Antimicrobial Strategies Based on Natural Sources and Biomimetic Materials

The high prevalence of postoperative infections represents a serious healthcare problem. A significant number of therapeutics derived from nature (i.e. biomaterials and bioactive compounds) developed in our group have demonstrated promising performance for distinct wound dressing applications. As an example, chitosan/aloe vera-based membranes presented high antibacterial activity without affecting human dermal fibroblasts viability. In a complementary attempt, electrospun chitosan fibrous meshes immobilizing liposomes loaded with gentamicin also present superior bactericidal activity. In yet another approach, gentamicin was encapsulated into dopamine-coated eumelanin nanoparticles. Both nanostructured delivery systems can protect the drug from degradation, decrease the risk of drug toxicity in high concentrations, and increase the therapeutic efficacy by the local release of the antibiotic.<br/>Antimicrobial drug-free biomaterials also emerged as an alternative to currently available solutions, aiming to overcome initial colonization resistant microorganisms to the material itself, while promoting an adequate host response to infection. Ion-doped bioactive glasses (BBGs) and silk fibroin scaffolds gained significant interest in bone tissue engineering. The inclusion of different ions (Mg, Ca, and Sr) has rendered these materials with antibacterial properties while promoting tissue regeneration. Alternatively, recombinant spider silk proteins with antimicrobial peptides as films, coatings, or in solution inhibit the early adhesion of pathogenic microbes, without impairing wound healing. In addition, platelet-based biomaterials like patches or hydrogels also demonstrated anti-infective properties, representing an endogenous and cost-effective source of antimicrobial compounds.<br/>In another innovative approach aiming to confer antimicrobial properties to commercial medical devices (i.e. gauze), a fatty acids eutectic blend based on lauric acid (LA) and myristic acid (MA) was loaded by supercritical fluids technology (i.e. a derived version of rapid expansion of supercritical solution). Indeed, mixtures of therapeutic deep eutectic solvents (THEDES) based in fatty acids (e.g. capric acid (CA)-LA and CA-MA) could be possibly used as broad-spectrum antimicrobial agents. In a complementary attempt, THEDES based on a mixture of perillyl alcohol and ibuprofen has shown to have great potential, both as an antimicrobial agent and as an anticancer agent.<br/>Finally, recently, polyphenols (i.e. vescalagin and castalagin) extracted from cork water also demonstrated bactericidal activity mainly against methicillin-resistant bacterial strains. Our ongoing work further highlights the potential of antimicrobial biomaterials as a new class of medical devices and for being used in Tissue Engineering.