Angelopoulou Μichailia, Botsialas Athanasios, Salapatas Alexandros, Petrou Panagiota S, Haasnoot Willem, Makarona Eleni, Jobst Gerhard, Goustouridis Dimitrios, Siafaka-Kapadai Athanasia, Raptis Ioannis, Misiakos Konstantinos, Kakabakos Sotirios E
Immunoassays/Ιmmunosensors Lab, INRaSTES, NCSR 'Demokritos', 15310, Aghia Paraskevi, Greece.
Anal Bioanal Chem. 2015 May;407(14):3995-4004. doi: 10.1007/s00216-015-8596-3. Epub 2015 Mar 22.
The label-free detection of bovine milk in goat milk through a miniaturized optical biosensor is presented. The biosensor consists of ten planar silicon nitride waveguide Broad-Band Mach-Zehnder interferometers (BB-MZIs) monolithically integrated and self-aligned with their respective silicon LEDs on the same Si chip. The BB-MZIs were transformed to biosensing transducers by functionalizing their sensing arm with bovine k-casein. Measurements were performed by continuously recording the transmission spectra of each interferometer through an external spectrometer. The amount of bovine milk in goat milk was determined through a competitive immunoassay by passing over the sensor mixtures of anti-k-casein antibodies with the calibrators or the samples. The output spectra of each BB-MZI recorded during the reaction were subjected to Discrete Fourier Transform in order to convert the observed spectral shifts to phase shifts in the wavenumber domain. The method had a detection limit of 0.04 % (v/v) bovine milk in goat milk, dynamic range 0.1-1.0 % (v/v), recoveries 93-110 %, and intra- and inter-assay coefficients of variation less than 12 and 15 %, respectively. The proposed biosensor compared well in terms of analytical performance with a competitive ELISA developed using the same monoclonal antibodies. Nevertheless, the duration of the biosensor assay was 10 min whereas the ELISA required 2 h. Thus, the fast and sensitive determinations along with the small size of the sensor make it ideal for incorporation into portable devices for assessment of goat or ewe's milk adulteration with bovine milk at the point-of-need.
本文介绍了一种通过小型化光学生物传感器对山羊奶中的牛奶进行无标记检测的方法。该生物传感器由十个平面氮化硅波导宽带马赫-曾德尔干涉仪（BB-MZIs）组成，它们在同一硅芯片上与各自的硅发光二极管单片集成且自对准。通过用牛κ-酪蛋白对BB-MZIs的传感臂进行功能化，将其转变为生物传感换能器。测量是通过外部光谱仪连续记录每个干涉仪的透射光谱来进行的。通过将抗κ-酪蛋白抗体与校准物或样品的混合物通过传感器，利用竞争性免疫测定法来测定山羊奶中牛奶的含量。对反应过程中记录的每个BB-MZI的输出光谱进行离散傅里叶变换，以便将观察到的光谱位移转换为波数域中的相移。该方法对山羊奶中牛奶的检测限为0.04%（v/v），动态范围为0.1 - 1.0%（v/v），回收率为93 - 110%，批内和批间变异系数分别小于12%和15%。所提出的生物传感器在分析性能方面与使用相同单克隆抗体制备的竞争性酶联免疫吸附测定法（ELISA）相当。然而，生物传感器测定的持续时间为10分钟，而ELISA需要2小时。因此，快速灵敏的测定以及传感器的小尺寸使其非常适合集成到便携式设备中，以便在需要时评估山羊奶或羊奶中是否掺有牛奶。
