González-Fernández Daniel, Torneiro Mercedes, Lazzari Massimo
Departamento de Química Física, Facultade de Química, and Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS), Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
Departamento de Química Orgánica, Facultade de Química, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
Polymers (Basel). 2020 Jun 2;12(6):1269. doi: 10.3390/polym12061269.
We provide fundamental guidelines in the form of a tutorial to be taken into account for the preparation and characterization of a specific class of poly(ethylene glycol) (PEG) derivatives, namely azide-terminated PEGs. Special attention is given to the effect of these chain end groups and their precursors on properties affecting the PEGylation of proteins, nanoparticles and nanostructured surfaces. Notwithstanding the presence of C satellite peaks, we show that H NMR enables not only the routine quantitative determination of chain-end substitution, but is also a unique method to calculate the absolute number average molecular weight of PEG derivatives. In the use of size exclusion chromatography to get molecular weight distributions, we highlight the importance of distinguishing between eventual secondary reactions involving molecular weight changes and the formation of PEG complexes due to residual amounts of metal cations from reactants. Finally, we show that azide end groups affect PEG melting behavior. In contrast to oxygen-containing end groups, azides do not interact with PEG segments, thus inducing defect formation in the crystal lattice and the reduction of crystal sizes. Melting temperature and degree of crystallinity decrease become especially relevant for PEGs with very low molecular weight, and its comprehension is particularly important for solid-state applications.
我们以教程的形式提供了基本指南，用于制备和表征一类特定的聚乙二醇（PEG）衍生物，即叠氮端基PEG。特别关注这些链端基团及其前体对影响蛋白质、纳米颗粒和纳米结构表面聚乙二醇化性质的作用。尽管存在碳卫星峰，但我们表明，氢核磁共振（H NMR）不仅能够常规定量测定链端取代度，而且还是计算PEG衍生物绝对数均分子量的独特方法。在使用尺寸排阻色谱法获得分子量分布时，我们强调了区分涉及分子量变化的最终二级反应与由于反应物中残留金属阳离子量而形成PEG络合物的重要性。最后，我们表明叠氮端基会影响PEG的熔化行为。与含氧端基不同，叠氮化物不与PEG链段相互作用，从而导致晶格中形成缺陷并减小晶体尺寸。熔化温度和结晶度降低对于极低分子量的PEG尤为重要，并且对其理解对于固态应用尤为重要。
