The largest number of nanoparticles has been used in medicine and biology. In medicine, commonly used are: silver (Ag), gold (Au), zinc (II) oxide (ZnO), tin dioxide (IV) (SnO2). All these substances in the form of nanoparticles have bactericidal properties. As a precious metal (not very reactive), gold is easily absorbed by the human body. These features allow it to be used in dentures and implants. Silver and its bactericidal properties were already known in ancient Greece and are widely used in many countries. In 2009, the Microbiological Test Report (20005/11858/09), prepared by the Specialized Research Laboratory “ITA-TEST”, on the influence of the preparation with silver colloid (50 ppm, 10 ppm and 0.5 ppm) on the growth of aerobic microorganisms was presented. grown in laboratory conditions, taken from the surface of the skin. The test results clearly showed that water with silver colloid at a concentration of both 50 ppm and 0.5 ppm showed antimicrobial properties against microorganisms isolated from various parts of the body within 15 minutes, 3 and 5 hours. The reduction in the number of the microbial mixture on individual plates in relation to the control plate (dilution fluid) clearly proves the antibacterial properties of the tested preparation. Already after 15 minutes of contact of the tested water with the microbial mixture, the growth of the microorganisms was weakened. However, after 3 and 5 hours of contact, their number was completely reduced.