Signal enhancement of protein chips

Biochip technology has been revolutionizing most fields of molecular biology. One of the main issues confronting further development of biochip technology is the strength of signals produced by probe-target interaction, especially in cases of low probe and target concentrations. In order to achieve stronger signals and lower detection limits, we aim at (a) the optimization of chip process parameters, (b) the use of gold particles as labels in surface-enhanced fluorescence detection and (c) increasing surface reflectivity by the addition of SiO2 and TiO2 layers. Process parameters optimized were print buffer, humidity control during arraying, and probe concentration. Surface chemistries, such as porous poly(styrene-co-4-vinylbenzylthiocyanate) (PST-co-VBT) and epoxy resin, have been tested as to their suitability for protein attachment. Surface enhanced fluorescence (SEF) was observed as a result of processing the array using Dy633- and Au-labelled target in different ratios. Enhancement of the reflectivity was achieved by incorporating high-index refractive TiO2 layers between two low-refractive polymer layers or between the glass substrate and the polymer layer by means of hydrothermal synthesis of nanostructured TiO2 particles or sol–gel technology. The characteristics of these interference coatings differed as to the refractive index of the layers, the film thickness and the stack design.