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Shard AG, Miisho A, Vorng J, Havelund R, Gilmore IS, Aoyagi S. A two‐point calibration method for quantifying organic binary mixtures using secondary ion mass spectrometry in the presence of matrix effects. SURF INTERFACE ANAL 2021. [DOI: 10.1002/sia.7042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
| | - Ako Miisho
- Kobelco Research Institute, Inc. Kobe Japan
| | | | - Rasmus Havelund
- National Physical Laboratory Teddington UK
- Department of Medical Physics Vejle Hospital Vejle Denmark
| | | | - Satoka Aoyagi
- Department of Materials and Life Science Seikei University Tokyo Japan
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2
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Taylor AJ, Graham DJ, Castner DG. Reconstructing accurate ToF-SIMS depth profiles for organic materials with differential sputter rates. Analyst 2015; 140:6005-14. [PMID: 26185799 PMCID: PMC4532557 DOI: 10.1039/c5an00860c] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
To properly process and reconstruct 3D ToF-SIMS data from systems such as multi-component polymers, drug delivery scaffolds, cells and tissues, it is important to understand the sputtering behavior of the sample. Modern cluster sources enable efficient and stable sputtering of many organics materials. However, not all materials sputter at the same rate and few studies have explored how different sputter rates may distort reconstructed depth profiles of multicomponent materials. In this study spun-cast bilayer polymer films of polystyrene and PMMA are used as model systems to optimize methods for the reconstruction of depth profiles in systems exhibiting different sputter rates between components. Transforming the bilayer depth profile from sputter time to depth using a single sputter rate fails to account for sputter rate variations during the profile. This leads to inaccurate apparent layer thicknesses and interfacial positions, as well as the appearance of continued sputtering into the substrate. Applying measured single component sputter rates to the bilayer films with a step change in sputter rate at the interfaces yields more accurate film thickness and interface positions. The transformation can be further improved by applying a linear sputter rate transition across the interface, thus modeling the sputter rate changes seen in polymer blends. This more closely reflects the expected sputtering behavior. This study highlights the need for both accurate evaluation of component sputter rates and the careful conversion of sputter time to depth, if accurate 3D reconstructions of complex multi-component organic and biological samples are to be achieved. The effects of errors in sputter rate determination are also explored.
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Affiliation(s)
- Adam J Taylor
- National ESCA and Surface Analysis Center for Biomedical Problems (NESAC/BIO), Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, USA.
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3
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Asakawa D, Hiraoka K. Surface characterization and depth profiling of biological molecules by electrospray droplet impact/SIMS. SURF INTERFACE ANAL 2011. [DOI: 10.1002/sia.3821] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Daiki Asakawa
- Graduate School in Nanobioscience; Yokohama City University, 22-2 Seto; Kanazawa-ku; Yokohama; 236-0027; Japan
| | - Kenzo Hiraoka
- Clean Energy Research Center; The University of Yamanashi, Takeda 4-3-11; Kofu; 400-8511; Japan
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4
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Surface analysis for compositional, chemical and structural imaging in pharmaceutics with mass spectrometry: A ToF-SIMS perspective. Int J Pharm 2011; 417:61-9. [DOI: 10.1016/j.ijpharm.2011.01.043] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2010] [Revised: 01/13/2011] [Accepted: 01/19/2011] [Indexed: 11/22/2022]
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5
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Inkinen S, Hakkarainen M, Albertsson AC, Södergård A. From Lactic Acid to Poly(lactic acid) (PLA): Characterization and Analysis of PLA and Its Precursors. Biomacromolecules 2011; 12:523-32. [DOI: 10.1021/bm101302t] [Citation(s) in RCA: 495] [Impact Index Per Article: 38.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Saara Inkinen
- Laboratory of Polymer Technology, Center for Functional Materials (FUNMAT), Åbo Akademi University, Piispankatu 8, 20100 Turku, Finland
| | - Minna Hakkarainen
- The Royal Institute of Technology (KTH), Department of Fibre and Polymer Technology, Teknikringen 56-58, 10044 Stockholm, Sweden
| | - Ann-Christine Albertsson
- The Royal Institute of Technology (KTH), Department of Fibre and Polymer Technology, Teknikringen 56-58, 10044 Stockholm, Sweden
| | - Anders Södergård
