Synthesis of cellulose nanocrystals from spinach waste for insulin delivery: comparison to chitosan nanoparticles

Abstract

It remains unknown what nanoparticles (NPs) could be a good candidate for insulin delivery, and there is still little research on the use of chitosan nanoparticles (ChNs) for this. The aim is to shed light on the efficacy of hairy cellulose nanocrystals (HCNs) in insulin delivery and compare it with that of ChNs. The NPs were synthesized and assessed using scanning electron microscopy (SEM), dynamic light scattering (DLS), zeta-potential analysis, Fourier transform infrared (FTIR) spectroscopy, and the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assay. Insulin was loaded into both types of NP and the insulin loading and encapsulation efficacy were measured. The release kinetics were also studied using zero order, first order, Korsmeyer-Peppas, and Higuchi models. The analysis revealed that the HCNs had a rod shape while the ChNs were spherical. The HCNs had a size of 100-150 nm with a zeta potential of +34.2 mV, while the ChNs were 100-200 nm in diameter and had a surface charge of +40.7 mV. Insulin loading reduced the zeta potentials to -26.08 mV and +19.47 mV for the HCNs and ChNs, respectively. The HCNs resulted in higher cell viability than the ChNs. Insulin release was higher for the HCNs compared to the ChNs. The Korsmeyer-Peppas model (R2 = 0.99, n = 0.741, K = 0.004) gave the best fit for the ChNs, while for the HCNs, both the Korsmeyer-Peppas (R2 = 0.97) and Higuchi models (R2 = 0.95) gave the best fit. To sum up, the HCNs showed higher potential in insulin loading and release compared to the ChNs. Cellulose nanocrystals were synthesized from waste spinach and their potential for use in insulin delivery was assessed and compared to that of chitosan nanoparticles.