Benchtop Nanoscale patterning using soft lithography for the printing of DNA molecules
DNA microarrays have rapidly evolved to become one of the essential tools to examine expression or mutation of thousands of genes simultaneously. There is a need for alternative patterning methods that must be very simple, reproducible, cost-effective, and eventually transferable to any laboratories for their own problematic situations. The microcontact printing (μCP) could fulfill this requirement as it is a printing technology that uses inexpensive elastomeric stamps made usually of polydimethylsiloxane (PDMS) and which exhibits relief patterns at the micron and nanoscale. Microcontact printing has been demonstrated as a technique for the parallel delivery of proteins as surface patterns onto a target substrate. A stamp made of an elastomeric material such as poly(dimethylsiloxane). (PDMS) can be topographically structured by casting the prepolymer against a 3D master. The stamp is inked with the molecules of interest, forming a more or less complete monolayer, rinsed with buffer, blown dry under a stream of nitrogen, and then printed onto the substrate surface. The two main steps of μCP are the adsorption of the DNA on the stamp (inking process) and the transfer of ink from the stamp to a target surface (contact printing). The contact times were as short as possible for optimizing the high throughput of the technique.
In this work we made a benchtop nanoscale pattering using soft lithographic techniques and made a PDMS stamp. This stamp is characterized using Atomic force microscope and Laser diffraction technique to confirm the nanoscale patterns. Genomic and plasmid DNA (Max-prep) are isolated from Ecoli cells using standard protocols and these biomolecules are immobilized on solid surfaces such as surface modified microscope glass slide and silicon wafers by micro contact printing. These printed surfaces are characterized and analyzed by Atomic Force Microscopy (AFM). The surface bound biomolecules find application in bio sensors, chromatography, diagnostic immune assays, cell culturing, expression studies and other analytical procedures.