# Novel Approaches to Combat Medical Device-Associated BioFilms
## 3 Novel Approaches to Combat Medical Device-Associated Biofilms
### Nanotechnology  
Nanotechnology is used to study the properties and applications of NMs. Nanometer is a unit of length that is equal to one billionth of a meter or \(10^{-9}\) m. NMs are materials with at least one dimension at the nanometer scale (1-100 nm) in three-dimensional space, and these materials exhibit some special physical and chemical properties that are different from those of macrolevel materials. NMs have a wide range of applications in the fields of electronics, optics, manufacturing, and biomedicine, and they have also been developed for use in a variety of medical diagnosis and treatment applications [209]. NMs, especially NPs, have an increased specific surface area and surface functionalization that enable them to interact closely with microbial membranes and exhibit antimicrobial activity, even at very small doses [210]. These properties contribute to the development of antibacterial drugs [210]. The antibacterial and antibioofilm activities of NPs have been widely demonstrated in different pathogens, and their biological activities depend on different characteristics, including the size, shape, surface charge, structure, material type, and concentration [210; 211]. The antibiofilm mechanisms of NPs are as follows. NPs can come into contact with bacterial cell walls and damage them through different interactions, induce changes in the membrane shape and function, induce oxidative stress and act as catalysts to interact with microbial cells, disturb the respiratory chain function, cross microbe membranes, interfere with metabolic pathways, interact with the microbial cellular machinery to inhibit enzymes, inactivate proteins, or modify gene expression levels [212; 213]. NPs can also be used as drug delivery carriers or as catalysts to promote the penetration of drugs into biofilms; improve the solubility, stability, and biocompatibility of drugs; or enhance the antibiofilm activity by physically destroying the structure of the biofilm [22]. The antibiofilm mechanism of NPs is well-described in the study by [PERSON] and others [1] (Figure 1). Nanotechnology has developed rapidly. As mentioned above, this technology has been applied for the surface modification and improvement of AMPs. In this section, we will focus on the research progress in NMs that have exhibited promising results against biofilms. Antibiofilm NMs include inorganic materials (such as gold and silver) [214; 215; 216; 217; 218; 219], polymers (such as the natural antibacterial substance chitosan, biodegradable polymer polylactic acid, and carbon-based polymer fullerene) [220; 221; 222; 223], lipids (such as liposomes) [224; 225], and molecular complexes (such as protein nanocomplexes) [226]. The following studies are examples of different NMs that are used against biofilms. Metal NPs exhibit bactericidal activity against a variety of microorganisms by releasing metal ions and are effective bactericides. At the same time, they have also been proven to have an impact on biofilms. Silver is currently one of the most widely studied metals in nm research. Biosynthetic AgNPs from _Planerochaete chrysosporium_ with a diameter of 45 nm exhibited a high negative surface charge close to 30 mV and showed colloidal stability from pH 3 to 9 under conditions of a high ionic strength ([NaCl] = 10-500 mM). It was shown that the AgNPs could kill bacteria by acting on fatty acids of _E. coli_ cells to destroy the integrity of cell membranes. Moreover, the results further demonstrated that these biosynthetic AgNPs displayed biofilm disruption activity. These biogenic AgNPs were added to preformed biofilms and incubated for 48 hours, leading to a 29% reduction in the biomass of _E. coli_ biofilms and an 80% reduction in the biomass of _C. albicans_ biofilms [212]. Another study showed that _P. aeruginosa_ biofilms treated with green synthesized seabxtthom AgNPs (SBT@AgNps) can significantly reduce the bacterial load in biofilms, disrupt the matrix structure and cell wall, and interact with the cell membrane.