I have successfully constructed a custom-made polarization-selective confocal microscope system. This also includes the development of a suited software package allowing for command & control, real time feedback to the experimentalist as well as dedicated signal analysis tool sets. With this system I have successfully obtained ensemble autocorrelation functions for 5 nm diameter gold nanoparticles as well as microemulsion nanodroplets, which are possess similar physical properties to proteins with masses of approximately 250 kDa. This is in line with the initial steps projected in the action’s proposal.
These autocorrelations exhibit a time resolution of few nanoseconds, which constitutes a more than 1000-fold improvement over the state of the art as well as an improvement of approx. 10- fold in particle size [Wulf et .al, The Journal of Physical Chemistry Letters 2016, 7, 4951-4955]. Autocorrelations curves represent an ensemble average over many single particle events. Observation of such single events is not possible with other state-of-the-art optical sensor systems.
The system constructed as result of this action, however, is capable of resolving events on a single-event basis – an example trace exhibiting such events is shown below. The events are indicated with red arrows.
The capacity to resolve single events constitutes a significant scientific breakthrough. It enables to extract information about the analyte and its behaviour which otherwise would be lost by ensemble averaging. Publication of these results in a high impact factor journal can be expected – the manuscript is in preparation.
While the technical challenges of resolving single events delayed the implementation of the initial idea of the proposal regarding thermophoretic fingerprinting – it will in the long run only enhance the initial idea and provide more solid understanding of the all observed analytes/processes.
