Radical-Induced Single-Chain Collapse of Passerini Sequence-Regulated Polymers Assessed by High-Resolution Mass Spectrometry
Radical-Induced Single-Chain Collapse of Passerini Sequence-Regulated Polymers Assessed by High-Resolution Mass Spectrometry
复制标题
通过高分辨率质谱评估帕塞里尼序列调控聚合物的自由基诱导单链塌缩
DOI：
10.1021/acs.macromol.8b00577
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发表时间：
2018
期刊：
影响因子：
5.5
通讯作者：
Barner- Kowollik
中科院分区：
文献类型：
--
作者：
Steinkoenig;Nitsche;Barner- Kowollik
我们评估的多功能性的高分辨率轨道阱电喷雾质谱（HR ESI MS）耦合到尺寸排阻色谱（SEC）的挑战，它与迄今为止最复杂的质谱分析-单链纳米粒子（SCNP）崩溃系统的前体复杂性和崩溃机制。在这里，序列调节的三聚体和四聚体制备的Passerini多组分逐步增长聚合作为理想的质谱复杂的前体结构，以确定关键参数成功的MS映射，从而了解自由基链内压缩过程。作为用于三元聚合的Passerini单体，将1，6-二异氰己烷（1当量）、HO 2C-PEG 10 -11-CO2 H（1当量）和配备有丙烯酸酯（2当量）的4-甲酰基香豆素用于随后的自由基诱导的单链塌陷。我们的证据表明，成功的崩溃，确认崩溃机制，通过双分子耦合或传播的特征质量物种。含有1，6-二异氰己烷（1当量）、HO 2C-PEG 10 -11-CO2 H（1当量）、苯甲醛（1.7当量）和4-甲酰基香豆素丙烯酸酯（0.3当量）的四元环也被折叠，但不能通过SEC-ESI MS映射，因为需要反应单元的链的数量太少，而扩散有序NMR光谱（DOSY）可以容易地证明压实。在这两个前体系统的基础上，我们能够确定前体和塌陷系统必须满足的标准，以获得成功的SEC-ESI MS表征。如果（i）存在最少四至五个SCNP内键，并且因此（ii）前体形成需要导致足够数量的以反应性香豆素丙烯酸酯单元为特征的链，则只能通过质量分析阐明塌陷机制。最后，（iii）化学上过于多样化的系统，如四分之一聚合物导致高重复单元多样性，这对MS分析提出了挑战，因为现代分辨率限制。
We assess the versatility of high-resolution Orbitrap electrospray mass spectrometry (HR ESI MS) coupled to size exclusion chromatography (SEC) by challenging it with the to date most complex—for mass spectrometric analysis—single chain nanoparticle (SCNP) collapse system in terms of both precursor complexity and collapse mechanism. Here, sequence-regulated ter- and quaterpolymers prepared by the Passerini multicomponent step-growth polymerization serve as ideal mass spectrometric complex precursor structures to identify critical parameters for successful MS mapping and thus understanding of the radical intrachain compaction process. As Passerini monomers for the terpolymerization, 1,6-diisocyanohexane (1 equiv), HO2C-PEG10–11-CO2H (1 equiv), and 4-formylcoumarin equipped with an acrylate (2 equiv) were utilized for subsequent radical-induced single-chain collapse. We evidence the characteristic mass species indicating successful collapse, confirming the collapse mechanism via bimolecular coupling or propagation. A quaterpolymer containing 1,6-diisocyanohexane (1 equiv), HO2C-PEG10–11-CO2H (1 equiv), benzaldehyde (1.7 equiv), and 4-formylcoumarin acrylate (0.3 equiv) is also collapsed, yet cannot be mapped via SEC-ESI MS, as the number of chains entailing a reactive unit is too small, while diffusion ordered NMR spectroscopy (DOSY) can readily witness the compaction. On the basis of these two precursor systems, we are able to identify criteria that the precursors and the collapse system have to fulfill for their successful SEC-ESI MS characterization. The collapse mechanism can only be elucidated via mass analysis if (i) a minimum of four to five intra SCNP linkages are present and, thus, (ii) the precursor formation needs to lead to a sufficient number of chains that feature reactive coumarin acrylate units. Finally, (iii) a chemically too diverse system such as the quarterpolymer leads to a high repeat unit diversity that challenges the MS analysis given the contemporary resolution limits.