Conformational sensitivity of conjugated poly(ethylene oxide)-poly(amidoamine) molecules to cations adducted upon electrospray ionization - A mass spectrometry, ion mobility and molecular modeling study

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• 作者：Aura Tintaru ; Christophe Chendo ; Qi Wang ; St茅phane Viel ; Gilles Qu茅l茅ver ; Ling Peng ; Paola Posocco ; Sabrina Pricl ; Laurence Charles
• 关键词：Conformation ; Ion mobility ; Poly(amidoamine) dendrimer ; Poly(ethylene oxide) ; Tandem mass spectrometry ; Molecular modeling
• 刊名：Analytica Chimica Acta
• 出版年：15 January, 2014
• 年：2014
• 卷：808
• 期：Complete
• 页码：163-174
• 全文大小：2849 K

文摘

Tandem mass spectrometry and ion mobility spectrometry experiments were performed on multiply charged molecules formed upon conjugation of a poly(amidoamine) (PAMAM) dendrimer with a poly(ethylene oxide) (PEO) linear polymer to evidence any conformational modification as a function of their charge state (2+ to 4+) and of the adducted cation (H⁺ vs Li⁺). Experimental findings were rationalized by molecular dynamics simulations. The G0 PAMAM head-group could accommodate up to three protons, with protonated terminal amine group enclosed in a pseudo 18-crown-6 ring formed by the PEO segment. This particular conformation enabled a hydrogen bond network which allowed long-range proton transfer to occur during collisionally activated dissociation. In contrast, lithium adduction was found to mainly occur onto oxygen atoms of the polyether, each Li⁺ cation being coordinated by a 12-crown-4 pseudo structure. As a result, for the studied polymeric segment (M_n = 1500 g mol^鈭?), PEO-PAMAM hybrid molecules exhibited a more expanded shape when adducted to lithium as compared to proton.