Static SIMS Investigation of Ag-Supported Amino Acids

Abstract

The static mode of secondary-ion mass-spectroscopy (static SIMS) was used to investigate Ag-supported amino acids, the amount of amino acids on the Ag surface being systematically controlled. It is shown in this report that a mono-molecular layer (full coverage θ=1) is produced at a surface concentration of about 5×1014 molecule/cm2. The possibility of the quantitative detection of amino acids with static SIMS for θ<1 is also demonstrated. The fact that the ratio (M-COOH)+/(M+H)+ from a mixture of two amino acids remains constant as the mixture ratio varies indicates that these ions are formed from amino acids in the same bonding state on the surface. The absolute probability of formation of these ions is, however, strongly affected by the presence of another amino acid coexisting on the surface. The secondary (M+H)+ and (M-COOH)+ ion intensities are used to calculate the absolute ion yields for 15 amino acids and most of these yields are found to be larger than 10-19.

Protein Kinase Assay on Peptide‐Conjugated Gold Nanoparticles by Using Secondary‐Ion Mass Spectrometric Imaging

“…By using an atomic primary ion, quasimolecular secondary‐ion signals were most strongly observed for [ M H−SH−COOH] + ( m / z 1085.61 for P Abl and m / z 857.52 for P Abl−s ) instead of [ M H] + , as shown in Figure 2 a and b. This result indicated that the cysteine sulfhydryl group (SH) was strongly attached onto the surface of the AuNPs by a thiol bond,7 and molecular ion signals with the subtraction of a carboxylic acid group reflect one of the sputtering features in amino acid analysis with SIMS 8…”

Influence of the organic layer thickness in (Metal-Assisted) secondary ion mass spectrometry using Ga+ and C60+ projectiles

“…Beyond 4 mg/mL, a drastic yield decrease is observed. Another work conducted with amino-acids [13] reported a linear relationship between the SI yield and the surface concentration ranging from 1 ϫ 10 13 to 5 ϫ 10 14 arginine molecule/cm 2 . The authors attributed these results to a complete monolayer of arginine being formed with 5 ϫ 10 14 molecule/cm 2 .…”

“…Without metallization, the effect of the PS sample concentration on the characteristic secondary ion yields is dramatic and strongly dependent on the chosen projectile type (Figure 2). For atomic projectile bombardment, maximums in the yield versus concentration curves have been already reported for polymers such as PS [11], PMMA [12,26], PVC [12], and for biological films [13]. Norrman et al [12] spin-coated PMMA and PVC on Si wafers using a range of polymer concentrations.…”

Organic surfaces excited by low-energy ions: atomic collisions, molecular desorption and buckminsterfullerenes

“…The mechanisms, however, are various, sample specific and difficult to model. Many molecules, especially polar species like amino acids 80,81 and amphiphile molecules, 82 ionize through the addition or loss of a proton, forming (M À H) À and (M þ H) 1 parent-like ions. As a function of their acid/base character they tend to aggregate with a cation or release a proton upon ejection.…”