Bacterial Cellulose Nanofibrils Research Articles

Recent advances on nanocellulose-graphene oxide composites: a review

AbstractNanocellulose (NC)/graphene oxide (GO) composites are attractive materials with a range of unique features obtained from the integration of NC and GO. These materials have high potential use in various sectors such as biomedicine, wastewater remediation, sensor/biosensor technology, and energy storage/conversion. The simple functionalization and modification of NC or GO afford an opportunity for tailoring these materials for anticipated applications. In wastewater treatment applications, they can be employed as reliable adsorbents for the removal of different pollutants, such as metals, dyes, oils, and pesticides as well as sensors for the detection and monitoring of these pollutants. Besides that, NC/GO composites can be applied as catalysts for catalytic degradation for a wide variety of pollutants. These materials have been also reported to be applicable in biomedical applications such as drug delivery, antibacterial and biosensing. Energy storage applications such as supercapacitors NC/GO-based materials were also utilized. This review summarizes NC/GO hybrid fabrication, characterization, and their application in different fields, i.e. sensing, energy storage, and wastewater remediation. It also covered a broad overview of the status of integrating GO with nanocellulose materials, i.e. bacterial cellulose, cellulose nanofibrils, and cellulose nanocrystals. We concluded with the challenges and outlook for NC/GO-based composites.

Poly(butylene succinate) reinforced by small amount of grafted nanofibrillated bacterial cellulose: Toughness variability based on nanocomposites preparation method

Polybutylene succinate (PBS) is a promising biodegradable polymer; however, its low mechanical performance limits its application. To address this issue, long fiber length nanofibrillated bacterial cellulose (HP-NFBC), produced by a bottom-up process using cellulose-producing bacterium and hydroxypropyl cellulose (HPC) as a dispersing agent was used as reinforcement agent. Hydrophobic moieties were grafted on HP-NFBC surface to increase surface compatibility. Nanocomposites prepared by both solvent casting and melt-kneading were evaluated. By solvent casting, the addition of 0.25 wt% of grafted HP-NFBC increased the toughness by 212%. Melt-kneading revealed an increase in flexural strength and young’s modulus. More evident improvement was observed when the nanocomposites were annealed, and the ultimate strength increased by 113 % at 2 wt% of grafted HP-NFBC incorporation. Great increased in toughness were achieved only by small incorporation of grafted HP-NFBC. Additionally, compost biodegradation tests were conducted to confirm that the nanocomposites had biodegradability similar to that of PBS.

Bacterial cellulose nanofibrils for the physical and oxidative stability of fish oil-loaded Pickering emulsions

Fish oil, a crucial unsaturated ω-3 unsaturated fatty acid supplement, is susceptible to oxidation. To improve the stability of fish oil, this study produced a fish oil Pickering emulsion via ultrahigh-pressure homogenization pressure (UHPH) using bacterial cellulose nanofibrils (BCNFs) as the water phase. The BCNFs exhibited a high aspect ratio fibril structure with an average diameter size of 12.64 nm. The results of particle size, zeta potential, emulsion properties, and oxidative stability showed that the emulsions with a 4:6 oil-water ratio and 0.15 % BCNFs exhibited excellent oxidative stability and good physical stability. The CLSM and rheological results suggested the BCNFs acted as a stabilizer and thickener, stabilizing the oil-water medium and enhancing the oxidation stability of fish oil Pickering emulsions. The Low-field nuclear magnetic analysis results indicated the emulsion had good physical stability, and water dispersed very well in the emulsion system. Moreover, the emulsions exhibited good stability at pH 6–12 and temperature 4–75 °C. This study provided a promising method for producing fish oil Pickering emulsions and improving the stability of fish oil.

