Bacterial Cellulose Network Research Articles

Bifunctional modified bacterial cellulose-based hydrogel through sequence-dependent crosslinking towards enhanced antibacterial and cutaneous wound healing.

Chronic wounds caused by microbial infection have emerged as a major challenge on patients and medical health system. Bacterial cellulose (BC) characterized by its excellent biocompatibility and porous network, holds promise for addressing complex wound issues. However, lack of inherent antibacterial activity and cross-linking sites in the molecular network of BC have constrained its efficacy in hydrogel design and treatment of bacterial-infected wounds. Additionally, few studies have explored the effects of precursor crosslinking sequences on hydrogel design and processing. Herein, a quaternary ammonium and aldehyde-biofunctionalized bacterial cellulose (OQBC) was synthesized and utilized for the development of double network (DN) hydrogels, incorporating the crosslinking sequences of thiol-alginate (SASH) and carboxymethyl chitosan (CMCS). Firstly, OQBC was characterized with bifunctional groups, which endows its inherent antibacterial activity and gel-forming property. Subsequently, DN hydrogels formed through thiol-aldehyde addition and amino-aldehyde reactions showed favorable injectability and self-healing ability. The sequential crosslinking via Schiff-base and thiohemiacetal bonds endowed the hydrogels with distinct features, including degradation behavior, pH-responsive swelling, water retention, surface roughness, and cell behavior. With the increasing OQBC content into hydrogels, bacteriostatic rate exceeded 90 % without obvious cytotoxicity. Hydrogels also exhibit antioxidant and sustained drug release properties. Moreover, in infected skin thickness defect rats, the selected hydrogel enhanced wound repair and regeneration by inhibiting inflammation and promoting collagen deposition and angiogenesis. This design of sequence-dependent crosslinked antibacterial DN hydrogel offers a promising tool for the development of advanced materials to treat infected wounds.

Bacterial Cellulose/Graphene Oxide/Hydroxyapatite Biocomposite: A Scaffold from Sustainable Sources for Bone Tissue Engineering.

Bone tissue engineering demands advanced biomaterials with tailored properties. In this regard, composite scaffolds offer a strategy to integrate the desired functionalities. These scaffolds are expected to provide sufficient cellular activities while maintaining the required strength necessary for the bone repair for which they are intended. Hence, attempts to obtain efficient composites are growing. However, in most cases, the conventional production methods of scaffolds are energy-intensive and leave an impact on the environment. This work aims to develop a biocomposite scaffold integrating bacterial cellulose (BC), hydroxyapatite (HAp), and graphene oxide (GO), designated as "BC/HAp/GO". All components are sourced primarily from agricultural and food waste as alternative means. BC, known for its biocompatibility, fine fiber network, and high porosity, serves as an ideal scaffold material. HAp, a naturally occurring bone component, contributes osteoconductive properties, while GO provides mechanical strength and biofunctionalization capabilities. The biomaterials were analyzed and characterized using a scanning electron microscope, a X-ray diffractometer, and a Fourier transform infrared spectrometer. The produced biocomposite scaffolds were tested for thermal stability, mechanical strength, and biocompatibility. The results showed a nanofibrous, porous network of BC, highly crystalline HAp particles, and well-oxygenated GO flakes with slight structural deformities. The synthesized biocomposite demonstrated promising characteristics, such as increased tensile strength due to added GO particles and higher bioactivity through the introduction of HAp. These inexpensively synthesized materials, marked by suitable surface morphology and cell adhesion properties, open potential applications in bone repair and regeneration.

