eFluor^® Nanocrystals are a unique and non-traditional type of semiconductor which enable diverse applications for the life sciences. The significant versatility of eFluor^® Nanocrystals derives from their adjustable size (2-10 nm in diameter, 10-50 atoms).

This property, together with their unique proprietary composition, allows eFluor^® Nanocrystals to be finely-tuned to the desired emission wavelength.

The eFluor^® Nanocrystals fluorescence emission is established by adjusting its size. The emission frequency of the nanocrystal is dependent on the bandgap, a physical property associated with the particle, which can be finely controlled to specify its "color" output. In addition to emissive advantages, nanocrystals possess advantageous absorptive properties. In contrast to bulk semiconductors, which display a rather uniform absorption spectrum, the absorption spectrum for nanocrystals appears as a series of overlapping peaks that get larger at shorter wavelengths resulting in maximal absorption in the UV/violet range.

eFluor^® Nanocrystals can be excited by multiple wavelengths providing the desired flexibility in applications such as flow cytometry and immunofluorescence microscopy. The peak emission wavelength is bell-shaped (Gaussian) and occurs at a longer wavelength than the lowest energy exciton peak (the absorption onset). This energy separation, known as the Stoke's Shift, is larger than that which occurs with organic dyes.

eFluor^® Nanocrystals are precisely manufactured to ensure uniform size and consistent performance. Their small size ensures that, upon cell binding, they do not interfere with normal cellular processes and, importantly for flow

cytometry, they do not alter the forward and side scatter profile of cells to which they are bound. The unique composition of eFluor^® Nanocrystals ensures that they are non-aggregating and will not cause cell-clumping.