Maas Michael B, Maybery Giles H C, Perold Willem J, Neveling Deon P, Dicks Leon M T
Department of Electrical & Electronic Engineering, Stellenbosch University, Banghoek Road, Stellenbosch, 7600, South Africa.
Department of Microbiology, Stellenbosch University, De Beer Street, Stellenbosch, 7600, South Africa.
Curr Microbiol. 2018 Feb;75(2):150-155. doi: 10.1007/s00284-017-1359-y. Epub 2017 Oct 24.
Polyclonal antibodies against Escherichia coli and fluorescent, secondary, antibodies were immobilized on borosilicate glass fibers pre-treated with 3-glycidyloxypropyl trimethoxysilane (GPS). Light with an average wavelength of 627 nm, emitted by a diode placed at one end of the glass fiber, was detected by an ultrasensitive photodiode with peak sensitivity at 640 nm. Changes in fluorescence, caused by binding of E. coli to the antibodies, changed the net refractive index of the glass fiber and thus the internal reflection of light. These evanescent changes in photon energy were recorded by an ultrasensitive photodiode. Signals were amplified and changes in voltage recorded with a digital multimeter. A linear increase in voltage readings was recorded over 2 h when 3.0 × 10 CFU/ml and 2.77 × 10 CFU/ml E. coli were adhered to the antibodies. Voltage readings were recorded with E. coli cell numbers from 2 × 10 CFU/ml to 2 × 10 CFU/ml, but readings remained unchanged for 2 h, indicating that the limit of detection is 3.0 × 10 CFU/ml. This simple technology may be used to develop a low-cost, portable, fiber-optic biosensor to detect E. coli in infections and may have applications in the medical field. Research is in progress to optimize the sensitivity of the fiber-optic biosensor and determine its specificity.
针对大肠杆菌的多克隆抗体以及荧光二抗被固定在经3-缩水甘油氧基丙基三甲氧基硅烷（GPS）预处理的硼硅酸盐玻璃纤维上。置于玻璃纤维一端的二极管发出平均波长为627 nm的光，由峰值灵敏度在640 nm的超灵敏光电二极管进行检测。大肠杆菌与抗体结合引起的荧光变化，改变了玻璃纤维的净折射率，进而改变了光的内反射。这些光子能量的倏逝变化由超灵敏光电二极管记录。信号被放大，并用数字万用表记录电压变化。当3.0×10 CFU/ml和2.77×10 CFU/ml的大肠杆菌附着于抗体时，在2小时内记录到电压读数呈线性增加。记录了2×10 CFU/ml至2×10 CFU/ml大肠杆菌细胞数时的电压读数，但读数在2小时内保持不变，表明检测限为3.0×10 CFU/ml。这种简单技术可用于开发一种低成本、便携式的光纤生物传感器，以检测感染中的大肠杆菌，可能在医学领域有应用。目前正在进行研究以优化光纤生物传感器的灵敏度并确定其特异性。
