Development of nanoparticle sizing system integrated with optical microscopy using fluorescence polarisation

There is a strong demand for the development of functional nanostructured devices. On the basis of fundamental chemistry, the fields of biotechnology and materials science have developed over the past three decades into powerful disciplines that allow the engineering of advanced technical devices. The functions of nanostructures are greatly influenced by their size and shape. In order to enable precise fabrication of nanostructured devices by bottom-up methods, real-time control based on in situ evaluation of nanoparticle growth and aggregation is needed. The fluorescence polarisation technique allows estimation of the size of a macromolecular structure from rotational diffusion constants, which can be obtained from the correlation of polarisation in fluorescence from fluorophores attached to the macromolecular structure. By analysing the degree of fluorescence polarisation, the theoretical size can be calculated by the Perrin-Weber formula. In this study, we investigated the degree of fluorescence polarisation dependency on different sizes of fluorescein-labelled nanoparticles.