Two-in-one sulfur and nitrogen co-doped fluorescent silicon nanoparticles: Simultaneous as the fluorescent probe and photocatalyst for in-situ real time visual monitoring and degradation of tetracycline antibiotics

Detection and removal of contaminants are significant for environmental monitoring and remediation. In the present study, two-in-one silicon nanoparticles (SiNPs) were designed and prepared to simultaneously act as the fluorescent probe and degradation catalyst to detect and remove tetracycline (TCs) antibiotics. Thiourea and 3-aminopropyltrimethoxysilane were dopant and silicon source to generate fluorescent sulfur and nitrogen co-doped SiNPs (SN-SiNPs). The blue fluorescence of SN-SiNPs was selectively quenched by TCs due to the inner filter effect, whilst accompanied by the newly appeared yellow-green fluorescence resulting from aggregation induced fluorescence emission effect. Based on this phenomenon, SN-SiNPs can be used as fluorescent colorimetric probes for detection of doxycycline, oxytetracycline and tetracycline with limits of detection of 1.8 mu g/L, 3.0 mu g/L and 4.2 mu g/L, respectively; the semi-quantitation can even be visually achieved by naked eyes. Particularly, SN-SiNPs were capable to catalyze the degradation of the three TCs effectively, achieving the removal rates of doxycycline, oxytetracycline and tetracycline of > 90 %, > 80 % and > 70 % after 240 min exposure to UV light. The catalytic ability of SN-SiNPs was derived from hydroxyl radical (center dot OH-), superoxide radical (center dot O-2(-)) and singlet oxygen (O-1(2)) produced by SN-SiNPs under UV irradiation. Moreover, integrating the fluorescent probe and photocatalyst together, the proposed SN-SiNPs simultaneously realized catalyzing the degradation of the three TCs and in-situ visually monitoring of the degradation process in real time. This study innovatively proposed an integrated probe for the detection and catalytic degradation of TCs, providing a new two-in-one strategy for rapid and simple detection and removal of drug pollutants.

Automated summary

In this study, two-in-one silicon nanoparticles were designed and prepared as a fluorescent probe and degradation catalyst for the detection and removal of tetracycline antibiotics. These nanoparticles can selectively quench the blue fluorescence upon interaction with tetracycline, while emitting yellow-green fluorescence. They can be used as fluorescent probes for the detection of doxycycline, oxytetracycline, and tetracycline with low limits of detection. Additionally, the nanoparticles were capable of catalyzing the degradation of the antibiotics under UV light. This study provides a new strategy for the rapid and simple detection and removal of drug pollutants.