Bacterial Nanocellulose Membranes Research Articles

Bacterial nanocellulose loaded with bromelain and nisin as a promising bioactive material for wound debridement

The bacterial nanocellulose (BnC) membranes were produced extracellularly by a novel aerobic acetic acid bacterium Komagataeibacter melomenusus. The BnC was modified in situ by adding carboxymethyl cellulose (CMC) into the culture media, obtaining a BnC-CMC product with denser fibril arrangement, improved rehydration ratio and elasticity in comparison to BnC. The proteolytic enzyme bromelain (Br) and antimicrobial peptide nisin (N) were immobilized to BnC matrix by ex situ covalent binding and/or adsorption. The optimal Br immobilization conditions towards the maximized specific proteolytic activity were investigated by response surface methodology as factor variables. At optimal conditions, i.e., 8.8 mg/mL CMC and 10 mg/mL Br, hyperactivation of the enzyme was achieved, leading to the specific proteolytic activity of 2.3 U/mg and immobilization efficiency of 39.1 %. The antimicrobial activity was observed against Gram-positive bacteria (S. epidermidis, S. aureus and E. faecalis) for membranes with immobilized N and was superior when in situ modified BnC membranes were used. N immobilized on the BnC or BnC-CMC membranes was cytocompatible and did not cause changes in normal human dermal fibroblast cell morphology. BnC membranes perform as an efficient carrier for Br or N immobilization, holding promise in wound debridement and providing antimicrobial action against Gram-positive bacteria, respectively.

Antibacterial Komagataeibacter hansenii nanocellulose membranes with avocado seed bioactive compounds

AbstractBiocompatible, mechanically stable, highly hydrophilic/swellable and safe antibacterial biomaterials are crucial for wound dressing and other applications in the health sector. Therefore, this study was conducted for the development of bacterial nanocellulose membranes, which were, for the first time, enriched with bacteriostatic and bactericidal effective avocado seed extracts prepared by different extraction techniques (ultrasonic, Soxhlet, high pressure with supercritical carbon dioxide). First, the production process of bacterial nanocellulose membranes from Komagataeibacter hansenii bacteria was optimized related to the fermentation media composition and culture conditions, resulting in bacterial nanocellulose membranes with up to 83% crystallinity and 54.5 g/L yield. The morphological structure of the membranes was varied further by using air- and freeze-drying processes. The Soxhlet and high pressure with supercritical carbon dioxide avocado seed extracts with the most charge negative surface (-33 mV) and smallest hydrodynamic size (0.1 µm) thus resulted in 100% reduction of both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus with up to log reduction of 2.56 and up to 100% bactericidal efficacy after 24 h of exposure, and at 14 mg/g of avocado seed extracts integrated in the bacterial nanocellulose membranes homogeneously. The high swelling (up to 600%) and water retention ability of avocado seed extracts enriched bacterial nanocellulose membranes, with a biocidal release up to 2.71 mg/mL, shows potential for antibacterial applications in the biomedicine, cosmetics, and pharmaceutical industries.

Study of the structure and characterization of membranes reinforced with CuO-NPs/Graphene Oxide using bacterial cellulose extracted from Sargassum sp. for water nanofiltration system

Bacterial cellulose membranes find extensive applications in industries involving water purification, wastewater treatment, and biomedical uses. Nevertheless, prevailing membranes suffer from drawbacks like water flow hindrances and fouling susceptibility. Hence, the pressing need for more efficient and robust BC membranes. This study aims to assess the impact of a hybrid treatment involving Copper Oxide nanoparticles (CuO-NPs) and Graphene Oxide (GO) on bacterial nanocellulose membranes. The research employed two treatments: (1) control (BNCA), and (2) Bacterial cellulose infused with 0.5 wt% CuO-NPs/GO. The nanocellulose production involved a high-pressure homogenizer, followed by acetate nanocellulose synthesis and nanocomposite membrane functionalization with CuO nanoparticles. SEM, FTIR, and XRD analyses characterized the membranes. Successfully formed seaweed-derived bacterial cellulose had a thickness of 1-3 cm. Characterization showed it belonged to Cellulose type I with a crystalline degree ranging from 82.3% to 83.1%. FTIR analysis of dry BNCA membranes indicated changes in transmittance at 1738, 1554, and 764 cm-1 due to CuO-NPs/GO addition, altering the O-H bond in bacterial cellulose. Based on the results of the above research, it is evident that the Membrane Reinforced with CuO-NPs/Graphene Oxide has been successfully developed and holds potential as a water nanofiltration system.

