Department of Chemistry, UGC Sponsored Centre for Advanced Studies-II , Guru Nanak Dev University , Amritsar 143005 , India.
Department of Biotechnology , Sri Guru Granth Sahib World University , Fatehgarh Sahib 140406 , India.
Langmuir. 2019 Mar 19;35(11):4085-4093. doi: 10.1021/acs.langmuir.9b00106. Epub 2019 Mar 11.
The development of new strategies for thermal stability and storage of enzymes is very important, considering the nonretention of catalytic activity by enzymes under harsh conditions of temperature. Following this, herein, a new approach based on the interfacial adsorption of lysozyme (LYZ) at nanointerfaces of ionic liquid (IL)-based microemulsions, for enhanced thermal stability of LYZ, is reported. Microemulsions (MEs) composed of dialkyl imidazolium-based surface active ILs (SAILs) as surfactants, ILs as the nonpolar phase, and ethylene glycol (EG) as the polar phase, without any cosurfactants, have been prepared and characterized in detail. Various regions corresponding to polar-in-IL, bicontinuous, and IL-in-polar phases have been characterized using conductivity measurements. Dynamic light scattering (DLS) measurements have provided insights into the size distribution of microdroplets, whereas temperature-dependent DLS measurements established the thermal stability of the MEs. Nanointerfaces formed by SAILs with EG in thermally stable reverse MEs act as fluid scaffolds to adsorb and provide thermal stability, up to 120 °C, to LYZ. Thermally treated LYZ upon extraction into a buffer shows enzyme activity owing to negligible change in the active site of LYZ, as marked by retention of microenvironment of Trp residues present in the active site of LYZ. The present work is expected to establish a new platform for the development of novel nanointerfaces utilizing biobased components for other biomedical applications.
考虑到酶在苛刻的温度条件下会失去催化活性，开发新的热稳定性和储存策略对于酶来说非常重要。有鉴于此，本文报道了一种新方法，即在基于离子液体（IL）的微乳液的纳米界面上通过溶菌酶（LYZ）的界面吸附，提高 LYZ 的热稳定性。详细制备并表征了由二烷基咪唑啉基表面活性 IL（SAIL）作为表面活性剂、IL 作为非极性相和乙二醇（EG）作为极性相组成的微乳液（MEs），无需添加任何助表面活性剂。使用电导率测量对对应于极性在 IL 中、双连续和 IL 在极性中的各种区域进行了表征。动态光散射（DLS）测量提供了关于微滴尺寸分布的见解，而温度依赖性 DLS 测量则确定了 MEs 的热稳定性。在热稳定的反向 MEs 中，SAIL 与 EG 形成的纳米界面充当流体支架，吸附并提供热稳定性，最高可达 120°C，使 LYZ 稳定。在缓冲液中提取热处理的 LYZ 后，由于 LYZ 活性位点中的色氨酸残基的微环境保持不变，表明 LYZ 活性位点的几乎没有变化，从而显示出酶活性。本工作有望为利用生物基成分开发用于其他生物医学应用的新型纳米界面建立一个新平台。
