how are microarrays made?
Currently microarrays come in many different types but they are only two real fabrication methods. • Synthesize DNA probes separately, using PCR for cDNAs or chemical synthesis for oligonuclotides. Then use a robot to spot these DNA probes onto your microarrays into very small grids. The substrate for your microarrays can be glass, plastic, or even nylon membranes. Most labs I know of are using glass microscope slides. This method is compartively cheap and flexible and Pat Brown’s lab posted plans to make the robot on the web. Some related technologies use an ink-jet like printer to spray oligonucleotide probes on the microarrays. • Synthesize DNA oligonucleotides directly on the microarray using UV-masks and photo-activated chemistry. Currently Affymetrix are the only people doing this. Affymetrix is a dominant player in commercial microarrays and the chemistry they use is just amazing. The technique used is as follows: deprotect sites that will have the next base (A,C,T, or G) bound
