Aptamer modified low-cost fibre optic surface plasmon resonance sensor

Surface plasmon resonance (SPR) is known as the gold-standard for label-free biosensors that can be used to monitor analytes via highly sensitive changes of the refractive index. However, due to their size and cost, SPR-based biosensors have only been applied in lab environments to date. In order to overcome this limitation we present a low-cost aptamer-modified fiber optic SPR sensor. Aptamers exhibit long-term stability, pH- and temperature-resistance, and cost-effective synthesis. Consequently, the sensor system can be applied as a robust and cost-effective sensor for in-field use. The fiber optic SPR sensor has been realized by using a 400 µm plastic cladded silica glass fibre and an easy-to-implement silver coating technique. The silver coating was modified with aptamers directed against ethanolamin (EA) as a model system. The aptamer was hybridized with a complementary oligonucleotide, which was released in the presence of EA. Thus, the sensor allows the detection of small molecules, which are otherwise hard to detect via SPR. By application of other aptamers the concept can be easily transferred to the detection of other analytes.