One-bead-one-compound (OBOC) solid-phase combinatorial chemistry has been used extensively in drug discovery. However, a major bottleneck has been the sorting of individual beads, while still swollen in organic solvent, into individual wells of a microwell plate. To solve this problem, we have constructed an automated bead sorting system with integrated quality control that is capable of sorting and placing large numbers of beads in bulk to single wells of a 384-well plate, all in an organic solvent. The bead sorter employs a unique, reciprocating fluidic design capable of depositing 1 bead every 1.5 s, with an average accuracy of 97%. We quantified the performance of this instrument by sorting over 8500 beads, followed by cleaving the conjugated compound and confirming the chemical identity of each by liquid chromatography/mass spectrometry (LC/MS). This instrument should enable more efficient screening of combinatorial small molecule libraries without the need to dry beads or otherwise change the chemical environment.
Keywords: OBOC; bead sorting; combinatorial libraries; high-throughput screening; organic solvents.