## 3 Bio-Based Antimicrobial Agents and Wound Dressings for Healing and Infection Control  
Antimicrobial wound dressings are applied to prevent wound contamination and treat wound infections by protecting the wound from microbial penetration and killing the invading microorganisms, respectively. In addition, antimicrobial dressings are also able to improve the healing process by promoting fibroblast migration [2; 35]. Currently, in an attempt to improve their antimicrobial properties along with antibiotic resistance, different natural compounds (inorganic compounds, honey, plant compounds, and natural polymers) and micro and nanoparticles were studied as potential antimicrobial agents to be incorporated in wound dressing [23]. So far, some inorganic antibacterial materials, such as silver and zinc oxide, are being studied and used to enhance wound fessing properties. [PERSON] et al. prepared a silver/alginate nanocomposite hydrogel and performed in vitro functional evaluation, with results showing antimicrobial activity against _S. aureus_ and _E. coli_[2]. Likewise, zinc oxide nanoparticles-loaded-sodium alginate-gum acacia was studied by in vitro wound healing against sheep fibroblast cell culture and antimicrobial tests, showing promising results [2]. On a smaller scale, copper is also being studied as an inorganic material with antimicrobial activity to be incorporated in wound dressings for wound care [30; 46]. Antimicrobial activity of copper-based dressings was already tested and proven against _E. coli_ and _S. aureus_[47]. In recent years, honey has also shown antimicrobial properties to improve the healing process of chronic wounds by minimizing inflammation and stimulating angiogenesis and epithelialization [2]. A study evaluated the antimicrobial properties and wound healing activity of honey by in vitro and in vivo assays, demonstrating the capacity to inhibit _Pseudomonas aeruginosa_, _S. aureus_, _Klebsiella pneumonia_, and _Streptococcus pyogenes_. Furthermore, in the same study, great wound healing properties in burn-induced wounds in mice were also demonstrated [48]. Nowadays, there are already a few wound dressings for chronic wounds available in the market, such as \(\text{Algivon}^{\text{\textregistered}}\) (Advancis Medical, Nottinghamshire, UK) and \(\text{MediHoney}^{\text{\textregistered}}\) (Derma Sciences, Plainsboro, NJ, USA), in which honey is the agent responsible for the antimicrobial activity [23]. In other respects, essential oils have also spurred interest as a source of antimicrobial agents that can be used in the treatment of chronic wounds. Henna (_Lawsonia inemis_) [49; 50] and essential oil of _Hypericum perforatum_[51] are two examples that are being studied as potential natural antimicrobial agents to functionalized wound dressings against _S. aureus_ and _E. coli_. \(\text{[PERSON] et al.}\) studied the antimicrobial potential of cellulose-based fibrous dressings with different essential oils, including cinnamon, lemongrass, and peppermint, revealing a potential capacity of the dressing to inhibit the growth of _E. coli_[52].  
The specific advantage of these essential oil compounds may be related to a synergistic effect of their components, with greater activity when applied as natural essential oils, compared with the effects of the individual compounds [53]. The activity of the main components could be raised by minor molecules present in essential oils composition [53]. In this sense, a number of reports established a link between strong antibacterial activity and the presence of monoterpenes, eugenol, cinnamaldehyde, carvacrol, and thymol in essential oils [54; 55]. Other components, such as sesquiterpenoid bisabolol, nerolidol, farnesol, and apritone compounds have also been explored as traditional antibiotics for their ability to enhance the bacterial permeability and susceptibility of several strains (i.e., _E. coli_ and _S. aureus_) to exogenous antimicrobial agents by affecting the membrane permeability of these bacteria [56].