A biomolecular array includes a substrate across which is distributed an array of discrete regions of a porous substance formed from a porogen-containing organosilicate material. The porous substance is designed to bind chemical targets useful in biotechnology applications, such as gene expression, protein, antibody, and antigen experiments. The regions are preferably optically isolated from each other and may be shaped to enhance detection of optical radiation emanating from the porous substance, e.g., as a result of irradiation of the regions with ultraviolet light. The discrete regions may be configured as microscopic wells within the substrate, or they may reside on top of the substrate in the form of microscopic mesas.