Protein profiled features patterned via confocal microscopy

Protein patterns were printed using conventional microlithographic materials in a bilayer arrangement and unconventional exposure tools. The bilayer resist stack consisted of a lower poly(tert-butyl methacrylate) layer and an upper diazonaphtoquinone/novolak layer. The protein features were printed in either 'contact printing', or 'step and repeat' mode. The latter printing mode can be managed in a flow-cell consisting of a standard microscope slide and cover slip, spaced apart by about 20 microm, as follows: (i) the exposure step is carried out in the cell using focused 488 nm beam of a confocal laser scanning microscope; (ii) the development step is performed by flowing the photoresist developer through the cell; (iii) the selective deposition of the protein (FITC-labelled avidin) is achieved via the flow of the protein solution through the cell until a desired contrast has been reached; (iv) the control of the process is assured using on-line monitoring of the photo-activated red fluorescence of the developing resist layer, and of the green fluorescence of the FITC-protein patterns, respectively. The protein printing technique uses equipment routinely available in biological laboratory. The 'step and repeat' patterning yields high and controllable resolution. The process can be applied in the fabrication of medical microanalysis devices.