A highly sensitive and selective "turn off" fluorescent sensor based on water soluble copper nanoclusters for morin and temperature sensing

A novel fluorescence detection method was developed for the determination of morin and temperature based on water soluble copper nanoclusters (Cu NCs) for the first time, which was fabricated by using tannic acid (TA) as the protecting agent and ascorbic acid as the reducing agent. The TA protected Cu NCs (TA-Cu NCs) were characterized through a series of methods. The characterization results showed that the as-prepared TA-Cu NCs possessed good water solubility and high photostability. Interestingly, the fluorescence intensity of TA-Cu NCs was obviously quenched in the presence of morin. Then, a rapid and facile morin probe was established based on TA-Cu NCs, and the fluorescence quenching mechanism was ascribed to the inner filter effect. The as-prepared probe showed excellent sensitivity and selectivity towards morin with a wider linear range from 0.5 to 110 mu M (R2 = 0.9949), and a lower detection limit could reach 0.062 mu M. In addition, the TA-Cu NCs were employed for temperature sensing. The practicability of the TA-Cu NCs for morin detection in bovine serum samples was also verified with the recoveries range from 92.5% to 107.7%, illustrating this detection method with great potential application in the field of analysis.