- Laboratory of Polymer Technology, Center for Functional Materials (FUNMAT), Åbo Akademi University, Piispankatu 8, 20100 Turku, Finland
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6
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TSUYAMA N, MIZUNO H, MASUJIMA T. Mass Spectrometry for Cellular and Tissue Analyses in a Very Small Region. ANAL SCI 2011; 27:163-70. [DOI: 10.2116/analsci.27.163] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Naohiro TSUYAMA
- Graduate School of Biomedical Sciences, Hiroshima University
| | - Hajime MIZUNO
- Graduate School of Biomedical Sciences, Hiroshima University
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7
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Wehbe N, Houssiau L. Comparative Study of the Usefulness of Low Energy Cs+, Xe+, and O2+ Ions for Depth Profiling Amino-Acid and Sugar Films. Anal Chem 2010; 82:10052-9. [DOI: 10.1021/ac101696c] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Nimer Wehbe
- Research Centre in Physics of Matter and Radiation (PMR), University of Namur (FUNDP), 61, rue de Bruxelles, B-5000 Namur, Belgium
| | - Laurent Houssiau
- Research Centre in Physics of Matter and Radiation (PMR), University of Namur (FUNDP), 61, rue de Bruxelles, B-5000 Namur, Belgium
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8
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Brewer TM, Szakal C, Gillen G. Method for improved secondary ion yields in cluster secondary ion mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2010; 24:593-598. [PMID: 20155758 DOI: 10.1002/rcm.4423] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A method to increase useful yields of organic molecules is investigated by cluster secondary ion mass spectrometry (SIMS). Glycerol drops were deposited onto various inkjet-printed arrays and the organic molecules in the film were rapidly incorporated into the drop. The resulting glycerol/analyte drops were then probed with fullerene primary ions under dynamic SIMS conditions. High primary ion beam currents were shown to aid in the mixing of the glycerol drop, thus replenishing the probed area and sustaining high secondary ion yields. Integrated secondary ion signals for tetrabutylammonium iodide and cocaine in the glycerol drops were enhanced by more than a factor of 100 compared with an analogous area on the surface, and a factor of 1000 over the lifetime of the glycerol drop. Once the analyte of interest is incorporated into the glycerol microdrop, the solution chemistry can be tailored for enhanced secondary ion yields, with examples shown for cyclotrimethylenetrinitramine (RDX) chloride adduct formation. In addition, depositing localized glycerol drops may enhance analyte secondary ion count rates to high enough levels to allow for site-specific chemical maps of molecules in complex matrices such as biological tissues.
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Affiliation(s)
- Tim M Brewer
- Surface and Microanalysis Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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9
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Mahoney CM. Cluster secondary ion mass spectrometry of polymers and related materials. MASS SPECTROMETRY REVIEWS 2010; 29:247-293. [PMID: 19449334 DOI: 10.1002/mas.20233] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Cluster secondary ion mass spectrometry (cluster SIMS) has played a critical role in the characterization of polymeric materials over the last decade, allowing for the ability to obtain spatially resolved surface and in-depth molecular information from many polymer systems. With the advent of new molecular sources such as C(60)(+), Au(3)(+), SF(5)(+), and Bi(3)(+), there are considerable increases in secondary ion signal as compared to more conventional atomic beams (Ar(+), Cs(+), or Ga(+)). In addition, compositional depth profiling in organic and polymeric systems is now feasible, without the rapid signal decay that is typically observed under atomic bombardment. The premise behind the success of cluster SIMS is that compared to atomic beams, polyatomic beams tend to cause surface-localized damage with rapid sputter removal rates, resulting in a system at equilibrium, where the damage created is rapidly removed before it can accumulate. Though this may be partly true, there are actually much more complex chemistries occurring under polyatomic bombardment of organic and polymeric materials, which need to be considered and discussed to better understand and define the important parameters for successful depth profiling. The following presents a review of the current literature on polymer analysis using cluster beams. This review will focus on the surface and in-depth characterization of polymer samples with cluster sources, but will also discuss the characterization of other relevant organic materials, and basic polymer radiation chemistry.
