Surface enhanced FRET for sensitive and selective detection of doxycycline using organosilicon nanodots as donors.

In order to achieve on-site fluorescent detection of antibiotic doxycycline (DOC) residue, a new kind of fluorescent organosilicon nanodots (OSiNDs) was successfully constructed by a one-pot strategy and used as a novel ratiometric fluorescent probe. This method could enhance the fluorescence of DOC by conformational fixation on the surface of OSiNDs, and subsequently induced fluorescence resonance energy transfer (FRET). Control experimental results showed that phenylamine functional groups on the as-prepared OSiNDs possessed favorable interactions with DOC by hydrogen bond/π-π stacking, leading to both conformational change of DOC molecules and fluorescence resonance energy transfer process from OSiNDs to DOC. This method was then adapted and optimized for visual sensitive and selective detection of DOC based on ratiometric fluorescence signal, displaying a good linear range for DOC in the range of 1-35 μM with an excellent limit detection of ∼80 nM. Other tetracycline derivatives (TCs) and possible interferences have little influence on the determination of DOC using the method. The spike and recovery test of DOC in real water samples demonstrated the feasibility of the OSiNDs for DOC assay in practical samples and a test paper was fabricated with OSiNDs loading, achieving easy and visual detection of DOC by naked eyes.