Stabilization of Pickering emulsions with bacterial cellulose nanofibrils (BCNFs) fabricated by electron beam irradiation

Bacterial cellulose (BC) had been considered as a promising Pickering stabilizer for its non-toxicity, high purity, and biocompatibility. The electron beam irradiation (EBI) technology had gained significant attention in the field of cellulose degradation due to its operational convenience and mild reaction conditions. Pickering emulsions using BC degraded by EBI as Pickering stabilizers were successfully prepared. Irradiated bacterial cellulose nanofibers (IBCNFs) exhibited a high aspect ratio(30–80 μm in length and 21–109 nm in width) and high absolute zeta potential (-50 mV). The optimal emulsification performance of IBCNFs was observed at an irradiation dosage of 100 kGy (IBC-100). The emulsions based on IBC-100 achieved an EI value of 96.15 ± 0.19%, while those based on IBC-500 obtained an EI value of 59.93 ± 1.47%. Stable Pickering emulsions were prepared when the concentration of IBC-100 stabilizer exceeded 0.3 wt% with a fixed oil phase of 30%, or when the rapeseed oil phase was below 50% while maintaining a fixed suspension of 0.5 wt% IBCNFs. Confocal laser scanning microscopy (CLSM) demonstrated that IBCNFs facilitated the formation of a dense interfacial layer at the oil-water interface and formed a three-dimensional network within the water phase. Which effectively hindered the aggregation and flocculation between individual oil droplets. Furthermore, rheological findings demonstrated that emulsions possessed primarily exhibited properties of elasticity, and their gel strength could be enhanced by adjusting the irradiation dosages of IBCNFs. Moreover, environmental stability experiments indicated that IBCNFs-based emulsions exhibited exceedingly high temperature (20–80 °C) and pH tolerance (4–12). Flocculation occurred under high acid (pH = 2) conditions and at high ionic levels (≥ 40 mM NaCl), without causing disruption to the emulsion droplet structure. This study provided an innovative approach to preparing cellulose nanofibers with high aspect ratio, which could be utilized as emulsion stabilizers. The study also demonstrated that Pickering emulsions based on IBCNFs exhibit excellent stability and rheological properties. IBCNFs have promising potential to serve as a natural Pickering emulsifier for stabilizing oil-in-water emulsions in various food applications, cosmetic and pharmaceutical formulations.

Modified bacterial nanofibril for application in superhydrophobic coating of food packaging

Superhydrophobic coatings applied to food packaging can significantly reduce unnecessary food waste. Inspired by nature, we proposed a simple method to prepare coatings with ecologically correct materials, such as beeswax and bacterial cellulose nanofibrils functionalized with nanoparticles of food silicon dioxide (BW/BCn- SiO2). The morphology of bacterial cellulose nanofibrils shows a strong reaction with SiO2 aggregated on the surface of the cellulosic material. The FTIR results confirm the efficiency of the functionalization. In addition, the functionalized material presents less thermal degradation. BW/BCn- SiO2, with a contact angle of 153° and a slip angle of 3°, features Cassie-Baxter-compatible micro/nanoscale roughness, self-cleaning properties, low-temperature storage stability, excellent adhesion and mechanical durability even after several treatments, considered nontoxic and with remarkable performance in repelling liquid foods with high viscosity, such as honey, yogurt and chocolate sauce. This work highlights the importance of innovations in food packaging that impact food waste, through superhydrophobic, ecological and safe coatings.

Tailoring the Heterogeneous Structure of Macro-Fibers Assembled by Bacterial Cellulose Nanofibrils for Tissue Engineering Scaffolds.

Bacterial cellulose/oxidized bacterial cellulose nanofibrils (BC/oxBCNFs) macro-fibers are developed as a novel scaffold for vascular tissue engineering. Utilizing a low-speed rotary coagulation spinning technique and precise solvent control, macro-fibers with a unique heterogeneous structure with dense surface and porous core are created. Enhanced by a polydopamine (PDA) coating, these macro-fibers offer robust mechanical integrity, high biocompatibility, and excellent cell adhesion. When cultured with endothelial cells (ECs) and smooth muscle cells (SMCs), the macro-fibers support healthy cell proliferation and exhibit a unique spiral SMC alignment, demonstrating their vascular suitability. This innovative strategy opens new avenues for advances in tissue engineering.

