Implementing heat transfer resistivity as a key element in a nanocrystalline diamond based single nucleotide polymorphism detection array

In this article, we report on the label-free real-time thermal monitoring of the denaturation of specific DNA fragments and its potential to detect and quantify single nucleotide polymorphisms (SNPs). Probe DNA, consisting of a 36-mer fragment was covalently immobilized on nanocrystalline chemical vapour deposition (CVD) diamond platforms and hybridized with a 29-mer target DNA fragment (full matching and/or with a point mutation). It was observed that the change in heat transfer resistance upon denaturation is dependent on the amount of DNA hybridized to the nanocrystalline diamond (NCD) surface. Furthermore the possibility to distinguish between a full matching sequence and its singularly mutated counterpart, when bound to the same NCD surface, was investigated. NCD surfaces were selectively hybridized with both full matching and mutated DNA fragments at different ratios (3:1, 2:2 and 1:3). A clear bipartite response in heat transfer resistivity was observed upon simultaneous denaturation of these DNA fragments. Denaturation temperature could be used to identify the DNA fragment to which each partial response could be attributed. Moreover, the partial increases in heat transfer resistivity related to the hybridized amount of non-mutated or mutated DNA, respectively. These results imply that heat transfer resistivity is a technique which can be used to (i) quantify DNA fragments of interest, (ii) detect and (iii) quantify SNPs in a mixture of mutated and non-mutated DNA fragments. Moreover, it illustrates the potential of this technique to detect SNPs without the necessity to design complex microarrays.