Inkjet Bioprinting on Parchment Paper for Hit Identification from Small Molecule Libraries

In this study, an inkjet bioprinting-based high-throughput screening (HTS) system was designed and applied for the first time to a catecholpyrimidine-based small molecule library to find hit compounds that inhibit c-Jun NH₂-terminal kinase1 (JNK1). JNK1 kinase, inactivated MAPKAPK2, and specific fluorescent peptides along with bioink were printed on parchment paper under optimized printing conditions that did not allow rapid evaporation of printed media based on Triton-X and glycerol. Subsequently, different small compounds were printed and tested against JNK1 kinase to evaluate their degree of phosphorylation inhibition. After printing and incubation, fluorescence intensities from the phosphorylated/nonphosphorylated peptide were acquired for the % phosphorylation analysis. The IM₅₀ (inhibitory mole 50) value was determined as 1.55 × 10^-15 mol for the hit compound, 22. Thus, this work demonstrated that inkjet bioprinting-based HTS can potentially be adopted for the drug discovery process using small molecule libraries, and cost-effective HTS can be expected to be established based on its low nano- to picoliter printing volume.