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A series of dialdehyde microcrystalline cellulose (DAMC) particles crosslinked with EPL (EPL-DAMCs) was successfully prepared by reacting DAMC with varying amounts of e-Poly-L-lysine (EPL). Based on the excellent antibacterial property of e-poly-L-lysine (EPL), the obtained EPL-DAMCs have a broad-spectrum antibacterial activity, and their physicochemical and antibacterial activities were also investigated. Fourier -transform infrared spectroscopy results demonstrated the formation of Schiff base between the aldehyde groups in DAMC and amino groups of EPL. The DAMC particles showed an aggregated structure of fibres. Among all DAMC crosslinked with EPL (EPL-DAMCs), the EPL-DAMC-4, with a lysine content of 0.46 ± 0.08 mg/g, showed the highest antimicrobial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Salmonella typhimurium, with the minimum inhibitory concentration (MIC) of 3.75, 15.0, 7.5 and 3.75 mg/mL, respectively. Compared with DAMC, the EPL-DAMC-4 exhibited the better inhibition effect and antimicrobial stability on the tested strains. These findings suggested that EPL-DAMCs might be used as antimicrobial biomaterial and have great potential in food packaging field.

The purpose of this study was to estimate the antibacterial properties of aqueous suspensions of dialdehyde microcrystalline cellulose (DAMC), and a model of the observed antibacterial kinetics was proposed and validated. The DAMC was prepared from microcrystalline cellulose by periodate oxidation. The bacterial inactivation kinetics of aqueous suspensions of DAMC was investigated by measuring the bactericidal effect after different contact times. The results indicated that with a DAMC aldehyde content of 6.34 mmol/g, the MICs for S. aureus, E. coli, B. subtilis and S. typhimurium were 15, 15, 15 and 30 mg/mL, respectively. This research thus establishes an antibacterial kinetics model of DAMC with 6.34 mmol/g of aldehyde content. At 37 °C and atmospheric pressure, the bacterial inactivation kinetic conformed to the equation: Log reduction of bacteria = - k [DAMC] t.

A cellulose-based Schiff base was synthetized via condensation reactions of dialdehyde cellulose (DAC) with l -lysine (Lys) and its antimicrobial activity was evaluated. The results of amino acid analysis, viscosity measurement, FTIR spectra, X-ray diffraction patterns, and solid-state cross-polarization (CP)/magic angle spinning (MAS) 13C-NMR indicated that the cellulose-based Schiff base (DAC-Lys) between DAC and Lys were formed. Thermogravimetric analysis (TGA) results showed that as compared with DAC, the DAC-Lys had diminished thermostability. When l -lysine content in DAC-Lys was 9.93 ± 0.35 g/100 g sample, the DAC-Lys exhibited high antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Salmonella typhimurium, and their MIC values were 7.5, 3.75, 7.5 and 3.75 mg/mL, respectively. The cellulose-based Schiff base, with good antibacterial activity, non-toxicity, and permissible biocompatibility, might be potential additives in papermaking for the introduction of antibacterial agents.