Soy protein isolate-carboxymethyl cellulose conjugates with pH sensitivity for sustained avermectin release.

Long Chen,Huayao Chen,Li Hao,Xinhua Zhou,Hongjun Zhou

doi:10.1098/rsos.190685

Abstract

Carboxymethyl cellulose (CMC) was grafted onto the surface of soy protein isolate (SPI) to obtain soy protein isolate-carboxymethyl cellulose conjugate (SPC). Avermectin (AVM) was hydrophobically encapsulated as a model drug to obtain SPC@AVM. The reaction between SPI and CMC was confirmed by infrared spectroscopy, thermal analysis and SDS-PAGE electrophoresis. The results of scanning electron microscopy showed that the average particle size of the drug-loaded microspheres was 129 nm and the shape of microspheres changed from block to spherical after the addition of AVM. After encapsulation of AVM, the absolute value of zeta potential was greater than 15 mV, which indicated better stability. Compared to AVM solution, SPC@AVM showed more wettability on the leaf surface and the contact angle on the leaves decreased from 71.64° to 57.33°. The maximum liquid holding capacity increased by 41.41%, from 8.85 to 12.52 mg cm−2, which effectively reduced leaf loss. SPC@AVM also prevented UV photolysis, wherein the half-life was extended from 18 to 68 min when exposed to UV light. Moreover, toxicity tests showed that the encapsulation of AVM was beneficial to retain the insecticidal effect of AVM in the presence of ultraviolet light. The release rate of AVM showed pH responsiveness and the release rate under neutral conditions was faster than acidic and alkaline conditions. Moreover, the process conformed to the Weibull model.

Highlights

Pesticides are commonly used in agriculture to control diseases, pests and weeds from affecting crops [1]
Both these findings indicated the successful formation of the amide bond between soy protein isolate (SPI) and Carboxymethyl cellulose (CMC) [34]
In the spectrum of soy protein isolatecarboxymethyl cellulose conjugate (SPC), peak due to in-plane bending vibration of the hydroxyl group of CMC appeared at 1326 cm−1, suggesting that a reaction occurred between SPI and CMC

Summary

Introduction

Pesticides are commonly used in agriculture to control diseases, pests and weeds from affecting crops [1]. Due to 2 factors such as foliar loss, evaporation, photodegradation, etc., the amount of the active ingredient of the pesticide acting on the target is less than 10% [3,4,5]. This implies that the amount of harmful substances used is very high, which has a negative impact on the environment and is a matter of great concern [6,7]. The second approach is to improve the utilization of pesticides by processing, mainly to reduce leaf loss, degradation and control their release [11,12]. The anti-ultraviolet photolysis ability of AVM was improved and the release time of AVM was prolonged

Objectives

Results

Conclusion