Growth in nanotechnology has been fuelled by miniaturization of electronic systems,
development of biomedical sciences and interest in nanomaterials that exhibit
interesting properties. Current techniques to fabricate small devices have difficulty in
accessing the size range between 10-100 nm, and conjugation of biomolecules with
inorganic nanoparticles (NPs) can potentially be used to bridge this gap. Biological
functions of living cells operate in the nanoscale and there is great potential in using
bionanotechnology to discover new biomedical applications in diagnostics, drug
delivery and cancer therapy.
In this thesis, N-fluorenylmethoxycarbonyl (Fmoc)-protected peptides are explored as
tethers to self-assemble gold NPs. Assembly is characterized by transmission electron
microscopy, UV-visible spectroscopy, Raman spectroscopy, zeta potential
measurements, dynamic light scattering and a new technique, Nanoparticle Tracking
Analysis system (NTA).
Solutions of gold NPs exhibit unique colour changes depending on their aggregation
state, and the use of peptide-functionalised NPs (peptide-NPs) in a novel approach of
protease sensing is developed here. Detection of the protease, Thermolysin from
Bacillus thermoproteolyticus Rokko was demonstrated, and design of peptide-NPs
was further optimized for detection of two medically relevant proteases, non-bindingto-
alpha-chymotrypsin prostate specific antigen (nACT-PSA) and human neutrophil
elastase (HNE). nACT-PSA and HNE are proteases related to prostate cancer and
lung diseases respectively, and detection of PSA using the engineered peptide-NPs
resulted in higher sensitivity than previously reported approaches.
Surface enhanced Raman scattering was also used to monitor thermolysin action on
peptide-NPs, in a novel approach which gave higher sensitivity than when using UVvisible
spectroscopy for detection. The quartz crystal microbalance was also applied
in complementary measurements to elucidate enzyme action on the peptides.

The successful approach demonstrated here of using peptides to self-assemble gold
NPs could pave new ways for the fabrication of small devices. Novel approaches of
protease-sensing using peptide-NPs further illustrate potential of nanomaterials for
new biomedical applications.