 Imagine what tiny gold nanoparticles can do. One thing every time a fast immunologic blood test was needed, they seemed to work faster than anything else. Gold nanoparticle tests for HIV and pregnancy actually give you a complete result from the time that you introduced the blood sample in less than 10 minutes. The one place where gold nanoparticles have fallen short is actually in cytometry. The incubation times for cell labeling have been very long and the cluster definition of single strength has been quite weak. So we got into the physics of nanoparticle binding to the CD4 antigen and lymphocytes. And we showed that once we overcame certain charge effects with these gold nanoparticles, binding could happen in less than a minute and the cluster separations were great. So gold nanoparticles are inherently electrically charged and what this means is that after a few particles, just a few, have gotten onto the cell surface, they electrostatically repel the rest of the particles that would like to get on. So what we did was to chemically neutralize the charge on these particles at the very last moment while the binding reaction was going on and we reduced the entire time to label cells to under a minute and as I say the cluster separation became very, very good. So we used some various wavelengths and we found that with a prudent choice of wavelength we could actually get cluster separations that were as good as fluorescence. The choice of wavelength actually seems to be covered by the size of particle aggregates that form on the surface of the cells. We got some other surprises. Since the gold nanoparticle is actually inert, it was very easy to lyophilize these conjugates and obtain conjugate stability of months to years at elevated temperatures and also having no fluorophores to bleach, we could work in bright light with these conjugates. We think the physics of how nanoparticles bind to cell surfaces is just unfolding. There's a lot of detail that needs to be developed. Why are the affinities so extraordinarily high? Why are the on-rates so extraordinarily fast? This is going to have implications in drug delivery systems and certainly implications in cytometry. But for now, I think we have some really exciting applications that we can develop based on these extremely high on-rates and robustness of these conjugates. So for now, the co-authors at Mass General Hospital, UBT, C2 diagnostics and point care technologies, wish you a happy read of the physics of a rapid CD4 lymphocyte count with colloidal gold. Thank you.