“…In this format, a wide variety of proteins, nucleic acids, or small molecules can be targeted by immobilizing different probe biomolecules, including proteins, peptides, antibodies, sugars, enzymes, or aptamers, with the requisite specificities. ,− Binding of the target is most often detected by measuring fluorescence intensity changes from labeled tags either on the target itself (direct mode) or on a 2° antibody (sandwich). Alternatively, new microarray formats have been developed that directly measure target concentrations via changes in the optical properties of the sensor itself as a function of bound target. − These label-free technologies can have high sensitivities but often have more stringent requirements for regular and uniform deposition of capture molecules, as compared to fluorescent methods, which are insensitive to localized variability in the z direction. , Regardless of the type of assay, the surface functionalization and immobilization procedures must be carefully considered since these directly affect the probe density and orientation on the substrate, which in turn affects the amount of target bound. − It has been observed that directly immobilizing biomolecules onto planar surfaces results in significant unfolding/denaturing of proteins, translating to a loss of ligand binding activity, adversely affecting the assay’s ultimate performance. − Thus, increasing the density, uniformity, and integrity of probe molecules on planar surfaces is an important subject of research.…”