Some New Advances and Challenges in Biological and Biomedical Materials Characterization

Braet, Filip; Soon, Lilian; Kelly, Thomas F.; Larson, David J.; Ringer, Simon P.

doi:10.1002/9783527610419.ntls0032

Cited by 3 publications

(4 citation statements)

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“…In order for APT to evolve into an accepted metrology for the life sciences, there are a number challenges to overcome (Panitz, 2005; Braet et al , 2006; Heeren et al , 2006): (1) specimen preparation techniques need to be developed to fashion or deposit the materials of interest into shapes suitable for APT and/or local‐electrode APT (Larson & Kelly, 2006) analysis, (2) controlled field evaporation of material from those specimens needs to be demonstrated, (3) specimen stability (both minimization of potential surface diffusion and bulk stability) under high‐field conditions needs to be verified to ensure an ability to reconstruct static spatial information, (4) fragmentation variability needs to be understood to support compatibility with available reconstruction methods and finally (5) correlation with currently accepted analytical methods must be established to overcome discipline‐specific barriers preventing large‐scale adoption by practitioners in the field. Many of these challenges are remnants of relevant work done in field‐electron emission and field‐ion microscopies (Müller, 1950; Abbott, 1965; Müller & Rendulic, 1967; Machlin et al , 1975; Panitz & Giaver, 1981; Panitz, 1982a, b).…”

Section: Introductionmentioning

confidence: 99%

Atom probe tomography analysis of poly(3‐alkylthiophene)s

Prosa

Keeney²,

Kelly

2010

Journal of Microscopy

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SummaryPulsed-laser atom-probe tomography is used to compare the field-evaporation mass spectrum and spatial distribution of molecular fragments from various poly(3-alkylthiophene) films deposited on sharpened aluminium specimen carriers using two different deposition methods. Films deposited via a modified solution-cast methodology yield small fragments with a uniform structural morphology whereas films deposited via an electrospray ionization methodology yield a wide range of fragments with a very non-uniform structural morphology. The main field-evaporated chemical species identified for both deposition types were, in order of typical relative abundance, C 2 H 5 + , CH 3 + , C 2 H 4 + , followed by C 3 H 7,8 + /SC + and SCH + . Thick electrospray depositions allowed investigation of the influence of laser-pulse energy on the analysis. Evidence is presented supporting the presence of a critical laser-pulse energy whereby changes in film morphology are signalled by the appearance of a new mass fragment at 190 Da.

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Section: Introductionmentioning

confidence: 99%

Atom probe tomography analysis of poly(3‐alkylthiophene)s

Prosa

Keeney²,

Kelly

2010

Journal of Microscopy

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“…Further challenges include understanding the complexities in the probing/imaging process, with respect to field evaporation of biological molecules on the tip apex in the pulsed-voltage mode. Similarly, laser–matter interaction of biological material under thermal field evaporation in the pulsed-laser mode requires further investigations. ,,, Finally, since APT is a relatively new technique for biological materials, establishing protocols for confident peak identification in the mass spectrum is essential for accurate elemental composition analysis of the acquired data.…”

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confidence: 99%

“…Similarly, laser−matter interaction of biological material under thermal field evaporation in the pulsed-laser mode requires further investigations. 18,22,32,33 Finally, since APT is a relatively new technique for biological materials, establishing protocols for confident peak identification in the mass spectrum is essential for accurate elemental composition analysis of the acquired data.…”

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confidence: 99%

Near-Atomic Three-Dimensional Mapping for Site-Specific Chemistry of ‘Superbugs’