Drug release kinetics from in-situ modulated agar/chitosan-bacterial cellulose patches for differently soluble drugs

Bacterial cellulose (BC) stands out as a promising candidate for novel drug delivery systems due to its micro-mesoporous nanofibrous interconnected structure. However, its performance is limited by the burst release of hydrophilic drugs and lower incorporation of the less water-soluble or insoluble drugs. In this study, we explored its potential as a drug carrier for two distinct types of drugs: Diclofenac sodium and Simvastatin, representing water-soluble and water insoluble compounds, respectively. To tune the morphology and drug-BC interaction, agar and chitosan were introduced into the culture medium during BC synthesis for in-situ modification. These modulated BCs are characterized and further analyzed through drug release studies and mathematical modeling to understand the mechanisms and key factors controlling the drug release behavior. Incorporating agar and chitosan into the BC network results in changes to its microstructure and crystallinity, which in turn affects the overall swelling, drug loading and release properties. Our results revealed that the BC followed a first-order quasi-Fickian kinetics for water-soluble drug and non-Fickian release mechanism for water-insoluble drug. In contrast, agar-modulated BC (A-MBC) demonstrated a non-Fickian first-order diffusion kinetics, with slow release for water-soluble drug and sustained release for the water-insoluble drug due to the higher density which impedes drug release. Chitosan-modulated BC (C-MBC) exhibited non-Fickian first-order kinetics, with slower release for water soluble drug. Further, C-MBC exhibited extended release for water insoluble drug to over 14 days, following first-order kinetics for the first 12 h, then transitioning to zero-order kinetics with a Case II release mechanism, attributed to drug-matrix interactions. These findings successfully demonstrate the possibility to tailor BC thus the release kinetics for both water-soluble and less soluble or insoluble drugs.

Impact of Carbon Source on Bacterial Cellulose Network Architecture and Prolonged Lidocaine Release.

The biosynthesis of bacterial cellulose (BC) is significantly influenced by the type of carbon source available in the growth medium, which in turn dictates the material's final properties. This study systematically investigates the effects of five carbon sources-raffinose (C18H32O16), sucrose (C12H22O11), glucose (C6H12O6), arabinose (C5H10O5), and glycerol (C3H8O3)-on BC production by Komagataeibacter hansenii. The varying molecular weights and structural characteristics of these carbon sources provide a framework for examining their influence on BC yield, fiber morphology, and network properties. BC production was monitored through daily measurements of optical density and pH levels in the fermentation media from day 1 to day 14, providing valuable insights into bacterial growth kinetics and cellulose synthesis rates. Scanning electron microscopy (SEM) was used to elucidate fibril diameter and pore size distribution. Wide-angle X-ray scattering (WAXS) provided a detailed assessment of crystallinity. Selected BC pellicles were further processed via freeze-drying to produce a foam-like material that maximally preserves the natural three-dimensional structure of BC, facilitating the incorporation and release of lidocaine hydrochloride (5%), a widely used local anesthetic. The lidocaine-loaded BC foams exhibited a sustained and controlled release profile over 14 days in simulated body fluid, highlighting the importance of the role of carbon source selection in shaping the BC network architecture and its impact on drug release profile. These results highlight the versatility and sustainability of BC as a platform for wound healing and drug delivery applications. The tunable properties of BC networks provide opportunities for optimizing therapeutic delivery and improving wound care outcomes, positioning BC as an effective material for enhanced wound management strategies.

Bacterial cellulose-graphene oxide composite membranes with enhanced fouling resistance for bio-effluents management

Bacterial cellulose composites hold promise as renewable bioinspired materials for industrial and environmental applications. However, their use as free-standing water filtration membranes is hindered by low compressive strength, fouling, and poor contaminant selectivity. This study investigates the potential of bacterial cellulose-graphene oxide composites membranes for fouling resistance in pressure-driven filtration. Graphene oxide dispersed in poly(ethylene glycol) (PEG-400) is incorporated as a reinforcing filler into 3D network of bacterial cellulose using an in-situ synthesis method. The effect of graphene oxide on in situ fermentation yield and the formation of percolated-network in the composites shows that the optimal membrane properties are reached at a graphene oxide loading of 2 mg/mL. The two-dimensional graphene oxide nanosheets uniformly dispersed into the matrix of bacterial cellulose nanofibers via hydrogen-bonded interactions demonstrated nearly twofold higher water flux (380 L m−2 h−1) with a molecular weight cut-off ranging between 100–200 KDa and a sixfold increase in wet compression strength than pristine BC. When exposed to synthetic organic foulants and bacterial rich feed solutions, the composite membranes showed more than 95% flux recovery. Additionally, the membranes achieved over 95% rejection of synthetic natural organic matter and bacterial rich solutions, showcasing their enhanced fouling resistance and selectivity.

