1. Introduction
Extracellular membrane (ECM) receptors are of significant importance to the development of new therapeutic agents, being the molecular targets for more than 60% of clinical drugs [1,2]. To discover new potential targets and to identify therapeutic agents, various diversity-oriented combinatorial libraries have been developed [3,4,5,6]. The small molecule microarray (SMM) is one of the most effective profiling solutions through the use of pre-patterned regions of interest (ROI), which provide chemical identity and functionality [7,8,9,10,11]. Although having significant potential, high-throughput SMM screening is currently limited due to the use of non-physiological contexts (e.g., absence of serum) and non-viable samples (e.g., cell lysates); most current methods also neglect ECM dynamics [12,13,14]. Microfluidics is a new technology that enables many assays using living cells, but it is not conducive to high-throughput chemical screening [15,16,17,18].
A simple alternative approach is direct panning of living cells over ligand-spotted microarrays, where each spot is a single, defined chemical entity. We have previously described functionalized microarray slides capable of rapid and high-throughput screening of over 5000 different chemical compounds binding to living bacteria, including quantitation of binding parameters [19,20,21]. In this study, we optimized the key experimental parameters for screening living mammalian cells using known small molecule ligands on the previously developed SMM, which requires simultaneous optimization of ligand presentation, the effect of motion, incubation time, ligand concentration, and the number of panned cells.