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Affiliation(s)
- Christine M Mahoney
- Chemical Science and Technology Laboratory, Surface and Microanalysis Science Division, National Institute of Standards and Technology, 100 Bureau Drive, Mail Stop 8371, Gaithersburg, MD 20899-8371, USA.
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10
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Vilay V, Mariatti M, Ahmad Z, Pasomsouk K, Todo M. Effect of PEO-PPO-PEO copolymer on the mechanical and thermal properties and morphological behavior of biodegradable poly (L-lactic acid) (PLLA) and poly (butylene succinate-co-L-lactate) (PBSL) blends. POLYM ADVAN TECHNOL 2010. [DOI: 10.1002/pat.1672] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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11
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Mahoney CM. Cluster SIMS depth profiling of stereo-specific PMMA thin films on Si. SURF INTERFACE ANAL 2010. [DOI: 10.1002/sia.3115] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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12
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Prestidge CA, Barnes TJ, Skinner W. Time-of-flight secondary-ion mass spectrometry for the surface characterization of solid-state pharmaceuticals. J Pharm Pharmacol 2010; 59:251-9. [PMID: 17270078 DOI: 10.1211/jpp.59.2.0011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Abstract
Time-of-flight secondary-ion mass spectrometry (ToF-SIMS) is a highly surface sensitive analytical method for surface chemical identification and surface chemical distribution analysis (mapping). Here we have explored the application of ToF-SIMS for the characterization of solid-state pharmaceuticals and highlight specific case studies concerning the distribution and stability of pharmaceutical actives within solid matrices (pellets and polymeric carriers) and the face-specific properties of pharmaceutical crystals.
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Affiliation(s)
- Clive A Prestidge
- Ian Wark Research Institute, The Australian Research Council Special Research Centre for Particle and Material Interfaces, University of South Australia, Mawson Lakes, SA 5095, Australia.
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13
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The role of molecular weight on the ToF-SIMS spectra of PMMA using Au+
and C60
+
primary ions. SURF INTERFACE ANAL 2010. [DOI: 10.1002/sia.3197] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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14
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Lee J, Yoon D, Shin K, Kim KJ, Lee Y. TOF-SIMS depth profiling of deuterated polystyrene-block-poly(n
-propyl methacrylate) diblock copolymer films. SURF INTERFACE ANAL 2010. [DOI: 10.1002/sia.3189] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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15
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Burns SA, Hard R, Hicks WL, Bright FV, Cohan D, Sigurdson L, Gardella JA. Determining the protein drug release characteristics and cell adhesion to a PLLA or PLGA biodegradable polymer membrane. J Biomed Mater Res A 2010; 94:27-37. [DOI: 10.1002/jbm.a.32654] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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16
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Yu J, Mahoney CM, Fahey AJ, Hicks WL, Hard R, Bright FV, Gardella JA. Phase separation at the surface of poly(ethylene oxide)-containing biodegradable poly(L-lactic acid) blends. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:11467-11471. [PMID: 19715326 PMCID: PMC3965193 DOI: 10.1021/la901239v] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The surface chemistry and in-depth distribution of the composition of a poly(ethylene oxide) (PEO)-containing biodegradable poly(L-lactic acid) (PLLA) blend matrix system have been investigated using X-ray photoelectron spectroscopy (XPS). This study reports detailed quantitative compositional information using a novel numerical method for determining depth profiles. The PEO system studied is an amphiphilic Pluronic P104 surfactant, PEO-b-poly(propylene oxide) (PPO)-b-PEO. The extent of phase separation is analyzed by determining the surface enrichment of the PEO component via measurement of chemical composition at the polymer-air interface. For this blend system, the combination of the PPO component in the Pluronic surfactants drives the formation of a surface excess of Pluronic in the blends with PLLA. The surface excess profile shows a rapid increase in Pluronic surface composition versus bulk Pluronic mass fractions of 1-5%, but the profile levels off above bulk Pluronic mass fractions of 5%.
