Discussion

Manual dilution of compounds can be laborious, time consuming and introduce operator variability. This can be a particular problem when diluting aqueous insoluble compounds for cell based assays where the final DMSO concentration is critical in maximising solubility.
The Tecan D300 digital dispenser is designed to dispense picolitre to microliter volumes of compound (DMSO) stocks directly into multi-well plate formats. It is rapid and highly accurate yet gentle enough to not disturb a cell monolayer.
Here, we demonstrate the increased accuracy of the Tecan digital dispenser compared to manual titration in a number of assay formats, both cell-based and biochemical. The ability to add low volumes of stock compound directly to wells has a number of advantages including; eliminating the need for intermediate aqueous buffer dilutions, maintaining low final DMSO concentrations and maximising the solubility of compounds across the concentration range.
The dispenser also enables a wide range of titration series to be programmed, not limited to the manual serial titrations typical in drug discovery e.g. half-log or 2-fold dilution. This has significant benefits and allows for unique curve profiles to be developed for compounds with poorly defined activities, whereby a cluster of compound concentrations can be targeted to any region of the concentration curve.