Green in situ immobilisation of gold nanoparticles on bacterial nanocellulose membranes using Tannic acid and its detection of Fe3.

Oxidative stress is one of the factors that promote melanogenesis. Trivalent iron ions play a key role in regulating the iron-catalysed oxidative stress response. A novel SERS flexible membrane sensor based on tannic acid with good sensitivity and uniformity was prepared by green in situ reduction of gold nanoparticles on bacterial cellulose membrane（BCM）with a simple and highly selective method to detect Fe3+. Under alkaline conditions, Fe3+ is adsorbed on the BCM-TA@Au NPs flexible membrane by tannic acid (TA) through chelation, thus enabling the detection of Fe3+. Furthermore, this simple detection system has a wide linear detection range and high sensitivity to effortlessly evaluate Fe3+ at concentrations up to 10-7 M. More importantly, the proposed SERS flexible substrate performed well in determining Fe3+ concentrations in B16 melanocytes, providing new insights into the factors affecting the melanin synthesis pathway and providing a potential biomarker for melanoma treatment.

Performance of bacterial nanocellulose packaging film functionalised in situ with zinc oxide: Migration onto chicken skin and antimicrobial activity

Zinc oxide nanoparticles (ZnO) are cost-effective antimicrobial agents with great potential for the active packaging industry. Bacterial NanoCellulose (BNC) features a porous fibre network, with high absorption capacity, flexible and with good mechanical properties, suitable as a carrier of active agents. In this work, BNCZnO films were developed and optimized regarding the particle size and ZnO concentration. The NaOH dropwise addition to BNC membranes immersed in Zn(CH3COO)2-PVOH enabled the production of ZnO nanoparticles with an z-average of 144 nm and a low polydispersity index. High ZnO incorporation (∼27%mZn/mBNCZnO) was obtained, with uniform distribution all over the BNC membranes. These composites were then characterized and evaluated for Zn migration using food simulants (10%, 20%, and 50% ethanol) with results lower than the limit. Migration into chicken skin, as a real food model, was low at 4 °C but exceeded the migration limit at 10 and 22 °C. Zn migration was also found to be temperature and pH dependent. When applied to chicken skin, BNCZnO was effective against E. coli, Salmonella (0.5–1.0 log reduction), and Campylobacter spp. (2.0 log reduction), indicating its potential for active packaging applications.

Super-Repellent and Flexible Lubricant-Infused Bacterial Nanocellulose Membranes with Superior Antithrombotic, Antibacterial, and Fatigue Resistance Properties.

Bacterial nanocellulose (BNC) is a naturally derived hydrogel that has recently paved its way in several biomedical applications. Despite its remarkable tissue-like properties, BNC does not express innate anticoagulant or antimicrobial properties; therefore, appropriate post-modification procedures are required to prevent nonspecific adhesion and enhance the hemocompatibility properties of BNC-based biointerface. Here, we report a new class of flexible, lubricant-infused BNC membranes with superior antithrombotic and antibacterial properties. Using chemical vapor deposition, porous BNC membranes were functionalized with fluorosilane molecules and further impregnated with a fluorocarbon-based lubricant. Compared with unmodified BNC membranes and commercially available poly(tetrafluoroethylene) (PTFE) felts, our developed lubricant-infused BNC samples significantly attenuated plasma and blood clot formation, and prevented bacterial migration, adhesion, and biofilm formation and exhibited superior fat and enzyme repellency properties. Moreover, when subjected to mechanical testing, the lubricant-infused BNC membranes demonstrated a significantly higher tensile strength and greater fatigue resistance when compared with unmodified BNC samples and PTFE felts. Overall, the superior mechanical strength and antithrombotic, antibacterial, and fat/enzyme resistant properties observed in the developed super-repellent BNC-based membranes render their application promising for various biofluid-contacting medical implants and tissue engineering constructs.

