Sophorolipids are one of the most important microbial biosurfactants, because of their large-scale production and applications developed so far in the fields of detergency, microbiology, cosmetics or environmental science. However, the structural variety of native sophorolipids is limited/restricted, a limiting fact for the development of new properties and their potential applications. In their open acidic form, C18:1 sophorolipids (SL) are classically composed of a sophorose headgroup and a carboxylic acid (COOH) end-group. The carboxyl group gives them unique pH-responsive properties, but it is a poorly reactive group and its charge can only be negative. To develop a new generation of pH-responsive, positively charged, SL and to improve their reactivity for further functionalization, we develop here SL with an amine (–NH₂) or terminal alkyne (–CCH) end-group analogues. The amine group generates positively charged SL and is more reactive than carboxylic acids, e.g. towards aldehydes; the alkyne group provides access to copper-based click chemistry. In this work, we synthesized (C18:1) and (C18:0) –NH₂ and (C18:1) –CCH sophorolipid derivatives and we study their self-assembly properties in response to pH and/or temperature changes by means of static and dynamic light scattering, small angle (X-ray, neutron) scattering and cryogenic electron microscopy. Monounsaturated aminyl SL-C18:1-NH₂ sophorolipids form a micellar phase in their neutral form at high pH and a mixed micellar-bilayer phase in their positively charged form at low pH. Saturated aminyl SL-C18:0-NH₂ sophorolipids form a micellar phase in their charged form at low pH and a twisted ribbon phase in their neutral form at high pH and monounsaturated alkynyl SL-C18:1-CCH sophorolipids form a main micellar phase at T > 51.8 °C and a twisted ribbon phase at T < 51.8 °C.

中文翻译：

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氨基和炔基取代的槐糖脂的合成与自组装

槐糖脂是最重要的微生物生物表面活性剂之一，因为迄今为止它们在洗涤剂，微生物学，化妆品或环境科学领域中已得到大规模生产和应用。然而，天然槐糖脂的结构多样性受到限制/限制，这是开发新特性及其潜在应用的一个限制事实。C18：1槐糖脂（SL）以开放的酸性形式经典地由槐糖糖头基和羧酸（COOH）端基组成。羧基赋予它们独特的pH响应特性，但它是反应性较差的基团，其电荷只能为负。为了开发新一代的pH响应，带正电荷的SL并提高其反应性以进一步官能化，我们在这里开发了一种带有胺（–NH₂）或末端炔烃（–CCH）端基类似物。胺基生成带正电荷的SL，并且比羧酸更具反应性，例如对醛而言；炔烃基团提供了使用铜基点击化学的途径。在这项工作中，我们合成了（C18：1）和（C18：0）–NH ₂和（C18：1）–CCH槐糖脂衍生物，并通过以下方法研究了它们对pH和/或温度变化的响应的自组装特性静态和动态光散射，小角度（X射线，中子）散射和低温电子显微镜的研究。单不饱和胺基SL-C18：1-NH ₂槐糖脂在高pH下以中性形式形成胶束相，在低pH下以正电荷形式形成混合胶束双层相。在低pH值下，饱和的氨基SL-C18：0-NH ₂槐糖脂以带电形式形成胶束相，在高pH值下，它们以中性形式形成扭曲的带状相，单不饱和炔基SL-C18：1-C CH槐糖脂形成主要的胶束。相在Ť > 51.8℃，并在扭绞带相Ť 51.8°C <。