Length-Dependent Gold Nanoparticle-Labeled Nucleic Acid Probe Based Dual Test Strip for Visualized Discrimination of Single Nucleotide Polymorphism

Single nucleotide polymorphism (SNP) is closely related to the susceptibility of various common diseases and adverse drug reactions. Conclusively, SNP detection is significant for early-stage disease diagnosis and personalized medicine. The gold nanoparticle nucleic acid strip has the advantages of low-cost and rapid visualization (within 5–10 min), and it was introduced into detecting cancer-related SNP sites (A/A, A/G, G/G) in the CYP1A1 gene. As an efficient visualized approach based on the observation of the test zone (TZ) on the strip, it is improper to develop color at the TZ toward the negative sample; otherwise, it may lead to invalid false positive results. Thus, it is crucial to avert such a situation. In this work, dual strips named A and G were prepared, which were completely complementary to the T/T site (complementary base of A/A site) and C/C site (complementary base of G/G site), respectively. Single-strand DNA (ssDNA) containing SNP sites was obtained by conventional two-step polymerase chain reaction (PCR). Then SNP sites could be directly visualized and accurately distinguished on the dual strips. Furthermore, the false positive result could be eliminated by optimizing the length of DNA modified on gold nanoparticle and the concentration of NaCl. The result for the detection of 21 human blood samples with this method was consistent with those of sequencing. The platform exhibits the benefits of rapidity, easily visual determination, is false-positive-free, and is low-cost and plays an important part in the initial screening of SNP-related diseases.