Glucose-Responsive Dextran-Coated Curcumin Nanoparticles Functionalized with Glucose Oxidase for α-Amylase Inhibition

Abstract

Curcumin is a natural compound with potential antidiabetic activity; however, its poor water solubility and low bioavailability limit its clinical application. This study aimed to synthesize dextran-coated curcumin nanoparticles (DCNPs) with glucose-responsive properties and evaluate their physicochemical characteristics and α-amylase inhibitory activity. DCNPs were prepared using the emulsification method with dextran as a stabilizing polymer and glucose oxidase enzyme as a glucose-sensitive agent. The nanoparticles were characterized for particle size, polydispersity index (PDI), zeta potential, morphology using transmission electron microscopy, encapsulation efficiency, and in vitro drug release in phosphate-buffered saline (PBS) with and without glucose (400 mg/dL). In addition, the α-amylase inhibitory activity was tested and compared to that of acarbose. The synthesized DCNPs exhibit a particle size of 172.1 ± 4.17 nm, PDI of 0,120 ± 0.10, and zeta potential of -18.8 ± 0.11 mV, indicating good homogeneity and moderate stability. The encapsulation efficiency reaches 95.45 ± 0.09%. The in vitro release study shows cumulative curcumin release of 40.18 ± 1.99% in PBS and 61.15 ± 3.37% in PBS with glucose after 8 hours, demonstrating glucose-responsive behavior. Furthermore, DCNPs exhibit an IC₅₀ of 228.60 ± 2.67 ppm against α-amylase, lower than that of acarbose (399.35 ± 4.05 ppm), indicating stronger enzyme inhibition. These findings demonstrate that the developed glucose-responsive dextran-coated curcumin nanoparticles (DCNPs) meet the physicochemical criteria and exhibit significant α-amylase inhibitory activity. It indicates their potential as a dual-functional system for glucose-triggered drug release and enzymatic inhibition, and as a promising candidate for natural antidiabetic therapy.