Total internal reflection fluorescence (TIRF) coupled with hydrogel-DNA droplet microarrays covalently bound on PMMA substrates presents a reusable, sensitive platform for evaluating DNA hybridization and for rapid biochip development. Hydrogel microarrays, which contain covalently bound DNA probes, are created via a simple printing and photocross-linking process. TIRF measurements of the arrays display robust reusability, show linear sensitivity down to 5 fmol of fluorescently labeled target DNA, and are sensitive to single basepair mismatches. Additionally, the ability to interrogate larger DNA is shown through studies with PCR amplification hybridization. We conclusively demonstrate an efficient, reproducible, low cost platform for DNA hybridization studies that could be used for fast high-throughput diagnostics as well as biochip development.
In this paper we present the fabrication and characterization of polymer nanomembranes filled with magnetic nanoparticles and attached covalently to a periodic array of free-standing silicon walls, forming an array of micro-channels with the membrane as a cover. The width of a micro-channel of about 1.4 microm sets a characteristic lateral size and the thickness of the polymer membrane ranges between 100 and 300 nm. The membrane is made of cross-linked hydrophilic polymers possessing a Young's modulus of only a few MPa. The presence of the magnetic particles within the membrane makes the film responsive to external magnetic fields. The mechanical and magnetic properties of the membrane are characterized by bulge tests and with atomic force microscopy.
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