The ability to detect DNA in a very low concentration and using a simple and fast analysis is important in an early stage diagnostic, which could be of a bacterial or viral disease or the diagnostic of cancer. The use of relaxation time of water protons as a signal is promising since most of the biological samples do not present a magnetic background. The goal of this work is to develop a new detection scheme based on the change in the magnetic relaxation of the water protons caused by the presence of a gadolinium center when submitted to a complementary sequence. We synthesized a nanoparticle containing gadolinium ion and we coupled this particle with a DNA sequence complementary the sequence that we want to detect. A linear relationship between the relaxation time and the concentration was observed from 15 to 142 nM and the scheme was able to differentiate between the complementary sequence and a sequence with a single mismatch. This approach is interesting since the analysis is simple, could be done in one step without the need of purification and use a simple instrumentation, which makes this technique promising for implementing in a point-of-care diagnostic test. This approach could also be used to analyze bacteria, proteins and tumor cells.

New sensing scheme based on magnetic relaxation to detect DNA

256th National Meeting (2018)

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