Comparative Study on the Efficiency of Mercury Removal From Wastewater Using Bacterial Cellulose Membranes and Their Oxidized Analogue.

A comparative study was conducted on the efficiency of mercury removal using bacterial nanocellulose (BNC) membranes obtained from the fermentation of the microorganism Komagataeibacter medellinensis, in contrast with its oxidized analog obtained by modifying the bacterial nanocellulose membranes via oxidation with 2,2,6,6-Tetramethylpiperidine-1-oxyl. Both types of membranes (modified and unmodified) were characterized to identify variations in the Physico-chemical parameters after modification. FTIR spectra confirmed the chemical modification of cellulose in all reaction conditions by the presence of a new characteristic band at ∼1730 cm−1, corresponding to the new carboxylic groups produced by the oxidative process, and the decline of the band at ∼1,650 cm−1, corresponding to the hydroxyl groups of the C6 carbon. While the XRD profiles indicated that the percentage of BNC crystallinity decreased and the SEM images showed that the nanoribbon network was interrupted as the amount of oxidizing agent increased. The kinetics of mercury removal from both types of membrane was evaluated by calculating the concentration of mercury at different times and establishing a mathematical model to describe the kinetics of this process. The modified membranes improved significantly the adsorption process of the metal ion and it was found that the modification that results in the greatest adsorption efficiency was BNC-m 7.5 with a value of 92.97%. The results obtained suggest that the modification of the bacterial nanocellulose membranes by oxidation transcendentally improves the mercury removal capacity, outlining the modified membranes as an excellent material for mercury removal in wastewater.

Development of a layered bacterial nanocellulose-PHBV composite for food packaging.

Most of the current materials used in food packaging are synthetic and non-degradable, raising environmental issues derived from the accumulation of plastics in landfills/waterways. The food industry increasingly needs eco-friendly sustainable materials that meet food-packaging requirements. Bacterial nanocellulose (BNC), a biopolymer obtained by fermentation, offers very good mechanical properties and the ability to carry and deliver active substances. However, its water-vapor permeability is too high for food-packaging applications. In this work, a layered biodegradable composite based on BNC and polyhydroxyalkanoate (PHBV) was produced, attempting to improve its overall barrier properties. Polyhydroxyalkanoate is a biopolymer with high degree of hydrophobicity and biodegradability, and is also obtained by fermentation. Wet BNC membranes produced by static culture were plasticized by impregnation of solutions of either glycerol (BNCgly ) or polyethylene glycol (MW 600) (BNCPEG ). The plasticized BNC was then coated with PHBV solution dissolved in formic acid, and oven dried at 148 °C. Overall, PHBV coating on plasticized BNC reduced water vapor permeability significantly (from 0.990 to 0.032 g.μm.m-2 .day-1 .Pa-1 ) under 50% relative humidity. It increased the hydrophobicity (contact angle from 10-40° to 80-90°) but decreased the stiffness (from 3.1GPa to 1.3 Gpa) of the composite. Overall, the mechanical and barrier properties of the layered composite obtained were considered suitable for food-packaging applications. The plasticizing (with glycerol or polyethylene glycol) of BNC significantly improved the mechanical performance and the PHBV coating reduced the water affinity (vapor and liquid state) on BNC. © 2022 Society of Chemical Industry.

