  The link between metals, Alzheimers disease (AD) and its implicated protein,
amyloid \b{eta} (A\b{eta}), is complex and highly studied. AD is believed to
occur as a result of the misfolding and aggregation of A\b{eta}. The
dyshomeostasis of metal ions and their propensity to interact with A\b{eta} has
also been implicated in AD. In this work, we use single molecule atomic force
spectroscopy to measure the rupture force required to dissociate two A\b{eta}
(1 42) peptides in the presence of copper ions, Cu2+. In addition, we use
atomic force microscopy to resolve the aggregation of A\b{eta} formed. Previous
research has shown that metal ions decrease the lag time associated with
A\b{eta} aggregation. We show that with the addition of copper ions the
unbinding force increases notably. This suggests that the reduction of lag time
associated with A\b{eta} aggregation occurs on a single molecule level as a
result of an increase in binding forces during the very initial interactions
between two A\b{eta} peptides. We attribute these results to copper ions acting
as a bridge between the two peptide molecules, increasing the stability of the
peptide-peptide complex.
