Refractive index sensitivity of triangular Ag nanoplates in solution and on glass substrate

We report the synthesis of Ag triangular nanoplates and its application for the detection of bulk refractive index change resulting from low molecular weight analyte molecules. Triangular nanoplates of different edge lengths were synthesized using seed mediated approach with small modification in the earlier reported method [Adv. Funct. Mater. 18, 2005–2016 (2008)]. Increase in the edge length of nanoplates was observed with decrease in the volume of seed nanoparticle used. The synthesized nanoplates in colloidal solution were investigated for the refractive index sensing. The nanoplates synthesized with 100 μL seed volume showed maximum sensitivity for glucose and glycerol as 465 and 461 nm/RIU respectively. Triangular nanoplates with highest sensitivity in the solution were immobilized on silanized glass surface using 3-aminopropyl-trimethoxysilane as an adhesion layer. The refractive index sensitivity of immobilized nanoplates was found to be 193 and 204 nm/RIU for glucose and glycerol solutions respectively. The significant decrease in sensitivity could be due to damping of plasmon resonance on substrate or non-availability of all surfaces. The immobilized nanoplates on glass surface can be used as nanoplasmonic sensor chip for chemical and biological analyte detection.