MALDI TOF of carbon clusters

Some of the most significant discoveries and achievements concerning the MALDI TOF mass spectra and gas phase ion chemistry of carbon clusters are reviewed. These include endohedral fullerenes comprising recent data on ion beam implantation and fullerene derivatives. Matrix assisted laser desorption/ionization (MALDI) coupled with reflectron time-of-flight (TOF) mass spectrometry has been applied to the analysis of such clusters. Using a structurally similar model analyte, this investigation includes the screening of two different compounds regarding their suitability as MALDI matrices. The appearance of positive- and negative-ion mass spectra has been detailed, and the analysis has been supported by delayed extraction experiments.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Tims and maldi tof of endohedral metallofullerenes

Mass spectral studies (both TIMS – thermal ionization and MALDI TOF – matrix-assisted laser desorption time-of-flight mass spectrometry) of the endohedral metallofullerenes, Li@C60,Li2C70 and 99mTc@C70,provided detailed structural and reactivity information about these unusual species. MS experiment revealed that both fullerenes and endohedral metallofullerenes fragment by multiple C2 loss. However, a difference in the terminal fragmentation products was observed for metallofullerene relative to C60, suggesting that the encapsulation metal strongly impactsthe fragmentation product. Singly charged cations of the metallofullerenes (M@Cn + ) were completely unreactive in the gas phase with oxygenated compounds such as ethylene oxide: however, the corresponding neutral species appear to react readily with oxygenated species. Collisional dissociation of the ionized endohedral fullerenes listed above revealed multiple C2 loss (either as sequential C2 loss or larger C2n eliminations) to generate similar terminal fragmentation products, which might be predicted due to the similar ionic radii of the encapsulated metals. The observed ionization energies of endohedral molecules were 5.9 ± 0.1 eV, 5.3 ± 0.1 eV and 5.7 ± 0.1 eV, respectively.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Surface ionization study of the non- stoichiometric LnFn-1 (n = 4 – 6) clusters

In this study we are presenting the results of the surface ionization of LinFn-1 (n=4- 6) clusters on rhenium surface impregnated with fullerenes using the magnetic mass spectrometer. The Li5F4 nanocubic cluster was detected for the first time. We determined values of ionization energies for Li4F3 and Li6F5, they are 4,3±0,2 eV, 4,0±0,2eV, respectively. The ionization energies agreed with theoretical ionization energies obtained by ab initio method, which indicates the excess electron localized in a specific site for non-stoichiometric clusters. The first ionization energy value for the Li4F3 was in accordance with earlier results obtained experimentally using photoionization time-of-flight mass spectrometer. There are currently no reliable experimental data for the ionization energy of Li6F5 cluster.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

The calcification of collagen by HAP functionalized carbon materials

Bone is composed of two phases. The organic phase is made of collagen fibrils assembled in broad fibers acting as a template for mineralization. The mineral phase comprises hydroxyapatite (HAP) crystals grown between and inside the collagen fibers. We have developed a material using functionalized carbon nanotubes, carbon fibers and glasy carbon as scaffold to initiate in vitro mineralization. Mentioned carbon materials are functionalized with carboxylic groups prior to decorating. All samples were dispersed in ultra-pure water and incubated for 2 weeks in a synthetic body fluid with dispersed HAP, in order to induce the calcification of the functionalized carbon materials. Atomic force microscopy (AFM) and transmision electron microscopy (TEM) showed that Ca2+ and PO4 3- ions were deposited as round-shaped nodules. Raman spectroscopic studies confirmed the HAP formation, and image analysis made on TEM pictures showed that HAP were packed around and inside the carbon materials together. All three types of investigated carbon materials leading to successful calcification of collagen. This suggests that it takes the presence of carbon materials to prevent it from calcification of collagen, independent of the structures of the material

Tims and maldi tof of endohedral 99mTc@C60 metallofullerene

Mass spectral studies (both TIMS – thermal ionization and MALDI TOF – matrixassisted laser desorption time-of-flight mass spectrometry) of the endohedral metallofullerenes, 99mTc@C60 and 99mTc@C70, provided detailed structural and reactivity information about these unusual species. MS experiment revealed that both fullerenes and endohedral metallofullerenes fragment by multiple C2 loss. However, a difference in the terminal fragmentation products was observed for metallofullerene relative to C60, suggesting that the encapsulation metal strongly impacts the fragmentation product. Singly charged cations of the metallofullerenes (M@Cn + ) were completely unreactive in the gas phase with oxygenated compounds such as ethylene oxide: however, the corresponding neutral species appear to react readily with oxygenated species. Collisional dissociation of the ionized endohedral fullerenes listed above revealed multiple C2 loss (either as sequential C2 loss or larger C2n eliminations) to generate similar terminal fragmentation products, which might be predicted due to the similar ionic radii of the encapsulated metals. The observed ionization energies of endohedral molecules were, 5.1 ± 0.1 eV and 5.3 ± 0.1 eV, respectively.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Molar-mass distribution of urea-formaldehyde resins of different degrees of polymerisation by MALDI-TOF mass spectrometry

