Recent Strategies in Fabrication of Gradient Hydrogels for Tissue Engineering Applications

Abstract

Hydrogels are widely used as scaffold in tissue engineering field because of their ability to mimic the cellular microenvironment. However, mimicking a completely natural cellular environment is complicated due to the differences in various physical and chemical properties of cellular environments. Recently, gradient hydrogels provide excellent heterogeneous environment to mimic the different cellular microenvironments. To create hydrogels with an anisotropic distribution, gradient hydrogels have been widely developed by adopting several gradient generation techniques. Herein, the various gradient hydrogel fabrication techniques, including dual syringe pump systems, microfluidic device, photolithography, diffusion, and bio‐printing are summarized. As the effects of gradient 3D hydrogels with stems have been reviewed elsewhere, this review focuses principally on gradient hydrogel fabrication for multi‐model tissue regeneration. This review provides new insights into the key points for fabrication of gradient hydrogels for multi‐model tissue regeneration.

Shape memory materials and 4D printing in pharmaceutics

“…In consideration of the high cost and limited bio-security of scaffolds containing in vitro-grown cells, cell-free shape-memory scaffolds were then proposed [122]. Porosity, which affects the formation of blood vessels through the scaffold, and biodegradation, required to occur in a specific period of time in order to make space for the grown tissue to take over, are of crucial importance in the development of scaffolds [125][126][127]. In this respect, hydrogels showing shape memory effect were widely employed in cell culture and tissue engineering as their internal structure easily allowed to provide enough support for cell growth using a limited amount of material.…”

Progress in Bioinspired Dry and Wet Gradient Materials from Design Principles to Engineering Applications

“…Earlier researches have demonstrated that some inorganic gradient devices and organic functional materials have a medical application in blood and tissue engineering ( Le Duigou and Castro, 2016 ; Di Luca et al., 2015 ; Karabanova et al., 2012 ; Major et al., 2007 ; Shi et al., 2019 ). Because of its outstanding stimuli-response and fast response capabilities, the functional gradient materials' applications in biomedical applications have been reviewed and include scaffolding ( Liu et al., 2009 ; Singh et al., 2010 ; Wang et al., 2019 ), hydrogel ( Wei et al., 2017 ; Jo et al., 2019 ; Khorshidi and Karkhaneh, 2018 ), bioimaging ( Ng et al., 2017 ; Zhao et al., 2019a ; Moreno and Smedby, 2015 ), biocompatibility ( Li et al., 2017 ; O'Connor et al., 2000 ; Donnelly et al., 2012 ), and therapeutic agent delivery system ( Li et al., 2014 ; Duan et al., 2016 ). Finally, the challenges for fabrication of these materials and future perspective are also summarized.…”

Injectable Microfluidic Hydrogel Microspheres for Cell and Drug Delivery

“…The delivery function of microfluidic hydrogel microspheres is defined by enabling the efficient, smart encapsulation of cells and/or drugs in microspheres for which the functionalities and features are effectively controlled, which lends itself to some unique properties. [ 10a,17 ] However, many types of microfluidic hydrogel microspheres are widely used in various medical fields, and their properties are different. Therefore, this review concretized the results of previous research, noted general trends, and highlighted the use of microfluidic hydrogel microspheres for cell and drug delivery as well as various medical applications, as shown in Figure .…”