Effect And Mechanisms Of Novel MOFs On Inhibiting The Growth Of Algal Cells

The serious pollution of water environment and the frequent occurrence of harmful algal blooms bring serious ecological hazards and even endanger the survival and safety of human beings.It is the constant pursuit of researchers to explore new and more efficient materials to inhibit algae.Allelochemicals have many advantages such as being degradable and environment-friendly,while MOFs contain metals that can effectively inhibit algal growth.For the first time,ferulic acid and Zn²⁺were combined for algae inhibition,and the synergistic effect of both would achieve better algae inhibition.In this paper,we prepared and characterized Zn-MOF-FA,an algal inhibitor of MOFs,and mainly investigated the effects of ferulic acid and Zn-MOF-FA on the growth inhibition of Microcystis aeruginosa cells and on the photosynthetic system and antioxidant system of algal cells.As well as the comparison of the algae inhibition effect of Zn-MOF-FA with the same dose of ferulic acid and Zn²⁺,to visually demonstrate the effect and advantage of Zn-MOF-FA to inhibit Microcystis aeruginosa.The algae inhibition experiments showed that 200 mg/L ferulic acid could inhibit algae growth to a certain extent within 7 days of the experiment,with the highest inhibition rate reaching 67.7%.Lower concentrations of ferulic acid could only inhibit algae growth for a short period of time,and the algae cells regained their normal growth capacity after a few days.In contrast,8 mg/L Zn-MOF-FA completely inactivated the algal cells on day 5 of the experiment,which shows that Zn-MOF-FA can inhibit the growth of algal cells more efficiently in a shorter time and at a lower dose.Zn-MOF-FA was higher than the sum of algae inhibition rate of ferulic acid and Zn²⁺at the same dose,and it should be that the synergistic effect of ferulic acid and Zn²⁺contributed to the higher inhibition effect.The experiment to investigate the effect on photosynthetic system found that 200 mg/L ferulic acid could have some effect on the maximal quantum yield（F_v/F_m）,maximal relative electron transport rate（rETRmax）and photosynthesis efficiency（α）of photosynthesis,and then inhibit the growth of algal cells,and the maximum inhibition rate was less than 50%,and the F_v/F_m,rETRmax andαof algal cells gradually increased after a few days,and the growth ability of algal cells was restored.In contrast,8 mg/L Zn-MOF-FA could inhibit F_v/F_m,rETRmax andαof algal cells to near 0 within 4 days,photosynthesis was inhibited and algal cells could not get energy replenishment and could only be gradually inactivated.Ferulic acid had little effect on the antioxidant system of algal cells.200 mg/L ferulic acid also inhibited the superoxide dismutase（SOD）and catalase（CAT）activities of algal cells to a certain extent,and could not scavenge reactive oxygen species（ROS）in time and caused slight oxidative damage to algal cells.8 mg/L Zn-MOF-FA was able to cause SOD and CAT activities of algal cells to be almost lost within 6 days.And the algal cells were unable to scavenge ROS and would eventually be inactivated by oxidative damage.In conclusion,the ferulic acid and Zn²⁺released from Zn-MOF-FA could synergistically and efficiently inhibit the growth of algae,and could inhibit the growth of algal cells at lower doses and more efficiently in a short period of time.At the same time,Zn-MOF-FA could also seriously damage the photosynthetic and antioxidant systems of algal cells and thus inhibit the growth of algal cells...