**1. Introduction**

Nanomaterials are becoming a new strategy to control and manipulate the nano and macro properties of hydrogels without hindering the exchange of nutrients with the surrounding environment [1]. Nanomaterials refer to synthetic or natural materials whose size does not exceed 100 nm, but for better medical applications, a diameter in the range of 10–100 nm is more required. Materials with a diameter of less than 10 nm are reactive and toxic due to their large specific surface area and activity and

materials larger than 100 nm can even cause embolism. In addition, it has been shown that nanotopology rather than microtopology is the main influence factor on cell structure and arrangement [2]. Usually, natural tissues also contain nano-scale substances, such as proteins, which can directly interact with cells. The nanocomposite hydrogel designed with a biomimetic structure is more suitable for host cell colonization. Therefore, nanomaterials have high biological activity (for example, cell-binding motifs), which are conducive to protein adsorption and cell adhesion and proliferation [3]. The properties of the obtained nanocomposite hydrogel can be the sum of the functions of the nanomaterial and the hydrogel, or the result of better properties, such as improved stiffness, stretchability, and even higher cell compatibility, which may be derived from synergistic interactions [4]. Liu et al. introduced hydroxyapatite (HAp) into the hydrogel network, which improved the modulus and toughness of the hydrogel, and had a qualitative impact on the differentiation behavior of mesenchymal stem cells (MSCs) [5]. Nanoparticles (NPs) can be cross-linked agents with polymers both chemically and physically to achieve dynamic system behavior and form shear-thinning hydrogels. The resulting hydrogels exhibit a temporarily reduced viscosity under shear stress and can be injected through a plug flow system, and then return to their original viscosity under low shear owing to the electrostatic interactions [3]. Because of these characteristics, they can be further applied to 3D bioprinting. Moreover, due to their structural characteristics, nanocomposite hydrogels can easily present a gradient biomolecules delivery by (porous) NPs. A nanocomposite hydrogel composed of a poly(amide amine) network and mesoporous silica NPs capable of releasing chemokines has been reported. They have been observed to play an important role in tissue regeneration *in vivo* through their influence on (MSCs) (**Figure 1**) [7].

Nanocomposites are defined as a combination of materials or phases, where one or more components is more concentrated and provide support, and other components enhance the performance of the prepared composite by adding extra characteristics [8]. In recent years, there have been more and more research toward nanocomposites by closely mimicking the biological environment and natural matrix. Especially, the properties of nanocomposites can be modified to meet the functional requirements of each tissue, which makes it an excellent choice for tissue engineering applications [9, 10]. Nanoscale scaffolds are needed to provide a suitable niche for interactions between cells and the extracellular matrix (ECM) and guide cell behaviors [11]. The emergence of nanocomposite materials provides more meaningful characteristics, combinations, and unique design possibilities for scaffolds, and finally provides a revolutionary platform for tissue engineering.

Nanocomposites involving biodegradable and bioactive properties have been regarded as strategies for tissue engineering and regeneration medicine [12]. Nanoscale fillers can greatly change the physical properties of the polymer matrix, thereby achieving improved engineering design of biomaterials. Compared with traditional ones, nanoparticles with a larger surface area, can form a tighter interface with the polymer matrix, provide better mechanical properties, while outstanding mechanical conductivity and biocompatibility of the filler, thereby affecting protein adsorption, cell adhesion, proliferation, and differentiation [13].

The components used to prepare the nanocomposite can be of natural or synthetic origin. The components obtained from natural sources include polysaccharides from microorganisms, such as chitin/chitosan, starch, alginate, and cellulose, while biopolymers from animal proteins include wool, silk, gelatin, and collagen. These polymers have been widely used in biomedical applications for their physical and chemical similarities to natural ECM [12]. These polymers provide favorable support

*Nanocomposite Biomaterials for Tissue Engineering and Regenerative Medicine Applications DOI: http://dx.doi.org/10.5772/intechopen.102417*

**Figure 1.** *Various topographical architecture of nanocomposite scaffolds affects the binding and spreading of seed cells [6].*

for living systems, including outstanding biological properties, adjustable degradation rates, and faster tissue regeneration [14, 15]. However, some disadvantages, including the risk of pathogen transmission, allergic reactions, poor mechanical strength, and high cost have also restricted their applications [16]. In recent years, researchers have begun to overcome these problems related to natural nanocomposite scaffolds. In tissue engineering, the developed scaffold can be used as a substitute for ECM. Scaffolds formulated with biodegradable polymers, cells, growth factors, and appropriate biochemical signals can repair or replace damaged tissues by providing the environment and conditions that enable cells to secrete their own new natural ECM [17, 18].

Tissue engineering and regenerative medicine (TERM) is a multidisciplinary research field that uses the principles of chemistry, biology, and engineering science to study the regeneration process of damaged tissues or organs [19]. Tissue engineering requires a combination of molecular biology and materials design for the urgent need of providing temporary artificial substrates for cell seeding. In general, the scaffold should exhibit high porosity, appropriate pore size, biocompatibility, and appropriate degradation rate [20]. Besides, the scaffold also needs to provide sufficient mechanical support to maintain the stress and load generated during the regeneration process *in vitro* or *in vivo*. For the purpose of improving mechanical properties and cell adhesion and proliferation, the incorporation of nanoparticles (such as apatite components, carbon nanostructures, and metal nanoparticles) has been extensively studied. Polymer/layered nanocomposites such as HAp, carbon nanotubes, and layered silicates have become the focus of attention in academia and industry [21, 22]. The introduction of a small amount of high-aspect-ratio silicate nanoparticles can significantly improve the mechanical and physical properties of the polymer matrix.

This chapter mainly introduces the current research trends of nanocomposite materials used in tissue engineering, the properties, types, manufacturing techniques, and applications of ideal nanocomposite scaffolds in various tissue engineering fields.
