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. alpha-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 (GAH) as labeled antibodies. The detection limits were 0.20, 0.14, and 0.012 ng mL-1 (3sigma) 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.
Direct application of available well-defined materials for mass spectrometry analysis represents a significant step in the combination of materials science and analytical chemistry. The present study introduces a facile vacuum filtration method for directly coating different commercially available materials onto the surface of filter paper. High sensitivity and quantitation precision have been demonstrated for different analytes including therapeutic drugs, proteins and volatile compounds in various matrices using the obtained papers as substrates for paper spray mass spectrometry. Fig. 1 (a) Experimental setup for paper coating and paper spray ionization. Photographs of (b) the prepared silica coating solution and (c) silica coated paper. (d) SEM image of silica coated paper. (e) Close-up image of the selected area in (d). 5382 | Anal. Methods, 2015, 7, 5381-5386 This journal is
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