β-Cyclodextrin/Azobenzene Microspheres Loaded with Paraquat Are Safe and Effective

Abstract

Although paraquat is a widely used herbicide, it is toxic to humans if ingested or absorbed through an open wound. To improve the safety of paraquat, a new formulation of paraquat based on photoresponsive polymers was exploited. Photoresponsive β-cyclodextrin polymer microspheres (AZO-CD) were synthesized via a host–guest interaction between β-cyclodextrin and azobenzene. AZO-CD were characterized by Fourier transform infrared spectrometry, circular dichroism, ultraviolet (UV) spectrophotometry, and thermogravimetric analysis, and their photoresponsiveness was also evaluated. AZO-CD were used to load paraquat, which yielded photoresponsive paraquat-loaded microspheres. For the paraquat-loaded microspheres, irradiation with UV light or sunlight induced the isomerization of azobenzene into the cis form. Then, the cis-azobenzene was liberated from the cavities of the β-cyclodextrin. The paraquat-loaded microspheres released paraquat continuously over time. Furthermore, under UV light, the herbicidal capacity of the paraquat-loaded microspheres against barnyard grass was comparable to that of free paraquat at the same dose. Our findings show that loading paraquat into AZO-CD provides a safe and environmentally friendly herbicide formulation.

Cyclodextrin-Coordinated Liposome-in-Gel for Transcutaneous Quercetin Delivery for Psoriasis Treatment

“…Liposome is a classical carrier for improving drug solubility and skin permeability in topical drug development . Yet, a common problem for liposomal drugs is physical instability and the loose coordination of liposomal structures. − The fluidity of the phospholipid bilayer causes the frequent intramolecular contact of QT, and long-term storage can lead to drug leakage and formation of QT crystals. − The pharmaceutical stability of liposomes can be improved by the surface coating using amphipathic polymers such as DSPE-PEG, Pluronic L61, and Tween 80. There is still a continuous need to search for efficient means to prolong the liposomal shelf life .…”