Radiolytically prepared blue photoluminescent Silicon Oxide nanocomposites for highly selective sensing of picric acid: Mechanism and development of paper strip-based detection

Abstract

Herein, we wish to report highly selective sensing of picric acid (PA), one of the primary explosive ingredients as well as a well-known environmental hazard in 100 % water medium. For the said purpose, radiolytically synthesized blue photoluminescent PEGylated silicon oxide nanocomposites (PEG@SiONCs) with ∼49 % quantum efficiency (QE) were used as fluorescence probe. The limit of detection (LOD) of PA was determined to be ∼0.16 μM in the 2–85 μM range. Substantial reduction in blue photoluminescence of PEG@SiONCs, and shift in the emission colour from blue towards green in presence of specific concentrations of PA, are the interesting highlights of the present work. This colour change can be utilized to confirm the presence of PA in the sample. Mechanistic investigations involving temperature-dependent steady-state photoluminescence, and PA concentration-dependent lifetime studies revealed inner filter effect (IFE) based photoluminescence quenching mechanism. In addition, the interference studies carried out in the presence of 21 other organic/inorganic compounds demonstrated the highly selective sensing of PA by PEG@SiONCs. The PA sensing ability of the nanocomposites was also tested in the pH window ranging from 2 to 12. Meanwhile, paper strips were prepared using PEGylated SiONCs, and samples containing various metal ions and organic compounds were tested to examine their suitability for real-time detection of PA.