 The limited chemical diversity of nucleic acid libraries used in CEL-X has been a major constraint, but by introducing functional groups and exploring modifications to uracil at the five position, we have developed SOM amers with low dissociation rate constants and increased hydrophobicity, allowing for more effective binding to proteins. This has led to the creation of a large collection of SOM amers targeting human proteins and expanding their potential applications in diagnostics and therapeutics. This article was authored by John C. Roloff, Amy DeGelinas, Thales C. Jarvis, and others.