Near-infrared SPR biosensor based on photonic crystal fiber for DNA hybridization detection

Surface plasmon resonance (SPR) sensing technology has been widely used in biometrics, but the weak detection capability and low sensitivity limit the development of SPR biosensors. In this work, we propose to employ the transition metal disulfide (TMD) material MoS₂ to induce the SPR effect into the near-infrared band. The aim of this work is to develop a near-infrared sensor capable of quantitatively detecting the concentration of cDNA, which is able to solve the problems of low sensitivity, parameter crosstalk and so on.

The results show that the sensitivity of the SPR sensor at infrared wavelengths is 1.69 times higher than that of visible, and the infrared wave is more suitable as an excitation source for the SPR effect because it has a stronger evanescent field. In addition, we have prepared a DNA hybridization sensor that can work in the near-infrared band to detect complementary DNA (cDNA) concentration. Moreover, a combined cascade and parallel strategy realized the temperature and PH detection. The sensor uses the photonic crystal fiber as the platform, silver film as an excitation layer, and MoS₂ as a modulation layer. The optimal parameters of the sensor were determined during the experiment, and the three-parameter detection was successfully realized. The experimental results show that the three sensing channels can work independently, and the DNA hybridization probe can achieve selective detection of cDNA with a sensitivity as high as 0.22 nm/(nmol/L).

The proposed three-channel DNA hybridization sensor has high sensitivity and accuracy. The innovation of this work is to demonstrate that infrared waves are more suitable to be used as the excitation source of SPR sensors and that the proposed three-channel sensor has a promising future in early diagnosis and biosensing.