BACTERIAL CELLULOSE NANOFIBRILS FROM A BY-PRODUCT OF THE GROWING KOMBUCHA BUSINESS: OBTENTION AND USE IN THE DEVELOPMENT OF POLY(LACTIC ACID) COMPOSITES

Bacterial cellulose nanofibrils were obtained from the floating pellicle developed at the air-liquid interface during Kombucha tea production. Kombucha-derived bacterial nanocellulose (KBNC) was purified by different treatments and characterized in terms of morphology, chemical structure, thermal decomposition pattern and crystallinity. 
 Purified KBNC was then employed in the production of poly(lactic acid) (PLA)-based composites obtained by melt compounding and compression molding. The morphology and the mechanical properties of the composites with increasing contents of KBNC (i.e. 1, 3, 5, 7 wt.%) were analyzed. Results showed that KBNC was suitable for the development of PLA composites with improved stiffness.

Force-Induced Alignment of Nanofibrillated Bacterial Cellulose for the Enhancement of Cellulose Composite Macrofibers.

Bacterial cellulose, as an important renewable bioresource, exhibits excellent mechanical properties along with intrinsic biodegradability. It is expected to replace non-degradable plastics and reduce severe environmental pollution. In this study, using dry jet-wet spinning and stretching methods, we fabricate cellulose composite macrofibers using nanofibrillated bacterial cellulose (BCNFs) which were obtained by agitated fermentation. Ionic liquid (IL) was used as a solvent to perform wet spinning. In this process, force-induced alignment of BCNFs was applied to enhance the mechanical properties of the macrofibers. The results of scanning electron microscopy revealed the well-aligned structure of BCNF along the fiber axis. The fiber prepared with an extrusion rate of 30 m min-1 and a stretching ratio of 46% exhibited a strength of 174 MPa and a Young's modulus of 13.7 GPa. In addition, we investigated the co-spinning of carboxymethyl cellulose-containing BCNF with chitosan using IL as a "container", which indicated the compatibility of BCNFs with other polysaccharides. Recycling of the ionic liquid was also verified to validate the sustainability of our strategy. This study provides a scalable method to fabricate bacterial cellulose composite fibers, which can be applied in the textile or biomaterial industries with further functionalization.

Nanoemulsion-integrated gelatin/bacterial cellulose nanofibril-based multifunctional film: Fabrication, characterization, and application

The current requirements of food safety regulations and the environmental impact stemming from plastic packaging can only be addressed by developing suitable bio-nanocomposite films. Therefore, this study is dedicated to the fabrication of multifunctional film composed of gelatin, bacterial cellulose nanofibrils (BCNF), and black pepper essential oil nanoemulsion (BPEONE) and application for duck meat preservation. BCNF was prepared through ultrasonication of cellulose derived from Komagataeibacter xylinus. BPEONE observed spherical morphology with a diameter ranging from 83.7 to 118 nm. A film matrix containing a higher gelatin proportion than BCNF was more effective in trapping BPEONE. However, increasing the BPEONE fraction showed more surface abrasion and voids in the film morphology. A flexible film with good interaction, crystallinity, and greater thermal stability (421 °C) was developed. Nevertheless, film hydrophobicity (118.89°) declined, resulting in a notable effect on water solubility, swelling, and water vapor permeability. Moreover, the film had improved antibacterial and antioxidant activities, coupled with controlled release characteristics. Consequently, the developed film effectively retarded the lipid oxidation, inhibited microbial growth, and extended the shelf life of duck meat at refrigeration (4 °C) by 3 days, and made the film a promising alternative in the realm of bio-active packaging technology.