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Affiliation(s)
- Jinxiang Yu
- Department of Chemistry, State University of New York, Buffalo, New York 14260
| | - Christine M. Mahoney
- Analytical Microscopy Group, Surface and Microanalysis Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899
| | - Albert J. Fahey
- Analytical Microscopy Group, Surface and Microanalysis Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899
| | - Wesley L. Hicks
- Department of Head and Neck Surgery, Roswell Park Cancer Institute, Buffalo, New York 14263
| | - Robert Hard
- Department of Anatomy/Cell Biology, State University of New York, Buffalo, New York 14214
| | - Frank V. Bright
- Department of Chemistry, State University of New York, Buffalo, New York 14260
| | - Joseph A. Gardella
- Department of Chemistry, State University of New York, Buffalo, New York 14260
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17
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Shard AG, Rafati A, Ogaki R, Lee JLS, Hutton S, Mishra G, Davies MC, Alexander MR. Organic Depth Profiling of a Binary System: the Compositional Effect on Secondary Ion Yield and a Model for Charge Transfer during Secondary Ion Emission. J Phys Chem B 2009; 113:11574-82. [DOI: 10.1021/jp904911n] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Alexander G. Shard
- Quality of Life Division, National Physical Laboratory, Teddington, Middlesex TW11 0LW, U.K.; Laboratory of Biophysics and Surface Analysis, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, U.K.; and Kratos Analytical, Wharfside, Trafford Wharf Road, Manchester M17 1GP, U.K
| | - Ali Rafati
- Quality of Life Division, National Physical Laboratory, Teddington, Middlesex TW11 0LW, U.K.; Laboratory of Biophysics and Surface Analysis, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, U.K.; and Kratos Analytical, Wharfside, Trafford Wharf Road, Manchester M17 1GP, U.K
| | - Ryosuke Ogaki
- Quality of Life Division, National Physical Laboratory, Teddington, Middlesex TW11 0LW, U.K.; Laboratory of Biophysics and Surface Analysis, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, U.K.; and Kratos Analytical, Wharfside, Trafford Wharf Road, Manchester M17 1GP, U.K
| | - Joanna L. S. Lee
- Quality of Life Division, National Physical Laboratory, Teddington, Middlesex TW11 0LW, U.K.; Laboratory of Biophysics and Surface Analysis, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, U.K.; and Kratos Analytical, Wharfside, Trafford Wharf Road, Manchester M17 1GP, U.K
| | - Simon Hutton
- Quality of Life Division, National Physical Laboratory, Teddington, Middlesex TW11 0LW, U.K.; Laboratory of Biophysics and Surface Analysis, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, U.K.; and Kratos Analytical, Wharfside, Trafford Wharf Road, Manchester M17 1GP, U.K
| | - Gautam Mishra
- Quality of Life Division, National Physical Laboratory, Teddington, Middlesex TW11 0LW, U.K.; Laboratory of Biophysics and Surface Analysis, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, U.K.; and Kratos Analytical, Wharfside, Trafford Wharf Road, Manchester M17 1GP, U.K
| | - Martyn C. Davies
- Quality of Life Division, National Physical Laboratory, Teddington, Middlesex TW11 0LW, U.K.; Laboratory of Biophysics and Surface Analysis, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, U.K.; and Kratos Analytical, Wharfside, Trafford Wharf Road, Manchester M17 1GP, U.K
| | - Morgan R. Alexander
- Quality of Life Division, National Physical Laboratory, Teddington, Middlesex TW11 0LW, U.K.; Laboratory of Biophysics and Surface Analysis, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, U.K.; and Kratos Analytical, Wharfside, Trafford Wharf Road, Manchester M17 1GP, U.K
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18
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Rafati A, Davies MC, Shard AG, Hutton S, Mishra G, Alexander MR. Quantitative XPS depth profiling of codeine loaded poly(l-lactic acid) films using a coronene ion sputter source. J Control Release 2009; 138:40-4. [PMID: 19427343 DOI: 10.1016/j.jconrel.2009.05.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Revised: 04/24/2009] [Accepted: 05/02/2009] [Indexed: 10/20/2022]
