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Thermo-sensitive micelles based on amphiphilic poly(butylene 2-methylsuccinate)-poly(ethylene glycol) multi-block copolyesters as the pesticide carriers

Han, Jiarui, Weng, Yunxuan, Xu, Jun, Guo, Baohua
Colloids and surfaces 2019 v.575 pp. 84-93
avermectins, biodegradability, catalysts, condensation reactions, dialysis, drug carriers, drugs, esterification, high performance liquid chromatography, hydrophobicity, micelles, pesticides, polyesters, polyethylene glycol, temperature, thermosensitivity
A novel bio-based and biodegradable aliphatic multi-block copolyester, poly(butylene 2-methylsuccinate)-poly(ethylene glycol) (PBMS-PEG), was synthesized from 1,4-butanediol (BDO), 2-methylsuccinate acid (MSA) and poly(ethylene glycol) (PEG) via direct esterification and polycondensation process with tetrabutyl titanate as catalyst. Thermo-sensitive PBMS-PEG micelles were obtained by self-assembly of amphiphilic block copolyesters in aqueous medium by dialysis method. These micelles with different PEG contents have sizes varying from 74.3 nm to 138.3 nm and are stable in water over 200 days without any precipitation. A hydrophobic pesticide, Avermectin, was encapsulated in micelles by the same dialysis method. Such PBMS-PEG micelles can be used as thermo-responsive drug carrier owing to their controlled lower critical solution temperature (LCST) which can be accurately adjusted by varying the PEG proportion. The LCST increases from 27.0 °C to 40.0 °C while increasing the PEG proportion from 30% to 60%. By using the HPLC measurements, the results show when the drug loading is up to 20%, the loading efficiency is still nearly 100%. The properties of these amphiphilic micelles show that the delivery system has a promising potential to be further explored for developing a highly effective and biodegradable hydrophobic-pesticide-release formulation.