Protein encapsulated gold nanoclusters for biological applications

  • Ben Allan Russell

Student thesis: Doctoral Thesis

Abstract

Sensing and imaging at the nanoscale using fluorescence based techniques has advanced the fields of biology and medical science. However there remain shortfalls with currently used fluorescent probes. One such problem is the lack of biologically inert fluorophores which emit in the red regime of the visible spectrum with good brightness.A class of newly developed fluorophores which have shown promise in fitting the required criteria are protein encapsulated gold nanoclusters (AuNCs). They have been shown to be non-toxic, red emitting, long-lived fluorophores however their low brightness has hindered their widespread use. The complexity of protein encapsulated AuNCs' fluorescence mechanism also remains poorly understood.Fluorescence based techniques, Molecular Dynamics simulations and physicochemical characterisation techniques have been employed to uncover important information critical to improving the fluorescence characteristics of protein encapsulated AuNCs. The AuNCs nucleation site within Human Serum Albumin (HSA) has been discovered which will allow for the intelligent modification of the fluorophores with the aim of improving their fluorescence intensity and low quantum yield.The effects of AuNCs on natural protein function have also been studied; indicating that the major drug binding site of HSA is blocked upon AuNCs synthesis. Further studies of the physicochemical changes in HSA upon AuNCs synthesis uncovered that the protein adopts a dimer state which could lead to complications when using as an in vivo sensor. Lysozyme encapsulated AuNCs displayed similar behaviour, forming dimers after AuNCs synthesis.Interestingly, the isoelectric point of this fluorophore was found to be the same as HSA encapsulated AuNCs, suggesting that protein encapsulated AuNCs share common features. Lysozyme encapsulated AuNCs displayed similar adsorption properties as native lysozyme; suggesting that in the future, unmodified AuNCs could be used to observe the formation of lysozyme fibrils which are a major bio-marker for currently incurable brain diseases such as Alzheimer’s and Parkinson’s.
Date of Award1 Apr 2017
LanguageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsEPSRC (Engineering and Physical Sciences Research Council)
SupervisorYu Chen (Supervisor) & Paul Mulheran (Supervisor)

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