## 3 Biomedical Applications of Yttrium Oxides Nanoparticles
### Actions as Antioxidant  
Currently, nanotechnology and nanoparticle usage is a growing research area. ROS represents hydroxyl radical (OH), superoxide radical (O\({}_{2}\)), and hydrogen peroxide (H\({}_{2}\)O\({}_{2}\)). Among them, (OH) group attracts and associates with lipids, proteins, and nucleic acids that lead to the disintegration of the outer membrane of organelles, and causes functional deterioration in genetic materials and proteins [101]. To compensate for the toxic effect of ROS, the body activates antioxidant defense responses, viz. enzymatic and nonenzymatic components [102]. Oxidative stress is known to cause several complex diseases, including diabetes mellitus [103]. Increased oxidative stress, coupled with an increased level of ROS caused the injury, and splitting cellular DNA strand was reported [104]. Y\({}_{2}\)O\({}_{3}\) is a metal oxide that exhibits remarkable free energy of oxide formation sourced from elemental oxide. Y\({}_{2}\)O\({}_{3}\) NPs enable protection of the cells from oxidative stress-induced cell death, based on the structure of the particles, and the unique nature of its size in the range (6-1000) nm [105]. In recent times, the use of silver nanoparticles in diabetic wound healing therapy was also reported. Other oxide NPs are synthesized, and proved to be a free radical scavenger [106].  
Several researchers on various cell types have investigated the antioxidant properties of Y\({}_{2}\)O\({}_{3}\). A higher concentration of Y\({}_{2}\)O\({}_{3}\) NPs enhanced the production of reactive oxygen species (ROS) in cells, leading to stimulating the immune system. A study conducted by [PERSON] et al. [96] reported the effects of cerium oxide NPs and Y\({}_{2}\)O\({}_{3}\) on pancreatic islets, and the effects of Y\({}_{2}\)O\({}_{3}\) and CeO\({}_{2}\) NPs on anti-apoptosis in a rat model. The combination of Y\({}_{2}\)O\({}_{3}\) and CeO\({}_{2}\) NPs inhibited the oxidant production and apoptosis and high viability of normal cells, and insulin secretion was also observed. These indicated Y\({}_{2}\)O\({}_{3}\) and CeO\({}_{2}\) NPs may be involved in the protection of beta-cell apoptosis by accelerating oxidative stress. Currently, another study carried out by [PERSON] et al. [107] has explored that Y\({}_{2}\)O\({}_{3}\) NPs and CeO\({}_{2}\) NPs exerted efficient antioxidant potential, and could be used in the proliferation of mesenchymal stem cells (MSCs). Various sizes of Y\({}_{2}\)O\({}_{3}\) influenced the morphology, and the proliferative potential of MSCs are proved to be Y\({}_{2}\)O\({}_{3}\), CeO\({}_{2}\) NPs participating in intensifying the proliferation process of the human dental pulp. Earlier reports have speculated that the well-known free radical scavenger effects of Y\({}_{2}\)O\({}_{3}\) NPs are attributed to their non-stoichiometric crystal structure [108]. In 2006, [PERSON] et al. [109] also studied the Y\({}_{2}\)O\({}_{3}\) NPs effects on nerve cells, and their protection from the lethality of the cells from oxidative stress and neuroprotection is reportedly independent of particle size. Yttriumoxide can serve as an antioxidant to control or neutralize the ROS needed to exterminate the cells. Therefore, Y\({}_{2}\)O\({}_{3}\) has played a crucial role in antioxidant and neuroprotective against oxidative stress and apoptosis in vivo.