Fluorescent conjuates of a-Bungarotoxin bind to the nicotinic acetylcholine receptor (AChR) with high affinity, and thus can be used to image the distribution of the receptor at the neuromuscular junctions. CF dyes are Biotium's line of next-generation fluorescent dyes with advantages in brightness, photostability, and conjugate specificity compared to other fluorescent dyes. Blue fluorescent CF405S has excitation/emission at 404/431 nm.