Efficient atmospheric water harvesting enabled by hierarchically structured cellulose foam

The sorption-based atmospheric water harvesting technique is an appealing solution for addressing the challenge of freshwater shortages. In this study, a composite foam was fabricated by confining hygroscopic salt (CaCl2) into a Cr-based metal–organic framework (MIL-101), which was then integrated into a bacterial cellulose (BC) skeleton. The hierarchical structure, which contains micron- and nanoscale pores, enhances water storage, transport, and vapor evaporation throughout the whole water capture and release process. The pore confinement effect of MIL-101 and the interconnected BC network effectively restricted the leakage of the liquefied salt solution. Interestingly, the color of the CaCl2@MIL-101@BC foam changed from light green to dark green as the amount of absorbed water increased. This moisture-induced color darkening improves the light absorption ability during the water release stage under sunlight. At 30 % relative humidity, the foam can absorb up to 0.78 g g−1 of water per cycle (8 h) and desorb quickly under solar radiation. This makes foam a promising method for water production in arid areas.

In-situ bioprocessing of bacterial cellulose aerogel with covalent organic frameworks for enhanced uranium extraction

Developing efficient and cost-effective uranium adsorbents remain a significant challenge due to the complex composition of seawater. Herein, this study for the first time utilized an in-situ spray gel-assisted biosynthesis strategy to homogeneously incorporate the covalent organic frameworks (COF) into the three-dimensional pores of bacterial cellulose (BC) hydrogel during the culture of K. sucrofermentans. The BCCOF-SO3NH4 aerogel was fabricated through ammoniating modification of BC/COF (BCCOF-SO3H) hydrogel and freeze-drying processes. The BCCOF-SO3NH4 aerogels are characterized by the in-situ entanglement of COF within the three-dimensional network of BC, resulting in enhanced mechanical strength and groups interactions. The experimental maximum adsorption capacity of BCCOF-SO3NH4 aerogel reached 883.44 mg g−1, demonstrating exceptional uranium adsorption capacity compared with most of the reported adsorbents. The adsorption process follows the pseudo-second-order model and Langmuir isotherm. Throughout seven adsorption–desorption cycles, BCCOF-SO3NH4 maintained a stable adsorption capacity and desorption efficiency. The adsorption mechanism is verified by experiments and DFT calculations, which involves not only the ion exchange between uranyl and NH4+, but also the strong coordination interaction between the active groups (sulfonic acid group, hydroxyl group) and uranium. The in-situ biosynthesis strategy of composites shows a great application prospect in the preparation of high adsorption performance materials.

High efficient dip catalyst for nitrophenol reduction using bacterial cellulose impregnated self-crosslinked glycol chitosan via formation of gold nanoparticles

A simple approach was used to create an environmentally friendly dip catalyst by incorporating gold nanoparticles (AuNPs) into bacterial cellulose (BC) via glycol chitosan (GCS), which acted as both a reducing and self-crosslinking agent. The BC-GCS-AuNPs dip catalyst was analyzed using UV–Vis spectroscopy, FTIR, SEM, XRD, and TEM to confirm the formation of AuNPs and GCS self-crosslinking within the BC network. The catalyst efficacy was tested for converting 4-nitrophenol (NP) to 4-amino phenol (AP). Results demonstrated excellent catalytic performance, achieving up to 98 % within 5 min. The dip catalyst present an appealing option for green and sustainable catalysis due to its outstanding performance, stability, and reusability.