Abstract
The controlled release of active pharmaceutical ingredients from polymers over prolonged periods of time is vital for the function of drug eluting stents and other drug loaded delivery devices. Characterisation of the drug distribution in polymers allows the in vitro and in vivo performance to be rationalised. We present the first X-ray photoelectron spectroscopy (XPS) depth profiling study of such a drug eluting stent system for which we employ a novel coronene ion sputter source. The rationale for this is to ascertain quantitative atomic concentration data through the thickness of flat films containing codeine and poly(l-lactic acid) (PLA) as a model of a drug loaded polymer device. A range of films of thickness of up to 96 nm are spun cast from chloroform onto Piranha cleaned silicon wafers. Ellipsometry of the films is undertaken prior to depth profiling to determine the total film thickness and provide a measure of the relative loading of drug within the PLA matrix through spectroscopic analysis. Progressive XPS analysis of the bottom of the sputter crater with sputter time indicated codeine to be depleted from the surface and segregated to the bulk of the polymer films by comparison with a uniform distribution calculated from the bulk loading. This serves to illustrate that surface depletion of drug occurs, which poses important implications for drug loaded polymer delivery systems.
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Affiliation(s)
- Ali Rafati
- Laboratory of Biophysics and Surface Analysis, University of Nottingham, School of Pharmacy, Nottingham, NG7 2RD, UK
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19
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Jecklin MC, Gamez G, Zenobi R. Fast polymer fingerprinting using flowing afterglow atmospheric pressure glow discharge mass spectrometry. Analyst 2009; 134:1629-36. [DOI: 10.1039/b819560a] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Green FM, Gilmore IS, Seah MP. Cluster ion beam profiling of organics by secondary ion mass spectrometry--does sodium affect the molecular ion intensity at interfaces? RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2008; 22:4178-4182. [PMID: 19039819 DOI: 10.1002/rcm.3840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The use of cluster ion beam sputtering for depth profiling organic materials is of growing technological importance and is a very active area of research. At the 44th IUVSTA Workshop on "Sputtering and Ion Emission by Cluster Ion Beams", recent results were presented of a cluster ion beam depth profile of a thin organic molecular layer on a silicon wafer substrate. Those data showed that the intensity of molecular secondary ions is observed to increase at the interface and this was explained in terms of the higher stopping power in the substrate and a consequently higher sputtering yield and even higher secondary ion molecular sputtering yield. An alternative hypothesis was postulated in the workshop discussion which may be paraphrased as: "under primary ion bombardment of an organic layer, mobile ions such as sodium may migrate to the interface with the inorganic substrate and this enhancement of the sodium concentration increases the ionisation probability, so increasing the molecular ion yield observed at the interface". It is important to understand if measurement artefacts occur at interfaces for quantification as these are of great technological relevance - for example, the concentration of drug in a drug delivery system. Here, we evaluate the above hypothesis using a sample that exhibits regions of high and low sodium concentration at both the organic surface and the interface with the silicon wafer substrate. There is no evidence to support the hypothesis that the probability of molecular secondary ion ionisation is related to the sodium concentration at these levels.
