Studies of the Gold-Sulphur Bonding in Nanotechnology

Abstract

This thesis explores the kinetics of gold nanoparticle surface modification with thiols and its potential applications in nanotechnologies. In chapter 3 the ideal functionalization time for thiols to bind to the surface of the AuNP was found to take more than one hour for completion. 7-mercapto-4-methylcoumarin was used to follow the process by fluorescence spectroscopy and serves as a convenient molecular probe to determine relative kinetics. Fluorescence spectroscopy studies with various thiols, such as aliphatic and aromatics, further support the slow surface modification kinetics observed by fluorescence spectroscopy. The formation of thiolate bonds is a relatively slow process; we recommend one to two hour wait for thiol binding to be essentially complete, while for disulfides, overnight incubation is suggested.

The application of gold nanoparticle surface modification was further investigated with its application in a Nanopore Assay as an amplification method for low concentration target proteins. Gold sulphur binding was utilised as a method to attach DNA on the surface of a AuNP in order to increase signalling 100 fold or more. Following low signal results, testing involving the loss of DNA to plastic tubing was investigated and it was noted that interactions with plastic can cause significant loss of sample to the surface of plastic non binding materials.