Assay development

Working with you, we will develop a robust and practical assay suitable for screening.

Optimization variables

Multiple assay conditions and assay types can be quickly surveyed using 384-well plates and our specialized equipment, including small molecular libraries, sgRNA and siRNA libraries, plate readers, liquid handlers, high-throughput microscopy, and a self-service lab. Examples include cell density and treatment time for cell-based assays; concentration and incubation times to ensure linearity; and order of addition for biochemical assays.

Controls

Assay-specific controls are used to ensure robust and reliable assay performance:

• negative control = vehicle (0% effect)
• positive control = mimics desired effect of screening hits (100% effect). Ideally, a positive control would be a drug for small molecule screening or an siRNA for siRNA screening.

Statistical measures of assay robustness

We use statistical measures of assay robustness, namely signal-to-background ratio, Z’, and coefficient of variations for control populations, to drive assay development and assess screen readiness.

• Signal-to-background ratio (S/B) = Mean_{high signal control} / Mean_{low signal control}
• Coefficient of variation (CV) = (STD_control / Mean_control )* 100
• Z’ = 1 - ((3STD_{pos control} + 3STD_{neg control} )/(Mean_{high signal control} – Mean_{low signal control}))