A hydrophilic polymer-based bifunctional nanosensor for sequential fluorescence sensing of Cu2+ and biothiols and constructing molecular logic gate

A hydrophilic polymer-based nanoparticles named PEIN was developed as a new bifunctional nanosensor for sequential fluorescence sensing of Cu 2+ and biothiols. PEIN could be easily prepared via a one-pot grafting reaction between commercially accessible polyethyleneimine and ninhydrin in water solution at room temperature for 1 h. In phosphate buffered aqueous media (pH5.0), the strong fluorescence of PEIN at 444 nm (excited at 360 nm) was rapidly and effectively quenched by Cu 2+ over the other common metal ions. The quenching mechanism has been proved to be a static process owing to the binding of PEIN with Cu 2+ . In addition, the reduced fluorescence of PEIN could return immediately upon the addition of biothiol (Cys or GSH) in PEIN-Cu 2+ system, but not recover with the attendances of other non-thiol amino acids. Therefore, PEIN was able to be used for the selective detection of Cu 2+ by fluorescence “turn off” mode, and the in site formed PEIN-Cu 2+ ensemble could be applied for determining biothiols by fluorescence “turn on” mode. Furthermore, in view of the fluorescence “on-off-on” switches of PEIN caused by Cu 2+ and Cys (or EDTA), a two-input molecular logic gate performing IMPLICATION operation was successfully constructed by employing PEIN as the communication material.