DNA Recognition Instruments

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DNA Recognition Instruments

With the advent of molecular detection techniques, the variety of forensic tools has grown considerably. The ability to detect deoxyribonucleic acid (DNA) and even to match the nucleic acid to its source can allow the forensic scientist to identify an individual, or to determine if the individual was at the scene of a particular investigation.

DNA recognition instruments allow rapid identification of the origin of DNA in an environmental or medical sample. Recognition of the source of DNA is important in pathogen (disease-causing agent) identification and in various public health, diagnostic, and military forensic applications.

DNA recognition instruments utilize two main methods for detection and identification. These are nucleic acid hybridization and the polymerase chain reaction (PCR). Hybridization of nucleic acids allows differentiation of sequences that differ by as little as one base pair. Hybridization relies on the fact that single stranded DNA reforms a double stranded helix with a complementary strand.

Engineers and biologists are designing new technologies to make DNA recognition rapid and accurate, with increased sensitivity of the assays, improved identification, and reduction of false positive results. Optical identification methods are primarily used in PCR-based instruments; however, new magnetic and electrochemical methods were developed for hybridization-based assays.

The great advantages of hybridization-based instruments are that they do not require any DNA amplification, are highly sensitive, and give rapid results.

Scientists in industry are currently producing instruments that are based on measuring electrical conductivity. One is known as the eSensor. The system consists of bioelectronic chips, reader, and special software. The chips contain capture probes and signaling probes. After an interaction with a target sequence, signaling probes induce electric current, which is detected and interpreted by the sensor’s software. For example, chips for identifying pathogens such as the bacteria responsible for anthrax are under development.

The newest technologies in PCR-based instruments involve instrument miniaturization and methods for handling and detecting multiple pathogens in multiple samples.

The advanced nucleic acid analyzer (ANAA) was the first DNA recognition instrument designed for work in the field. It was portable, but still large and was superseded by a hand-held ANAA (HANAA).

A different technology, but still PCR-based, uses a high-performance liquid chromatography to separate the PCR products and identify mutations. The advantage of the system is that it can detect mutations in any genes that could have been altered for designing biological weapons, thus, potentially complementing any other detection methods.

DNA recognition instruments are used in general monitoring of the environment, investigation of suspicious objects, and in diagnostics. In all of these applications, detection must be rapid and accurate in order to introduce prevention measures or allow rapid treatment.