Hydrogel-Encapsulated Beads Enable Proximity-Driven Encoded Library Synthesis and Screening

Encoded combinatorial library technologies have dramaticallyexpandedthe chemical space for screening but are usually only analyzed byaffinity selection binding. It would be highly advantageous to reformatselection outputs to "one-bead-one-compound" solid-phaselibraries, unlocking activity-based and cellular screening capabilities.Here, we describe hydrogel-encapsulated magnetic beads that enablesuch a transformation. Bulk emulsion polymerization of polyacrylamidehydrogel shells around magnetic microbeads yielded uniform particles(7 & PLUSMN; 2 & mu;m diameter) that are compatible with diverse in-gelfunctionalization (amine, alkyne, oligonucleotides) and transformationsassociated with DNA-encoded library synthesis (acylation, enzymaticDNA ligation). In a case study of reformatting mRNA display libraries,transcription from DNA-templated magnetic beads encapsulated in gelparticles colocalized both RNA synthesis via hybridization with copolymerizedcomplementary DNA and translation via puromycin labeling. Two controlepitope templates (V5, HA) were successfully enriched (50- and 99-fold,respectively) from an NNK5 library bead screen via FACS.Proximity-driven library synthesis in concert with magnetic samplemanipulation provides a plausible means for reformatting encoded combinatoriallibraries at scale. Bead-templatedgel particles via emulsion polymerizationcan scalably transform display-type encoded libraries into one-bead-one-compoundlibraries suitable for functional screening.