Evaluation of chitosan-coated and kanamycin-loaded zinc ferrite nanoparticles against resistant and non-resistant bacteria

Abstract

Antimicrobial resistance (AMR) is a serious problem on a global scale, especially when it involves gram-negative bacterial pathogens which often have a limited number of options to be treated using traditional antibiotics. Although most of the nanoparticle based strategies are towards improving already existing drugs, the present study tested the newly synthesized kanamycin loaded chitosan coated zinc ferrite (KCHZnF) as a new, single, integrated nanomedicine candidate. The synthesis of Zinc Ferrite (ZnFe2O4) nanoparticles was done by green synthesis using Syzygium aromaticum (clove) extract, and then the nanoparticles were coated with chitosan by electrostatic cross-linking with sodium tripolyphosphate (STPP) and finally loaded with a comparatively low dose (30 μg/ml) of kanamycin. The KCHZnF showed a higher antimicrobial activity than chitosan-coated zinc ferrite (CHZnF) and bare zinc ferrite (ZnF) in all concentrations in agar well diffusion assays with maximum inhibition zones of 32 mm for K. pneumoniae, 22 mm for P. aeruginosa and 35 mm for E. coli at 50 mg/mL. The inhibition zone of bare ZnF was not observed on the agar because of diffusion limitation. Time-kill viability assays over 5 hours of exposure also confirmed significant and time dependent reduction in bacterial survival by both CHZnF and KCHZnF, while Minimum inhibitory concentration (MIC) determination by resazurin microdilution assay confirmed the same. Later PCR-based analysis of the treatment supernatants revealed the presence of extracellular target DNA, which is indicative of bacterial membrane disruption. In conclusion, the results presented herein demonstrate proof-of-concept that KCHZnF can be an efficient, low-dose nanomedicine platform with potent antibacterial activity regardless of pre-existing aminoglycoside resistance profiles.