High-quality RNA is a major issue for researchers who analyse gene expression profiles. Due to increasing competition, they are seeking appropriate purification methods which are as efficient as possible. Automated solutions are therefore highly desirable. While automated platforms are already wellestablished in high-throughput laboratories, innovative technologies for low-throughput have only just been introduced.

The history of gene expression analysis began when laboratory methods were developed to examine the expression of individual genes. In the late 1970s, the ‘northern blot’ technique was the first method developed to detect gene expression. Since then, the rate at which new technologies are developed has been accelerating at an astounding pace and the range of starting materials being used in this type of experiment has broadened significantly. These novel technologies include quantitative real-time PCR and microarrays, which not only provide information on whether a gene is expressed at a given time or under specific conditions, but also allow the determination of quantitative levels of expression of target genes.

However, due to the high sensitivity of these methods, the accuracy of results is highly dependent on the quality of RNA samples, since any inconsistencies in sample preparation will be amplified in subsequent steps. Moreover, the purified RNA must also be free of contaminants such as chloroform and phenol, which may lead to inhibition of enzymes used in amplification and detection reactions.

SPIN COLUMN TECHNOLOGY

The introduction of silica membrane-based spin columns revolutionised the way RNA extraction is performed in life science research. The first spin column was developed for plasmid DNA purification in 1986. Since then, the technique has become the method used most often for DNA and RNA purification in laboratories worldwide. The principle behind this type of separation relies on nucleic acid molecules binding to a silica surface in the presence of specific salts and under certain pH conditions. Nucleic acids are adsorbed to silica surfaces in the presence of chaotropic salts, which remove water from hydrated molecules in solution. As polysaccharides and proteins are not adsorbed, they can easily be removed by various washing steps. After this procedure, the pure nucleic acids are eluted under low- or no-salt conditions, and ready for immediate use in demanding downstream applications, such as microarray analysis. To address the individual challenges of each starting material, numerous optimised kits have been developed.

AUTOMATED SOLUTIONS FOR IMPROVING STANDARDISATION AND LABOUR EFFICIENCIES

Due to the increasing amount of competition in the life science industry, researchers are looking for solutions that are as efficient as possible. Therefore, purification of nucleic acids has had to be taken to a higher, more time-saving and standardised level, and the development of a reliable, fully integrated and automated system was required. The development of automated medium- to high-throughput applications started over 15 years ago. In general, such applications are based on either 96-well formats or magnetic bead technologies. While automated systems are now wellestablished in high-throughput laboratories, the constantly increasing demand for automated solutions in low-throughput purification remained, and they have become available only recently. At first, the systems were based on magnetic bead technology. Currently, a small number of platforms based on this technology are available. The latest milestone has been achieved with the introduction of the first system capable of automating spin column technologies.