A Comparison Study of Antiultraviolet and Sustained Release Properties of Polydopamine/Avermectin Microcapsule and Microsphere

Abstract

By using dopamine (DA) as the monomer, the model drug avermectin (AVM) was loaded on polydopamine microspheres (AVM/PDAMS) and polydopamine microcapsules (AVM@PDAMC) by the method of impregnation and encapsulation, respectively. The materials’ structures were systematically characterized using Fourier transform infrared spectroscopy (FTIR), zeta potential analysis, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The comparison of antiultraviolet capability as well as release behaviors under different pH values of the materials were studied. The results showed that a spherical appearance was observed from both materials. The use of AVM/PDAMS and AVM@PDAMC made the decomposition temperature of AVM increase to 235°C and 245°C, respectively. After being exposed to ultraviolet light for 1400 min, the residual ratios of AVM of AVM/PDAMS and AVM@PDAMC were 42% and 54%, respectively. Both AVM/PDAMS and AVM@PDAMC showed acid sensitivity. AVM/PDAMS and AVM@PDAMC took about 13 h and 60 h to reach the release rate of 50% under pH 3. The release process of AVM/PDAMS could be explained by the Weibull model at pH 3, while the release behavior of AVM@PDAMC fitted the Baker–Lonsdale equation. At pH 7 and pH 9, both of the delivery materials followed the Korsmeyer–Peppas model and belonged to the Fick diffusion.

Construction of a photothermal controlled-release microcapsule pesticide delivery system

“…Therefore, the positive charge of the chitosan layers and PDA layers generated the repulsive force, resulting in the faster release of AVM under acidic conditions. 52 …”

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

“…The release factors of SPC-41@AVM and SPC-81@AVM were similar, and the values of the statistical analysis results were similar. f 1 less than 15 and f 2 greater than 50 indicate that the difference was not significant compared to that of SPC-11@AVM, and the release rate was only slightly higher than them [46,47].…”

“…The release factors of SPC-41@AVM and SPC-81@AVM were similar, and the values of the statistical analysis results were similar. f 1 less than 15 and f 2 greater than 50 indicate that the difference was not significant compared to that of SPC-11@AVM, and the release rate was only slightly higher than them[46,47].Unlike the encapsulation process of drugs, when AVM molecule enters the interiors of the microspheres, in addition to constraint by hydrophobic forces, the negative charge of carboxymethyl group on microsphere surface also generates electrostatic repulsion, making it more difficult to escape. As described above, SPC-11@AVM carried a greater number of negative charges and its release rate was slower.…”

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“…1i). When the temperature was increased to 200 °C, the weight of PDA-FDM-23 began to drop, which was assigned to the decomposition of PDA, 45 suggesting the outstanding stability of PDA-FDM-23 under physiological conditions.…”