A rhodamine scaffold immobilized onto mesoporous silica as a fluorescent probe for the detection of Fe (III) and applications in bio-imaging and microfluidic chips

• The rhodamine 6G based chemosensor was successfully immobilized with mesoporous.
• The prepared sensing particle exhibited high selectivity toward Fe (III).
• Fe (III) led to CHEF effect of sensing particle with showing greenish yellow fluorescence.
• Sensing particle showed high potential ability for application of biology and microfluidics.

A novel ethylenediamine derivative of a rhodamine 6G silica particle (RSSP) was covalently grafted onto the surface of mesoporous silica to create a fluorescent chemosensing hybrid material for the detection of Fe3+. The prepared RSSP was dispersed in water, and its optical sensing response to various metal cations (Ag+, Na+, Li+, K+, Cs+, Hg2+, Cu2+, Ca2+, Cd2+, Co2+, Fe2+, Mg2+, Ni2+, Pb2+, Zn2+, Fe3+ and Al3+) was evaluated through the resulting fluorescence spectra. Upon coordination with Fe3+, the promoted ring opening of the rhodamine spirolactam ring in the RSSP activated a fluorescence response via CHEF (chelation enhancement fluorescence). This fluorescence enhancement was induced by the spirolactam ring system of the chemosensor immobilized in the pore. Conversely, the fluorescence response of the RSSP–Fe3+ complex was quenched by the addition of EDTA, which abstracted the Fe3+ ion from the complex and turned the sensor off, confirming that the recognition process was reversible. The proposed chemosensor also exhibited excellent selectivity for Fe3+ over competing environmentally relevant metal ions. The chemosensor can also be used over a wide pH range and was readily regenerated. The sensing ability of RSSP makes it desirable for practical applications in microfluidics analysis tools, intracellular bio-imaging and lab-on-a-chip development.

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