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Analysis of nucleotides and oligonucleotides immobilized as self‐assembled monolayers by static secondary ion mass spectrometry
Author(s) -
Patrick Jeffrey S.,
Cooks R. Graham,
Pachuta Steven J.
Publication year - 1994
Publication title -
biological mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1052-9306
DOI - 10.1002/bms.1200231102
Subject(s) - chemistry , nucleic acid , monolayer , covalent bond , oligonucleotide , adduct , polynucleotide , mass spectrometry , inorganic chemistry , analytical chemistry (journal) , dna , chromatography , organic chemistry , biochemistry
Abstract Nucleic acic 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, poly‐nucleotides (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 (BH 2 + ). 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 in mobilized dGMP showed the characteristic loss of ammonia from the released BH 2 + 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.