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Title: Charge transport across phospholipid bilayer membranes via functionalised gold nanoparticles
Author: Danks, Stephen
ISNI:       0000 0004 9358 9423
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2019
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Charge transfer across phospholipid bilayer membranes is an integral process for all biological species. The aim of this project was to mimic this process using functionalised gold nanoparticles. Two distinct platforms were developed to allow the study of the phospholipid membranes electrochemically. These were characterised using cyclic voltammetry and potential measurements. Each platform was tested using the model ionophore gramicidin. Using the first platform, a membrane formed across an aperture, it was shown that gramicidin channels are blocked by divalent ions. The second platform used a droplet-based system, and Nernst-Donnan behaviour was confirmed in the presence of an electrochemical gradient of protons across the membrane. Mercapto-carborane functionalised gold nanoparticles, which had been identified as potential ion-carriers in previous research, were examined using various metal-chlorides. These were found to be ion-selective ionophores that could themselves partition across the membrane and generate an electrochemical potential. 12-Crown-4 functionalised gold nanoparticles were also shown to act as charge transporters. Focusing on H+ transport, these particles demonstrated two separate mechanisms of charge transfer that were dependent on the surrounding H+ concentration. At low H+ concentrations, the particles appeared to act as membrane-penetrating poly-anions. At high H+ concentrations, they appeared to become hydrophobic and facilitate proton transfer across the membrane. Ion and H+ transport across synthetic phospholipid bilayer membranes have been demonstrated separately using two varieties of functionalised gold nanoparticles. This project reinforces and extends the conviction that metallic nanoparticles can be developed and used as artificial ionophores.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral