Detection of Copper Nanoparticles Templated by DNA Using Etched Fibre Bragg Grating Sensor

In recent years, DNA-templated copper nanoparticles have been used to detect several important analytes, primarily through fluorescence spectrometry. However, the fluorescence of these nanoparticles decays within a few minutes making the quantitative estimation of analytes difficult. Despite the loss of fluorescence, the nanoparticles remain intact as evidenced by microscopy techniques like TEM and AFM. Here, etched fibre Bragg Grating (eFBG) sensors are presented as a detection/characterization tool for copper nanoparticles templated by double stranded DNA. The proposed sensor has a sensitivity of 1.5395 nm/RIU and a resolution of 0.00612 RIU. The formation of the copper nanoparticles on the DNA template attached to the eFBG sensor leads to a significant shift of ≈ 58 pm in the reflected Bragg wavelength signal. Further, the application of the proposed eFBG sensors for analyte detection utilizing the interruption in the synthesis of copper nanoparticles is demonstrated here with the example of melamine detection. The Bragg wavelength shift varies linearly with the log concentration of melamine (R
²
= 0.9482) and the sensor can detect up to 0.1 ppm of melamine.