Biochip

In molecular biology, biochips are engineered substrates ("miniaturized laboratories") that can host large numbers of simultaneous biochemical reactions.

One of the goals of biochip technology is to efficiently screen large numbers of biological analytes, with potential applications ranging from disease diagnosis to detection of bioterrorism agents.

[3] In 1953, Watson and Crick announced their discovery of the now familiar double helix structure of DNA molecules and set the stage for genetics research that continues to the present day.

[4] The development of sequencing techniques in 1977 by Gilbert[5] and Sanger[6] (working separately) enabled researchers to directly read the genetic codes that provide instructions for protein synthesis.

Secondly in 1986 Hood and co-workers devised a method to label DNA molecules with fluorescent tags instead of radiolabels,[7] thus enabling hybridization experiments to be observed optically.

Their "GeneChip" products contain thousands of individual DNA sensors for use in sensing defects, or single nucleotide polymorphisms (SNPs), in genes such as p53 (a tumor suppressor) and BRCA1 and BRCA2 (related to breast cancer).

Typically, the sensors are deposited on a flat substrate, which may either be passive (e.g. silicon or glass) or active, the latter consisting of integrated electronics or micromechanical devices that perform or assist signal transduction.

The fabrication of microarrays is non-trivial and is a major economic and technological hurdle that may ultimately decide the success of future biochip platforms.

Various means exist to achieve the placement, but typically robotic micro-pipetting[9] or micro-printing[10] systems are used to place tiny spots of sensor material on the chip surface.

As the figure shows, such a design was first demonstrated (and later commercialized by Illumina) using functionalized beads placed randomly in the wells of an etched fiber optic cable.

Performing multiple analyses simultaneously, described as multiplexing, allows a significant reduction in processing time and the amount of patient sample required.

The test regions are located using a grid pattern then the chemiluminescence signals are analysed by imaging software to rapidly and simultaneously quantify the individual analytes.