Wound infection antimicrobial materials

Cationic polymer-functionalised gold NP have large concentrations of positive charge, which promote their adsorption onto negatively charged bacterial membranes via electrostatic interactions. This kind of antimicrobial material, with effective antibacterial activity and better biocompatibility, can promote the healing of microbially infected wounds and could have promising applications in the biomedical field. 

Microbial cellulose is found to be an optimal material for skin tissue repair due to its ability to provide a moist environment for wound healing and pain free dress changing. Unfortrmately, microbial cellulose itself has no antimicrobial activity to prevent wound infection. However the lack of antimicrobial activity of microbial cellulose is the main issue to be tackled. To improve the antimicrobial activity of microbial cellulose, researchers have introduced different materials such as benzalkonium chloride, chitosan and metallic nanoparticles into microbial cellulose. Among them metallic nanoparticles such as copper, silver [56] and ZnO [57] have been recently reported as excellent antimicrobial agents. Due to the electron-rich oxygen atoms in the microbial cellulose macromolecules and the large surface area of nanoporous microbial cellulose effective as nanoreactor, the in-situ metallization technique was successfully applied to the synthesis of Ag and microbial cellulose nanocomposite, which could in turn serve as antimicrobial skin tissue repair material. 

Current research focus in wound closure suture is to incorporate extra functionality to the suture besides closing the wound. These efforts include control of wound infection by developing antimicrobial sutures, and acceleration of wound heating process by using bioactive material such as chitin, or to deliver therapeutics that can impact wound heating response. 

For patients with infected wounds, two basic treatment protocols are available for medical practioners systemic administration of antibiotics, and topical appUcation of antimicrobial agents on the wounded area directly. While systemic antibiotics are outside the scope of this ch ter, over the years many topical antimicrobial agents have been used to treat wound infection. These are briefly summarized below. In addition to these main materials, other antimicrobial agents that can be used in wound management include tea tree oil and gentian violet ointmaiL Extracts of tea are also said to have inhibitory effects on MRS A. 

In developing antimicrobial dressings to manage wonnd infection, it should be noted that since wound dressings are directly in contact with a broken skin, there are strict requirements for the type of applicable antimicrobial materials. In particular, these materials should meet the following requirements. 

Figure 22.7 Seal prevented fluid escape in one patient causing infection in the foam by Day 14. With strips of seal removed and the wound treated with antimicrobial dressings, the infection subsided and the material integrated. Residual seal removed at Day 35, graft applied, and successful take.

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