Label-free glyphosate biosensor based on tilted fiber Bragg grating with gold nanostars.

Glyphosate is one of the most widely used herbicides in the world, primarily valued for its effectiveness, broad-spectrum action, and economic benefits in agriculture. However, due to its widespread use worldwide and presence in soil and water, there are concerns about its environmental persistence and potential toxicity to humans. In this context, our work introduces what are assumed to be novel label-free biosensors for its detection utilizing tilted fiber Bragg gratings (TFBG), whose sensitivity is boosted by gold spherical nanoparticles (NP) and nanostars (NS). The experimental findings have been also validated by numerical simulations using Finite Element Method (FEM). This innovative approach resulted in lowering the limit of detection to 10-8 µg/L in the case of TFBG with NS deposition with respect to bare TFBG, as well as covering a wide concentration range from 10-7 to 1 µg/L. The study also thoroughly examines the sensor selectivity to distinguish glyphosate from glycine.