Introduction: Nanotechnology is known as a rapidly growing and developing technology. The term nanomaterials is used for materials with a size between 1 and 100 nanometers. Medical nanotechnology was first proposed in the late 1950s by Dr. Richard P. Feynman, which has various applications; For example, it is important in the fields of therapeutic indications, preventive signs, diagnostic signs and other related matters. In fact, as medical science progresses, the use of nanoparticles in this science is also increasing. Along with the useful applications of nanoparticles in medical science, their possible toxicity should also be considered. Recent studies have shown that some nanoparticles cause toxicity to humans and thus the environment. In this article, we review the users of nanoparticles in medical science and categorize these different applications. Methods: To write this article, we used Google Scholar and PubMed databases. We limited the time of the articles between 2019 and 2023 and reviewed the related articles in these 4 years. After categorizing the articles, the articles were used to write different sections. Various words and phrases were used for the search, which included: application of nanoparticles in medical science/application of nanoparticles in drug delivery/application of nanoparticles in medical imaging/application of nanoparticles in veterinary medicine/nanoparticles in head diagnosis/nanoparticles in cancer treatment. Results: Nanotechnology has a variety of applications in medical science, which we categorize some of these applications below: Veterinary medicine: 1. Management of drugs, vitamins and nutritional supplements 2. Diagnosis and elimination of the causes of infection without using surgery 3. Improvement of growth rate 4. Elimination of reproductive disorders of animals 5. Elimination of digestive problems (for example, elimination of diarrhea in pigs) 6. Production of medical livestock vaccines Medical imaging: Nanoparticles are used for medical imaging due to features such as very small size, suitable half-life in blood circulation, cell absorption and high penetration in the tumor, and suitable targeting power, and help in early diagnosis of the disease. It creates a proper distinction between normal tissues and abnormal wastes. Forensic Medicine: Some nanoparticles have the ability to detect human fingerprints and in this way help the possibility of discovery at crime scenes. Antimicrobial properties: Some nanoparticles limit the growth of certain microorganisms and also biofilms and destroy them, and in this way they have antimicrobial properties. Other applications of nanoparticles in medicine: orthopedics, dental medicine, genetic engineering and gene therapy, production of biosensors, fluorescent biological tags, tumor destruction through hyperthermia, pharmacotherapy and drug delivery, protection against radiation, making burn ointments, etc. Conclusion: Although the application of nanoparticles in medical science is still in the research and development stage, it is a progressing knowledge that covers various aspects of medical science. It is expected that in the future, more research will clarify the role and nature of the application of nanoparticles in this science. So that effective processes can be clearly explained. It is also important to note that the knowledge of medical nanotechnology is an interdisciplinary specialty and requires the cooperation of experts in different fields. Another important point is that in addition to the research related to the understanding of the role of nanoparticles in medical science, the research on the possible toxicity of nanoparticles should become more important and the effect of different nanoparticles with different doses on different organs of the human body as well as its impact on the environment should be carefully investigated.
