DNA Microarray Technology: Beyond Molecular Profiling
Over the past decades, microarray technology has revolutionized modern human medico-diagnostic research through its rapid and multianalysis assays. In 2003, this technology was introduced in the clinical field for molecular diagnosis and in 2004 the gene expression of the entire human genome was performed in a single layer of DNA microarray. Microarrays provide rapid and high-throughput biosensing platforms for the measurement of gene expression, bacterial/viral species identification, mutation detection, drug resistance, and pharmacogenomics, together with the development of sensing applications for molecular diagnostics. A DNA microarray works through a mechanism which includes DNA probe sequences corresponding to specific genes placed on a solid support. This probe is hybridized with cDNA prepared from the mRNA extracted from the sample and labeled with a fluorescent/radioactive label. The amount of hybridization displaying the gene expression is measured by scanning the wavelength or color change.
Since the historic rise to this technology in the field of biotechnology from photolithography, till it became one of the most significant tools in the field of medical diagnosis, the concept of DNA microarray is emphasized on two main variants: oligonucleotide microarray and cDNA microarray. Microarray technology provides reliable and accurate quantification of all known mRNA transcripts of pathways related to complex disorders such as hypertension and to study the periodic cell cycle genes of cancer cells. Oligonucleotide microarrays can separate differentially expressed genes in acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Further, DNA microarray is used to study the gene expression during stress response and aging. In addition, chromosomal microarray identifies copy number aberrations (CNAs) in hematologic neoplasms with greater resolution as compared to G-banding and FISH, and can also detect copy-neutral loss of heterozygosity (CN-LOH) for cytogenetic testing.
Moreover, portable protein microarrays using nano-fountain pen (NFP) provide rapid assessment of multiple protein–protein interactions in a sample, thus act as a valuable tool on the cusp of cancer research and disease diagnostics. Similarly, the single-panel multi-allergosorbent assay provides rapid analysis of several IgE antibodies in a single assay format in epidemiological studies. In contrast to costly and less flexible next-generation platforms, microarray technology is still a very challenging area because it allows designing and fabricating low-cost devices for molecular diagnostics.
