Highly efficient ferric ion sensing and high resolution latent fingerprint imaging based on fluorescent silicon...

Expanding the application of silicon based luminescent materials is a fast-growing interdisciplinary field. Herein, a novel fluorescent bifunctional probe based on silicon quantum dots (SiQDs) for highly sensitive Fe³⁺ sensing and high-resolution latent fingerprint (LFP) imaging was subtly devised. The SiQD solution was mildly prepared using 3-aminopropyl trimethoxysilane as the silicon source and sodium ascorbate as the reductant, showing green emission at 515 nm under UV irradiation with a quantum yield of 19.8%. As a highly sensitive fluorescent sensor, the SiQD was demonstrated to have a highly selective quenching with Fe³⁺ in the concentration range of 2-1000 μM with the LOD of 0.086 μM in water. The quenching rate constant and association constant of the SiQDs-Fe³⁺ complex was calculated to be 1.05 × 10¹² mol/s and 6.8 × 10³ L/mol, respectively, suggesting a static quenching effect between them. Moreover, to achieve high-resolution LFP imaging, a novel SiO₂@SiQDs composite powder was further fabricated. The SiQDs were covalently anchored on the surface of silica nanospheres to conquer aggregation-caused quenching for the high-solid fluorescence. In the demonstration of LFP imaging, this silicon based luminescent composite exhibited high developing sensitivity, high selectivity and high contrast, indicating its practical value as a fingerprint developer at crime scenes.