Optical Properties, Antibacterial Activity, and Relaxation Behavior Investigation of Chitosan/Green Synthesized Silver Nanoparticles by Thermally Stimulated Depolarization Current Technique

Chitosan/green synthesized silver nanoparticles have been prepared electrochemically in one compartment electrochemical cell under nitrogen gas pressure. The analysis of UV–Vis spectroscopy of Cs/AgNPs revealed that chitosan is characterized by a shoulder centered at 250 nm and an absorption peak at 304 nm attributed to n → π* and π → π* transition of C=O. On the other hand, Cs/AgNPs spectrum showed a surface plasmon resonance (SPR) peak in the range from 410 to 420 nm and is attributed to spherical colloidal silver nanoparticles absorption due to the excitation of surface plasmon vibration. It is found that with increasing AgNPs content, the values of E_dg decreased until to reach the value of 4.96 eV in comparison to pure chitosan which has a value of 5.16 eV. FTIR spectroscopy displayed that, a relative decrease in transmittance of the band at 3300–3430 cm^–1 and the band of carbonyl group has been shifted from 1728 to 1734 cm^–1. The intensity of the bands at 1559 and 1411 cm^–1 characterizing amide II and C–H in alkanes has been changed with increasing the content of AgNPs. The swelling measurements showed that, the maximum swelling ratio decreases with increasing the content of AgNPs because of formation of intramolecular or intramolecular linkages because of the interaction between silver and amino groups of chitosan. Antibacterial activity measurements showed that Cs/AgNPs samples had a strong effect against the different types of bacteria under study, both Gram-positive and Gram-negative. Global TSDC spectra of Cs/AgNPs have been investigated in a wide range of temperature and the molecular parameters characterizing these samples have been estimated.