Use this URL to cite or link to this record in EThOS:
Title: Lipsome encapsulated antimicrobial metal ions and essential oils
Author: Low, Wan Li
ISNI:       0000 0004 2715 5491
Awarding Body: University of Wolverhampton
Current Institution: University of Wolverhampton
Date of Award: 2012
Availability of Full Text:
Access from EThOS:
Access from Institution:
This study investigates the feasibility of using TTO and Ag+ alone and in combination either as free or liposome encapsulated agents. Based on the minimum lethal concentration (MLC), the fractional lethal concentration index (FLCI) showed that treatment with unencapsulated combinations of TTO and Ag+ exerted a synergistic effect against P. aeruginosa (FLCI = 0.263) and indifferent effects against S. aureus and C. albicans (0.663 and 0.880, respectively). Using polyvinyl alcohol (PVA) emulsified agents in combination, showed synergistic effects against P. aeruginosa and S. aureus (FLCI = 0.325 and 0.375, respectively), but C. albicans remained indifferent (FLCI = 0.733). Time kill experiments revealed that the combined agent concentrations and elimination time (to the lowest limit of detection, LOD) are as follows: C. albicans: 0.12%v/vTTO:2.5x10-4Ag+:1.5hrs, P. aeruginosa: 1%v/vTTO:3.2x10-4Ag+:15mins and S. aureus: 1.2%v/vTTO:3.2x10-4Ag+:30mins. Repeating these experiments with emulsified TTO encapsulated in liposomes (lipo-TTO:PVA30-70kDa) against P. aeruginosa and S. aureus reduced the effective amount of TTO required (compared to free TTO). However, this was not observed in C. albicans. The required effective concentration of Ag+ from liposome encapsulated Ag+ (lipo-Ag+) was shown to remain the same as free Ag+. The effective concentration and elimination time of liposomal agents in combination are as follows: C. albicans: 0.05%v/vTTO:PVA:8.9x10-5Ag:PVA:2.0hrs, P. aeruginosa: 0.25%v/vTTO:PVA:3.2x10-4Ag:PVA:30mins and S. aureus: 0.05%v/vTTO:PVA:6.0x10-4Ag:PVA:1.5hrs. These results showed the potential of using TTO and Ag+ in combination, along with liposome delivery systems to effectively lower the MLC. Scanning electron micrographs of microorganisms exposed to Ag+ showed a reduction in cell size when compared to untreated cells. Transmission electron micrograph of C. albicans showed the cell surface damaging potential of Ag+. Furthermore, this investigation also demonstrated the feasibility of using chitosan hydrogels as an alternative delivery system for TTO and/or Ag+. The development of these controlled release systems to deliver alternative antimicrobial agents may allow sustained targeted delivery at microbiocidal concentrations.
Supervisor: Kenward, M. A. ; Martin, Claire ; Hill, D. J. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: hydrogel ; liposome ; tea tree oil ; silver ; candida ; pseudomonas ; staphylococcus ; Antimicrobial