et al. 2016

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Emergence of multi-drug resistant Gram-negative bacteria has caused a global health crisis and last-line class of antibiotics such as polymyxins are increasingly used. The chemical composition at the cell surface plays a key role in antibiotic resistance. Unlike imaging the cellular ultrastructure with well-developed electron microscopy, acquisition of a high-resolution chemical map of the bacterial surface still remains a technological challenge. In this study, we developed an atom probe tomography (APT) analysis approach to acquire mass spectra in the pulsed-voltage mode and reconstructed the 3D chemical distribution of atoms and molecules in the subcellular domain at the near-atomic scale. Using focused ion beam (FIB) milling together with micromanipulation, site-specific samples were retrieved from a single cell of Acinetobacter baumannii prepared as needle-shaped tips with end radii less than 60 nm, followed by a nano-scale coating of silver in the order of 10 nm. The significantly elevated conductivity provided by the metallic coating enabled successful and routine field evaporation of the biological material, with all the benefits of pulsed-voltage APT. In parallel with conventional cryo-TEM imaging, our novel approach was applied to investigate polymyxin-susceptible and -resistant strains of A. baumannii after treatment of polymyxin B. Acquired atom probe mass spectra from the cell envelope revealed characteristic fragments of phosphocholine from the polymyxin-susceptible strain, but limited signals from this molecule were detected in the polymyxin-resistant strain. This study promises unprecedented capacity for 3D nanoscale imaging and chemical mapping of bacterial cells at the ultimate 3D spatial resolution using APT.

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Laser Atom Probe Tomography: Application to Polymers

Prosa

Kostrna

Kelly

2006

2006 19th International Vacuum Nanoelectronics Conference

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Controlled field evaporation of organic materials has been a long-term challenge for 3-dimensional (3D) atom probe tomography (APT) [1]. Complications arising from sample electrical/thermal requirements, sample preparation methodologies, and hardware configurations have all conspired to limit APT application for this class of materials. Although polymer laser APT studies have been reported on various polymers including polystyrene [2], polypyrrole [2], and polythiophene [3], these reports have focused on field ionized mass spectroscopy (FIMS) of the polymer and have not even attempted 3D reconstructions.We present data on laser local electrode atom probe (LEAP®) [4] investigations of alkanethiol self-assembled monolayers (SAMs) and poly-3-alkylthiophenes (P3ATs). Alkanethiols represent an opportunity to understand APT field ionization and reconstruction issues, as applied to polymers, at their most basic level. Alkanethiols are monodisperse short-chain molecules which are covalently bonded to a pre-sharpened metal specimen to form a dense, well-ordered SAM on the tip surface. The well understood microstructure [5] and limited potential for molecular fragment permutations of alkanethiols provides a desirable set of well-defined boundaries for subsequent analyses.P3ATs are another family of conducting polymers that have a chemical architecture similar to polypyrrole and polythiophene and thus invite comparison to previously reported results. At their heart, P3ATs are polythiophene with alkane side-chains attached to the conducting polymer main-chain so that P3ATs also bear some similarity to alkanethiols. This investigation of two families of polymers promises to provide a more complete understanding of laser APT than studies of each polymer family individually. 10000 4 CH3+ t o lo 20 30 4SCH2040Hi 7 'CHji. mv;}~~~~~~~~~~~~~mlq (ani) -RoJ u~, |Figure 1: Laser LEAP analIysis of dodecanethiol on Pd tip. 3D reconstruction [left] of mass-to-charge spectrum [top] can be interpreted as low-field alkane fragments (small 7 dark circles) originating from the tip surface. A lack of events at intermediate field results 3 e in a gap artifact in the reconstruction. Peaks at 12, 32, and 33 amu (large gray squares) 0 o |~~~~reside exclusively within the Pd bulk. A number of molecules oniginate from the interface ><. U between alkane and Pd corresponding to peaks at 63, 64, and 65 amu (large light shaded 7 6 5 4 3 2 1 circles). Their location is highly suggestive of fragments corresponding to a missing thiol Depth (nm) component of the dodecanethiol molecule (see chemical diagram top-right insert). Figure 1 shows laser LEAP data for a dodecanethiol coated Pd specimen. Pd wire (99.995 %/ purity) was electropolished to form an APT compatible specimen. A SAM was formed on the tip by submersion in a~-5 mM solution of dodecanethiol in ethanol for~3 hrs. Field evaporation evolution was consistent with fragments of dodecanethiol molecules evaporating at very low field. Once the Pd surface was uncovered, a significantly higher field was n...

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Some New Advances and Challenges in Biological and Biomedical Materials Characterization

Cited by 3 publications

References 40 publications

Atom probe tomography analysis of poly(3‐alkylthiophene)s

Atom probe tomography analysis of poly(3‐alkylthiophene)s

Near-Atomic Three-Dimensional Mapping for Site-Specific Chemistry of ‘Superbugs’

Laser Atom Probe Tomography: Application to Polymers

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