• DNA
• Chemiluminescence
• Photodiodes

DNA contains instructions for everything our cells do, from conception until death. Studying the human genome—all the DNA in our cells—allows us to explore fundamental details about ourselves. The Human Genome Project, the international quest to understand the genomes of humans and other organisms, will shed light on a wide range of basic questions, like how many genes we have, how cells work, how living things evolved, how single cells develop into complex creatures, and what exactly happens when we become ill. Besides answering innumerable questions about our molecular selves, a deeper understanding of the fundamental mechanisms of life promises to lead to an era of molecular medicine, with precise new ways to prevent diagnose and treat disease.
The Human Genome Project (HGP) began in the United States in 1990, when the National Institutes of Health and the Department of Energy joined forces with international partners to decipher the massive amount of information contained in our genomes. The HGP began with a set of ambitious goals but has exceeded nearly all of its targets. Frequently ahead of schedule, HGP scientists have produced an increasingly detailed series of maps that help geneticists navigate through human DNA. They have mapped and sequenced the genomes of important experimental organisms. They completed a working draft covering 90 percent of the genome in 2000, and in 2003 they had finished the sequence with accuracy greater than 99.99 percent.
Genes are made of DNA, a long, thread-like molecule. Almost all human cells contain 23 pairs of chromosomes; each chromosome contains a molecule of DNA with hundreds to thousands of genes arrayed along it.
Genes usually code for proteins, the diverse molecules that perform a wide variety of specialized tasks. For example, proteins transmit messages between cells, fight infections, turn genes on or off, sense light and scents and flavors, and form structures, such as tendons and hair. The instructions for making proteins are written with a four-letter alphabet—A, G, C, and T—where each letter represents one of the four chemical units strung together in DNA.
A single misspelling in the DNA sequence can make a protein malfunction, which, in turn, may cause disease. Connecting a gene with a disease was a slow, arduous, painstaking, and frequently imprecise process before the advent of the HGP.
With more and more DNA sequence deposited in electronic databases, researchers spend less time collecting data with their own experiments and more time analyzing the wealth of data available to them. They can electronically scan long stretches of DNA to find genes in the sequence that may be responsible for a particular disease.
Molecular biology has long held out the promise of transforming medicine from a matter of serendipity to a rational pursuit grounded in a fundamental understanding of the mechanisms of life. Genomics will hasten the advance of molecular biology into the practice of medicine. As the molecular foundations of diseases become clearer, we may be able to prevent them in many cases and in other cases, design accurate, individualized treatments for them. Genetic tests will routinely predict individual susceptibility to disease. Diagnoses of many conditions will be much more thorough and specific than now. New drugs, derived from a detailed molecular understanding of common illnesses like diabetes and high blood pressure, will target molecules logically. Drugs like those for cancer will routinely be matched to a patient's likely response.
In these directions, there is the need for inexpensive tools that operate in a variety of environments outside the laboratory. But today the reading of DNA chips is usually based on fluorescence labeling of hybridized target molecules- as it will explained in detail in following paragraphs. Combined with the use of confocal fluorescence scanners, this approach shows very high performances in terms of accuracy and sensitivity, but remains costly and not transportable. This prevents the use of DNA chips, both for decentralized testing (point of care, air or water control, food testing . . .), and as a routine tool in the field of diagnostics, where this technique has to replace existing tests.
That’s in this direction, in an effort to reduce the size and cost of the reader, that our work takes place.