Synthesis of Nanomaterials

Biomaterials have been utilized in healthcare applications a number of times. Nowadays, subsequent evolution and the increase in the life expectancy of world’s population have made biomaterials more attractive and versatile, and have increased their utility. Concerning the manufacturing of medical devices and pharmacy, the development of new biomaterials, new manufacturing methods and techniques has always been the researchers’ focus. Recently, nanotechnology and nanomedicine have attracted a great deal of attention, which would further enhance the use of biomaterials in medical devices and pharmacy. In the development of medical devices and pharmacy, the selection of the proper material to be used is of utmost importance. This chapter aims to provide a review of the most used biomaterials. After an explanation of what biomaterials are and what defines them, a more in-depth approach to the major types of biomaterials is presented, such as metal, polymer, ceramic, and composites; also, the advantages and disadvantages of biomaterials, their main characteristics, and preferred applications in the area of medical devices and pharmacy are discussed.

Polymers have been employed for the development of medical devices and implants as some of them are biocompatible. Synthetic procedures and extraction techniques have allowed the obtention of different polymers, classified in this chapter as synthetic and natural polymers. In the process of synthesis of the polymer, its properties can be modulated to obtain more flexible or thermostable materials, nontoxic or transparent, depending on the desired properties of the final product. A wide range of polymers have been used for the manufacturing of catheters, valves, tubes, and other medical devices; therefore, in this chapter, there is a brief description of some of them, their chemical structure and properties, and finally, their application in medicine is shown.

Nanomedicine aims to control, repair, or comprehensively improve all human biological systems, working from a molecular level with engineering devices and nanostructures to achieve medical benefits. This science has had a greater development in recent years, thanks to the great technological advances achieved in developed countries, which is due to the large investment that is made due to the promising incursion of nanotechnology in the diagnosis and treatment of various diseases. This chapter covers this topic from a technical point of view that involves the synthesis of materials and the development of techniques with their respective biomedical application. In addition, the ethical issues related to its application and the actions that have been taken to regulate it are detailed.

Natural and synthetic biomaterials are useful for different biological and industrial applications, and their impact, as well as the interest (in both academy and industry) in those materials, have grown up in the last few years. This chapter presents some advances in the synthesis of biopolymers and related materials using different synthetic and non-synthetic strategies (from conventional chemical synthesis using click reactions and more sophisticated ones, such as electrospinning) and their applications in the field of medicine and biology. For the treatment of diseases and tissue engineering, we describe several biomaterials prepared by different extraction methodologies from natural sources (e.g., chitosan and collagen) and their benefits as biodegradability, circular economy, and recycling. Several synthetic approximations for the preparation of biopolymers and their potential in several applications are discussed based on the available information about synthesis, application, and biodegradability. As several approaches are currently applied for the synthesis of biomaterials with different applications, in the second and last sections, we discuss some of these strategies considering the green chemistry principles. In many cases, an appropriate building and synthesis of biopolymers could optimize chemical and physical properties, such as solubility, viscosity, adhesiveness, degradability, and in vivo response. In this chapter, also the conditions of synthesis of monomers will be discussed, focusing on some advanced and green strategies for replacing toxic solvents (and even complexes) that are used and make the process of obtaining green materials difficult according to the desired target biopolymers. Finally, some applications related to pharmacology and tissue engineering will be presented. 

Hydrogels and nanogels are exciting and promising materials for many applications due to their versatile features, such as interacting and absorbing a significant amount of water and other solvents, excellent mechanical properties, and adhesiveness. These materials are obtained based on the nature of the raw materials (natural or synthetic) and the synthesis route. There are many ways to synthesize hydrogels and nanogels; however, these routes can be classified as physical or chemical. Physical synthesis forms a reversible cross-linking. In contrast, chemical synthesis can generate a stable, rigid, and irreversible polymeric structure. Nowadays, the term “smart hydrogel” has gained significant attention due to its response to external factors, such as pH, temperature, light, electricity, and magnetic, and even an internal approach as substrate. Besides, the characteristics and properties of these polymeric matrices can be enhanced through the synergic relationship with nanoparticles. The inner and outer structure and the behavior of these materials can be studied through characterization techniques, such as light scattering, gel permeation chromatography, viscometry, thermal analysis, spectroscopies, microscopies, and swelling. 

Self-healing systems have a high capacity for regeneration, managing to regain their functionality after suffering structural damage. This characteristic provides the materials with high durability and security in their use. Living organisms are the ideal self-healing systems, which is why they have served as inspiration for the development of these materials. Self-healing synthetic systems also show biomimetic characteristics and are widely studied as biomaterials. Different ceramic, metallic and polymeric materials can show self-healing capacity, although the polymeric selfhealing systems have versatility, adaptability, and ease of synthesis. This chapter describes the general aspects, properties, and classification of polymeric self-healing materials, focusing on extrinsic and intrinsic self-healing materials. The self-healing behavior of extrinsic materials depends on microcapsules and vascular structures that act as healing agents’ delivery systems. The self-healing behavior of intrinsic materials is governed by the presence of a dynamic crosslinking based on dynamic covalent bonds or non-covalent intermolecular interactions. In addition, examples of current developments in this field are shown.

 Biomedicine research has gained momentum for the development of various computational and theoretical techniques. Researchers working in biomedicine and bioinformatics depend on computational intelligence and its widespread applications. New algorithms have been described that enable computational simulations and mathematical modelling in coordination with analytical methods to comprehensively study biological systems. Many algorithms, such as Artificial Neural Networks (ANNs), Rough Sets (RS), Fuzzy Sets (FS), Particle Swarm Optimization (PSO), Evolutionary Algorithm (EA), etc., allow reliable and accurate analysis of vast data sets in biomedicine. Computational techniques analyse gene expression data obtained from microarray experiments, predict protein-protein interactions, model the human body in disease conditions, such as Alzheimer’s disease or cancer, follow the progression of the diseases, classify tumours, analyse which genotype responds to certain drugs, etc. Multiscale modelling of the human body in various disease conditions is a topic of interest in this context. Relevantly, the “Virtual Human” project has initiated the study of human organs and systems in disease conditions based on computational modelling. Therefore, many computational and theoretical techniques have been developed for intelligent information processing to lead an expansion in biomedicine research. 

It is well-known that bioactive compounds have many positive advantages for human health. The extension of their shelf life and their applications in the food and pharmaceutical sectors are important issues. Microencapsulation is one of the proven methods to protect bioactive compounds and enable various applications. In this chapter, microencapsulation technology, including the important steps of understanding the physicochemical properties of the bioactive compounds, selection of suitable encapsulation, and microencapsulation methods, is presented. Understanding of physicochemical properties of bioactive compounds and wall materials is the first important step. There are a variety of microencapsulation methods that can be selected to encapsulate the bioactive compounds, depending on the application purpose of the resultant microencapsulated product. In addition, the release rate and release mechanism of microencapsulated particles also play an important role, determined by the selection of wall materials and microencapsulation methods. Finally, methods to evaluate the physicochemical stability of the solution before microencapsulation and the characterization of the microencapsulated particles are also presented. Several examples of successful encapsulation technology and recommendations for further studies of the bioactive compounds are also reported throughout the chapter.