Cultivating High-Performance Flexible All-in-One Supercapacitors With 3D Network Through Continuous Biosynthesis.

Flexible supercapacitors can potentially power next-generation flexible electronics. However, the mechanical and electrochemical stability of flexible supercapacitors under different flexible conditions is limited by the weak bonding between adjacent layers, posing a significant hindrance to their practical applicability. Herein, based on the uninterrupted 3D network during the growth of bacterial cellulose (BC), a flexible all-in-one supercapacitor is cultivated through a continuous biosynthesis process. This strategy ensures the continuity of the 3D network of BC throughout the material, thereby forming a continuous electrode-separator-electrode structure. Benefitting from this bioinspired structure, the all-in-one supercapacitor not only achieves a high areal capacitance (3.79 F cm-2) of electrodes but also demonstrates the integration of high tensile strength (2.15MPa), high shear strength (more than 54.6kPa), and high bending resistance, indicating a novel pathway toward high-performance flexible power sources.

Comparative study and characterization of water-treated bacterial cellulose produced by solid or liquid inoculum of Komagateibacter sucrofermentans

Structural and physicochemical properties of two types of bacterial cellulose (BC) produced by Komagateibacter sucrofermentans strain DSM 15973T after 7 days through either immobilized bacteria (solid inoculum) forming BCS7 or free bacteria (liquid inoculum) forming BCL7, followed by a water-based purification as a chem-free alternative treatment, were investigated in this study. SEM verifies the effectiveness of the water-based purification on BC network and reveals the insufficient interfibrillar space of BCS7 compared to BCL7. BCL7 was generally proved to be superior to BCS7 regarding degree of purification, BC yield, overall higher porosity, water swell ability, and water holding capacity (WHC), exhibiting higher hydrophilicity. However, thermally resistant BCS7 reveals a 35% residual up to 800 ºC compared to BCL7 (15%) and prevailed in terms of water retention rate. Both water-treated BC7 were proved to be Iα-rich cellulose type and exhibited a typical type IV(a) isotherm with an H3 type of hysteresis loop, a similar pore distribution, crystallinity index (~77%), crystallite size (~7.5 cm), same levels of moisture content (~98%) and the same poor levels of rehydration after the freeze-drying process. During BCL kinetics in 20 mL of HS medium over 7 days, K. sucrofermentans, 2D pellicle formation was observed until day 3 and then 3D. The highest WHC was obtained on day 4 (116 g water/g cellulose), while the lowest on day 1 (19 g water/g cellulose). Overall, we discussed the preparation and characterization of two different BCs water-treated for purification as an eco-friendly alternative method towards functional, and sustainable application.Graphical

Bacterial cellulose-based composite films with liquid metal/graphene synergistic conductive pathways for superior electromagnetic interference shielding and Joule heating performance

Modern integrated electronics are in great demand for high-performance electromagnetic interference (EMI) shielding materials with exceptional mechanical properties. Liquid metal (LM) has demonstrated great potential in EMI shielding by its superior electrical conductivity. However, its real-world EMI application is limited by the poor compatibility, insulating oxide shells, and unpredictable leakage. Here, graphene oxide (GO) is used to encapsulate LM to form LM@GO microdroplets dispersion, and bacterial cellulose (BC) is applied to construct a biocompatible fabric network. Moreover, GO is in-situ reduced by hydrazine vapor, which generates synergistic LM/reduced graphene oxide (rGO) conductive pathways with the aid of roll-in process, obtaining flexible LM/rGO/BC (LGB) composite film with outstanding electrical conductivity of 4.5 × 104 S/m and exceptional shielding effectiveness of 64.0 dB. The rGO sheets and BC network demonstrate layered structure after roll-in process, effectively impeding the leakage and oxidation of LM and achieving a tensile strength up to 62.9 MPa of LGB films. Meanwhile, the LGB films exhibit exceptional Joule heating performance, and the stable surface temperature reaches 110 °C with high stability and reliability when the applied voltage is 4 V. This work provides a feasible engineering approach to prepare LM-based films for applications in EMI shielding and wearable electronics.

