Most genetic differences between people are caused by single-nucleotide polymorphisms (SNPs). These sequence variations occur when a single nucleotide (A, G, T or C) in the DNA sequence is altered, and although most SNPS have no effect on cell function, many are thought to influence how people respond to disease or drug treatments. Understanding SNPs and detecting them in individuals is therefore of considerable interest, and a report in the June issue of Nature Materials may offer a new fast and simple method for identifying these genetic signatures.
Most techniques for detecting single base-pair mutations require labelling of the nucleic acid or the DNA probe. The main advantage of the new technique developed by Peter Nilsson and Olle Inganäs at Linköping University in Sweden is that it relies only on electrostatic interactions between a luminescent zwitterionic polymer and single DNA strands to produce a fluorescent signal. The authors tested their polymer system against DNA strands carrying one, two or three single base-pair mismatches, and found they could detect single-base mismatches within five minutes.
Previous work in this area has demonstrated good selectivity and sensitivity for detecting DNA in solutions of similar polymers, but Nilsson and Inganäs show that their system works equally well when deposited and patterned on a surface. This is important because the ability to make DNA chips (micro-arrays) for detecting multiple sequence variations is essential for quick and cost-effective detection of SNPs in the population at large.
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