A resonance light scattering sensor based on methylene blue-sodium dodecyl benzene sulfonate for ultrasensitive detection of guanine base associated mutations.

A resonance light scattering (RLS) sensor for guanine base associated mutations has been developed on the basis of the high selectivity of methylene blue (MB) for guanine bases in the presence of sodium dodecyl benzene sulfonate (SDBS). MB, when bound to SDBS, underwent a dramatic enhancement of its RLS intensity. However, the addition of double-stranded DNA (dsDNA) and single-stranded DNA (ssDNA) caused the strong RLS intensity of MB-SDBS to decrease, and the RLS intensity of MB-SDBS-ssDNA was much lower than that of MB-SDBS-dsDNA. Consequently, it can be concluded that the binding abilities of MB-SDBS with ssDNA and dsDNA were different. Besides, the experimental results showed that MB-SDBS could bind specifically to oligonucleotides rich in guanine bases. Short DNA targets with sequences related to β-thalassaemia, thrombophilia and psoriasis, all of which are guanine base relevant mutations, were synthesized. It was found that MB-SDBS could recognize the single-base mismatches in the mutational DNA, followed by different RLS signal changes between MB-SDBS-normal DNA systems and MB-SDBS-mutational DNA systems. The ultrasensitive sensor allows simple, rapid, sensitive and selective detection of guanine base associated mutations, indicating its potential application in the medical field.