| abstract |
The present invention provides an array having various densities, specifically a method for making a high density array. In general, the method includes a printing step and an irradiation step. In the printing step, a predetermined volume of the reagent solution containing receptor molecules is applied to the solid support in a desired pattern. In one embodiment, the receptor molecule is derivatized with a photoreactive agent. In an alternative embodiment, the solid support includes a photoreactive agent. In a preferred embodiment, the receptor molecule is a nucleic acid. In the irradiation step, the photoreactive group is irradiated to immobilize the receptor molecule on the solid support. In one embodiment, a mask having the same center-to-center distance (eg, “pitch”) as the printed spot but having a smaller diameter is placed on the printed pattern and illuminated. The mask preferably irradiates a spot having a smaller diameter than the spot to be printed. Thus, according to the present invention, the immobilized reagent spot has a smaller diameter than the original printed spot. In an alternative embodiment, the irradiation step can be performed using mirrored laser technology. If desired, offset spot application and irradiation can be repeated to form a high density array. |