Exploring the design and evaluation of chitosan pyridinium salts: Morphological analysis and antioxidant activity

This study focuses on the synthesis, characterization, surface morphology analysis, and antioxidant evaluation of chitosan pyridinium salt derivatives. Chitosan was derivatized to 4APATC and 2A3HPATC via conjugation of 6-O-chloroacetyl-2-N, N, N-trimethyl chitosan (CTMC) with 4-aminopyridine and 2-amino-3-hydroxy pyridine, respectively. The newly synthesized compounds were characterized by Fourier Transform Infrared (FT-IR) spectroscopy and Proton Nuclear Magnetic Resonance (¹H-NMR) spectroscopy, proving the victorious incorporation of functional groups. FTIR spectra revealed distinguishing peaks corresponding to O-H, N-H, C = O, and C-H stretching vibrations, while ¹H-NMR spectra provided detailed insight into the structural framework of each derivative. Surface morphology examined through Scanning Electron Microscopy (SEM) demonstrated notable changes, including enhanced porosity, increased roughness, and varied particle size, due to chemical modifications. Energy-dispersive X-ray Spectroscopy (EDS) analysis endorsed the elemental composition and supported the structural changes observed. Additionally, antioxidant activities of the synthesized derivatives were evaluated using DPPH, ABTS, and FRAP assays throughout a concentration range of (100–1000 µg/mL). The results showed a concentration-dependent radical scavenging effect, with 2A3HPATC exhibiting superior antioxidant potential compared to CTMC and 4APATC, indicating the effectiveness of pyridinium functionalization in enhancing antioxidant activity.