LB技术和FRET研究胆固醇衍生物和磷脂（DPPC）混合膜：胆固醇传感器的设计,Sensors and Actuators B: Chemical

在这项工作中，使用Langmuir-Blodgett（LB）研究了胆固醇衍生物5α，6α-环氧胆甾醇3β-ol（Chol）和名为1,2-二棕榈酰-sn-甘油-3-磷酸胆碱（DPPC）的磷脂的混合膜行为。 ）技术。进行了表面压力区域（π-A）等温线，紫外可见光谱，荧光光谱和布鲁斯特角显微镜（BAM）研究，以表征空气-水界面和固体基质上的薄膜。π-A等温线以及对多余面积的分析和吉布的自由能表明，混合单层中Chol和DPPC之间存在相互作用。但是，Chol和DPPC之间的相互作用在Chol摩尔分数（X Chol）0.77导致稳定且几乎理想的混合单层。BAM研究提供了交互作用的直观证据，表明与纯对等物相比，DPPC-Chol混合单层的结构域/性质发生了变化。荧光共振能量转移（FRET）用于检测脂质双层膜中Chol的存在。cri啶黄（Acf）和若丹明B（RhB）分别用作供体和受体。发现FRET效率随脂质双层中Chol浓度线性变化。通过适当的校准，有可能使用本研究中的系统来感测细胞膜中的Chol。建议的传感系统也已使用真实的血清样本进行了测试。

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In this work mixed film behavior of Cholesterol derivative 5α, 6α-Epoxycholestan-3β-ol (Chol) and a Phospholipid named 1,2-Dipalmitoyl-sn-glycero-3-phosphorylcholine (DPPC) have been investigated using Langmuir-Blodgett (LB) technique. Surface pressure-area (π-A) isotherms, UV–vis, and fluorescence spectroscopy and Brewster Angle Microscopy (BAM) studies were carried out for characterizations of the films at air – water interface and solid substrate. π-A isotherms as well as analysis of excess area and Gibb’s free energy suggested interaction between Chol and DPPC in the mixed monolayer. However, interaction between Chol and DPPC balances at Chol mole fraction (XChol) 0.77 resulting in a stable and almost ideally mixed monolayer. BAM investigations give visual evidence of interaction showing change in domain structure/nature in the DPPC-Chol mixed monolayer compared to their pure counterpart. Fluorescence Resonance Energy Transfer (FRET) was employed to sense the presence of Chol in the lipid bilayer film. Acriflavine (Acf) and Rhodamine B (RhB) were used as donor and acceptor respectively. It was found that FRET efficiency linearly changes with Chol concentration in the lipid bilayer. With proper calibration, it may be possible to use this present system under investigation to sense Chol in cell membrane. Proposed sensing system has also been tested using real serum sample.