**César M. Gómez**

Department of Construction, Building Services and Structures at the University of Navarra, Pamplona, Spain

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than synthetic materials [11].

**Chapter 1**

**Abstract**

**1. Introduction**

Bioprinting

Bio-Inspired Hydrogels via 3D

*Lei Nie, Can Wang, Yaling Deng and Amin Shavandi*

Many soft tissues of the human body such as cartilages, muscles, and ligaments are mainly composed of biological hydrogels possessing excellent mechanical properties and delicate structures. Nowadays, bio-inspired hydrogels have been intensively explored due to their promising potential applications in tissue engineering. However, the traditional manufacturing technology is challenging to produce the bio-inspired hydrogels, and the typical biological composite topologies of bioinspired hydrogels are accessible completed using 3D bioprinting at micrometer resolution. In this chapter, the 3D bioprinting techniques used for the fabrication of bio-inspired hydrogels were summarized, and the materials used were outlined. This chapter also focuses on the applications of bio-inspired hydrogels fabricated using available 3D bioprinting technologies. The development of 3D bioprinting techniques in the future would bring us closer to the fabrication capabilities of living organisms, which would be widely used in biomedical applications.

**Keywords:** 3D bioprinting, hydrogels, biopolymers, tissue engineering, biomaterials

The design of scaffold materials that can guide tissue regeneration is a very challenging goal [1]. In addition, to support and promote the growth and differentiation of specific cells, an ideal scaffold requires careful control of the material's structure in the range of nanometers to centimeters, and some natural materials with complex structure exist in nature, which provides ideas for the design of ideal scaffolds [2]. These natural materials, such as mammal bones, abalone pearl layers and fish scales, which are composed of multi-layer biominerals and biopolymers, have complex microstructure, which can control the crack growth and fracture in three-dimensional (3D) direction, producing much more strength and toughness than their constituent materials [3–5]. Jellyfish and sea anemones, with a water content of up to 90%, show that their gelatinous bodies exhibit exciting mechanical properties and are able to respond quickly to various environmental stimuli [6–8]. There are also some soft support tissues (such as tendons, ligaments, meniscus, and cartilage), showing softness, toughness and impact resistance [9]. Because of the beneficial properties of natural composite materials, the design of bionic materials has attracted significant attention. Bio-inspired material is considered as a kind of material inspired by nature or biology and then developed by simulating some characteristics [10], and usually, the bio-inspired materials provide better functions **Chapter 1**