Cinnamon essential oil Pickering emulsions: Stabilization by bacterial cellulose nanofibrils and applications for active packaging films

Pickering emulsions are emulsions stabilized by solid particles with a wide range of potential applications as they typically provide more stable systems than surface-stabilized emulsions. Among the various solid stabilizers, bacterial cellulose (BC) may open up new opportunities for future Pickering emulsions due to its unique nano-size, amphiphilicity and other excellent properties. In this study, BC, TEMPO-oxidized BC (TOBC) and dialdehyde cellulose (DAC) were used as emulsifiers to stabilize cinnamon essential oil (CEO) Pickering emulsions. The microstructure, oil droplet size distribution, storage and loss moduli of the Pickering emulsions were affected by the type of emulsifier used. Compared to BC and DAC nanofibers, TOBC nanofibers exhibited better emulsifying capacity. TOBC (1%)-stabilized Pickering emulsion showed smaller droplet size, narrower size distributions, better stability and sustained release ability. Moreover, the Pickering emulsions showed high antibacterial activities against Gram-positive bacteria S. aureus and Gram-negative bacteria E. coli. Active gelatin composite films containing TOBC (1%)-stabilized CEO Pickering emulsions were successfully fabricated and showed good antibacterial and antioxidant properties, which make them suitable for food packaging application.

Silver phosphate–bacterial cellulose nanocomposites as visible light photocatalyst for wastewater purification

Silver phosphate (Ag3PO4) nanoparticles were deposited on bacterial cellulose (BC) nanofibrils as an eco-friendly, efficient, and reusable visible light active photocatalyst. BC–Ag3PO4 nanocomposites (BCAgP) with different BC/Ag3PO4 weight ratios were prepared by solution-precipitation method. The nanocomposites were characterized by UV-Visible diffuse reflection spectroscopy, XRD, FTIR, BET, and FESEM. Highly crystalline Ag3PO4 nanoparticles were well entrapped inside nano fibrillated BC matrix and eventually deposited along the fibers. Photocatalytic activity of the BCAgP nanocomposites were investigated by dye degradation experiments under solar light. The composite with BC: Ag3PO4 weight ratio of 1:4 (BCAgP14) showed the highest photocatalytic efficiency compared to other weight ratios and pure Ag3PO4. The sample also shows good photocatalytic activity even after 4 runs indicating its photostability. Higher photocatalytic efficiency of BCAgP14 nanocomposite was explained due to optimum Ag3PO4 loading and higher visible light absorption capacity. Bacterial cellulose is supposed to improve the photocatalytic activity of silver phosphate by promoting the adsorption of dyes and extending the charge recombination time under visible light of Ag3PO4 photocatalyst.

Soy protein isolate/kappa-carrageenan/cellulose nanofibrils composite film incorporated with zenian essential oil-loaded MOFs for food packaging

Edible films applied in food packaging must possess excellent inhibitory and mechanical properties. Protein-based films exhibit a high capacity for film formation and offer good gas barrier properties. However, they have weak mechanical and water barrier characteristics. The objective of this research was to develop active composite films based on reinforced soy protein isolate (SPI)/Kappa-carrageenan (K) with varying concentrations of bacterial cellulose nanofibrils (BCN). Increasing the BCN concentration improved the morphological, structural, mechanical, water vapor barrier, and moisture content properties. In comparison to the pure SPI film (S), the film with a high BCN concentration demonstrated a significant decrease in WS (22.98 ± 0.78 %), MC (21.72 ± 0.68 %), WVP (1.22 ± 0.14 g mm-1 S-1 Pa-1 10-10), and EAB (57.77 ± 5.25 %) properties. It should be emphasized that there was no significant alteration in the physicomechanical properties of the optimal film (SKB0.75) containing Zenian-loaded metal-organic frameworks (ZM). However, it substantially enhanced the thermal stability of this film, which can be attributed to the strong interfacial interactions between polymer chains and ZM. Furthermore, the ZM films inhibited the growth of pathogenic bacteria and increased the DPPH antioxidant activity. Thus, SKB0.75-ZM2 films can be utilized as practical components in food packaging.

