# Additive Manufacturing and Chemical Engineering: Looking for Synergies from a Bibliometric Study
## 4 Review of Research Focused on Additive Manufacturing and Chemical Engineering
### Additive Manufacturing and Biofabrication  
Biofabrication, bioprinting, and biomedical applications have been identified as a notable focus in the bibliometric study, with the keyword analysis and the network mapping underscoring its significance. The findings indicated that this topic has become a well-established research area, receiving considerable attention. The impact of this topic is such that even when the search was limited to the chemical engineering subject area, it was identified as a central spotlight. Biofabrication involves the automated generation of biologically functional products with structural organization using bioactive molecules; biomaterials; living cells; cell aggregates such as micro-tissues and micro-organs on chips; and hybrid cell-material constructs. This is achieved through bioprinting or bioassembly, followed by the subsequent tissue maturation processes [68]. Bioprinting specifically refers to the use of additive manufacturing techniques to combine living and non-living materials (including cells, growth factors, bioinks, and biomaterials) to fabricate bioengineered functional structures [48]. These structures can be utilized in a variety of fields, including regenerative medicine, pharmacokinetics, and basic cellular biology studies, although recent efforts have expanded their use to new applications such as biosensing and environmental remediation. Bioassembly refers to the fabrication of hierarchical constructs with a prescribed 2D or 3D organization through the automated assembly of pre-formed cell-containing fabrication units generated via cell-driven self-organization or through the preparation of hybrid cell-material building blocks, typically by applying enabling technologies, including microfabricated molds or microfluidic [68]. Therefore, bioassembly techniques do not require bioprinters for the assembly of larger cellular and material constructions from smaller components. Biomanufacturing in general and bioprinting in particular provide core and vital support for tissue engineering and regenerative medicine. While tissue engineering considers the use of physical, chemical, biological, and engineering processes to control and direct the aggregate behavior of cells, regenerative medicine has been defined as the application of tissue science, tissue engineering, and related biological and engineering principles that restore the structure and function of damaged tissues and organs [68].  
The process of bioprinting requires the previous preparation of the model required by the printing device and the materials to be used. The anatomical configuration of the functional biofructure must be delineated through the utilization of appropriate imaging methodologies, including computed tomography and magnetic resonance imaging. Subsequently, specialized software is employed to translate the image into a CAD drawing of cross-sectional layers and the corresponding final format file, thus enabling the printing device to add them in a layer-by-layer process. In addition, the liquid mixtures of cells, matrix, and nutrients known as bioinks must be prepared, although other biological materials can be employed. Bioprinting for fabricating biological constructs typically involvesdispensing these bioinks and other additive factors onto a biocompatible scaffold using a successive layer-by-layer approach to generate tissue-like three-dimensional structures. The precision, stability, and viability of these biological constructs are highly dependent on the employed technologies. Subsequently, the constructed biostructure must be subjected to further processing in a bioreactor, which recreates the requisite in vivo environment for maintaining tissue viability during the maturation period. To create a stable structure from this bioprinted construct, both mechanical and chemical stimulations are needed, since these stimulations send signals to the cells to control the remodeling and growth of tissues [69].