Application Forum. DNA Decontamination: Novel DNA-ExitusPlus in comparison with conventional reagents

the technology of DNA amplification [1]. Rapid extension of PCR technologies resulted in multiple new applications [2, 3]. Latest protocols and enzyme variants for PCR reactions allow the detection of even single DNA molecules [1]. One important consequence resulting from the improved sensitivity in DNA amplification is the necessity to avoid any contaminations from unwanted external DNA molecules. In addition advanced experiments in gene technology demonstrate that often even free DNA molecules cause biological effects [4, 5]. Thereby infections, biological transformations or recombination of genomes are generated by free DNA plasmids or fragments [4 7]. Changes in viral and bacterial infectivity are observed and are related to the phenomenon of multiple resistances against antibiotics [8]. With respect to these findings, the decontamination of even the smallest quantities of DNA molecules from surfaces and equipment is critical. DNA decontamination reagents use three different molecular principles for destruction or inactivation of genetic material: modification, denaturation and degradation (see Figure 1). Safe DNA decontaminations depend on the degradation of DNA into very small fragments. We developed a DNA degradation test to compare conventional decontamination reagents with the novel DNA-ExitusPlusTM. This test allows sensitive quantification of the fragmentation process (see Figure 2). One surprising result was the finding that some of the conventional reagents only use the principle of modification or denaturation for the inactivation of DNA molecules. This was determined in the test by the complete absence of any degraded DNA molecule. The genetic information encoded in these DNA strands is only masked but not destroyed. By chemical demasking reactions the genetic information of these molecules would be available again and could also be amplified by enzymatic reactions. Based on our knowledge about gene technology and the principles of recombination, we concluded that these reagents are no longer appropriate. But even reagents that show degradation of DNA cause only limited and partial destructions. Hence, very large DNA fragments, even containing the complete genetic information, still survive treatment. Only our novel DNA-ExitusPlusTM achieves rapid and efficient degradation. Another severe disadvantage of conventional reagents is revealed in a test for their corrosive potential. For this purpose different metal plates were incubated with aliquots of the reagents (see Figure 3). This test demonstrates that all conventional products contain aggressive chemicals with corrosive, harmful or even toxic effects. Known ingredients of conventional reagents are azides, mineralic acids like phosphoric acid or hydrochloric acid, aggressive peroxides or strong alkaline substances like sodium hydroxide. Therefore, even after only 20 minutes of incubation irreversible damages of metal surfaces are observed (see Figure 3). The newly developed DNA-ExitusPlusTM exhibits its unique characteristics especially in this test. For all metal surfaces no corrosions are observed. DNA-ExitusPlusTM was also tested on many different plastic surfaces without any indication of damages (data not shown). DNA-ExitusPlusTM offers an efficient, gentle and DNA Decontamination: Novel DNA-ExitusPlusTM in comparison with conventional reagents