A highly sensitive assay of DNA based on inductively coupled plasma mass spectrometry detection with gold nanoparticle amplification and isothermal circular strand-displacement polymerization reaction

In this work, a simple, sensitive and specific assay for DNA was proposed by combining inductively coupled plasma mass spectrometry (ICP-MS) detection with gold nanoparticle (AuNPs) amplification and isothermal circular strand-displacement polymerization reaction (ICSDPR). First, AuNPs were decorated with hairpin-structured DNA (HP-DNA) through Au-S bond to form the AuNPs probe. The ICSDPR was conducted on AuNPs probe in a homogeneous phase to realize the dual amplification and simplify the analytical process at the same time. By using a biotin modified primer, AuNPs were connected with biotins after the ICSDPR, then captured by the streptavidin modified magnetic beads (SA-MBs), and finally detected by ICP-MS. Many key factors including probe volume, hybridization time, polymerase amount, primer concentration, enzyme reaction time, SA-MBs capture time and desorption time were optimized. Under the optimized condition, the proposed method could detect target DNA as low as 45 zmol (8.9 fM in 5 mu L) in a relative short time (about 4.5 h) with good specificity, and the linear range of this method is 0.1-10000 pM, the relative standard deviations are in the range of 3.6-6.4%. The proposed method was applied for determination of target DNA in human serum samples, the recovery for the spiked human serum samples is in the range of 84-120%. It demonstrates a good application potential of the developed method for biological studies and clinical diagnosis of human pathogenic diseases.