The unique properties of silicon quantum dots (SQDs), such as their unique optical properties, low toxicity, and ease of surface functionalization have made them great candidates for various biological and optoelectronic applications. Unfortunately, the low quantum yield, unstable photoluminescence, and poor colloidal stability of SQDs hindered their wide applicability. Herein, we report the synthesis of four assemblies of SQDs (1.6 – 1.8 nm average diameter) functionalized with fluorescein dye through isothiocyanate (-NCS) and carboxylate (COO) spacers to produce the dyads Am-SQD-Fl, DiAm-SQD-Fl, Urea-SQD-Fl, and SiF. The photophysical results showed that the interaction between SQDs and Fluorescein chromophores in the dyads Am-SQD-Fl, DiAm-SQD-Fl, and SiF is mainly proceeding through photoinduced electron transfer at different rates, while energy transfer was confirmed to be the predominant process in the dyad Urea-SQD-Fl. Furthermore, the utilization of the isothiocyanate spacer in the dyads led to a significant improvement in the quantum efficiency of SQDs (up to 65%) and extended their photostability for a year. The nature of the spacer played a keyl role toward directing and controlling the optical properties of SQDs. To demonstrate the suitability of the functionalized SQDs for bioimaging, the four dyads were examined for fluorescent imaging of human bone cancerous U2OS cells.<br/>

Impact of spacers on controlling the optical properties of silicon quantum dots: Fluorescein dyad

2019 Fall National Meeting

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