Chapter 14 - Hydrogels for 3D Bioprinting Applications
Abstract
Hydrogels are highly hydrated polymeric networks used in tissue engineering to homogenously encapsulate cells and other biological molecules. This class of biomaterials is of particular interest because of their structural similarity to a cell’s natural extracellular matrix. Hydrogels can be derived from various sources, including natural and synthesized derivatives. Hydrogels can be induced to quickly solidify using a number of methods to introduce cross-links and covalent bonding between polymer strands. Due to their high biocompatibility and processability, hydrogels have become the choice medium to pattern cells in a volumetric space using three-dimensional (3D) bioprinting, an additive manufacturing process that deposits biomaterials in a layer-by-layer fashion to fabricate a 3D tissue construct. In this chapter, we will review important general principles that make a hydrogel useful for bioprinting, followed by a discussion of the specific hydrogels used for bioprinting applications.
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Application of 3D- printed hydrogels in wound healing and regenerative medicine
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Recent advances in 3D bioprinted tumor models for personalized medicine
2023, Translational OncologyCancerous tumors are among the most fatal diseases worldwide, claiming nearly 10 million lives in 2020. Due to their complex and dynamic nature, modeling tumors accurately is a challenging task. Current models suffer from inadequate translation between in vitro and in vivo results, primarily due to the isotropic nature of tumors and their microenvironment's relationship. To address these limitations, hydrogel-based 3D bioprinting is emerging as a promising approach to mimic cancer development and behavior. It provides precise control over individual elements' size and distribution within the cancer microenvironment and enables the use of patient-derived tumor cells, rather than commercial lines. Consequently, hydrogel bioprinting is expected to become a state-of-the-art technique for cancer research. This manuscript presents an overview of cancer statistics, current modeling methods, and their limitations. Additionally, we highlight the significance of bioprinting, its applications in cancer modeling, and the importance of hydrogel selection. We further explore the current state of creating models for the five deadliest cancers using 3D bioprinting. Finally, we discuss current trends and future perspectives on the clinical use of cancer modeling using hydrogel bioprinting.
Biomaterials / bioinks and extrusion bioprinting
2023, Bioactive MaterialsBioinks are formulations of biomaterials and living cells, sometimes with growth factors or other biomolecules, while extrusion bioprinting is an emerging technique to apply or deposit these bioinks or biomaterial solutions to create three-dimensional (3D) constructs with architectures and mechanical/biological properties that mimic those of native human tissue or organs. Printed constructs have found wide applications in tissue engineering for repairing or treating tissue/organ injuries, as well as in vitro tissue modelling for testing or validating newly developed therapeutics and vaccines prior to their use in humans. Successful printing of constructs and their subsequent applications rely on the properties of the formulated bioinks, including the rheological, mechanical, and biological properties, as well as the printing process. This article critically reviews the latest developments in bioinks and biomaterial solutions for extrusion bioprinting, focusing on bioink synthesis and characterization, as well as the influence of bioink properties on the printing process. Key issues and challenges are also discussed along with recommendations for future research.
Assessing cell migration in hydrogels: An overview of relevant materials and methods
2023, Materials Today BioCell migration is essential in numerous living processes, including embryonic development, wound healing, immune responses, and cancer metastasis. From individual cells to collectively migrating epithelial sheets, the locomotion of cells is tightly regulated by multiple structural, chemical, and biological factors. However, the high complexity of this process limits the understanding of the influence of each factor. Recent advances in materials science, tissue engineering, and microtechnology have expanded the toolbox and allowed the development of biomimetic in vitro assays to investigate the mechanisms of cell migration. Particularly, three-dimensional (3D) hydrogels have demonstrated a superior ability to mimic the extracellular environment. They are therefore well suited to studying cell migration in a physiologically relevant and more straightforward manner than in vivo approaches. A myriad of synthetic and naturally derived hydrogels with heterogeneous characteristics and functional properties have been reported. The extensive portfolio of available hydrogels with different mechanical and biological properties can trigger distinct biological responses in cells affecting their locomotion dynamics in 3D. Herein, we describe the most relevant hydrogels and their associated physico-chemical characteristics typically employed to study cell migration, including established cell migration assays and tracking methods. We aim to give the reader insight into existing literature and practical details necessary for performing cell migration studies in 3D environments.
Hydrogels for extrusion-based bioprinting: General considerations
2022, BioprintingCitation Excerpt :Conversely, if the hydrogel degrades too quickly: for tissue constructs cells will lose their anchoring substrate precluding its development; for drugs, the release may be not controllable [105]. In the tissue engineering area, attempting to simulate the behavior and responses of the natural extracellular matrix (ECM) is known as biomimicry [105]. The ECM is a complex dynamic environment, composed of hundreds of proteins and carbohydrates that are constantly remodeling themselves, expressing cell-instructive factors, and presenting factors for growth, migration, and differentiation [106].
Extrusion-based bioprinting (EBB) is a biofabrication technique that has been widely used by researchers in the last two decades, mainly due to its versatility, ease to use, and low cost. EBB can deposit many materials, different cell types, and biomolecules in a predetermined position to generate 3D complex architectures for its usage in tissue engineering, regenerative medicine, and drug delivery areas. Hydrogels are the most chosen biomaterials for bioprinting, because of their biological and mechanical properties. In the present work, the basis and classification of different extrusion methods, the printing parameters to be considered, and the properties, and applications of hydrogels for EBB are addressed.
Three-dimensional electrodes
2022, Electrochemical Sensors: From Working Electrodes to Functionalization and Miniaturized DevicesToday, chemical sensors with the ability to convert physical, chemical, or biological changes into measurable signals are very attractive. Among the different kinds of chemical sensors, electrochemical biosensors have attracted considerable attention and are widely used in recent decades due to their unique features such as, easy to construction, fast response time, biocompatibility, low cost, high sensitivity and selectivity, portability, and easy miniaturization. Remarkable achievements in nanotechnology and nanoscience have led to the creation of a broad vision in improving both sensitivity and selectivity of electrochemical biosensors. To achieve a high-performance electrochemical biosensor, the type of electrode materials and the structure of the designed sensor have a very crucial role. During the last years, different types of electrochemical biosensors have been designed using a variety of carbon, graphene, polymer, and metal compounds in one, two, or three-dimensional structures. One of the common challenges of high sensitivity electrochemical biosensors is the need for the fabrication of three-dimensional electrodes. Three-dimensional electrodes offer great advantages, such as a large electroactive surface area, enhanced ion and electron transport, good inner and outer surface contact with the analyte, increased material loading per unit substrate area, improved mechanical stability, and good electrochemical sensitivity. 3D-materials are promising compounds as three-dimensional electrochemical biosensors. On the other hand, the use of 3D printers is a promising way to the design of electrochemical biosensors. 3D printing methods have been reported as a remarkable technology for the development of electrochemical devices, due to no design constraints, waste minimization, and, most importantly, fast prototyping. Following the importance of these issues, in this chapter three-dimensional electrodes are examined in detail.