Cellulose extraction from hemp fiber and carbonized nanocellulose production, characterization, antibiotic loading, and comparison of antibacterial properties

This study focused on the extraction of cellulose from hemp fiber and production of carbonized nanocelluloses (CCN) from cellulose, characterization, antibiotic loading and investigation of antibacterial properties of cellulose and CCN. Cellulose with a diameter of approximately 4.5 μm was successfully extracted from the untreated hemp fiber that had an average diameter of approximately 10 μm. After the acid hydrolysis, the dried hemp fiber powders were subjected to preoxidation and carbonization and then CCN with a diameter of 34.7 nm was produced. Ciprofloxacin (CIP) was selected as the model antibiotic for investigation of the antibacterial property of the cellulose and CCN. The optimum conditions for CIP loading onto cellulose and CCN were determined to be pH 7.00 for CIP concentrations of 5.0 mg L⁻¹ and the adsorbent dose was 1.0 g L⁻¹ with the loading efficiency of 85.05% and 90.80%, respectively. No chain break was observed with CCN up to 50 mg L⁻¹, but a single chain break was observed for concentrations ≥ 100 mg L⁻¹. The antibacterial activity studies showed that although pristine cellulose and CCN had considerable antibacterial property their modification with CIP (C + CIP and CCN + CIP) increased their activity. At 50 mg mL⁻¹ concentrations, the antibiofilm effectiveness for CCN and cellulose were found to be 52.38% and 4.28%, respectively. The antibiofilm activity of CCN + CIP was also found to be higher than that of cellulose + CIP against both P. aeruginosa and Staphylococcus aureus in the concentrations range studied and the antibiofilm activity was observed to be 94.74% and 86.62% for CCN + CIP and cellulose + CIP, respectively, at 50 mg mL⁻¹. All these results showed that CIP could successfully be loaded onto carbonized nanocelluloses extracted from hemp fibers and they showed considerable antibacterial properties.

Graphical abstract