Читать книгу Nanobiotechnology in Diagnosis, Drug Delivery and Treatment - Группа авторов - Страница 41

The distinctive behavior of nano‐scale materials, as compared to conventional chemicals or biological agents, in biological systems is mainly expected due to their minute size. The minuscule size allows them to enter not only organs, tissues, and cells, but also cell organelles, e.g. mitochondria and nuclei, by crossing various barriers (Auría‐Soro et al. 2019; Tang et al. 2019). However, this may drastically modulate the structures of macromolecules, thereby impeding critical biological functions (Patel et al. 2015). They can also initiate blood coagulation pathways and stimulate platelet aggregation resulting in thrombosis. Various mechanisms as proposed by research scientists after evaluating in vivo toxicity of the nanomaterials is mainly through the generation of oxidative responses via the formation of free radicals and reactive oxygen species which may cause oxidative stress, inflammation, and damage to DNA, proteins, and membranes, ultimately leading to toxicity. The clearance of these materials by the reticuloendothelial system protects other tissues but engenders oxidative stress in organs such as liver and spleen (Badar et al. 2019).

Several toxicological studies have demonstrated that the toxic effect of nanomaterials is also regulated by their route of entry into the body, such as oral, skin, respiratory route, site of injection, and digestive canal, and further translocation and distribution according to the size determine additional toxic manifestations. The reduction in size leads to an increase in a number of surface atoms and as the surface area increases, it confronts dose‐dependent increments in oxidation and DNA‐damaging abilities. This also brings about an increase in surface energy further initiating binding of proteins that send a signal to macrophages and in turn engulfs the nanosized particles (Werner et al. 2018). Apart from this, certain unpredictable reactions can also take place inside the body due to unanticipated interactions and behavior of these particles. The research fraternities believe that the toxicity of nanomaterials strongly depends on their physical and chemical properties, such as the shape, size, electric charge, solubility, presence of functional groups, and chemical compositions of the core and shell. Reckoning with these facts of the toxicity and safety of nanosized materials presents a challenge in its clinical translation for drug delivery, diagnosis, and treatment of diseases (Gatoo et al. 2014). In recent years, when nanomaterials are becoming a part of daily life, toxicity concerns should not be ignored and accurate methods must be established to evaluate both the short‐term and long‐term toxicity analysis of nanosized drug delivery systems. Other significant hurdles faced are various biological challenges, fate and behavior in the environment, biocompatibility, safety, large‐scale manufacturing, intellectual property, government regulations, and cost‐effectiveness as compared to traditional therapy (Hua et al. 2018).

Although nanomaterials hold great promise in medicine, their production, use, and disposal lead to discharges into air, soil, and aquatic systems. It thus becomes imperative to assess the impact of such material with unknown toxicological properties on environmental health in addition to various pre‐processing procedures investigated before disposal. The vagueness associated with the risks of using nanomedicine in living beings cannot be ignored and they cannot be regarded as an ideal form of therapy. The science of using nanosized materials in the field of medicine has dynamically developed in recent times, but the ambiguity surrounding their characterization about safety and toxicity, and the lack of effective regulation with necessary closer cooperation between regulatory agencies, put forward the utmost challenge to evaluate their real impact in the healthcare system.