Immobilized carbon nanotubes as matrix for MALDI-TOF-MS analysis: Applications to neutral small carbohydrates

Abstract

In this work, we reported on the advantages of immobilized carbon nanotubes as a novel MALDI-matrix. Recently, carbon nanotubes have been reported to be an effective MALDI matrix for small molecules (Anal. Chem. 2003, 75, 6191), as it can eliminate the interfering matrix peaks as well as form a web morphology to fully disperse the analyte and allow strong ultraviolet absorption for enhanced pulsed laser desorption and ionization. In our study, to overcome the problem that the carbon nanotube matrix may fly off from the target, a type of polyurethane adhesive, NIPPOLAN-DC-205, is introduced to immobilize carbon nanotubes on the target, which enables widespread application of carbon nanotubes as matrix for MALDI-MS analysis. At the same time, the properties of the carbon nanotubes as an efficient matrix remained after immobilization. The presence of NIPPO-LAN-DC-205 increases the time for analysis at a particular desorption spot by minimizing the time-consuming search for "hot spots" and facilitating experiments such as post source decay (PSD) which need longer-lasting signals. Moreover, NIPPOLAN-DC-205 produces no interference peaks and can easily be cleaned with acetone. Fast evaporation technology may be used to enhance signal reproducibility in MALDI analysis using carbon nanotubes as matrix. Consequently, the applicability of the carbon nanotube as matrix for matrixassisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis of low molecular mass analytes is highly improved. The feasibility of the method employing polyurethane is demonstrated by comparison of the results produced from the carbon nanotube matrix with and without immobilization. In addition, neutral small carbohydrates, which are difficult to be ionized normally, can be cationized with high efficiency by MALDI-TOF-MS using the immobilized carbon nanotube matrix. The method was further applied to analyze peptides and detect urine glucose successfully. (J Am Soc Mass Spectrom 2005, 16, 333-339)

A novel laser desorption/ionization method using through hole porous alumina membranes

“…To date a number of ionization techniques that belong to SALDI have been proposed,1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, ...…”

“…nanoparticles as typical, in treatable forms such as suspension liquids in order to ensure that the photon energies of the laser can act to desorp and ionize analytes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45. Indeed, the soft ionization laser method such as the original form of MALDI also belongs to this category 1.…”

High surface area of porous silicon drives desorption of intact molecules

“…Other surfaces have also been shown to generate intact molecular ions into the gas phase, including GaAs and GaN [5], immobilized carbon nanotubes [6], silicon nanowires [7,8], and lithographically patterned and roughened silicon surfaces [9]. In particular, the porous silicon surface has demonstrated unique performance capabilities, allowing the analysis of a wide range of molecules [10] and peptide analysis at the 800 yoctomole level [11].…”

Surface-assisted laser desorption/ionization-mass spectrometry using TiO2-coated steel targets for the analysis of small molecules

“…More recently, direct laser desorption/ionization on carbon nanotubes or silicon nanowires has been reported [36,37].…”