Wound dressings based on bacterial cellulose (BC) can form a soft and conformable protective layer that can stimulate wound healing while preventing bacteria from entering the wound. Bacteria already present in the wound can, however, thrive in the moist environment created by the BC dressing which can aggravate the healing process. Possibilities to render the BC antimicrobial without affecting the beneficial structural and mechanical properties of the material would hence be highly attractive. Here we present methods for functionalization of BC with ε-poly-L-Lysine (ε-PLL), a non-toxic biopolymer with broad-spectrum antimicrobial activity. Low molecular weight ε-PLL was cross-linked in pristine BC membranes and to carboxymethyl cellulose functionalized BC using carbodiimide chemistry. The functionalization of BC with ε-PLL inhibited growth of S. epidermidis on the membranes but did not affect the cytocompatibility to cultured human fibroblasts as compared to native BC. The functionalization had no significant effects on the nanofibrous structure and mechanical properties of the BC. The possibility to functionalize BC with ε-PLL is a promising, green and versatile approach to improve the performance of BC in wound care and other biomedical applications.

Nanocomposites of metal nanoparticles (NPs) and bacterial nanocellulose (BC) enable fabrication of soft and biocompatible materials for optical, catalytic, electronic, and biomedical applications. Current BC-NP nanocomposites are typically prepared by in situ synthesis of the NPs or electrostatic adsorption of surface functionalized NPs, which limits possibilities to control and tune NP size, shape, concentration, and surface chemistry and influences the properties and performance of the materials. Here a self-assembly strategy is described for fabrication of complex and well-defined BC-NP composites using colloidal gold and silver NPs of different sizes, shapes, and concentrations. The self-assembly process results in nanocomposites with distinct biophysical and optical properties. In addition to antibacterial materials and materials with excellent senor performance, materials with unique mechanoplasmonic properties are developed. The homogenous incorporation of plasmonic gold NPs in the BC enables extensive modulation of the optical properties by mechanical stimuli. Compression gives rise to near-field coupling between adsorbed NPs, resulting in tunable spectral variations and enhanced broadband absorption that amplify both nonlinear optical and thermoplasmonic effects and enables novel biosensing strategies.

The use of conventional antibiotics has substantial clinical efficacy, however these vital antimicrobial agents are becoming less effective due to the dramatic increase in antibiotic-resistant bacteria. Novel approaches to combat bacterial infections are urgently needed and bacteriocins represent a promising alternative. In this study, the activities of the two-peptide bacteriocin PLNC8 αβ were investigated against different Staphylococcus spp. The peptide sequences of PLNC8 α and β were modified, either through truncation or replacement of all L-amino acids with D-amino acids. Both Land D-PLNC8 αβ caused rapid disruption of lipid membrane integrity and were effective against both susceptible and antibiotic resistant strains. the D-enantiomer was stable against proteolytic degradation by trypsin compared to the L-enantiomer. Of the truncated peptides, β1-22, β7-34 and β1-20 retained an inhibitory activity. The peptides diffused rapidly (2 min) through the bacterial cell wall and permeabilized the cell membrane, causing swelling with a disorganized peptidoglycan layer. Interestingly, sub-MIC concentrations of PLNC8 αβ substantially enhanced the effects of different antibiotics in an additive or synergistic manner. This study shows that PLNC8 αβ is active against Staphylococcus spp. and may be developed as adjuvant in combination therapy to potentiate the effects of antibiotics and reduce their overall use. Although antibiotics are the most effective treatment against bacteria of the genus Staphylococcus (including the species S. aureus and S. epidermidis), these opportunistic pathogens are one of the leading causes of severe bacterial infections in humans connected to chronic wounds and medical devices, e.g. catheters and prosthetic implants 1. These persistent infections are generally difficult to treat, which increases the risk for bacterial dissemination and development of systemic complications 2,3. Furthermore, considering the gradual increase in antimicrobial resistance, treatment may be even more difficult to achieve as the available options become limited 4. Consequently, there is an urgent need to find new approaches in human medicine against bacterial infections, and bacteriocins represent a promising avenue that requires more consideration 5,6. Bacteriocins are antimicrobial peptides that are produced by most microorganisms that contribute their defence mechanisms. These peptides are divided into class I-V based on their structural characteristics. Class I includes small peptides (<5 kDa) with unusual amino acids, such as lanthionine and β-methyllanthionine that are post-translationally introduced and class II peptides are synthesized in precursor forms and processed (<10 kDa), and includes bacteriocins composed of two peptides (class IIb), such as PLNC8 αβ. Class III bacteriocins are large (>10 kDa) and sensitive to heat, class IV are small (<10 kDa) and circular peptides. Class V are small (<5 kDa), circular or linear peptides that are characterized by containing cross-linkages between cysteine residu...

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OBJECTIVE:Wound dressings that use biosynthetic cellulose may be a good alternative to dressings currently used to treat chronic and acute ulcers because their nanostructure is similar to collagen. The objective of this study was to evaluate a wound dressing created with a new material that is composed of a fibrillary network of biosynthetic cellulose.METHODS:A case series of 8 patients in primary healthcare centers in Östergötland county council, Sweden, with chronic and acute lower limb wounds were treated with a wound dressing based on eiratex (S2Medical AB, Linköping, Sweden). The dressing was applied to traumatic (n = 5) and venous ulcers (n = 3). All ulcers were considered healed at the end of the treatment.MAIN OUTCOME MEASURE:The wounds were examined at regular intervals by a physician to determine healing time, number of dressing changes, and number of visits.MAIN RESULTS:Mean healing time was 43 ± 6 days after the first application of the dressing. The mean number of visits was 5.7 ± 0.6, and the mean number of dressings used per patient was 1.7 ± 0.2.CONCLUSIONS:These results demonstrate the efficacy of a wound dressing made of eiratex to heal chronic and acute ulcers. The data show that the number of dressings used and dressing changes needed to heal the ulcers are lower than what have been reported in the literature for other dressing materials.