Rapid selection of aptamers based on protein microarray

We report a novel method for the efficient screening of aptamers from a complex ssDNA library based on a microarray chip, which was named Microarray-SELEX. In this method, the target protein (lactoferrin) and negative proteins (α-lactalbumin, β-lactoglobulin, bovine serum albumin, and casein) were each dotted and immobilized on a slide to form a protein microarray. Moreover, the library was added to this chip to interact with negative proteins, then with the target protein. The process of SELEX could be monitored on-line using a fluorescent microarray scanner and the whole process was performed in only six rounds. Finally, five aptamers (YFL-1, YFL-4, YFL-5, YFL-6 and YFL-7) were obtained, which showed good specificity towards lactoferrin in the presence of negative proteins. The equilibrium dissociation constants (K _d) of the aptamers were in the nanomolar range. Briefly, Microarray-SELEX is a rapid, easy, sensitive and efficient method for screening aptamers.