Biocompatible, breathable and degradable microbial cellulose based triboelectric nanogenerator for wearable transient electronics

Advances in the processing of natural biomaterials have brought to the fore new approaches for the development of biofriendly and sustainable triboelectric nanogenerators (TENGs). In particular, bacterial cellulose (BC)-based TENGs have attracted considerable attention even though they still lack the key combination for transient wearable electronics. Herein, we report on a novel and facile method for in situ chemical modification of BC for the fabrication of degradable, breathable and biocompatible triboelectric nanogenerators (TENG). To achieve that, nanocoatings of polydopamine, polypyrrole or SiO2 have been used to decorate BC nanofibrils and thus tune the surface potential of the BC layer. Such a modification enables the repositioning of BC in the triboelectric series, allowing for the fabrication of various BC-based TENG devices. Polydopamine based BC TENG is found to exhibit superior performance (when coupled with a PVDF as negative triboelectric) with a maximum output voltage of ∼1010 V and a power density of ∼8.7 W/m2, a 7-fold enhancement in the power density as compared to pristine BC (VOC = 530 V and Pout = 1.1 W/m2). It is worthmentioning that all the nanocoated-BC films are found to be breathable, bio-/hemo-compatible and degradable, fulfilling the main criteria for transient electronics. As a proof of concept, we also demonstrate an on-body biomechanical energy harvester based on a single electrode All-BC TENG with the capability to generate an output voltage of 40 V upon physical motion. This TENG technology provides a unique combination of properties and has the potential to be implemented in wearables electronics and in vivo applications.

Fabrication of a double-network high internal phase emulsion gel stabilized by bacterial cellulose nanofibrils: Enhancement of heat stability and 3D printing

The semi-fluid properties required for 3D printing of high internal phase emulsion (HIPE) gels are incompatible with high mechanical strength, thereby limiting the application of HIPE gels in simulated meat products. In this study, pea protein (PeaP)-stabilized HIPEs reinforced with bacterial cellulose nanofibrils (BCNFs) were constructed and deformed into PeaP/sodium alginate (SA) double-network HIPE gels by further cross-linking of transglutaminase (TGase) and Ca2+. Increasing the BCNF concentration decreased the interfacial tension of water-in-oil HIPE emulsions from 11.91 mN/m to 9.49 mN/m, and reduced the average diameter of the droplets from 27 ± 3.1 μm to 11.3 ± 0.6 μm. The HIPEs also showed a thicker interfacial layer and improved viscoelastic properties at higher BCNF concentrations. The HIPEs were transformed from a semi-solid material to a rigid solid HIPE gel after the formation of a double-network structure. The fracture stress of the double-network HIPE gel containing 0.16% BCNFs was 0.015 MPa, which was greater than that of 0.001 MP and 0.007 MPa for the single-network SA and PeaP HIPE gels. The double-network HPIE gels fabricated with 0.08%–0.16% BCNF concentrations had high-temperature stability. The synergistic effect of the PeaP covalent network and the SA-Ca2+ ionic network produced a HIPE gel with good extrusion printability and strong self-supporting properties. This work could provide new insights into the design of high-strength HIPE gels with 3D printability that will facilitate the use of emulsion gels in plant-based meat products.

Hydrogen-bonding topological remodeling modulated ultra-fine bacterial cellulose nanofibril-reinforced hydrogels for sustainable bioelectronics

