Department of Chemistry and Centre for Advanced Studies in Chemistry, Panjab University - Chandigarh, Sector 14, Chandigarh 160014, India.
Food Colloids and Bioprocessing Group, School of Food Science and Nutrition, University of Leeds, Leeds LS2 9JT, U.K.
Langmuir. 2020 Sep 1;36(34):10091-10102. doi: 10.1021/acs.langmuir.0c01345. Epub 2020 Aug 20.
Herein, we report a novel approach that involves Pickering stabilization of micometer-sized liquid crystal (LC) droplets with biocompatible soft materials such as a whey protein microgel (WPM) to facilitate the analysis of analyte-induced configurational transition of the LC droplets. The WPM particles were able to irreversibly adsorb at the LC-water interface, and the resulting WPM-stabilized LC droplets possessed a remarkable stability against coalescence over time. Although the LC droplets were successfully protected by a continuous network of the WPM layer, the LC-water interface was still accessible for small molecules such as sodium dodecyl sulfate (SDS) that could diffuse through the meshes of the adsorbed WPM network or through the interfacial pores and induce an LC response. This approach was exploited to investigate the dynamic range of the WPM-stabilized LC droplet response to SDS. Nevertheless, the presence of the unadsorbed WPM in the aqueous medium reduced the access of SDS molecules to the LC droplets, thus suppressing the configuration transition. An improved LC response to SDS with a lower detection limit was achieved after washing off the unadsorbed WPM. Interestingly, the LC exhibited a detection limit as low as ∼0.85 mM for SDS within the initial WPM concentration ranging from 0.005 to 0.1 wt %. Furthermore, we demonstrate that the dose-response behavior was strongly influenced by the number of droplets exposed to the aqueous analytes and the type of surfactants such as anionic SDS, cationic dodecyltrimethylammonium bromide (DTAB), and nonionic tetra(ethylene glycol)monododecyl ether (CE). Thus, our results address key issues associated with the quantification of aqueous analytes and provide a promising colloidal platform toward the development of new classes of biocompatible LC droplet-based optical sensors.
本文报道了一种新方法，涉及使用乳清蛋白微凝胶（WPM）等生物相容性软质材料对微米级液晶（LC）液滴进行 Pickering 稳定化，以促进分析 LC 液滴中分析物诱导的构象转变。WPM 颗粒能够不可逆地吸附在 LC-水界面上，并且所得的 WPM 稳定化的 LC 液滴具有随时间推移而不易聚结的显著稳定性。尽管 LC 液滴被 WPM 层的连续网络成功保护，但 LC-水界面仍然可供诸如十二烷基硫酸钠（SDS）等小分子通过吸附的 WPM 网络的网眼或通过界面孔隙扩散并诱导 LC 响应。该方法被用于研究 SDS 对 WPM 稳定化的 LC 液滴响应的动态范围。然而，在水介质中存在未被吸附的 WPM 会减少 SDS 分子到达 LC 液滴的机会，从而抑制构象转变。在洗掉未被吸附的 WPM 后，LC 对 SDS 的响应得到改善，检测限降低。有趣的是，在初始 WPM 浓度范围为 0.005 至 0.1wt%时，LC 对 SDS 的检测限低至约 0.85mM。此外，我们证明了剂量-响应行为强烈受暴露于水相分析物的液滴数量和表面活性剂类型（例如阴离子 SDS、阳离子十二烷基三甲基溴化铵（DTAB）和非离子四（乙二醇）单十二烷基醚（CE））的影响。因此，我们的结果解决了与水相分析物的定量相关的关键问题，并为开发基于新类生物相容性 LC 液滴的光学传感器提供了有前途的胶体平台。
