Inkjet printing methodologies for drug screening.

We show for the first time a contactless, low-cost, and rapid drug screening methodology by employing inkjet printing for molecular dispensing in a microarray format. Picoliter drops containing a model substrate (d-glucose)/inhibitor (d-glucal) couple were accurately dispensed on a single layer consisting of the enzymatic target (glucose oxidase) covalently linked to a functionalized silicon oxide support. A simple colorimetric detection method allowed one to prove the screening capability of the microarray with the possibility to assay with high reproducibility at the single spot level. Measurements of the optical signal as a function of concentration and of time verified the occurrence at the solid-liquid interface of the competitive enzymatic inhibition with a similar behavior occurring for this system in a solution phase along with overcoming competition effects. We propose this methodology as a general application for drug screening purposes, since it may be extended to any kind of enzyme-substrate/inhibitor or ligand-target biochemical system.