Analysis of nucleotides and oligonucleotides immobilized as self-assembled monolayers by static secondary ion mass spectrometry

Biol Mass Spectrom. 1994 Nov;23(11):653-9. doi: 10.1002/bms.1200231102.

Abstract

Nucleic acid constituents can be bound to a metal surface in the form of self-assembled monolayers. Binding is achieved either through ionic interactions with a self-assembled 2-aminoethanethiol monolayer or by direct covalent binding of a dithiophosphate oligonucleotide to a metal surface through a sulfur-metal bond. Nucleotides, polynucleotides (both normal and a dithiophosphate analog) and double-stranded DNA have all been bound to surfaces. When the surfaces are interrogated using static secondary ion mass spectrometry (SIMS), the surface-bound nucleic acid constituents are observed in the form of the characteristic protonated nucleic acid base ions (BH2+). While a silver foil substrate was found to provide the highest absolute signal, vapor-deposited gold yields the best signal-to-noise ratio for ionically bound deoxyguanosine monophosphate. Under comparable conditions, a Cs+ projectile produces a 10-fold increase in the secondary ion signal relative to a Ga+ projectile. The experiment has been extended to a triple-quadrupole instrument where tandem mass spectrometric experiments on ionically immobilized dGMP showed the characteristic loss of ammonia from the released BH2+ ion. When a 'biomimetic' surface formed by ionically immobilizing double-stranded DNA is exposed to a solution containing ethidium bromide, ions corresponding to the non-covalent adduct are readily detectable using SIMS. This adduct and the nucleic acid constituents can be monitored at levels below 10 fmol.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • DNA / analysis
  • Guanine / analysis
  • Nucleotides / analysis*
  • Nucleotides / chemistry
  • Oligonucleotides / analysis*
  • Oligonucleotides / chemistry
  • Spectrometry, Mass, Secondary Ion
  • Sulfhydryl Compounds

Substances

  • Nucleotides
  • Oligonucleotides
  • Sulfhydryl Compounds
  • Guanine
  • DNA