Drug-loaded Fe₃O₄/lignin nanoparticles to treat bacterial infections

Lignin is a biopolymer employed for various biomedical applications. Nevertheless, the drug loading and release mechanism of Fe₃O₄ nanoparticles with surface functionalization by lignin has yet to be described. Hence, this study functionalizes Fe₃O₄ nanoparticles surface with lignin (Fe₃O₄/Lig) for ciprofloxacin delivery and examines its adsorption-release mechanisms. The presence of lignin and ciprofloxacin on Fe₃O₄ nanoparticles were verified using FT-IR that shows distinct peaks for each functional group of lignin and ciprofloxacin. The study has proved selective adsorption of ciprofloxacin ions via electrostatic interactions. The optimal adsorption efficiency in the examined region was 65 %, with a capacity of 9.55 mg/g. Drug release efficiency was evaluated in buffer at pH 7.4 and pH 1.2-6.8, yielding ∼66 % and ∼100 %, respectively. The release profile fits Peppas's model, which uses a diffusion and disintegration mechanism. Furthermore, the HET-CAM model study presented that the substance does not irritate the cell membranes of the egg, indicating that it is safe for mucosa and tissues. The IC₅₀ value for antibacterial activity against Gram-negative Salmonella enterica and Escherichia coli was 10.00 ± 0.76 μg/mL and 1.87 ± 0.06 μg/mL, respectively. In summary, the study effectively prepared Fe₃O₄/Lig-CIP nanoparticles, as well as remained antibacterial properties against both Gram (+) and Gram (-) microorganisms.