# Novel Approaches to Combat Medical Device-Associated BioFilms
## 3 Novel Approaches to Combat Medical Device-Associated Biofilms
### Surface Modification  
Applying antibacterial agents or antiadhesion agents to the surface of medical devices through surface engineering can effectively inhibit the adhesion and growth of microorganisms and prevent the formation of biofilms, which has become an important strategy for combatting biofilms related to medical devices. Antibacterial coating approaches prevent the formation and development of biofilms on medical devices through bacteriostatic or bactericidal effects. Traditional antibacterial coatings, such as chlorhexidine, gentamicin, minocycline, rifampicin, silver sulfadiazine, amikacin, and vancomycin, have been widely used in clinical practice, showing the efficacy of preventing catheter-related and other implant-related infections [138; 139; 140]. The combination of multiple antimicrobials, such as the combination of the antibiotics minocycline and rifampicin, has also shown good results in preventing single-drug resistance [138]. On the other hand, the extensive use of antimicrobial coatings may lead to bacterial resistance to antibiotics. To date, studies of antibacterial coatings have focused on the development of novel compound coatings with antibacterial effects or antibiotic delivery functions to prevent the formation of biofilms. We have summarized the novel surface-modifying compounds used against biofilms and mechanisms of action in Table 2.  
Antimicrobial compound coatings or antiadhesion coatings are used to modify the surfaces of medical device materials to inhibit biofilm formation by killing bacteria or reducing bacterial adhesion (Figure 1). An isoeigenol coating has been shown to prevent the formation of biofilms on stainless steel and polyethylene surfaces due to its good antibacterial activity [141]. N-acetyl cysteine is an Food and Drug Administration (FDA) -approved drug that is widely used to treat many different clinical diseases, such as chronic bronchitis, cardiac ischemia-reperfusion injury, and paracetamol poisoning [142]. The drug has been suggested to not only have antibacterial activity [143], but also reduce bacterial adhesion and prevent biofilm formation. Because of its excellent safety performance, it has been widely studied as a coating for medical implants, such as bone-related implants [144]. Existing methods of coating biomaterials with antibiotics and other reagents produce surfaces that are prone to degradation over time. Metal-based materials have a long history as antibacterial agents [145], such as the silver coatings used on a variety of medical devices. NMs exhibit enhanced antibacterial activity and a reduced cytotoxicity [146]. Silver nanoparticle (AgNP) coatings are also used to prevent bacteria from becoming attached to medical devices [147]. A recent study has shown that the topographical effects of nanostructure surfaces may have significant impacts on the adherence pattern and stretching degree of the bacterial cell membrane [148]. New alloys and metal-ceramic compounds are also used in anti-medical device biofilms. For example, a copper-bearing titanium alloy has been shown to efficiently kill the attached bacteria by damaging cell membranes and cell walls and strongly inhibit the biofilm formation and prevent bacterial infection associated with dental implants, meaning that it has great potential for application in dental implants with an excellent antibacterial viability and positive effect against bone resorption induced by peri-implantitis [149]. The tantalum processed by micro-Arc oxidation increased its surface roughness, hydrophilicity, and corrosion resistance, and improved its antibacterial activity against _S. aureus_, meaning that it exhibits great potential for application as a material for hard tissue implants [150]. Polycrystalline Zirconium Dioxide Ceramic presents the same characteristics for _S. mutans_ biofilm formation as polymer-infiltrated ceramic, which can inhibit biofilm formation, and they both have a good biocompatibility with human fibroblasts.