Microarray technology was originally developed for putting small spots of DNA onto a glass slide. But the technology is generally applicable to transferring any type of chemical in small quantities to a glass slide. One application of microarray technology is the small molecule microarray, in which thousands of different small molecules are placed on a glass slide. To see how this is done, view the video clip named “Making a Small Molecule Microarray.”/nOne technique for screening small molecules uses glass slides that have been machine-printed with an array of dots, each dot containing different small molecules. This is known as a small molecule microarray. Each slide contains 12,000 small dots, corresponding to 12,000 different small molecules. The slides are then washed with a single known protein that has been tagged with a fluorescent marker. If the protein binds with a small molecule on the slide, it will glow, indicating that the small molecule contained in that particular dot is a potentially useful one for studying that particular protein function.