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21
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Milillo TM, Gardella JA. Spatial Analysis of Time of Flight−Secondary Ion Mass Spectrometric Images by Ordinary Kriging and Inverse Distance Weighted Interpolation Techniques. Anal Chem 2008; 80:4896-905. [DOI: 10.1021/ac702640v] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tammy M. Milillo
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260
| | - Joseph A. Gardella
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260
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22
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Shard AG, Green FM, Brewer PJ, Seah MP, Gilmore IS. Quantitative molecular depth profiling of organic delta-layers by C60 ion sputtering and SIMS. J Phys Chem B 2008; 112:2596-605. [PMID: 18254619 DOI: 10.1021/jp077325n] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Alternating layers of two different organic materials, Irganox1010 and Irganox3114, have been created using vapor deposition. The layers of Irganox3114 were very thin ( approximately 2.5 nm) in comparison to the layers of Irganox1010 ( approximately 55 or approximately 90 nm) to create an organic equivalent of the inorganic 'delta-layers' commonly employed as reference materials in dynamic secondary ion mass spectrometry. Both materials have identical sputtering yields, and we show that organic delta layers may be used to determine some of the important metrological parameters for cluster ion beam depth profiling. We demonstrate, using a C(60) ion source, that the sputtering yield, S, diminishes with ion dose and that the depth resolution also degrades. By comparison with atomic force microscopy data for films of pure Irganox1010, we show that the degradation in depth resolution is caused by the development of topography. Secondary ion intensities are a well-behaved function of sputtering yield and may be employed to obtain useful analytical information. Fragments characteristic of highly damaged material have intensity proportional to S, and those fragments with minimal molecular rearrangment exhibit intensities proportional to S(2). We demonstrate quantitative analysis of the amount of substance in buried layers of a few nanometer thickness with an accuracy of approximately 10%. Organic delta layers are valuable reference materials for comparing the capabilities of different cluster ion sources and experimental arrangements for the depth profiling of organic materials.
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Mahoney CM, Fahey AJ, Belu AM. Three-dimensional compositional analysis of drug eluting stent coatings using cluster secondary ion mass spectrometry. Anal Chem 2008; 80:624-32. [PMID: 18179243 DOI: 10.1021/ac701644j] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cluster secondary ion mass spectrometry (cluster SIMS) employing an SF5+ polyatomic primary ion sputter source in conjunction with a Bi3+ analysis source was used to obtain three-dimensional molecular information in polymeric-based drug-eluting stent coatings. The formulations of the coatings varied from 0% to 50% (w/w) sirolimus drug in poly(lactic-co-glycolic acid) and were prepared on both MP35N metal alloy coupons and bare metal stents. All cluster SIMS depth profiles obtained indicated a drug-enriched surface region, followed by a drug-depletion region, and finally a constant bulk composition region, similar to previous data obtained in polymeric blend systems. The drug overlayer thickness was determined to increase with increasing sirolimus content. Sample temperature was determined to play an important role in the resulting depth profiles, where it was shown that the best profiles were obtained at low temperatures (-100 degrees C). At these temperatures, molecular signals typically remained constant through the entire depth of the film (approximately 6.5 microm) in some cases, as opposed to the typical 1 microm-2 microm depth limit, which is achievable at room temperature. The 3-D imaging capabilities of cluster SIMS were successfully demonstrated and indicated a significant amount of subsurface domain formation in the 25% and 50% sirolimus samples, but not in the 5% sample, which was homogeneous. These results clearly illustrate the utility of cluster SIMS for probing the 3-D structure in polymeric-based drug delivery devices.
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Affiliation(s)
- Christine M Mahoney
- National Institute of Standards and Technology, 100 Bureau Drive, Mail Stop 8371, Gaithersburg, Maryland 20899, USA.
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24
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Zheng L, Wucher A, Winograd N. Chemically alternating Langmuir-Blodgett thin films as a model for molecular depth profiling by mass spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2008; 19:96-102. [PMID: 18293488 PMCID: PMC2553707 DOI: 10.1016/j.jasms.2007.10.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Langmuir-Blodgett multilayers of alternating barium arachidate and barium dimyristoyl phosphatidate are characterized by secondary ion mass spectrometry employing a 40 keV buckminsterfullerene (C60) ion source. These films exhibit well-defined structures with minimal chemical mixing between layers, making them an intriguing platform to study fundamental issues associated with molecular depth profiling. The experiments were performed using three different substrates of 306 nm, 177 nm, and 90 nm in thickness, each containing six subunits with alternating chemistry. The molecular subunits are successfully resolved for the 306 nm and 177 nm films by cluster ion depth profiling at cryogenic temperatures. In the depth profile, very little degradation was found for the molecular ion signal of the underneath layers compared with that of the top layer, indicating that the formation of chemical damage is removed as rapidly as it is formed. The resolving power decreases as the thickness of the alternating subunits decrease, allowing a depth resolution of 20 to 25 nm to be achieved. The results show the potential of LB films as an experimental model system for studying fundamental features of molecular depth profiling.
