Simultaneous immobilization of protein microarrays by a micro stamper with back-filling reservoir

This paper proposes a novel stamping system using a back-filling Micro-Stamp Chip with discrete dispensing channels to pattern precise and uniform protein microarrays for disease diagnosis or drug screening. Unlike the micro arrayer which spots biosamples in serial, this novel device can simultaneously spot hundreds to thousands of bioreagents into a dense array in 1 min. Surface tension is the major mechanism in reservoir filling, solution transportation, micro/nano printing, and droplet breakdown processes of the micro stamp system. The passive channel design requires no actuation or external energy sources to manipulate the bioreagents. The fabrication of the back-filling Micro-Stamp Chip involves thick photoresist lithography, evaporation, PDMS (polydimethylsiloxane) molding, PDMS dry etching, and oxygen-plasma oxidization for the hydrophilic treatment of stamp surface. The Bio-Assay Chip is prepared by treating the surface of a glass slide with aminopropyltrimethoxysilane (APTS) for amino-derivitization and then with bis-sulfo-succinimidyl suberate (BS3) for surface activation. Both simulation and experiment have demonstrated the capability of this system to accurately transfer proteins in uniform arrays. Experimental results verify that the spot size and intensity variations of spotted protein arrays were less than 5% across the whole chip with 144 protein spots, and the size discrepancy between the imprinted spot and fabricated stamp is about 5%. Simulation results provided the guidelines to generate uniform protein spots, such as the hydrophilic degree of the micro stamp tip and Bio-Assay Chip surface, and the departing speed of the Micro-Stamp Chip from the Bio-Assay Chip.