One-pot microbial approach to synthesize carbon dots from baker's yeast-derived compounds for the preparation of antimicrobial membrane

Multifunctional carbon dots (CDs) were synthesized hydrothermally from secreted metabolites (so-called postbiotics) of baker's yeast. The CDs were verified and characterized by particle size analyzer, transmission electronic microscopy, UV–visible/fluorescence, Fourier-transform infrared, and X-ray photoelectron spectroscopic. Homogeneous N and P-doped CDs (∼4.1 nm) with abundant functional groups showed a dose-dependent antimicrobial activity on Gram-positive, Gram-negative, and fungal strains. A concentration-dependent antioxidant power based on reducing the power of iron in the presence of CDs was reported. CDs were found to be non-toxic at concentrations below 3.5 mg/mL in the human colon cancer cell line (HCT-116) and TM4 cells (mouse Sertoli cell line). Moreover, CDs were used for the fabrication of antimicrobial bacterial nanocellulose membranes. Biocellulose-CDs membrane depicted broad-spectrum antimicrobial activity on nine selected bacterial and fungal strains. Taken together, the synthesized CDs and biocellulose membrane could be considered as potential antimicrobial/antioxidant additive and antimicrobial packaging material, respectively.

Bioactive Bacterial Nanocellulose Membranes Enriched with Eucalyptus globulus Labill. Leaves Aqueous Extract for Anti-Aging Skin Care Applications.

Bacterial nanocellulose (BNC) membranes, with remarkable physical and mechanical properties, emerged as a versatile biopolymeric carrier of bioactive compounds for skin care applications. In this study, BNC membranes were loaded with glycerol (as plasticizer and humectant agent) and different doses (1–3 μg cm−2) of an aqueous extract obtained from the hydro-distillation of Eucalyptus globulus Labill. leaves (HDE), for application as sheet facial masks. All membranes are resistant and highly malleable at dry and wet states, with similar or even better mechanical properties than those of a commercial BNC mask. Moreover, the HDE was found to confer a dose-dependent antioxidant activity to pure BNC. Additionally, upon 3 months of storage at 22–25 °C and 52% relative humidity (RH) or at 40 °C and 75% RH, it was confirmed that the antioxidant activity and the macroscopic aspect of the membrane with 2 μg cm−2 of HDE were maintained. Membranes were also shown to be non-cytotoxic towards HaCaT and NIH/3T3 cells, and the membrane with 2 μg cm−2 of HDE caused a significant reduction in the senescence-associated β-galactosidase activity in NIH/3T3 cells. These findings suggest the suitability and potential of the obtained membranes as bioactive facial masks for anti-aging applications.

Evaluation of wet nanocellulose membranes produced by different bacterial strains for healing full-thickness skin defects

Bacterial nanocellulose (BNC) is an excellent candidate biomaterial for wound dressing applications, although its preparation should consider the differences in wound healing resulting from BNC biosynthesized by different bacterial strains. This study design aimed to characterize the BNC produced by three different bacterial strains and compare their effectiveness for wound healing applications. The results demonstrated that the upper surfaces of the BNC membranes were clearly denser and more compact than the lower surfaces, while all varieties were capable of serving as a physical barrier to the invasion of bacteria. The growth of fibroblasts demonstrated that the lower surfaces of BNC membranes exhibited biocompatibility superior to that of the upper surfaces. In vivo analysis indicated that, of all samples, wounds treated with the BNC membrane synthesized by DHU-WX-1 displayed the greatest wound repair efficacy. The results indicate that BNC biosynthesized by different strains displayed different wound healing effectiveness. Placing the lower surface of BNC membranes in contact with wounds, with the denser upper surface outward, satisfied the clinical requirements of a wound repair biomaterial.