This paper describes some results obtained in an investigation of urea-formaldehyde (UF) resins of different degrees of polymerisation by matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometry (MS). MALDI-TOF MS proved to be an appropriate technique for analyzing these types of polymers, bearing in mind that the results of the analysis correspond with previous physical and chemical measurements. This technique enables a relatively swift determination of the degree of polymerrisation through the monitoring of key changes in the structure of a polymer. Thus, in the analysis of UF resins, it may be possible to monitor a decrease in the intensity of the monohydroxymethyl urea (MMU) signal, which corresponds to an increase of the mass spectra values in the mass range of higher homologues, above 1000 g mol(-1). A noticeable difference concerns the signal intensities in the higher mass ranges (up to 1400 g mol(-1)), which corresponds to more branched and longer homologues of the polymers. Especially, a significantly more intensive signal of MMU was registered. The average molecular weight (MW) of the examined samples was between 936 and 1324 g mol(-1), with a maximal deviation of 20 %, depending on the ratios of the reactants

MALDI TOF Mass Spectrometry Characterization of Collagen

Collagen is the most frequently occuring fibrillar protein in mammals, which can be found in cartilage, tendon, bone, ligament, skin, etc. The structure of collagen is based on a complicated helix structure of single chains of amino acids (most abundant is glicine-Gly, proline-Pro and hydroxyproline-Hyp) which are connected by hydrogen bonds. We tried to establish MALDI method to get better resolution of collagen’s mass spectra. Digested collagen (type II from bovine Achilles tendon which was digested with collagenase from Clostridium histolycium) has been analysed on MALDI-TOF MS in order to find peptide’s fragments that are characteristic for collagen. In mass spetra we found peaks of peptides, which is highly indicative for collagen (GlyPro-Hyp, Gly-Pro-Asp, Gly-Pro-Glu ect.) We hope that it should be possible to obtain MS analysis and structure characterization of collagen by MALDI-TOF/TOF in future

A TPD-MS study of glassy carbon surfaces oxidized by CO2 and O-2

The temperature-programmed desorption (TPD) method combined with mass spectrometric (MS) analysis has been applied to investigate the surface properties of carbon materials. The apparatus consisting of a temperature-programmed furnace and a quadrupole Mass spectrometer was constructed in order to characterize the surface of differently treated glassy carbon samples. In this work, samples of glassy carbon exposed to air, CO2 and O-2 were examined. The desorption of H2O, CO and CO2, as major products, indicated the presence of different oxide groups. The amount of these groups for all samples was calculated. It is concluded that oxidation affects the nature and the amount of die surface oxide groups and contributes to their increased stability

Mass spectrometric investigation of silver clusters

Silver clusters were produced by two different synthesis procedures, related with different reduction species. PVA (polyvinyl alcohol) was successfully utilized as a source to reduce silver (Ag) metal ions without using any additional reducing agents to obtain Ag clusters. Silver clusters with atoms numbering 5-29 are registered through mass spectrometry using MALDI TOF and MALDI TOF/TOF techniques. Analysis showed that clusters with magic numbers are the largest, while those with an odd number of atoms are larger than clusters with an even number of atoms. Stability of these molecules, magic number actually, is in relation with their electronic configuration

MALDI TOF and AFM studies of DNA/SWNT hybrids

A primer is a strand of nucleic acid that serves as a starting point for DNA synthesis. DNA, as a large molecule, is very difficult for analysis by means of mass spectrometry. However, primer, as a short sequence of nucleic acid, is much more convinient for e.g. MALDI TOF MS analysis. Mass spectrometric experiment resulted in quality MALDI TOF spectra of 3 primers. Compound 3-HPA (3- hydroxypicolinic acid) showed the best results as matrix. AFM studies were also conducted, for both pure primer samples and hybrids of primer molecule with single wall carbon nanotubes (SWNT). Thus, obtained functionalisation of SWNT with DNA primers was confirmed by AFM imaging. AFM images clearly showed wrapping of DNA structures around nanotube „template“. Functionalisation of SWNT is very important for potential applications of nanotubes in biomedical field. MALDI TOF mass spectrometry, in combination with AFM imaging, proved its great potential in analysis of short DNA sequences, and indicated the possibility of investigating more complex DNA structures.Physical chemistry 2012 : 11th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 201