Samad Khaksar

Cobalt is an essential trace element in biochemistry that plays a crucial role in the structure and function of several important biomolecules. In this review, vitamin B12 is discussed as one of the best-known examples in this area. Various forms of this vitamin, including methylcobalamin and adenosylcobalamin, play a crucial role in metabolic reactions in mammals and prokaryotes. It also discusses cobalt-containing enzymes that are essential for various biological processes. These enzymes are B12-dependent enzymes, which are well studied, and cobalt-containing enzymes, which are less well known, such as methionine aminopeptidase, nitrile hydratase, glucose isomerase, and prolidase. In addition to the significant role of cobalt complexes in biochemistry, these complexes are considered potent anticancer agents that can exert their antiproliferative effects through the production of ROS, cell cycle arrest, MMP breakdown, and induction of apoptosis in cancer cells. Cobalt complexes are also being explained here for their antimicrobial properties against a variety of pathogens, including bacteria, fungi, and viruses. Furthermore, examples of these complexes are presented as promising agents for the suppression of AD, which could be effective by binding to Aβ-peptides and preventing their aggregation, which is a central feature of the pathogenesis of AD, or by combating the oxidative damage associated with the disease, or even by interfering with the enzyme activities associated with this disease. Finally, the challenges related to the toxicity of cobalt and its compounds in medicine are discussed, and chelation therapy is considered an effective treatment for cobalt poisoning.

Copper is a necessary micronutrient for maintaining the well-being of the human body. The biological activity of organic ligands, especially their anticancer activity, is often enhanced when they coordinate with copper(I) and (II) ions. Copper and its compounds are capable of inducing tumor cell death through various mechanisms of action, including activation of apoptosis signaling pathways by reactive oxygen species (ROS), inhibition of angiogenesis, induction of cuproptosis, and paraptosis. Some of the copper complexes are currently being evaluated in clinical trials for their ability to map tumor hypoxia in various cancers, including locally advanced rectal cancer and bulky tumors. Several studies have shown that copper nanoparticles can be used as effective agents in chemodynamic therapy, phototherapy, hyperthermia, and immunotherapy. Despite the promising anticancer activity of copper-based compounds, their use in clinical trials is subject to certain limitations. Elevated copper concentrations may promote tumor growth, angiogenesis, and metastasis by affecting cellular processes.

Three-dimensional (3D) printing is one of the most interesting subjects in recent years due to its capability to construct multifunctional devices. Nanomaterials are materials having at least one dimension in the range of 1–100 nm. Nanomaterial properties depend on their size. Hence, by tailoring their size, various characteristics can be observed. Fabricating nanomaterials with 3D printing methods can enhance mechanical, optical, electrical, biological, and thermal properties which could not be gained by conventional fabrication methods. Nanofibers, nanoparticles, nanosheets, nanocrystals, and nanopatterning are potential material forms that can be fabricated by 3D printing. These materials have a vital role in electronics, customization of biomedical devices, and bioelectronics. The aim of this chapter is to highlight different nanomaterials fabricated by 3D printing and discuss their application. Finally, we discuss possible limitations and their solution and provide a future perspective in this field.