Hard carbon with embedded graphitic nanofibers for fast-charge sodium-ion batteries

The development of fast-charging sodium-ion batteries need the anode to have a high rate capacity with a long and reversible charging plateau at low voltage (<0.1 V). Hard carbons are extensively investigated as the anodes for sodium-ion batteries, but slow charge-transfer kinetics and low reversible capacity at low potential region are still major obstacles for their practical applications. Herein, we develop a facile strategy via in-situ carbonization of the cross-linking network of bacterial cellulose and resin to synthesize hard carbons with intrinsically embedded graphitic nanofibers. The nanostructured hard carbons anodes have a reversible capacity of 345 mAh g−1 and an ultra-large low-voltage plateau capacity of 165.5 mAh g−1 (72.7% of the reversible capacity) at 2 A g−1. Kinetics and mechanism studies reveal that the embedded graphitic nanofibers greatly boost the charge transfer and ionic diffusion, i.e. the Na+ diffusion coefficient at the plateau region can be readily improved from ≈10−10.2 to ≈10−9.0 cm2 s−1. Evidence from in/ex-situ transmission electron microscopy (TEM) demonstrates that the graphic nanofibers, with an expanded interlayer spacing, provide sufficient diffusion channels for Na+ ions’ migration and storage. Full-cell sodium-ion batteries using the nanostructured hard carbon as anodes achieve superior fast-charge capability, showing great potential applications of the nanostructured hard carbon in the low-cost and environmentally friendly energy storage devices.

Reversible Deacidification and Preventive Conservation of Paper-Based Cultural Relics by Mineralized Bacterial Cellulose.

Paper-based cultural relics experience irreversible aging and deterioration during long-term preservation. The most common process of paper degradation is the acid-catalyzed hydrolysis of cellulose. Nowadays, deacidification has been considered as a practical way to protect acidified literature; however, two important criteria of minimal intervention and reversibility should be considered. Inspired by the superior properties of bacterial cellulose (BC) and its structural similarity to paper, herein, the mineralized BC membranes are applied to deacidification and conservation of paper-based materials for the first time. Based on the enzyme-induced mineralization process, the homogeneous and high-loaded calcifications of hydroxyapatite (HAP) and calcium carbonate (CaCO3) nanoparticles onto the nanofibers of BC networks have been achieved, respectively. The size, morphology, structure of minerals, as well as the alkalinity and alkali reserve of BC membranes are well controlled by regulating enzyme concentration and mineralization time. Compared with HAP/CaCO3-immersed method, HAP/CaCO3-BC membranes show more efficient and sustained deacidification performance on paper. The weak alkalinity of mineralized BC membranes avoids the negative effect of alkali on paper, and the high alkali reserve implies a good sustained-release effect of alkali to neutralize the future generated acid. The multiscale nanochannels of the BC membrane provide ion exchange and acid/alkali neutralization channels between paper and the BC membrane, and the final pH of protected paper can be well stabilized in a certain range. Most importantly, this BC-deacidified method is reversible since the BC membrane can be removed without causing any damage to paper and the original structure and fiber morphology of paper are well preserved. In addition, the mineralized BC membrane provides excellent flame-retardant performance on paper thanks to its unique organic-inorganic composite structure. All of these advantages of the mineralized BC membrane indicate its potential use as an effective protection material for the reversible deacidification and preventive conservation of paper-based cultural relics.

