Application Of A Novel Aggregation-induced Emission Fluorengen In Detection Of Mercury Ion In Microalgae

In this study,a novel methodology was developed using a specified aggregation-induced emission fluorogen（AIEgen m-TPE-RNS）to monitor and quantify the complex bioaccumulation process in a microcosm aquatic ecosystem.The results showed as follows:The AIE features of m-TPE-RNS were investigated in water/ACN mixtures at 3:2.In the presence of Hg²⁺,the m-TPE-RNS displayed strong fluorescence emission under 350 nm UV light excitation,and photoexcitation at 590 nm was induced and displayed on the PL spectra.The research indicated that there was a linear relationship between photoluminescence（PL）intensity and Hg²⁺ concentration when the ratio of AIE concentration and Hg²⁺ concentration was less than 1.Euglena gracilis was used to characterize Hg²⁺ absorption.Euglena gracilis cells contracted into a “ball” shape and became immobile with the increase in Hg²⁺ concentration from 0 to 30 μM.The contractile vacuole disappeared and the central part of the algal cells became condensed and wrinkled after treatment with Hg²⁺ at 30 μM.The algal recovery ratio in clean water over 24 h after incubation with 10,20 and 30 μM Hg²⁺ for 1 h were 93 %,67 % and 10%,respectively.A significant drop in PL intensity occurred at the very beginning for both Hg²⁺ concentrations of 10 μM and 20 μM,which indicated the significant initial uptake of Hg²⁺ by algal cells.The PL intensity leveled off and plateaued after 1 h in both Hg²⁺ concentrations.Therefore,1 h was used as the incubation time in the subsequent study.In the medium with 10 and 20μM Hg²⁺,the amount of Hg²⁺ inside algal cells increased from zero to 0.64 and 1.13μg/mg respectively within the first 30 min.Further incubation did not enhance bioaccumulation much and the amount of Hg²⁺ augment inside algae did not increase significantly.The ratio of Hg²⁺ accumulation（tR）increased to 4 and 5 within 1 h in the medium with 10 and 20 μM Hg²⁺.Algae were harvested after incubation in 20 μM HgCl₂ for 45 min,and then transferred into clean water.Subsequently,the amounts of 0.02 and 0.013 μg Hg²⁺/mg algae were detected in the clean water at 3 h and 24 h,respectively.There is a dynamic balance exists between the intracellular and extracellular environments.If a higher Hg²⁺ concentration gradient exists between the intracellular and extracellular environments,higher release efficiency can be achieved.