Pesticides detection by SERS using dendritic structures grown in glass

We demonstrate that dendritic structures formed in glass by electrolysis of silver ions-enriched glass allow detection of low concentration of pesticide thiram using surface- enhanced Raman scattering spectroscopy. Thiram detection  is an important issue due to its toxicity for humans. Silver ions were embedded in glass using Ag⁺↔Na⁺ ion exchange procedure. Electrolysis was performed at 250 ˚C under 600 V and resulted in formation of silver dendrites under the glass surface. To remove the surface glass layer and ensure the access of pesticide to the dendritic structures for Raman spectroscopy we etched the glass in low-concentrated HF solution. Pesticide was adsorbed on the  surface of the dendrites via drying a droplet of its aqueous solution. The detection limit and Raman enhancement were estimated, being 4.6∙10^-10 g/mm² (about a monolayer) and ~ 4·10⁵, respectively. The influence of the  morphology of the dendritic structures on Raman signal distribution and enhancement were also studied.