TY - JOUR
T1 - Quantifiable correlation of ToF‐SIMS and XPS data from polymer surfaces with controlled amino acid and peptide content
AU - Taylor, Michael
AU - Simoes, Fabio
AU - Smith, James
AU - Genapathy, Sivaneswary
AU - Canning, Anne
AU - Lledos, Marina
AU - Chan, Weng C.
AU - Denning, Chris
AU - Scurr, David J.
AU - Steven, Rory T.
AU - Spencer, Steve J.
AU - Shard, Alexander G.
AU - Alexander, Morgan R.
AU - Zelzer, Mischa
N1 - Special Issue: Martin P Seah MBE—Shining a light on surface chemical analysis
Funding Information: This work was supported by EURAMET through an EMRP Researcher Grant (Grant HLT04‐REG4) and the Chemical and Biological Programme of the National Measurement System. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. M.L. was supported by the Leverhulme Trust (Grant RPG‐2016‐199), and M.T. and A.C. were supported by the EPSRC CTD in Regenerative Medicine (Grant EP/F/500491/1). We are grateful to Caterina Minelli for useful comments on the manuscript.
PY - 2022/4
Y1 - 2022/4
N2 - Peptide-coated surfaces are widely employed in biomaterial design, but quantifiable correlation between surface composition and biological response is challenging due to, for example, instrumental limitations, a lack of suitable model surfaces or limitations in quantitatively correlating data from different surface analytical techniques. Here, we first establish a reference material that allows control over amino acid content. Reversible addition-fragmentation chain-transfer (RAFT) polymerisation is used to prepare a copolymer containing alkyne and furan units with well-defined chain length and composition. Huisgen Cu(I)-catalysed azide-alkyne cycloaddition reaction is used to attach the model azido-polyethyleneglycol-amide-modified pentafluoro-l-phenylalanine to the polymer. Different compositional ratios of the polymer provide a surface with varying amino acid content that is analysed by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Nitrogen-related signals are compared with fluorine signals from both techniques. Fluorine and nitrogen signals from both techniques are found to be related to the copolymer compositions, but the homopolymer data deviate from this trend. The approach is then translated to a heparin-binding peptide that supports cell adhesion. Human embryonic stem cells cultured on copolymer surfaces presenting different amounts of heparin-binding peptide show strong cell growth while maintaining pluripotency after 72 h of culture. The early cell adhesion at 24 h can be correlated to the logarithm of the normalised CH4N+ ion intensity from ToF-SIMS data, which is established as a suitable and generalisable marker ion for amino acids and peptides. This work contributes to the ability to use ToF-SIMS in a more quantitative manner for the analysis of amino acid and peptide surfaces.
AB - Peptide-coated surfaces are widely employed in biomaterial design, but quantifiable correlation between surface composition and biological response is challenging due to, for example, instrumental limitations, a lack of suitable model surfaces or limitations in quantitatively correlating data from different surface analytical techniques. Here, we first establish a reference material that allows control over amino acid content. Reversible addition-fragmentation chain-transfer (RAFT) polymerisation is used to prepare a copolymer containing alkyne and furan units with well-defined chain length and composition. Huisgen Cu(I)-catalysed azide-alkyne cycloaddition reaction is used to attach the model azido-polyethyleneglycol-amide-modified pentafluoro-l-phenylalanine to the polymer. Different compositional ratios of the polymer provide a surface with varying amino acid content that is analysed by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Nitrogen-related signals are compared with fluorine signals from both techniques. Fluorine and nitrogen signals from both techniques are found to be related to the copolymer compositions, but the homopolymer data deviate from this trend. The approach is then translated to a heparin-binding peptide that supports cell adhesion. Human embryonic stem cells cultured on copolymer surfaces presenting different amounts of heparin-binding peptide show strong cell growth while maintaining pluripotency after 72 h of culture. The early cell adhesion at 24 h can be correlated to the logarithm of the normalised CH4N+ ion intensity from ToF-SIMS data, which is established as a suitable and generalisable marker ion for amino acids and peptides. This work contributes to the ability to use ToF-SIMS in a more quantitative manner for the analysis of amino acid and peptide surfaces.
UR - http://www.scopus.com/inward/record.url?scp=85123476528&partnerID=8YFLogxK
U2 - 10.1002/sia.7052
DO - 10.1002/sia.7052
M3 - Article
VL - 54
SP - 417
EP - 432
JO - Surface and Interface Analysis
JF - Surface and Interface Analysis
SN - 0142-2421
IS - 4
ER -