Optical Microscopy for Detecting Binding on Small Molecule Microarrays

: Small molecule microarrays (SMMs) have revolutionized parallel screening of multiple biological interactions. SMMs are a high-throughput technique for simultaneous detection of up to thousands of biological interactions. Conventional detection technique employed in SMMs is fluorescence spectroscopy. However, the possibility of fluorescent labels affecting the binding properties of small molecules drives the development of label-free screening techniques. Here, we describe two label-free detection techniques using optical microscopy for the detection of binding on SMMs. The first optical detection technique-ellipsometry, and more specifically, oblique incidence reflectivity difference to study the kinetics of the association between small molecule targets and protein probes is discussed. Then, we describe another optical detection technique-surface plasmon resonance microscopy. The sample preparation steps and protocols of the two techniques to study the interactions between SMMs and their protein targets are elaborated in great detail.