Biomedical applications of nano-antioxidant

For centuries now, antioxidants have been known to provide better health by neutralizing the free radicals which are continuously produced in the human body. In normal circumstances, self-antioxidant defense system of the human body is capable of quantitatively managing the free radicals. However, in certain cases, which are at the threshold of developing diseases like diabetes and Alzheimer's, the human body calls for an external source of antioxidants. Since orally delivered antioxidants are easily destroyed by acids and enzymes present in the human system, only a small portion of what is consumed actually gets absorbed. Hence, there is a recognized and urgent need to develop effective methods for efficiently delivering antioxidants to the required sites. This chapter provides an in-depth overview and analysis of two such methods and processes-nano-encapsulation and nano-dendrimers. Among the various nanoscale delivery mechanisms, nano-encapsulation has emerged as a key and efficient delivery process. Designed as a spongelike polymer, nano-encapsulated antioxidants provide a protective vehicle which keeps antioxidants from being destroyed in the human gut and ensures their better absorption in the digestive tract. In fact, the nano-capsules bind themselves to the intestinal walls and pour antioxidants directly into the intestinal cells, which allow them to be absorbed directly into the blood stream. Another distinguished and popular mode for delivering antioxidants is that of nano-polymers known as dendrimers. Dendrimers involve multiple branches and sub-branches of atoms radiating out from a central core. Dendrimers afford a high level of control over their architectural design, including their size, shape, branching length or density, and surface functionality. Such flexibility makes these nanostructures ideal carriers in biomedical applications such as drug delivery, gene transfection, and imaging. Antioxidant dendrimers, made out of numerous units of antioxidants connected with each other in a branched fashion, provide numerous possible sites to couple with an active species and have enhanced free radicals scavenging potency. These dendrimer chains are biocompatible, biodegradable with nontoxic degradation products, and well suited for targeted drug delivery and other biomedical applications. Recent successes in simplifying and optimizing the synthesis of dendrimers, such as the "lego" and "click" approaches, provide a large variety of structures while at the same time reducing the cost of their production. The use of these highly branched, nanometer-sized, polymeric materials as nano-antioxidants for prevention and treatment of human diseases, associated with oxidative stress, is of immense public health relevance globally.