Bacterial cellulose (BC) with its inherent nanofibrils framework is an attractive building block for the fabrication of sustainable bioelectronics, but there still lacks an effective and green strategy to regulate the hydrogen-bonding topological structure of BC to improve its optical transparency and mechanical stretchability. Herein, we report an ultra-fine nanofibril-reinforced composite hydrogel by utilizing gelatin and glycerol as hydrogen-bonding donor/acceptor to mediate the rearrangement of the hydrogen-bonding topological structure of BC. Attributing to the hydrogen-bonding structural transition, the ultra-fine nanofibrils were extracted from the original BC nanofibrils, which reduced the light scattering and endowed the hydrogel with high transparency. Meanwhile, the extracted nanofibrils were connected with gelatin and glycerol to establish an effective energy dissipation network, leading to an increase in stretchability and toughness of hydrogels. The hydrogel also displayed tissue-adhesiveness and long-lasting water-retaining capacity, which acted as bio-electronic skin to stably acquire the electrophysiological signals and external stimuli even after the hydrogel was exposing to air condition for 30 days. Moreover, the transparent hydrogel could also serve as a smart skin dressing for optical identification of bacterial infection and on-demand antibacterial therapy after combined with phenol red and indocyanine green. This work offers a strategy to regulate the hierarchical structure of natural materials for designing skin-like bioelectronics toward green, low cost, and sustainability.

Hydrophobically modified silica nanolaces-armored water-in-oil pickering emulsions with enhanced interfacial attachment energy

HypothesisAnisotropic particles with a high aspect ratio led to favorable interfacial adhesion, thus enabling Pickering emulsion stabilization. Herein, we hypothesized that pearl necklace-shaped colloid particles would play a key role in stabilizing water-in-silicone oil (W/S) emulsions by taking advantage of their enhanced interfacial attachment energy. ExperimentsWe fabricated hydrophobically modified silica nanolaces (SiNLs) by depositing silica onto bacterial cellulose nanofibril templates and subsequently grafting alkyl chains with tuned amounts and chain lengths onto the nanograins comprising the SiNLs. FindingsThe SiNLs, of which nanograin has the same dimension and surface chemistry as the silica nanospheres (SiNSs), showed more favorable wettability than SiNSs at the W/S interface, which was supported by the approximately 50 times higher attachment energy theoretically calculated using the hit-and-miss Monte Carlo method. The SiNLs with longer alkyl chains from C6 to C18 more effectively assembled at the W/S interface to produce a fibrillary interfacial membrane with a 10 times higher interfacial modulus, preventing water droplets from coalescing and improving the sedimentation stability and bulk viscoelasticity. These results demonstrate that the SiNLs acted as a promising colloidal surfactant for W/S Pickering emulsion stabilization, thereby allowing the exploration of diverse pharmaceutical and cosmetic formulations.

Bacterial Cellulose Nanofibers Modified with Quaternary Ammonium Salts for Antimicrobial Applications

Nanofibrillated bacterial cellulose (NFBC) is a recyclable, biodegradable, and nontoxic biopolymer whose fibers are much longer than other cellulose nanofibers prepared from wood pulp. NFBC is a promising material for use as an additive in food and pharmaceutical industries and as a nanofiller in fiber-reinforced nanocomposite resins; however, it is easily microbially degraded and, consequently, cannot be used in long-term applications. In this study, NFBC was endowed with antimicrobial properties through modification by an aqueous alkaline solution of 2,3-epoxypropyltrimethylammonium chloride (EPTMAC). The structure of the modified NFBC was analyzed in detail using solid-state NMR and infrared spectroscopy, as well as X-ray diffractometry, which revealed that only the surface layer of each fiber had been conjugated with quaternary ammonium EPTMAC groups, with the amount of EPTMAC added during preparation determining the degree of molar substitution (MS) of the cationic groups. In addition, increasing the MS of the modified NFBC resulted in a positive surface charge that led to an increase in the transparency of the nanofiber dispersion owing to electrostatic repulsion between nanofibers. Despite these differences, the fiber morphologies and crystal structures of the modified fibers were almost identical to those of pristine NFBC, suggesting that EPTMAC selectively reacts with the surface hydroxyl groups of NFBC. In addition, bacterial cell culture experiments revealed that the modified nanofibers are antimicrobial against Klebsiella pneumoniae, a Gram-negative bacterium, most likely because the surface of the modified NFBC is positively charged. Therefore, the quaternary-ammonium-salt-modified NFBC is a functional nanofiber endowed with both nanofiber features and antimicrobial properties and can possibly be used in fiber-reinforced nanofillers and as a flocculant for water-based paints and polar resins.

