Please see the period at the end of this sentence. What is the use of particles that are only 1/10000 in size for this period? The answer is beyond your imagination. These are nanoscale particles, and technology based on nanoscale materials is playing an increasingly important role in our world. For example, carbon nanofibers can increase the strength of aircraft and bicycle frames, silver nanoparticles can be made into antibacterial fabrics, and moisturizing nanoparticles called nanoliposomes can be used in cosmetics. Nanotechnology is also revolutionizing medicine. Because nanoparticles can easily pass through the blood-brain barrier, they will assist in the treatment of diseases such as brain diseases, cancer, and dementia in the future; The nanoparticles in eye drops may assist in correcting vision; Implanting nanoparticles into the eyes, ears, or brain can significantly improve human night vision or hearing abilities; Even nanoparticles can allow people to control their smart homes and cars with their brains. This is not science fiction, these are currently hot research areas. However, the framework for evaluating the safety and ethics of nanoparticles has not kept up with the pace of research. If the standards are not updated, it is difficult to determine whether nanotechnology will make our world a better place. What exactly are nanoparticles? Any particle or material between 1-100 nanometers in size can be classified as a "nanoparticle". The diameter of human hair is about 100000 nanometers, but this number is too large to belong to the category of nanometers. In nature, the diameter of a single coronavirus is about 100 nanometers, and the diameter of smoke particles generated by forest fires can be as small as 10 nanometers. These are two examples of naturally occurring nanoparticles. Nanoparticles can also be produced in the laboratory. The adenovirus vector, nano lipid carrier and mRNA used in COVID-19 vaccine are engineering nanoparticles; Zinc oxide and titanium dioxide used in mineral sunscreen are also engineering nanoparticles; The same goes for carbon nanofibers in airplanes. Nanoparticles have properties that are completely different from larger materials, and even if they have the same chemical composition, they will exhibit different behaviors. For example, large particle zinc oxide cannot dissolve in water, while nanoscale zinc oxide can be stably dispersed in water. The latter can be used for sunscreen, although it appears almost transparent, it can reflect sunlight off the surface of the skin to prevent sunburn. Nanoscale zinc oxide also exhibits antifungal properties and can be used to manufacture antibacterial surfaces, but its antibacterial mechanism is not fully understood. That's where the problem lies. Although scientists are very interested in the beneficial aspects of nanomaterials for humans, their behavior is still not well understood. Is nanotechnology safe? Nanoparticles have great appeal to biomedical researchers because they can easily penetrate cell membranes, making them highly effective in vaccines and some treatments. Scientists also speculate that the antibacterial properties of nanoscale zinc oxide may be related to their ability to penetrate bacterial cell membranes. And people's concerns about nanoparticles are partly due to their ability to penetrate human cell membranes. Take zinc oxide as an example. In the United States, zinc oxide is considered safe and effective by the US Food and Drug Administration and can be used in products such as sunscreen, as zinc oxide is unlikely to have an impact on sunscreen