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Affiliation(s)
- Leiliang Zheng
- Department of Chemistry, The Pennsylvania State University, University Park 16802, USA.
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Balss KM, Llanos G, Papandreou G, Maryanoff CA. Quantitative spatial distribution of sirolimus and polymers in drug-eluting stents using confocal Raman microscopy. J Biomed Mater Res A 2008; 85:258-70. [PMID: 17876804 DOI: 10.1002/jbm.a.31535] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Raman spectroscopy was used to differentiate each component found in the CYPHER Sirolimus-eluting Coronary Stent. The unique spectral features identified for each component were then used to develop three separate calibration curves to describe the solid phase distribution found on drug-polymer coated stents. The calibration curves were obtained by analyzing confocal Raman spectral depth profiles from a set of 16 unique formulations of drug-polymer coatings sprayed onto stents and planar substrates. The sirolimus model was linear from 0 to 100 wt % of drug. The individual polymer calibration curves for poly(ethylene-co-vinyl acetate) [PEVA] and poly(n-butyl methacrylate) [PBMA] were also linear from 0 to 100 wt %. The calibration curves were tested on three independent drug-polymer coated stents. The sirolimus calibration predicted the drug content within 1 wt % of the laboratory assay value. The polymer calibrations predicted the content within 7 wt % of the formulation solution content. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra from five formulations confirmed a linear response to changes in sirolimus and polymer content.
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Affiliation(s)
- K M Balss
- Cordis Corporation, a Johnson & Johnson Company, Welsh and McKean Roads, Spring House, Pennsylvania 19477, USA.
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26
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Mahoney CM, Fahey AJ, Gillen G, Xu C, Batteas JD. Temperature-Controlled Depth Profiling of Poly(methyl methacrylate) Using Cluster Secondary Ion Mass Spectrometry. 2. Investigation of Sputter-Induced Topography, Chemical Damage, and Depolymerization Effects. Anal Chem 2007. [DOI: 10.1021/ac061357+] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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27
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Braun RM, Cheng J, Parsonage EE, Moeller J, Winograd N. Surface and depth profiling investigation of a drug-loaded copolymer utilized to coat taxus express2 stents. Anal Chem 2007; 78:8347-53. [PMID: 17165826 DOI: 10.1021/ac0615089] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The surface of a styrene-b-isobutylene-b-styrene triblock copolymer, containing a solid-phase drug, was studied by time-of-flight secondary ion mass spectrometry employing 15-keV Ga+ and 20-keV C60+ ion sources. This polymer/drug system has direct application in the cardiac stent arena, where it has been used to treat restenosis or renarrowing of arterial walls after stent or angioplasty procedures. Overall, the results illustrate the successful use of a cluster ion beam for greatly enhancing the high-mass fragment ion and molecular ion intensities from the surface and bulk of the polymer system. The use of C60+ also established the ability to remove common overlayers like poly(dimethylsiloxane), which was not possible using a Ga+ ion source. Furthermore, the use of C60+ allowed depth profiles to be obtained using primary ion dose densities in excess of 6 x 1014 C60+/cm2. Resultant sputter craters reached depths of approximately 2 microm and possessed relatively flat bottoms without the need for sample rotation. AFM and profilometry studies support the relatively gentile removal of surface species via phase contrast and topographic imaging. In addition, the findings suggest that relatively high ion doses do not significantly alter the phase distribution or surface topography of the polymer surface; however, a slight increase in surface roughness was detected.
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Affiliation(s)
- Robert M Braun
- Polymer and Surface Science Group, Bausch & Lomb Inc., 1400 North Goodman Street, Rochester, New York 14609, USA.
