Preparation and characterization of anti-algal sustained-release granules and their inhibitory effects on algae

Abstract

The objectives of this work were to prepare and characterize an anti-algal sustained-release granule, then study its mode of action on Microcystis aeruginosa. The anti-algal sustained-release granule was prepared with artemisinin using alginate–chitosan microcapsule technology and characterized by a high performance liquid chromatography with an evaporative light-scattering detector, Fourier transform infrared spectral analysis, and a scanning electron microscope. The optimum preparation (in %, w/v) using the orthogonal method was: 2.5 sodium alginate; 0.25 chloride; 0.6 artemisinin; 2 calcium chloride; and 1.5mL of the cross-linking agent, glutaraldehyde. These artemisinin sustained-release granules had a high encapsulation efficiency (up to 68%) and good release properties (release time of more than 40d). Artemisinin sustained-release granules released cumulatively in a solution containing M. aeruginosa, and the stress on algae increased gradually within 30d. Artemisinin sustained-release granules decreased the content of the soluble protein, Chlorophyll a in 30d, increased the superoxide dismutase activity of M. aeruginosa, but exerted no effect on the soluble sugar content. Compared to direct dosing of artemisinin, algae can be inhibited longer and more effectively by the artemisinin sustained-release granules. The results of our research can aid in the development of new anti-algal sustained-release granules and lead to further study of their application in the field.