In his opening remarks, Sergio Fantini, the moderator of Saturday night’s BiOS Hot Topics session, noted that the evening’s talks represented the state of the art in biomedical optics. And indeed they did. Reflecting a diverse set of interests – including both basic science and clinical applications – and a host of various techniques, the studies presented showed how far the field of optics has come in recent years while underscoring the promise it holds for the future. Just a couple of highlights: The series of quick 10-minute talks kicked off with “Nanoscopy with Far-Field Optics,” presented by Stefan W. Hell of Max-Planck-Institut für Biophysikalische Chemie in Göttingen, Germany. He demonstrated significant improvements in resolution using stimulated emission depletion (STED) microscopy, well beyond the diffraction limit, in fact. By producing exceptionally small regions of fluorescence excitation, he and colleagues achieved resolution down to 8 nm, sufficient to image dendritic spines in living neurons. On the clinical front, Christopher Contag of Stanford University in California reported a means to target cancer stem cells, or “initiating” cells, using optical imaging for visualization. These cells still linger in the body during cancer remission, Contag said, even though the hallmarks of the disease are absent. He and his co-workers showed, however, that by combining natural killer T cells and an engineered virus, they could find and attack the cells. They tested the technique in animals and effectively prevented relapse in almost all cases. And when they reintroduced tumor cells six months later, the tumors rapidly cleared. Thus, in a sense, the method served to inoculate the animals against cancer after the initial therapy. The other talks on Saturday evening were “Advanced Studies in Photoporation,” by Kishan Dholakia; “Tracking Stem Cells In Vivo,” by Charles P. Lin; “First In-Human Clinical Trial of the FLARE Image-Guided Surgery System,” by Summer L. Gibbs; “OCT and Fluorescence Spectroscopy for Cancer Detection,” by Jennifer Barton; “Diffuse Optics for Acute Stroke Management,” by Arjun G. Yodh; and “Biodegradable Silk Optics,” by Fiorenzo Omenetto. Gary Boas gboas@eggship-media.com