Biochips - Present and future Applications

The concept of biochips dates back to the early 1990s, but it was in the 2000s that developments began to take off and revolutionize the biotech sector, notably with the rise of DNA chips. In fact, the idea isn't exactly new. The DNA chip represents the fusion of two discoveries made over fifty years ago:

• the work of J. Watson and F. Crick – 1962 Nobel Prize in Physics – who discovered that DNA, the molecule that determines genetic inheritance, is composed of two complementary strands forming a double helix structure;

• the development of electronic chips.

All that remained was to bring these two discoveries together. The idea is very simple: each strand of DNA is made up of a sequence of nucleotides which bind to its complementary strand in exact symmetry. All that's needed is to attach one of these strands to a chip: when it meets its labelled complement, a fluorescent message is emitted, picked up by a scanner and analyzed by the appropriate software. This is the magic of this concentrated technology: transforming a biological reaction into an electronic signal. This ingenious idea saw its development and applications flourish in the 2000s, when the vast project to decode the human genome, the Human Genome Project (HGP), came to fruition. Since then, the very concept of biochips has only grown and strengthened. Based on a combination of multi-disciplinary technologies integrating microelectronics, chemistry, image analysis, bioinformatics and mathematics, the biochip has become a tool for multiplexed analysis of interactions between a probe fixed on a support and a target (analyte) in solution, marked and extracted from biological systems. The probes are deposited at precise positions by mechanical means, or synthesized directly on the surface of the chip support, and are biomolecules of different natures, depending on the type of chip referred to:

• nucleic acids, in the case of DNA chips;

• proteins or peptides, in the case of protein chips;

• glycans or glycosylated biomolecules, in the case of sugar chips;

• whole cells, in the case of cell chips.

This article describes the different types of biochips, as well as their wide range of often little-known applications. We will then discuss the limitations of this technology, but also its strengths, which, despite the emergence of new cutting-edge technologies such as next-generation sequencing, make it a robust and popular technology in many laboratories. Today, microarrays are still widely used in laboratories for applications as varied as the study of gene expression,...