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28
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Hinder SJ, Lowe C, Watts JF. ToF-SIMS depth profiling of a complex polymeric coating employing a C60 sputter source. SURF INTERFACE ANAL 2007. [DOI: 10.1002/sia.2546] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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29
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Mahoney CM, Fahey AJ, Gillen G. Temperature-Controlled Depth Profiling of Poly(methyl methacrylate) Using Cluster Secondary Ion Mass Spectrometry. 1. Investigation of Depth Profile Characteristics. Anal Chem 2006. [DOI: 10.1021/ac061356h] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Christine M. Mahoney
- National Institute of Standards and Technology, 100 Bureau Drive, Mail Stop 8371, Gaithersburg, Maryland 20899-8371
| | - Albert J. Fahey
- National Institute of Standards and Technology, 100 Bureau Drive, Mail Stop 8371, Gaithersburg, Maryland 20899-8371
| | - Greg Gillen
- National Institute of Standards and Technology, 100 Bureau Drive, Mail Stop 8371, Gaithersburg, Maryland 20899-8371
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30
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Affiliation(s)
- Patricia M Peacock
- DuPont Corporate Center for Analytical Sciences, Wilmington, Delaware 19880, USA
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31
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Harton SE, Stevie FA, Zhu Z, Ade H. Carbon-13 Labeled Polymers: An Alternative Tracer for Depth Profiling of Polymer Films and Multilayers Using Secondary Ion Mass Spectrometry. Anal Chem 2006; 78:3452-60. [PMID: 16689549 DOI: 10.1021/ac060133o] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
13C labeling is introduced as a tracer for depth profiling of polymer films and multilayers using secondary ion mass spectrometry (SIMS). Deuterium substitution has traditionally been used in depth profiling of polymers but can affect the phase behavior of the polymer constituents with reported changes in both bulk-phase behavior and surface and interfacial interactions. SIMS can provide contrast by examining various functional groups, chemical moieties, or isotopic labels. 13C-Labeled PS (13C-PS) and unlabeled PS (12C-PS) and PMMA were synthesized using atom-transfer radical polymerization and assembled in several model thin-film systems. Depth profiles were recorded using a Cameca IMS-6f magnetic sector mass spectrometer using both 6.0-keV impact energy Cs+ and 5.5-keV impact energy O2+ primary ion bombardment with detection of negative and positive secondary ions, respectively. Although complete separation of 12C1H from 13C is achieved using both primary ion species, 6.0-keV Cs+ clearly shows improved detection sensitivity and signal-to-noise ratio for detection of 12C, 12C1H, and 13C secondary ions. The use of Cs+ primary ion bombardment results in somewhat anomalous, nonmonotonic changes in the 12C, 12C1H, and 13C secondary ion yields through the PS/PMMA interface; however, it is shown that this behavior is not due to sample charging. Through normalization of the 13C secondary ion yield to the total C (12C + 13C) ion yield, the observed effects through the PS/PMMA interface can be greatly minimized, thereby significantly improving analysis of polymer films and multilayers using SIMS. Mass spectra of 13C-PS and 12C-PS were also analyzed using a PHI TRIFT I time-of-flight mass spectrometer, with 15-keV Ga+ primary ion bombardment and detection of positive secondary ions. The (12)C7(1)H7 ion fragment and its 13C-enriched analogues have significant secondary ion yields with negligible mass interferences, providing an early indication of the potential for future use of this technique for cluster probe depth profiling of high molecular weight 13C-labeled fragments.
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Affiliation(s)
- S E Harton
- Department of Materials Science & Engineering, Analytical Instrumentation Facility, North Carolina State University, Raleigh, NC 27695, USA
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32
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Current literature in mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2006; 41:128-39. [PMID: 16402416 DOI: 10.1002/jms.948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
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33
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Francis JT, McIntyre NS. Enhancement of the positive secondary ion yield during low-energy, dual-beam depth profiling of polytetrafluoroethylene with 1-keV Cs+. SURF INTERFACE ANAL 2005. [DOI: 10.1002/sia.2073] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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