Direct immobilization in poly(dimethylsiloxane) for DNA, protein and enzyme fluidic biochips

A new arraying method is presented based on the properties of poly(dimethylsiloxane) (PDMS) polymer to entrap beads bearing biologically active compounds. It is shown that such beads could be spotted and dried at the surface of a poly(vinyl chloride) master and subsequently transferred at the PDMS interface by direct moulding of the polymer on the mask. Moreover, the use of the PDMS-assisted-immobilization enables the development of either a low density array (100 spots) or a micro-channel biochip with a direct incorporation of the sensing element in a fluidic system for the quantitative detection of enzyme substrates, antigens and oligonucleotides, depending on the immobilized sensing element. All biochip formats were revealed by a chemiluminescent reaction detected with a charge coupled device camera. As a result, arrays of beads bearing active enzymes, antibodies and oligonucleotides were successfully obtained and enabled the achievement of biochips for the chemiluminescent detection of enzyme substrates, protein antigens and oligonucleotides sequence with detection limit of 1 (mu)M, 1.5×10^7 molecules and 10^8 molecules, respectively.