CLSM photostability images. Left-hand images correspond to the emission signal of QDs and Alexas conjugated to streptavidin before the irradiation period (t = 0 min) with the 561 nm laser line at its maximum power. Right-hand images show the emission signal of QDs and Alexas at the end of the irradiation period (t = 8 min). Note the loss of fluorescence intensity in the delimited area. Scale bar = 10 μm.