Self-Supported Smart Bacterial Nanocellulose–Phosphotungstic Acid Nanocomposites for Photochromic Applications

Bacterial nanocellulose (BNC) is a natural biopolymer obtained by gram-negative bacteria by means of a green and inexhaustible biotechnological process using glucose as producing source. BCN hydrogels is formed by cellulose nanofibrils that maintain an open network structure, an ideal matrix to produce new class of organic-inorganic nanocomposites (OIN) for multifunctional applications. The polyoxometalates (POMs) are complex molecules with several metallic ions sharing oxide ions, forming a highly symmetrical metal oxide cluster. Phosphotungstic acid (PWA), H3PW12O40 photoreduction process activated under ultraviolet irradiation, promoting color change. In this work, photochromic organic-inorganic nanocomposites were prepared by soaking phosphotungstic acid (H3PW12O40) in wet BNC membranes mats at room temperature. Semi-transparent and free-standing BNC/PWA nanocomposite with paper-like aspect were obtained. BNC network was able to control, stabilize and disperse PWA particles in a narrow nanometric distribution, and FTIR spectra indicated that the primary Keggin structure was also preserved in the nanocomposites, independently on the PWA content. The nanoparticles present a narrow distribution of around 16 nm, independently on the PWA concentration. BNC/PWA nanocomposites showed reversible photochromic behavior characteristic of the equilibrium between different tungsten oxidation states. PWA reduction (W6+→ W5+) and organic matrix oxidation is proposed to occur through a radical process involving the interaction of one electron from the oxygen atom of the PWA and one hydrogen from BNC matrix. The photochromic effect vanishes almost completely after 5 h. This mechanism is real in the presence of oxygen, however, if the membranes are left in nitrogen or under vacuum the blue color remains longer than 45 days. Photo-electrochemical behavior was studied by spectroelectrochemistry measurements. It is worth noting that all processes were still reversible in the timescale of the experiment and color changes were observed in several cycles.

Evaluation of Bacterial Nanocellulose Membranes Loaded or Not with Nisin as a Complementary Treatment in Surgical Dehorning Wounds in Bovines.

Treatments of postsurgical dehorning in cattle usually includes topical application of healing agents in wounds. The Bacterial Nanocellulose (BNC) may come to a complementary treatment for these wounds. Two new complementary treatments with BNC and BNC loaded with nisin were evaluated for wound healing in surgical dehorning in bovine. Hence, two groups of experiments were run, and 12 animals were used in each group. All animals, in right and left horns, received antisepsis treatment. For the first group, the left horn was the control, and on the right one the BNC was applied. For the second group, BNC was applied on the left horn (control) and on the right ones BNC+nisin was applied. In both experiments, wounds were evaluated macroscopically by photographic images and microscopically by histology. For macroscopic evaluations, a significant difference was observed over time, but only in the comparison within the same groups. Microscopic analyzes did not showed significant differences in any type of comparison. In conclusion, there was a clinical improvement in the wound healing response with the application of BNC. However, there was no significant difference between BNC compared to the nisin loaded in BNC. For the first time it was applied a BNC in surgical dehorning wounds in bovines and evaluated the efficacy of treatment in a real animal handling situation.

Hemostatic Dressings Made of Oxidized Bacterial Nanocellulose Membranes

Surgicel® (regenerated oxidized cellulose) is a bio-absorbable hemostatic material widely applied to prevent surgery-derived adhesions. Some critical issues have been reported associated with this biomaterial, which we aimed to overcome by producing bacterial nanocellulose (BNC) membranes with hemostatic activity, through electrochemical oxidation using the tetramethylpiperidine-1-oxyl (TEMPO) radical. Samples were characterized by FTIR, NMR, SEM, XRD and their degree of polymerization. The oxidation degree was evaluated by titration of the carboxyl groups and the hemostatic behavior by whole-blood-clotting assays. In vitro and in vivo biodegradability of oxidized BNC membranes were evaluated and compared with that of Surgicel®. The oxidation degree increased from 4% to 7% and up to 15%, corresponding to an applied charge of 400, 700 and 1200 Coulombs, respectively. The oxidized BNC preserved the crystallinity and the 3D nano-fibrillar network, and demonstrated hemostatic activity, although not as effective as that of Surgicel®. In vivo assays demonstrated that the oxidized membranes did not induce an inflammatory response, revealing a good biocompatibility. However, non-degraded oxidized BNC was still detected at the implantation site after 56 days.

