Spectroscopic ellipsometry characterisation of Streptavidin Alexa binding to PLL-g-PEGbiotin(50%)

We characterized the functionalization of glass platforms with PLL-g-PEGbiotin(50%) and Streptavidin Alexa 555 (SAvAlexa) by spectroscopic ellispometry to obtain the precise surface mass density of both molecules. We used a SE (RC2, J.A. Woollam, USA) on auxiliary silicon wafers covered with 60 nm thermal SiO2. Molecules were injected one after the other into the liquid chamber (500 µl liquid cell, J.A. Woollam) and analysed in dynamic mode by SE. At saturation PLL-g-PEGbiotin50% adsorbed with 119.8 ± 9.2 ng/cm2 and SAvAlexa with 246.3 ± 36.4 ng/cm2. The experiment has been repeated 3 times and in the excel sheet here uploaded all the dynamic data of thickness (n_Biofilm), refractive index (A_Biofilm) and area mass density are reported for the PLL-g-PEGbiotin(50%) layer and for the SAvAlexa are reported.

本研究采用光谱椭偏术（spectroscopic ellipsometry）对修饰有50%取代聚赖氨酸接枝聚乙二醇生物素（PLL-g-PEGbiotin(50%)）与Alexa 555标记链霉亲和素（Streptavidin Alexa 555，简称SAvAlexa）的玻璃载体功能化过程进行表征，以精准获取两种分子的表面质量密度。实验采用型号为RC2的光谱椭偏仪（SE，美国J.A. Woollam公司），以表面覆盖60 nm热氧化二氧化硅的辅助硅晶圆作为测试基底。将两种分子依次注入500 μL液池（J.A. Woollam公司）中，并通过光谱椭偏仪以动态模式对修饰过程进行实时分析。当吸附达到饱和状态时，PLL-g-PEGbiotin(50%)的表面吸附量为119.8 ± 9.2 ng/cm²，SAvAlexa的表面吸附量为246.3 ± 36.4 ng/cm²。本实验重复开展3次，本次上传的Excel工作表中完整记录了PLL-g-PEGbiotin(50%)修饰层的动态厚度（n_Biofilm）、生物膜折射率（A_Biofilm）与面质量密度数据，同时也包含SAvAlexa修饰层的对应测试数据。