Design and optimization of chitosan-alginate nanoparticles for plant growth hormone indole-3-acetic acid

Abstract

Excessive use of agrochemicals can lead to environmental degradation, and thus, a potential solution is to control their release using biodegradable polymeric nanoparticles. This study aimed to fabricate indole-3-acetic acid chitosan/alginate nanoparticles (IAA-CANPs) through o/w emulsification and ionotropic gelation, employing a Box-Behnken design (BBD) to evaluate the influence of various factors (alginate: chitosan mass ratio (ALG:CS), TweenTM 80, and IAA concentration) on particle size, zeta potential, and encapsulation efficiency (EE). Response surface methodology (RSM) was used to determine the optimum conditions for nanoparticle fabrication, which were ALG:CS mass ratio of 1:0.10, TweenTM 80 of 1.5% w/v, and IAA of 15 mg/mL. The IAA-CANPs produced under these optimal conditions exhibited an average particle size of 275 ± 19 nm, a polydispersity index (PDI) of 0.37 ± 0.9, a zeta potential of -23.8 ± 0.8 mV, and an EE of 68.5 ± 1.4%. The IAA-CANPs also demonstrated superior physico-chemical stability under UV irradiation exposure compared to free IAA. The IAA-CANPs had stability up to 3 months at 4°C. The release pattern in dissolution media at pH 5.5 and 7.5 indicated a sustained-release behavior, which fit well with the Peppas-Sahlin kinetic model, indicating anomalous diffusion, a non-Fickian diffusion mechanism. These findings suggest that CANPs could be a promising approach for encapsulating and controlling the release of IAA, exhibiting excellent physicochemical stability and potential for agricultural applications.