Functional bacterial cellulose nanofibrils with silver nanoparticles and its antibacterial application

Bacterial cellulose (BC) with good biocompatibility and superior mechanical properties has broad applications. BC functionalized with silver nanoparticles (AgNPs) has been assessed as an antimicrobial membrane for wound-healing treatment. During the AgNPs synthesis, avoiding the use of toxic chemicals is very necessary for the development of environmentally friendly procedures. Herein, a Komagataeibacter xylinus-based direct biosynthetic method to fabricate D-Saccharic acid potassium salt (SA)-grafted BC (SABC) through in situ bacterial metabolism was firstly explored. Subsequently, the SABC pellicles were immersed in AgNO3 solution for ion-exchanged process, and the silver nanoparticles (AgNPs) with diameter of ∼25.2 nm were in situ synthesized on SABC nanofiber surfaces by thermal reduction instead of using a reducing agent. The morphology and microstructure of SABC/AgNPs pellicles were analyzed by field-emission scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectra. Moreover, antibacterial activity measurement performed against the Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) by disk diffusion and plate count methods, showed high-efficiency bacteria-killing performance of SABC/AgNPs pellicles. This work proposed a new method by using microbial metabolism to prepare BC pellicles with functional groups, and antimicrobial films containing AgNPs was prepared by thermal reduction, exhibiting valuable prospects in wound healing treatment.

Bacterial Cellulose–Polyvinyl Alcohol Based Complex Composites for Controlled Drug Release

Drug-loaded mono- and multilayer composite membranes were prepared. The composites, based on nano-fibrillated bacterial cellulose, nano-powdered bacterial cellulose, and polyvinyl alcohol, all biocompatible and biodegradable, were characterized in terms of basic factors related to drug diffusivity and mass transfer: swelling ability, water solubility, and water vapor permeability. Tetracycline hydrochloride was used in this case as drug model. Drug release was evaluated in an aqueous environment for two concentration levels of the antibiotic, and mathematical modeling was applied to fit experimental data. Tetracycline release was influenced by a membranes’ structure, layers’ composition, and by a membranes’ thickness. Bacterial cellulose nanofibrils proved to be the key factor in achieving suitable drug release profiles. Thus, sustained antibiotic delivery was obtained for several days in the case of multilayer composites. The composites proved drug stability and antibacterial efficiency before and after TC-HCl continuous release for several days.

Development of antibacterial nanocomposites by combination of bacterial cellulose/chitin nanofibrils and all-natural bioactive nanoparticles

In this study, a functional composite membrane was facilely fabricated by using a dual nanofibril system of bacterial cellulose (BC) and chitin (CH) nanofibrils as bio-based building blocks. The BC-CH membranes with enhanced antibacterial activity were constructed by incorporation of all-natural bioactive nanoparticles (GBTPs), which were formed by spontaneous molecular interactions of three naturally occurring active small molecules, i.e., glycyrrhizic acid (GA), berberine (BR), and tannic acid (TA). The microstructure, physicochemical properties, and antibacterial behaviors of the resulting BC-CH-GBTPs nanocomposites were then characterized. The obtained results showed that the GBTPs with a diameter of around 50–100 nm and membrane matrix were bound by non-covalent interactions, and the addition of GBTPs did not compromise the structural integrity and thermal stability of the composites, which retained good mechanical properties. Furthermore, the addition of GBTPs led to a rougher surface structure and increased the water contact angle of the membrane surfaces from 48.13° to 59.80°. The antimicrobial tests indicate that the BC-CH-GBTPs nanocomposites exhibited significant inhibitory effects against Escherichia coli and Staphylococcus aureus, showing a satisfactory antibacterial ability. These results suggest that the BC-CH-GBTPs nanocomposites based on all-natural, plant-based building blocks, hold promising potentials as active packaging materials for sustainable applications.