid design and fabrication of shape-morphing hydrogel architectures with potential application in soft robotics, hydrogel actuators, and tissue engineering.

The threat of arsenic contamination to public health, particularly in developing countries, has become a serious problem. Millions of people in their daily lives are still highly dependent on groundwater containing high levels of arsenic, which causes excessive exposure to this toxic element, due to the high cost and lack of water-treatment infrastructures. Therefore, a technique for large-scale treatment of water in rural areas to remove arsenic is needed and should be low-cost, be easily customized, and not rely on electrical power. In this study, in an effort to fulfill those requirements, we introduce a three-dimensional (3D), printed water-filtration system for arsenic removal. Three-dimensional printing can provide a compact, customized filtration system that can fulfill the above-mentioned requirements and that can be made from plastic materials, which are abundant. Armed with the versatility of 3D printing, we were able to design the internal surface areas of filters, after which we modified the surfaces of the 3D, printed filters by using iron (III) oxide as an adsorbent for arsenite. We investigated the effects of the controlled surface area on the flow rate and the deposition of the adsorbent, which are directly related to the adsorption of arsenic. We conducted isotherm studies to quantify the adsorption of arsenic on our 3D, printed filtration system.

As part of regenerative medicine, artificial, hierarchical tissue engineering is a favorable approach to satisfy the needs of patients for new tissues and organs to replace those with defects caused by age, disease, or trauma or to correct congenital disabilities. However, the application of tissue engineering faces critical issues, such as the biocompatibility of the fabricated tissues and organs, the scaffolding, the complex biomechanical processes within cells, and the regulation of cell biology. Although fabrication strategies, including the traditional bioprinting, photolithography, and organ‐on‐a‐chip methods, as well as combinations of fabrication processes, face many challenges, they are methods that can be used in hierarchical tissue engineering. The strategic approach to synthetic, hierarchical tissue engineering is to use a combination of several technologies incorporating material science, cell biology, additive manufacturing (AM), on‐a‐chip strategies, and biomechanics. Herein, in a review, the current materials and biofabrication strategies of various artificial hierarchical tissues are discussed based on the level of tissue complexity from nano to macrosize and the adaptive interactions between cells and the scaffolding surrounding the incorporated cells.