Enhanced Antimicrobial Activity and Structural Transitions of a Nanofibrillated Cellulose–Nisin Biocomposite Suspension

Abstract

Resistance to antibiotics has posed a high demand for novel strategies to fight bacterial infections. Antimicrobial peptides (AMPs) are a promising alternative to conventional antibiotics. However, their poor solubility in water and sensitivity to degradation has limited their application. Here, we report the design of a smart, pH-responsive antimicrobial nanobiocomposite material based on the AMP nisin and 2,2,6,6-tetramethyl-1-piperidinyloxyl-oxidized nanofibrillated cellulose (TONFC). Morphological transformations of the nanoscale structure of nisin functionalized-TONFC fibrils were discovered at pH values between 5.8 and 8.0 using small-angle X-ray scattering. Complementary ζ potential measurements indicate that electrostatic attractions between the negatively charged TONFC surface and the positively charged nisin molecules are responsible for the integration of nisin. Modification of the pH level or increasing the ionic strength reduces the nisin binding capacity of TONFC. Biological evaluation studies using a bioluminescence-based reporter strain of Bacillus subtilis and a clinically relevant strain of Staphylococcus aureus indicated a significantly higher antimicrobial activity of the TONFC-nisin biocomposite compared to the pure nisin against both strains under physiological pH and ionic strength conditions. The in-depth characterization of this new class of antimicrobial biocomposite material based on nanocellulose and nisin may guide the rational design of sustainable antimicrobial materials.

Antibacterial, Cytocompatible, Sustainably Sourced: Cellulose Membranes with Bifunctional Peptides for Advanced Wound Dressings

“…This so‐called substrate effect can additionally change the antibacterial efficiency (MIC) of AMPs in response to the underlying material. [ 35 ] Despite considerable differences in the macroscopic and microscopic morphology between BC films and CPU membranes, our data do not give evidence for such a material‐induced effect. This can be attributed to the architectural structure in the micrometer to sub‐micrometer range that is by magnitudes larger than the dimensions of nanofibrillated cellulose (NFC, 10–20 nm) where such an effect was observed.…”

“…Previous work in our group reported on enhanced antimicrobial activity of a nanocellulose‐nisin biocomposite, exposed to bacteria in suspension compared to nisin alone. [ 35 ] The study indicated no direct correlation of the activity of material‐tethered AMP nisin with the activity, or MIC, of nisin in suspension. It is suggested that the increased activity can arise from controlled orientation and thus increased availability of peptides on the nanocarriers.…”

“…This can be attributed to the architectural structure in the micrometer to sub‐micrometer range that is by magnitudes larger than the dimensions of nanofibrillated cellulose (NFC, 10–20 nm) where such an effect was observed. [ 35 ] To fully elucidate the effect of the underlying substrate on the antimicrobial activity, further studies are necessary, in particular focusing on cellulose substrates of different architectural dimensions in the nanometer range.…”

Trends in Advanced Functional Material Applications of Nanocellulose

“…Overall the nisin active PLA-CNC film contained all three essential packaging properties: antimicrobial activity, strength and biodegradability. Weishaupt et al [75] reported the self-assembly of nanofibrilled cellulose-nisin biocomposite. TEMPO-oxidized nano-fibrillated cellulose containing carboxylic groups provided a negative surface for nisin to be adsorbed onto the surface [75].…”

“…Weishaupt et al [75] reported the self-assembly of nanofibrilled cellulose-nisin biocomposite. TEMPO-oxidized nano-fibrillated cellulose containing carboxylic groups provided a negative surface for nisin to be adsorbed onto the surface [75]. The binding of nisin to nanocellulose was greatly affected by electrostatic interactions.…”