A novel antimicrobial-containing nanocellulose scaffold for regenerative endodontics.

ObjectivesThe aim of this study was to evaluate bacterial nanocellulose (BNC) membranes incorporated with antimicrobial agents regarding cytotoxicity in fibroblasts of the periodontal ligament (PDLF), antimicrobial activity, and inhibition of multispecies biofilm formation.Materials and MethodsThe tested BNC membranes were BNC + 1% clindamycin (BNC/CLI); BNC + 0.12% chlorhexidine (BNC/CHX); BNC + nitric oxide (BNC/NO); and conventional BNC (BNC; control). After PDLF culture, the BNC membranes were positioned in the wells and maintained for 24 hours. Cell viability was then evaluated using the MTS calorimetric test. Antimicrobial activity against Enterococcus faecalis, Actinomyces naeslundii, and Streptococcus sanguinis (S. sanguinis) was evaluated using the agar diffusion test. To assess the antibiofilm activity, BNC membranes were exposed for 24 hours to the mixed culture. After sonicating the BNC membranes to remove the remaining biofilm and plating the suspension on agar, the number of colony-forming units (CFU)/mL was determined. Data were analyzed by 1-way analysis of variance and the Tukey, Kruskal-Wallis, and Dunn tests (α = 5%).ResultsPDLF metabolic activity after contact with BNC/CHX, BNC/CLI, and BNC/NO was 35%, 61% and 97%, respectively, compared to BNC. BNC/NO showed biocompatibility similar to that of BNC (p = 0.78). BNC/CLI showed the largest inhibition halos, and was superior to the other BNC membranes against S. sanguinis (p < 0.05). The experimental BNC membranes inhibited biofilm formation, with about a 3-fold log CFU reduction compared to BNC (p < 0.05).ConclusionsBNC/NO showed excellent biocompatibility and inhibited multispecies biofilm formation, similarly to BNC/CLI and BNC/CHX.

Bacterial nanocellulose membranes as potential chronic wound dressing: influence of alternative culture media on nanofiber diameter - a brief review

Bacterial nanocellulose membranes as potential chronic wound dressing: influence of alternative culture media on nanofiber diameter - a brief review

Optimization and characterization of bacterial nanocellulose produced by Komagataeibacter rhaeticus K3

In this work, a novel Bacterial NanoCellulose (BNC) producing strain, from Kombucha tea, was isolated and characterized. Based on 16S rRNA analysis the strain was identified as Komagataeibacter rhaeticus. Under static culture, K. rhaeticus K3 produces membranes with a relaxed structure, as observed by Scanning Electron Microscopy (SEM). The addition of 2% (v/v) ethanol to the culture media enhanced by more than 3-fold of the BNC yield.Response surface methodology (RSM) was performed with K. rhaeticus K3, using a new low cost Eucalyptus Biomass Hydrolysate (EBH). The maximum experimental BNC yield was of 5.46 g/L, obtained with the following composition: 31.4 g/L of EBH; 2.89% (v/v) of ethanol and 10.8 g/L of Yeast extract/peptone.Texture Profile Analysis (TPA) of BNC membranes obtained using Hestrin-Schramm culture (HS) medium and optimized medium from EBH showed that membranes from EBH had higher resistance to compression, higher cohesiveness and resilience.

Topical Drug Delivery Systems Based on Bacterial Nanocellulose: Accelerated Stability Testing.

