Colloidal, water soluble probes constructed with quantum dots and amphiphilic poly(ferrocenylsilane) for smart redox sensing

• A novel redox responsive coating for water soluble nanoparticles.
• Organometallic poly(ferrocenylsilanes) (PFS) used as a carrier medium.
• Redox modulated fluorescence from quantum dots.
• Colloidal probe for bioapplications.

Poly(ferrocenylsilane) (PFS), consisting of main chains that feature ferrocene bridged by substituted silane units, was used to construct redox responsive shells on hydrophobic CdSe/ZnS quantum dots (QDs). The novel coating renders QD colloids stable in water in both reduced and oxidized forms of the ferrocene. Reversible fluorescence quenching was observed for chemically induced redox reactions of the colloidal assembly. Electrochemical oxidation studied in the bulk solution and in layer-by-layer composite films featuring combinations of QDs, PFSs, and other polymers, led to irreversible quenching of QDs. Finally, applications for sensing are briefly discussed.

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