Synthesis and characterization of novel antibacterial chitosan-AgIO3 bionanocomposites

Due to the increase of infectious diseases and the development of antibiotic resistance, new antibacterial substances are needed. In the presented study, novel chitosan-AgIO₃ bionanocomposites were synthesized and their antibacterial properties were investigated.

SYNTHESIS AND CHARACTERIZATION OF NOVEL ECO-FRIENDLY CHITOSAN AgIO₃ BIONANOCOMPOSITE AND STUDY ITS ANTIBACTERIAL ACTIVITY

Ahghari, M.A., Ahghari, M.R., Kamalzare, M. et al. Design, synthesis, and characterization of novel eco-friendly chitosan-AgIO₃ bionanocomposite and study its antibacterial activity. Sci Rep 12, 10491 (2022). https://doi.org/10.1038/s41598-022-14501-6

The increase of bacterial infectious diseases with a parallel increase of antibiotic resistances make the development and synthesis of new antibacterial agents necessary. Pathogenic microorganisms such as Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus saprophyticus, Staphylococcus aureus or Escherichia coli are conventionally treated with antibiotics such as penicillin. An alternative option, e.g. as a wound dressing, can be silver hydrazine.

Nanomaterials also have a high potential for combating pathogenic bacteria. These have a large contact surface for microorganisms due to their high surface-to-volume ratio. When synthesized by Green Chemistry, bionanomaterials can be synthesized in an environmentally friendly manner under mild reaction conditions. Biopolymers such as chitosan are particularly interesting as materials. On the one hand, these are biodegradable and, in the case of chitosan, the large number of hydroxide and amine groups ensures that the bionanocomposites are highly modifiable.

Another material known for its antimicrobial capabilities is silver nanoparticles (AgNPs). These nanoparticles can attack cell membranes of microorganisms by forming reactive oxygen species, thereby eliminating them. To exploit all these capabilities, chitosan-AgIO₃ bionanocomposites were prepared in the presented study. These were then analyzed and characterized in terms of their antibacterial capabilities against different microorganisms (Staphylococcus aureus and Escherichia coli). The bionanocomposites were compared with penicillin and silver hydrazine.

RESULTS

• Change FTIR spectrum of chitosan after synthesis with AgIO₃-NPs, presence of peaks at 1072 cm^-1 and 748 cm^-1 indicate binding with AgIO₃-NPs
• Detection of C, O, N, Ag and I via X-ray spectroscopy → further confirmation of coupling of chitosan with AgIO₃-NPs
• Via SEM observation that AgIO₃-NPs cover the chitosan surface, detection of a particle size of 57 nm
• Via plate counting method, all bacterial colonies of E. coli and St. aureus were killed with the chitosan-AgIO3 bionanocomposites
• When optical density was measured after 3 h, 6 h, and 18 h, E. coli numbers were reduced by 71.96 % (3 h), 84.37 % (6 h), and 85.1 % (18 h), and St. aureus numbers were reduced by 64.7 % (3 h), 71.88 % (6 h), and 75.69 % (18 h), respectively
• Evidence via flow cytometry that microorganisms are killed by chitosan - AgIO₃ bionanocomposites via ROS → three times higher ROS levels than in the control group

Summary: In the presented study, chitosan-AgIO₃ bionanocomposites were successfully synthesized. In this process, the AgIO₃-NPs were deposited uniformly on the chitosan surface. Moreover, the antibacterial activity of the chitosan-AgIO₃ bionanocomposites was confirmed via the plate counting method and optical density, which could partially match with conventional agents. Overall, therefore, chitosan-AgIO₃ bionanocomposites are a promising new approach to combat microbial infections.

Link to article: Design, synthesis, and characterization of novel eco-friendly chitosan-AgIO3 bionanocomposite and study its antibacterial activity | Scientific Reports (nature.com)