MALDI mass spectrometry nanoparticles

Mass spectrometry is also used for nanoparticles investigations. Two ionization techniques often used with liquid and solid biological samples include electrospray ionization (ESI) and matrix-assisted laser desorption/ioiuzation (MALDI). Inductively coupled plasma (ICP) sources are mainly used for metal analysis. In general,... 

Recent detection methods for glycan array include fluorescent assay, SPR, MALDI-TOF mass spectrometry, and nanoparticle assay. Fluorescence-based measurement is the prevalent principle for detecting binding to glycan microarrays. Rhodamine [9],... 

Keywords cell surface, nanoparticle, MALDI, TPD, mass spectrometry 1. Introduction... 

Interaction of nanomaterials with native cells is an important problem in modem life science. Recent progress in mass spectrometry provides a vital tool to study this problem. Advances in applications of mass spectrometry for investigating the interaction of nanoparticles with cell membranes and biomacromolecules are based on at least two methods. The first is matrix-assisted laser desorption ionization (MALDI),1 and the second is temperature-programmed desorption mass spectrometry (TPD MS), newly developed to study the interaction of nanoparticles with a cell surface.2 ... 

Figure 3.11 summarizes such key experimental points. As a first point, we have to choose the appropriate ionization method for the detection of small metabolites, we have alternative choices other than MALDI, such as secondary ion mass spectrometry (SIMS) [15], nanostructure-initiator mass spectrometry (NIMS) [20,21], desorption/ionization on silicon (DIOS) [22], nanoparticle-assisted laser desorptiopn/ ionization (nano-PALDI) [23], and even laser desorption/ionization (LDI) [24,25]. We consider that MALDI is stiU the most versatile method, particularly due to the soft ionization capability of intact analyte. However, other methods each have unique advantages for example, SIMS and nano-PALDI have achieved higher spatial resolution than conventional MALDI-IMS, and above aU, these mentioned alternative methods are all matrix-free methods, and thus can exclude the interruption of the matrix cluster ion. Next, if MALDI is chosen, experimenters should choose a suitable matrix compound, solvent composition, and further matrix application method for their target analyte. All these factors are critical to obtain sufficient sensitivity because they affect efficiency of analyte extraction, condition of cocrystallization, and, above all, analyte-ionization efficiency. In addition, based on the charge state of the analyte molecule, suitable MS polarity (i.e., positive/ negative ion detection mode) should be used in MS measurement. Below, we shall describe the key experimental points for MALDI-IMS applications of representative metabolites. 

For example, by using the nanostructure-initiator mass spectrometry, Patti and colleagues [130] detected intact cholesterol and its derivative molecules in situ to provide the first images of brain sterol localization in a knockout mouse model of 7-dehydrocholesterol reductase. Other nanomaterials (e.g silver nanoparticles) have also been used to analyze lipids directly from tissue samples [133], From a thin film of colloidal graphite on rat brain tissue, direct lipid profiling was performed by graphite-assisted laser desorption/ionization mass spectrometry, which allowed to detect 22 HexCer species, whereas only eight HexCer species are detected with MALDI-TOF/MS [132], Chemically selective analysis for HexCer and ST species was successfully obtained. 

Modified silver nanoparticle as a hydrophobic affinity probe for analysis of peptides and proteins in biological samples by using liquid-liquid microextraction coupled to AP-MALDI-lon trap and MALDl-TOF mass spectrometry. Analytical Chemistry, 80(7), 2583-9. 

Bauer F, Sauerland V, Ernst H, Glasel HA, Naumov S and Mehnert R, Preparation of scratch- and abrasion-resistant polymeric nanocomposites by monomer grafting onto nanopaiticles, 4 - Application of MALDI-TOF mass spectrometry to the characterization of surface modified nanoparticles , Macromol Chem Phys 2003 204(3) 375-83. 

---