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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]

The development of material science increasingly calls for rapid characterization methods with low limits of detection and high spatial resolution. Here we report a depth profile analysis method for thin layer coatings by combining low temperature plasma (LTP) probe with inductively coupled plasma mass speclrometiy (ICP-MS). The LTP probe with diameter of several tens of micrometers served as a tool for mass removal, which is generated by the discharge in a quartz capillaiy at ambient condition. The sample material is ablated by the LTP probe and converted into an aerosol, and transported by a carrier gas flow to the ICP-MS, where the decomposed and ionized aerosol particles are analyzed with high sensitivity. Scanning electron microscope (SEM) micrographs reveal that the trace after ablation by the LTP probe is a hole with a diameter less than 10 pm. A lateral resolution of approximately 200 pm has been achieved by analyzing an electron component with interval metal stripes. Depth profiling of a 100 nm single layer sample and a multiple layer sample (100 nm Al/250 nm SiOillOO nm Au150 nm Cr) on a silicon substrate have been successfully performed at ambient condition. The present method offers unique advantages in terms of high spatial resolution, fast analysis speed and ease of implementation. It might be considered a complementary technique to existing depth profiling methods such as GDMS/OES, AES, and SIMS. In addition, the simple-to fabricate LTP probe is easily coupled to various other elemental analysis tools for thin layer or direct solid sample analysis in micro area. [ABSTRACT FROM AUTHOR]

Inductively coupled plasma mass spectrometry (ICPMS) has been successfully used for the detection of element-tagged biomolecules with the advantage of multielement capability. However, this technique cannot be used for microarray detection due to the necessity to dissolve the elemental tags before introducing them to the plasma source. Here, we report the detection of multiple proteins on each spot of the immuno-microarray by laser ablation ICPMS. α-Fetoprotein IgG (AFP), carcinoembryonic antigen (CEA), and human IgG, as model proteins, have been detected on the basis of sandwich-type immunoreactions on a microarray with Sm3+-labeled AFP antibody, Eu3+-labeled CEA antibody, and Au-labeled goat-anti-human IgG (GAB) as labeled antibodies. The detection limits were 0.20, 0.14, and 0.0 12 ng mL-1 (3σ) with the RSD of 5.7%, 2.6%, and 2.3% at the concentration of 1.0 ng mL-1 for AFP, CEA, and human IgG, respectively. The present detection method permits detecting multiple analytes from each spot of microarray with a spatial resolution at micrometer range, which can alleviate the stress to fabricate high-density arrays. Furthermore, the substrate materials and immobilized proteins do not interfere with the detection. The present technique provides a new strategy for readout of microarray. [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.