2-D Nanofluidic bioarray for nucleic acid analysis

Nucleic acid hybridization techniques feature the use of a probe nucleic acid molecule and a target nucleic acid molecule. Here, probe molecules are usually short single-stranded nucleic acids (DNA or RNA) or oligonucleotides with known sequences; whereas target molecules are prepared from polymerase chain reaction (PCR) amplification of genomic extracts. Probe-target hybridization leads to the formation of a double-stranded molecule, called a duplex. The method of DNA bioarray hybridization evolved from Southern blotting technology based on solid-phase hybridization in the early 1990s [1]. This method relies on the immobilization of the probe molecules onto a solid surface to recognize their complementary DNA target sequences by hybridization. Millions of features have been integrated onto a standard glass or silicon slide by microprinting or in situ synthesis of oligonucleotides [2,3]. The relative abundance of nucleic acid sequences in the target solution can be measured from chip hybridization results optically, electrochemically, or radiochemically, with proper detection labels [4]. DNA bioarrays have dramatically accelerated many types of investigations including gene expression profiling, comparative genomic hybridization, protein-DNA interaction studies (chromatin immunoprecipitation), single-nucleotide polymorphism (SNP) detection, as well as nucleic acid diagnostic applications. The progress of DNA bioarray technology during the last couple of years has been summarized in many books and reviews [4-8].