Sol-Gel Materials with Pesticide Delivery Properties

Abstract

Pesticides are widely used in agriculture, although they may create hazards both to humans and to the environment. In order to reduce the harmful effects of their administration, there has been made a great effort to find solutions. The porous sol-gel silica materials which are able to entrap different organic molecules represent new studied controlled release carriers. The aim of the present work was to prepare and characterize sol-gel composites based on trichlorfon as organophosphorous pesticide embedded in silica matrices generated from three different SiO2 sources: tetraethylorthosilicate (TEOS), colloidal silica (CS), and sodium silicate (SS). Similar samples to those containing only trichlorfon have also been synthesised, in which α-, β-, and γ-cyclodextrin have been included in order to study the possibility of improving the release of the pesticide from the silica matrices. The porous sol-gel silica materials generated from TEOS and CS are able to entrap the trichlorfon and ensure an efficient delivery of the pesticide. In the absence of cyclodextrins, better results are obtained in the case of TEOS precursor, compared to colloidal silica. The addition of cyclodextrins in order to improve the release of the pesticide from the silica matrices was successful only in the case of CS as SiO2 precursor. The best release of the pesticide was obtained with β-CD

Sol–gel zirconia nanopowders with α-cyclodextrin as organic additive

“…In its presence the temperature corresponding to the cyclodextrin combustion is significantly modified. Thus, ␣-CD is eliminated from the sample at much lower temperature (267 and 450 • C) compared to the temperature of combustion of the pure cyclodextrin which is around 499 • C. This observation is also valid in the case of sol-gel silica matrices [40] and could be considered as a proof of the fact that the cyclodextrin was included in the zirconia matrix. Based on the thermal behaviour study, the temperature of the thermal treatment has been chosen, in order to eliminate the organic molecules from the zirconia sample.…”

“…1) has been fully described in a previous paper [40]. It evidences the following thermal effects: (a) two endothermic effects corresponding to 73 and 107 • C, respectively, due to water elimination; (b) one endothermic effect at 274 • C which is assigned to cyclodextrin decomposition; and finally (c) an exothermic effect at 499 • C, due to the cyclodextrin combustion.…”

Synthesis of water soluble polyrotaxanes by end-capping polypseudo-rotaxanes of γ-CDs with PHEMA-PPO-PEO-PPO-PHEMA using ATRP of MPC

“…The spectra of the PMPC block containing samples exhibit distinct featured peaks of MPC unit at 788 cm -1 (P-O-CH 2 55 stretching vibration) and 1088 cm -1 (CH 2 -N-CH 3 stretching vibration) 36 . Besides those two characteristic vibrations, FTIR band frequencies of the two PR samples tested at 1028 cm -1 and 584 cm -1 are registered as bend vibration of O-H in γ-CDs and the pyranose ring pulsation vibration, respectively 37,38 . Moreover, the 60 absorption bands of pyranose ring pulsation vibrations are slightly broadened for the formation of inclusion complexes, similar to the case observed by Roik et al 39 .…”

Novel nanoscale pheromone dispenser for more accurate evaluation of Grapholita molesta (Lepidoptera: Tortricidae) attract‐and‐kill strategies in the laboratory

“…Pesticides play an important role in agriculture, as they help in preventing and reducing crop losses caused by pests . However, less than 1% of the applied pesticides actually reaches the target pests .…”

“…Pesticides play an important role in agriculture, as they help in preventing and reducing crop losses caused by pests. 1 However, less than 1% of the applied pesticides actually reaches the target pests. 2,3 Indiscriminate pesticide usage increases pathogen and insect resistance, reduces soil biodiversity, diminishes nitrogen fixation, contributes to toxic bioaccumulation and negatively affects beneficial organisms.…”