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Title: Development of polymer films embedded with anisotropic metal nanoparticles and a photosensitizer dye for antimicrobial purposes
Author: Rossi, Francesco
ISNI:       0000 0005 0288 6594
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2020
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The infections caused by drug resistant bacteria are an increasing concern for the health systems around the world, both for their cost and causality rate. An effective strategy to combat these infections is to prevent them, improving the disinfection of facilities where high concentrations of drugs are used. This research presents a novel polymeric antimicrobial film containing gold nanorods (Au NRs) or nanostars (NSs) and a photosensitizer dye, able to kill bacteria by generating reactive oxygen species (ROS), when exposed to light. Two types of anisotropic nanoparticles were synthetized and characterized with multiples techniques. While the introduction of the nanoparticles in the polymer film and the dye diffusion was followed through UV-vis spectroscopy. Interactions between dye and gold NRs/NSs were studied inside the film and in solution. The surface plasmon resonance (SPR) of the particles, simulated with the finite-difference time-domain (FDTD) method was used to predict their coupling with the dye. While, the overlapping between SPR and dye absorption were confronted with the amount of ROS produced by the film. The results against bacteria were calculated counting the surviving colony forming unit (cfu) after exposure to the activated film. Using the simulations, the parts of the SPR absorption participating to the plasmonic coupling were identified. While the efficiency against Gram(+) and Gram(-) bacteria was explored. The films were more effective against E. coli than S. aureus. The film modified with AuNSs could kill 5 orders of magnitudes (5-log) of E. coli in 4 h and 4-log when modified with AuNRs. For S. aureus, it was able to kill 2.5-log when containing AuNSs and 3-log with AuNRs. There was direct dependency between ROS production and Gram(-) population reduction, at the same time the effect against Gram(+) suggests some difference in the type of ROS produced by the film according to the nanoparticles used.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available