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A multiplex DNA assay based on nanoparticle (NP) tags detection utilizing single particle mode inductively coupled plasma mass spectrometry (SP-ICP-MS) as ultrasensitive readout has been demonstrated in the article. Three DNA targets associated with clinical diseases (HIV, HAV, and HBV) down to 1 pM were detected by DNA probes labeled with AuNPs, AgNPs, and PtNPs via DNA sandwich assay. Single nucleotide polymorphisms in genes can also be effectively discriminated. Since our method is unaffected by the sample matrix, it is well-suited for diagnostic applications. Moreover, with the high sensitivity of SP-ICP-MS and the variety of NPs detectable by SP-ICP-MS, high-throughput DNA assay could be achieved without signal amplification or chain reaction amplification. [ABSTRACT FROM AUTHOR]

Fluorescent gold nanoparticle (GNP) is an easily synthesized and biocompatible optical platform for sensing and imaging with tunable near-infrared (NTR) emission. However, the relatively low fluorescence (FL) quantum yield limits the further improvement of sensitivity and application. Here, we find that, on plasmonic substrates, the FL intensity of protein-directed synthesized GNPs can be enhanced significantly (~20-fold). Moreover, protein analytes can interact with GNPs and influence the enhanced fluorescence process so that we can obtain distinct FL image patterns. Then, using the array-based sensing strategy, protein discrimination can be achieved. In our present experiment, five GNPs were used as sensing elements and 10 kinds of proteins at three concentrations (0.2, 03, and 1 μM) were successfully identified. This array-based sensing strategy using enhanced-fluorescence from GNPs is highly sensitive and differentiable, expanding the application field of GNPs. [ABSTRACT FROM AUTHOR]

Describes the study of atomization of nanoparticles using inductively coupled plasma mass spectrometry (ICPMS). Sensitivity of the gold signal to the organic matrix; Correlation between the method and enzyme-linked immunosorbent assay; Advantages of ICPMS-based nonisotopic immunoassay method for the determination of biologic analytes.