The development of nanotechnology is a promising technological trend that can have a great impact in many fields, such as physics and biology, medicine, electronics, food, water quality, textile industry, air quality and biomechanics. 1. It is defined as “a science and technology conducted in a billion (10-9) about the meter,” ie, on the nanoscale (1–100 nm).
There are many types of nanoparticles, such as metallic, nonmetallic, organic, and inorganic nanoparticles 2. Titanium, copper, and silver nanoparticles are examples of metallic nanoparticles. Titanium dioxide (TiO2) has unique properties, such as low cost, stability, low toxicity, high refractive index, high optical properties, high ultraviolet absorbance, strong redox ability, high energy gap (ie, 3.2-5.2 eV), and has good electrical, optical and magnetic properties 3,4. It is necessary to fully define the characteristics of nanoparticles, such as their size, shape, surface morphology, crystallinity, and light absorption, using appropriate characterization methods. 5, such as microscopy techniques (electron microscopy or scanning probe microscopy). In addition, optical techniques (spectroscopy) can be used to study the characteristics of nanoparticles, such as reflectance, transmittance, photochemistry, and luminescence. 6. Brunauer-Emmett-Teller (BET), X-ray diffractometry (XRD), and infrared spectroscopy (IR) are the most widely used techniques for characterizing NP structures and can be used to characterize the phase , particle size, type, and crystalline nature of nanoparticles. The surface quality of nanoparticles is influenced by their mechanical properties, which include stress, surface coatings, hardness, strain, friction, and adhesiveness. The characteristics of TiO2 include stability, low cost, nontoxicity, biocompatibility, optical, and electrical properties. It usually occurs in three distinct forms, including brookite, anatase, and rutile, which have different structures. Thermodynamic simulations show that during heating, anatase and brookite transform into rutile, which is more stable at all temperatures and pressures below 60 kbar. 7. Nanomaterials, such as TiO2 photocatalysts, show unique activity in the photodegradation of various organic and inorganic pollutants. Since organic contaminants can be completely degraded to harmless materials under normal conditions of temperature and pressure, it is expected that photocatalysis will soon become one of the most efficient methods to deal with various types of waste. Pollutants, including herbicides, carboxylic acids, and alcohols, can be completely broken down into carbon dioxide, water, and simple minerals. 8. The photocatalyst must have certain qualities, such as the correct particle size, shape, crystallinity, and anatase to rutile ratio, to be effective. The most commonly used methods to produce TiO2 nanoparticles are electrodeposition, reverse micelles, sol-gel method, metal organic chemical vapor deposition, flame combustion method, gas phase (aerosol) synthesis, hydrothermal method, wet-chemical synthesis by the precipitation. of hydroxides from salts, and microemulsion-mediated methods 9. The sol-gel process is a wet-chemical technique commonly used in the fields of materials science and ceramic engineering. It can be defined as the conversion of a primary solution into an inorganic solid by water-induced polymerization reactions. 10. Hydrolysis forms a sol which is basically a dispersion of colloid particles in a liquid, and condensation leads to the formation of a gel. Compared to the methods mentioned above, the sol-gel process is excellent for the synthesis and preparation of inorganic and organic-inorganic hybrid nanomaterials because it allows the use of low processing temperatures (<100 °C) and homogeneity level of molecular composition. 10. Particle size and shape can be easily controlled using the sol-gel method. The sol-gel process produces fine, spherical powders of uniform size and is widely used to synthesize TiO2 materials and usually proceed through an acid-catalysed step of titanium (IV) alkoxides 11. One of the most attractive features of the sol-gel process is the possibility of molding the resulting material in the desired forms, such as fiber, film and monodispersed powder. Several steps and conditions are used in the sol-gel process to control the final morphology, as suggested by Mehrotra and Singh. 10. The use of TiO2 as a photocatalyst to kill microorganisms has been known for a long time 12. The antibacterial properties and mechanisms of nanotechnology are widely discussed, including TiO2 nanoparticles, which are widely used due to their photocatalytic properties to break down and remove dirt, odors, and kill bacteria. The mechanism of this technique depends on the generation of reactive superoxide radicals (O2− and ·OH) on the surface of TiO2 molecules during the photocatalysis process when exposed to light of the appropriate wavelength 13,14,15. Oxygen radicles affect bacterial cells through different mechanisms, leading to their death. The two types of bacteria differ from each other in their response to antibacterial nanoparticles. Disinfection is defined as a treatment method used to eliminate pathogenic microorganisms, but it does not eliminate bacterial spores. 16. In recent decades, TiO2 in the form of nanoparticles has been known to have several antibacterial activities. 17,18. Fabric face masks are materials used to protect against respiratory pathogens (bacterial or viral) 19. They are classified as TREES masks, half mask, and quarter mask. The effectiveness of the filter on Face masks vary from one to another depending on the density of the face mask material 20. With continuous use of face masks without regular exchange, improper washing can contaminate the surfaces, because the temperature and humidity enable moisture and therefore microbial colonization; In addition, improper use may lead to the risk of pathogen spread 21,22,23,24,25. The disposal of face masks leads to a large increase in waste, which is classified as “dangerous with an infectious risk”, and face masks are discarded as biological hazards. 26. Nanoparticles have been shown to be able to kill a wide range of organisms, including gram-negative and gram-positive bacteria, which differ in terms of their cellular wall and envelope and therefore their resistance to disinfectants. 27. In addition, many other organisms, including viruses, fungi, algae and protozoa, have been shown to be killed by TiO2 nanoparticles. 12. It has been shown that these nanoparticles are useful for disinfecting face masks 16,17. TiO2-coated face masks are widely used for their improved self-cleaning and antibacterial properties to control infectious diseases, such as COVID-19 28. This paper aims to evaluate the antibacterial properties of face masks coated with TiO2 nanoparticles.
