Gold nanoparticle-based inductively coupled plasma mass spectrometry amplification and magnetic separation for the sensitive detection of a virus-specific RNA sequence

We have developed a sensitive gold nanoparticle (AuNP)-based inductively coupled plasma mass spectrometry (ICP-MS) amplification and magnetic separation method for the detection of oligonucleotide sequences. The assay relies on (i) the sandwich-type binding of two designed probe sequences that specifically recognize the target oligonucleotide sequences, (ii) magnetic bead separation, and (iii) AuNP-based ICP-MS amplification detection. To enhance the analytical signal and minimize the background signal resulting from nonspecific binding, we performed a series of experiments to evaluate the effects of various parameters (the concentration of the capture probe; the time required for hybridization; the number of washings required to eliminate nonspecific binding) on the oligonucleotide detection. Under the optimized conditions, the detection limit was 80zmol (corresponding to 1.6fM of the target sequence in a sample volume of 50μL). Moreover, it employs a shorter hybridization step and ICP-MS, this procedure is relatively simple and rapid (ca. 1.5h). Based on the analytical results obtained using complementary and mismatched sequences, our method exhibits good performance in distinguishing complementary and random oligonucleotides. Compared with the "gold standard" methodology (plaque assay) for the quantification of dengue virus, our method has the capability to allow early detection of dengue virus in complicated and small-volume samples, with high specificity, good analytical sensitivity, and superior time-effectiveness.