Natural Products for Use in Antimicrobial Microcapsules for Textiles: Novel and Green

Axillary odour, athlete’s foot, eczema and infected wounds, are all conditions that are caused by organisms such as Staphylococcus aureus, Staphylococcus epidermidis, Trichophyton rubrum, Escherichia coli and Pseudomonas aeruginosa. Antimicrobial textiles may go some way in combating such diseases. Essential oils (EOs) via a novel microencapsulation process were explored for there antimicrobial activity on textiles. Ten EOs were screened by the disc diffusion method against S. aureus, P. aeruginosa, E. coli, S. epidermidis and T. rubrum. The Minimum Inhibitory Concentrations (MICs), Minimum Bactericidal Concentrations (MBCs) and Fractional Inhibitory Concentrations (FICs) of Litsea, Lemon and Rosemary EOs were determined using the microdilution method. Litsea oil was most effective, with an average zone of inhibition (ZoI) of 47 mm, 20 mm, 53 mm, 43 mm and 90mm against S. aureus, P. aeruginosa, E. coli, S. epidermidis and T. rubrum respectively. Lemon and Rosemary were the only other EOs effective against P. aeruginosa (ZoI 21 and 24 mm respectively), as well as inhibiting all other microorganisms. Litsea EO gave the greatest inhibition against all microorganisms, with the lowest MIC and MBC observed against S. epidermidis (0.60 and 1.30 mg/ml respectively). Synergistic interactions between the three EOs were observed for E. coli only (FIC index = 0.50); all other interactions were additive. The nanoemulsion encapsulation process of the EOs involved using a self-assembly technique in which the polymer molecules of chitosan (positively charged) and sodium alginate (negatively charged) spontaneously assemble in the presence of the calcium chloride. The microcapsules were then padded onto 100% knitted cotton and polyester and antimicrobial activity assessed at one and seven days after treatment. The coated textiles were inhibitory to all microorganisms with the textiles efficacy increasing over time, T rubrum was the most susceptible microorganism with no growth observed. EOs are promising natural antimicrobials which can inhibit the growth of Gram-positive & Gram-negative bacteria and dermatophytes; the EO can inhibit bacteria individually and synergistically and are therefore good microencapsulation core material candidates for use in functional antimicrobial textiles which are eco-friendly and could be used to alleviate skin conditions and malodour. The potential of the microencapsulated EO will be explored for anti-mosquito functions.