Bacterial nanocellulose (BNC) membranes have enormous potential as systems for topical drug delivery due to their intrinsic biocompatibility and three-dimensional nanoporous structure, which can house all kinds of active pharmaceutical ingredients (APIs). Thus, the present study investigated the long-term storage stability of BNC membranes loaded with both hydrophilic and lipophilic APIs, namely, caffeine, lidocaine, ibuprofen and diclofenac. The storage stability was evaluated under accelerated testing conditions at different temperatures and relative humidity (RH), i.e., 75% RH/40 °C, 60% RH/25 °C and 0% RH/40 °C. All systems were quite stable under these storage conditions with no significant structural and morphological changes or variations in the drug release profile. The only difference observed was in the moisture-uptake, which increased with RH due to the hydrophilic nature of BNC. Furthermore, the caffeine-loaded BNC membrane was selected for in vivo cutaneous compatibility studies, where patches were applied in the volar forearm of twenty volunteers for 24 h. The cutaneous responses were assessed by non-invasive measurements and the tests revealed good compatibility for caffeine-loaded BNC membranes. These results highlight the good storage stability of the API-loaded BNC membranes and their cutaneous compatibility, which confirms the real potential of these dermal delivery systems.

Bacterial nanocellulose membranes loaded with vitamin B-based ionic liquids for dermal care applications

The development of innovative bio-based skin care products has received an increased attention in the latter years. In the present work, the synthesis of original active principle ingredients based on ionic liquids (ILs) with cholinium cation and vitamins B anions, followed by their incorporation in bacterial nanocellulose (BC) membranes for topical applications, is reported. Three ILs, namely cholinium nicotinate [Ch][B3], cholinium pantothenate [Ch][B5] and cholinium pyridoxylate [Ch][B6], were synthesized through a metathesis reaction and their structure characterized in detail. Thermal analysis confirmed their denomination as ILs and their high thermal resistance. The solubility of these ILs was higher than their vitamin precursors, especially in the case of [Ch][B3] whose solubility increased 30.6-fold enhancing the bioavailability of this vitamin. The incorporation of ILs in BC led to translucent and homogeneous membranes stable up to 190 °C. ILs acted as plasticizers reducing BC brittleness that facilitated their application on irregular skin regions. Moreover, the re-hydration ability of BC-ILs membranes was improved 2.9 to 4.8-fold in comparison to BC, ensuring adequate hydration for ILs release, while the release of ILs in buffer solutions was more complete and faster than the release of vitamins. Finally, BC-ILs were proven not cytotoxic to skin epithelial cells and thus are suitable materials for skin care applications.

Enhanced Electrochemical Performance of Nanocellulose/PPy·CuCl2 Electrodes for All-Cellulose-Based Supercapacitors

Supercapacitive devices using a bacterial nanocellulose (BNC)-based separator and electrodes, providing mechanical support with high surface area while allowing the permeability of ions and avoiding short circuits, have been assembled and characterized. For the electrodes, BNC membranes were incorporated with polypyrrole (PPy) at different concentrations using copper chloride as oxidizing agent. As the separator, pure nanocellulose membranes were used. Scanning electron microscopy analysis revealed that increasing the pyrrole concentration from 0.04 mol/L to 0.08 mol/L and the molar ratio of oxidizing agent to monomer (CuCl2:Py) from 2:1 to 4:1 resulted in a uniform BNC coating. Symmetrical supercapacitor devices were assembled and subjected to cyclic voltammetry, charge–discharge measurements, and cycle stability testing. A maximum specific capacitance value of 1789 mF/cm2 was extracted from the voltammetry curves for the device constructed using the membrane with the highest Py concentration and oxidizing agent-to-monomer ratio. The best power density and energy density values obtained during discharge testing at 1 mA/cm2 were 5.47 mW/cm2 and 187 μWh/cm2, respectively. These promising results confirm the feasibility of using BNC as both the separator and electrodes when building supercapacitors.