Enantioselective ecotoxicity of the herbicide dichlorprop and complexes formed with chitosan in two fresh water green algae

Abstract

To reduce the leaching potential, to prevent groundwater contamination and to maintain the efficacy of a pesticide, natural polysaccharides have received increasing attention due to their biocompatibility and useful biological reactivity for controlled release formulations (CRFs) of pesticides. In this paper, the toxicities of the chiral herbicide dichlorprop (DCPP) and its complexes with chitosan molecules (DCPP-CS) and chitosan nanoparticles (DCPP-NP) to two different green algae were determined and compared. The inhibition rates of DCPP, DCPP-CS and DCPP-NP were determined at 24, 48, 72, 96, 120, 144, 168 h, and the results show that (S)-DCPP was more toxic to Chlorella vulgaris than (R)-DCPP, while the (R)-DCPP was more toxic to Scenedesmus obliquus than (S)-DCPP. The study also found that the chiral selectivity of DCPP to Chlorella vulgaris and Scenedesmus obliquus could be changed when DCPP was complexed with chitosan molecules (CS) or chitosan nanoparticles (NP). For Chlorella vulgaris, the order of inhibition was (R)-DCPP-CS > (S)-DCPP-CS and (R)-DCPP-NP > (S)-DCPP-NP; for Scenedesmus obliquus, the order was (S)-DCPP-CS > (R)-DCPP-CS and (S)-DCPP-NP > (R)-DCPP-NP. This phenomenon suggests that the enantioselective behaviors of chiral compounds might shift when interactions with other chiral receptors coexist in different biological environments. Additionally, chitosan molecules and chitosan nanoparticles also showed different toxicities, which could be ascribed to the difference in the physicochemical properties between CS and NP or the differences in the cell walls of the two fresh water green algae.

Direct and indirect toxic effects of cotton-derived cellulose nanofibres on filamentous green algae

“…Lima et al (2010) showed that chitosan NPs reduced mitotic index in Allium cepa. In green microalga, chitosan NP inhibited the growth of Chlorella vulgaris (Wen et al, 2011). However, bulk chitosan could protect plant cells from stress of high chemical oxygen demands concentration polluted water (Xu et al, 2007).…”

Chitosan nanoparticle based delivery systems for sustainable agriculture

“…The use of this type of formulation could help to limit the mobility of anionic pesticides in the environment, reducing risks of contamination of surface and subterranean water bodies. Wen et al [212] studied the bioavailability of the chiral herbicide dichlorprop to the green alga Chlorella pyrenoidosa, in the absence and presence of chitosan nanoparticles. These observations provided a clear indication that chitosan was able to modify the enantioselective bioavailability of the herbicide, which could be of use in environmental protection applications.…”

Chitosan Effects on Plant Systems

“…A nanocomposite material of CHT and montmorillonite was used to adsorb and remove the herbicide clopyralid present in water and soil [ 134 ]. Wen et al demonstrated that CHT enhances the bioavailability of the chiral herbicide dichlorprop to the green alga Chlorella pyrenoidosa [ 135 ], and a plant esterase-CHT/gold nanoparticles−graphene nanosheet composite-based material was successfully tested for ultrasensitive detection of organophosphate pesticides in different samples [ 136 ]. CHT microcapsules from pollens of Acer negundo , Cupressus sempervirens , and Populus nigra were used to remove trace elements [ 137 ].…”