Field ion microscopy of biomolecules

Abstract

A new type of image, existing only at field strengths below the denaturation field strengths of molecules, has been discorvered. This type of image has structure, is not symmetrical and thus differs from previously reported low field strength images. The possibility that macromolecules adsorbed on tip surfaces produce such structured images has been exhaustively investigated. The result is that no observation has been found which disproves this hypothesis and many tests conducted in such attempts yielded correlations consistent with this hypothesis. It is therefore concluded that it is highly probable that biomolecules produce structured images and that it is highly improbable that these correlations represent a chance event. On the other hand, these correlations may be due to some cause unknown to the authors; but we consider this possibility to be unlikely. Some micrographs have been obtained which provide a reasonable basis for the hope that tertiary structure information may be defrived from low field strength imaging of partially embedded biomolecules or of biomolecules that are resistant to field denaturation during imaging. Information may presently be obtained from analysis of low field strength ion micrographs about the size and shape of some biomolecules.

Atom probe tomography

“…In 1975, Machlin et al reported two-dimensional 1 -2 nm resolution field ion microscope ͑FIM͒ images of freeze-dried tRNA dimers. 152 A major problem discussed in some detail by Machlin et al is that the high field strengths for FIM imaging ͑ϳ5-15 V/nm͒ appeared to cause desorption and fragmentation of adsorbed biomolecules. 152 In the 1980s, Panitz reported FIM and field desorption imaging of biological materials including ferritin 153,154 and unstained DNA.…”

“…152 A major problem discussed in some detail by Machlin et al is that the high field strengths for FIM imaging ͑ϳ5-15 V/nm͒ appeared to cause desorption and fragmentation of adsorbed biomolecules. 152 In the 1980s, Panitz reported FIM and field desorption imaging of biological materials including ferritin 153,154 and unstained DNA. 155 Other than a few additional publications by these research groups, this is essentially the entire history of biological atom probe and FIM imaging.…”

Atom Probe Tomography of Molecular Organic Materials: Sub-Dalton Nanometer-Scale Quantification

“…38,39,42 Despite APT's excellent spatial and chemical resolution and the relative maturity of the technique, the body of APT analyses of organic systems is small. [43][44][45][46][47][48][49][50][51] Most of these studies looked at polymers, which, because of their chain structure, fragment during field evaporation. [47][48][49][50][51] In 2012, Joester et al examined a blend of poly(3hexylthiophene-2,5-diyl) (P3HT) and C 60 ; 51 as before, the P3HT polymer proved difficult to study due to uneven fragmentation, but the mass-spectrum had a clear C 60 signal, suggesting that small-molecule organic systems should be amenable to study with APT.…”

Advanced spectroscopic, microscopic, and tomographic characterization techniques to study biogeochemical interfaces in soil

“…These may contain atoms of the same type such as C 2 or C 4 clusters but also clusters with different atoms such as CH 2 or CO (Kelly and Miller 2007). A further problem is that high field strengths cause desorption and fragmentation of biomolecules when studying freeze-dried tRNA dimers (Machlin et al 1975). Generally, organic specimen must be stabilized against deformation, vaporization, and environmental degradation during sample preparation (Kelly et al 2009).…”