Fluorescent silicon nanoparticles for sensing Hg2+ and Ag+ as well visualization of latent fingerprints

We herein used a low cost and facile one-step method for synthesizing fluorescent carbon-doped silicon nano particles (Si NPs) under mild reaction conditions. The fluorescence spectra of Si NPs showed maximum excitation and emission wavelengths at 370 nm and 450 nm, respectively. The fluorescence of the obtained Si NPs can be selectively and efficiently quenched by the Hg2+ and Ag+. The fluorescent Si NPs showed high sensitivity toward Hg2+ and Ag+ with detection limits of 2.676 mu M and 0.457 mu M, respectively. Moreover, the sensing ability of Si NPs for Hg2+ and Ag+ were successfully carried out in real water samples, which offered the merits of high sensitivity and high selectivity. In addition, Si NPs were also successfully employed as a promising fluorescent label for the visualization of latent fingerprints. As far as we know, this is first time that silicon nanoparticles are used to visualize latent fingerprints. The fingerprints on different surfaces (silicon wafer, patterned coin, glass sheet, copper sheet and rough plastic board) developed with this Si NPs showed very good fluorescent images with the third level under ultraviolet excitation. The method using fluorescent Si NPs as fluorescent marks provides a variety of advantages including enhanced contrast, retaining stability and non toxicity. In addition, Si NPs showed highly non-toxic for cellular media, the efficient bioimaging of cellular imaging was enabled after incubation of HepG2 cells in the presence of Si NPs.