Читать книгу Sustainable Nanotechnology - Группа авторов - Страница 47

The characteristic that brings the unique performance of NMs is its nanoscale structured engineering. At the same time, this physicochemical property creates opportunity for increased interaction with biological tissues at molecular level having similar size and structure. This same principle has caused pharmaceutical companies to formulate highly efficient and intelligent drug delivery systems for several diseases, which was not possible in their conventional size formulation. Not only in health care but also in all other sectors, these NMs have improved their characteristics such as strength, weight, appearance, efficiency, and durability. A research for pharmacological action based on NP size shows that NPs < 50 nm diffuse quickly to tissues of living things and bring potential toxicity to those tissues, while NPs >50 nm taken up by a cleaning system of mammalians, reticuloendothelial system (RES), and the RES organs, viz., liver, spleen, and lymph nodes, will become the target of oxidative stress [23]. Few other researchers show that particles <10 nm get deposited in the tracheobronchial of the lung, while all the other <100 nm particles are deposited all over the lungs and cause respiratory adverse effects [24–26]. Several other toxic effects, such as mitochondrial perturbation by silica [27], damage to nervous system [28], endothelial dysfunction [29], generation of neoantigens [30], and immune toxicity [31], are reported with limited clinical evidence. The uptake and interaction in biological tissues observed previously and substances generally regarded as safe now show adverse responses. The NPs generated during manufacturing may get inhaled, and ultrafine particles (<100 nm) induce pulmonary inflammation, oxidative stress, and distal organ involvement or get absorbed through the lungs and can create toxicity in vital systemic circulation. As the size reduces, it increases surface area and finally enhances capability to react with oxygen. Due to increased reaction with oxygen, it enhances inflammation, fibrosis, cytotoxicity, oxidative injury, and carbon deposition in lungs [32]. It is the sole responsibility of the researcher to involve toxicology scientists and closely monitor the toxicity of NPs during each development stage until robust regulatory guidelines based on size and surface area become available. One also needs to take care until the airborne NP hazard has been appropriately assessed; this risk should be managed by taking steps to avoid large quantities of these NPs becoming airborne.