Optimization of Sol−Gel Formulations and Surface Treatments for the Development of Pin-Printed Protein Microarrays

We report on the development and optimization of a sol−gel-based method for the preparation of protein microarrays that has the potential to allow pin-spotting of active proteins for high throughput multianalyte biosensing and screening of protein−small molecule interactions. Microarrays were printed onto bare and chemically modified surfaces using the commercially available sol−gel precursors tetraethyl orthosilicate and sodium silicate and the newly developed biocompatible sol−gel precursors monosorbitol silane and diglyceryl silane. Parameters such as the type and level of the buffer, the water-to-silane ratio, and the solution pH were also varied to assess the factors that controlled the production of optimal microarrays. Such factors included the ability to pin-print without clogging of the pins, the adhesion of the sol−gel spot to the substrate, the dimensions of the microspot, and the stability of both the microspot and the entrapped protein. The microarraying of active antibodies was successfully demonstrated using an optimized combination of parameters, and such arrays were shown to have significantly higher signal-to-background levels than conventional arrays formed by covalent immobilization of antibodies on chemically derivatized surfaces.