The invention relates to a method for performing single step assays for the determination of the presence or absence of an analyte in a liquid sample, on a solid surface. The method disclosed, comprise an aptamer coated and signal molecule loaded porous silica particles immobilized on a porous solid material. Specific interaction of the analyte with the aptamers coated on the silica beads, cause release of the signal molecules which result in a detectable signal on the solid support. Also provided are assay devices for the detection platform.