Nanoparticle assisted nuclear relaxation-based oligonucleotide detection

We present a proof-of-concept “on-off” detection scheme, which uses gadolinium phthalocyanine (GdTcPc)-grafted silica nanoparticles as paramagnetic centers, capable of modifying the transverse relaxation time (T2) of water protons in solution. A DNA strand (as probe) was conjugated to the GdTcPc to act as a recognition element. In the presence of the target DNA, which was complementary to the probe, an increase in the T2 value was detected, with magnitude proportional to the target DNA concentration. The linear range was observed from 30 to 140 nM, with limit of detection of 15 nM. The developed nuclear relaxation-based detection scheme is shown to be a simple, fast and selective method to detect DNA and could be useful in point-of-care diagnostic applications. We report nuclear relaxation-based method to selectively detect oligonucleotides using a gadolinium (III) phthalocyanine-grafted silica nanoparticles as the paramagnetic center. [Display omitted] •A novel method based on nuclear relaxation for highly specific and sensitive DNA detection.•Measurement of transverse relaxation time of water protons in solution for sensing.•Use of paramagnetic silica nanoparticles, instead of superparamagnetic nanoparticles, in nuclear relaxation measurement.