Highly-sensitive detection of 2,4-dinitrotoluene using colloidal gold nanospheres

The propagation of plasmons formed at the metal-dielectric interface enables the surface to respond to changes in its refractive index exceptionally sensitively. Surface Plasmon Resonance (SPR) is an optical technique that is widely used for the generation of plasmons. SPRs provide reliable results in various fields, such as medical diagnosis, security, and molecular sensing. The utilization of colloidal lithography offers a viable option for the fabrication of plasmonic sensors in contrast to other complicated manufacturing methods. In this study, colloidal lithography is used to locate gold-coated polystyrene (PS) nanospheres with a diameter of 320 nm onto a glass substrate. Surface plasmons occurring at the PS and Au interface rendered the surface of this sensor highly sensitive to refractive index changes. The primary production material of 2,4,6-trinitrotoluene (TNT), namely 2,4-dinitrotoluene (DNT), is detected at 0.001 ppm concentration levels. The spectral shifts occurring in the transmission spectrum of the sensor have demonstrated the molecular detection capability of very low concentrations, such as 0.001 ppm. Our findings have shown that the proposed structure holds excellent potential for the detection of DNT, which is a vital substance both in terms of military and environmental security.