Miniaturized, spatially addressable microchips of peptides and peptidomimetics are powerful tools for high-throughput biomedical and pharmaceutical research and the advancement of proteomics. Here we report an efficient and flexible method for the parallel synthesis of peptides on individually addressable microchips, using digital photolithography and photogenerated acid in the deprotection step. We demonstrate that we are able to synthesize thousands of peptides in a 1 cm2 area on a microchip using 20 natural amino acids as well as synthetic amino acid analogs, with high stepwise yields and short reaction-cycle times.
We have applied a systematic procedure to characterize and evaluate the surface chemistry on the well-known alkyl monolayer modified Si(1 1 1) surface. Protein molecules are immobilized on the surface through chemical bonds, and the specific recognition is observed. The surface protein density has been determined by the combination of Atomic Force Microscopy and immobilization kinetics. The affinity of the surface immobilized IgG molecules is examined by fluorescence detection incorporated with the Langmuir isotherm. In addition, specificity, sensitivity, and homogeneity are also discussed.
Epitope screening experiments using a p53 antibody (PAb240) produced clearly defined binding patterns. The peptidomimetic sequences on the microchip show specific antibody binding and provide insights into the molecular details responsible for specificity of epitope binding. Our approach requires just a conventional synthesizer and a computer-controllable optical module, thereby allowing potential development of peptide microchips for various pharmaceutical and proteomic applications in routine research laboratories.