Effect of molecular weight of chitosan on quercetin‐loaded chitosan nanoparticles

Abstract BACKGROUND The widespread use of quercetin is limited by its instability, low solubility and poor oral bioavailability. Encapsulation of quercetin using a nanoparticle delivery system is an effective way to overcome these drawbacks. RESULTS The effect of the molecular weight ( M w ) of chitosan (CS) (100, 200, 500 and 1000 kDa) on quercetin‐loaded chitosan nanoparticles (QCNPs) was investigated. The structure, stability, release properties and antioxidant activities of the nanoparticles (QCNP‐10, QCNP‐20, QCNP‐50 and QCNP‐100) were assessed. Particle size of QCNPs decreased and polydispersity index increased with the increasing M w of CS. The main forces involved in the formation of QCNPs were hydrogen bonding and hydrophobic interaction. X‐ray diffraction verified that quercetin was loaded into CS nanoparticles. The photostability and thermal stability of QCNPs increased with increasing M w of CS. QCNP‐100 exhibited the lowest release rate in a mixture of water and anhydrous ethanol. The antioxidant activities of QCNPs were enhanced with increasing M w of CS, and QCNP‐100 possessed the highest antioxidant activities, which might be relevant to its smallest particle size. CONCLUSION Overall, these results revealed that the M w of CS affected the properties of QCNPs, and QCNP‐100 possessed the smallest particle, best stability, lowest release rate and highest antioxidant activities. © 2024 Society of Chemical Industry.