A wet bacterial cellulose film self-anchored by phosphotungstic acid: Flexible, quick-response and stable cycling performance for photochromic application

Bacterial cellulose (BC) has been recognized as an ideal supporter owning to its abundant hydroxyl groups on the surface. In this work, Keggin-type phosphotungstic acid (H3PW12O40, PWA) is self-anchored on the three-dimensional network of BC by a simple diffusion method at room-temperature. BC fibers can protect the well-dispersed PWA with high transparency, high mechanical strength, and high stability. When PWA/BC serves as a photochromic material, the coloration time and bleaching time are only 3 min and 30 min respectively. After 6 cycles, the photochromic ability of the PWA/BC composite film almost unchanged. At the same time, we convert the coloration and bleaching degree into quantitative data including a color difference calculation of ΔE2000 and the remaining degree of color (RC%). Within the BC system, PWA exhibits a special linear relationship between RC% and bleaching time (0–30 min). The processes of PWA/BC reduction (W6+→W5+) and oxidation (W5+→W6+) are analysed by photo-electrochromic, XPS and ESR characterizations. The revealed excellent photochromic properties of soft PWA/BC films highlight their potential as the photoresponsive materials.

Nata de coco as an abundant bacterial cellulose resource to prepare aerogels for the removal of organic dyes in water

A hydrogel-like product of the bacterial fermentation of coconut water is well-known as nata de coco which contains low-cost and high-quality bacterial cellulose. In this work, nata de coco was applied for the facile preparation of lightweight bacterial cellulose aerogels upon grinding and subsequent freeze-drying. The obtained aerogels possessed the three-dimensional network containing bacterial cellulose fibers with high crystallinity and porosity. The experimental results proved the high affinity of the bacterial cellulose network to the cationic dyes with adsorption capacities from 25 to 81 mg/g. By contrast, the aerogel was inefficient with most of the tested anionic dyes except for congo red which afforded a significant adsorption capacity of 145 mg/g. The promising results were obtained without any further chemical modification being applied to the bacterial cellulose aerogels and notably comparable to the previous performances of biomass-based sorbents. This biomaterial showed a great potential in environmentally-friendly treating organic dyes-polluted wastewater.

Features of formation and structure of bacterial cellulose-carbon nanotube composites

This paper examines the features of formation and structure of bacterial cellulose (BC) composites with carbon nanotubes (CNTs). We aim to study the influence of initial components on structure and crystallinity of BC composites. We use optical microscopy and scanning electron microscopy in order to investigate the surface morphology of BC composite films and X-ray diffraction analysis to determine the crystallographic structure of prepared samples. It is shown that CNT agglomerates in BC composite interact only with the surface layers of BC. CNTs and their bundles up to 50 nm in diameter are able to effectively penetrate into the BC network.

Production efficiency and properties of bacterial cellulose membranes in a novel grape pomace hydrolysate by Komagataeibacter melomenusus AV436T and Komagataeibacter xylinus LMG 1518

The microbial production of cellulose using different bacterial species has been extensively examined for various industrial applications. However, the cost-effectiveness of all these biotechnological processes is strongly related to the culture medium for bacterial cellulose (BC) production. Herein, we examined a simple and modified procedure for preparing grape pomace (GP) hydrolysate, without enzymatic treatment, as a sole growth medium for BC production by acetic acid bacteria (AAB). The central composite design (CCD) was used to optimise the GP hydrolysate preparation toward the highest reducing sugar contents (10.4 g/L) and minimal phenolic contents (4.8 g/L). The experimental screening of 4 differently prepared hydrolysates and 20 AAB strains identified the recently described species Komagataeibacter melomenusus AV436T as the most efficient BC producer (up to 1.24 g/L dry BC membrane), followed by Komagataeibacter xylinus LMG 1518 (up to 0.98 g/L dry BC membrane). The membranes were synthesized in only 4 days of bacteria culturing, 1 st day with shaking, followed by 3 days of static incubation. The produced BC membranes in GP-hydrolysates showed, in comparison to the membranes made in a complex RAE medium 34 % reduction of crystallinity index with the presence of diverse cellulose allomorphs, presence of GP-related components within the BC network responsible for the increase of hydrophobicity, the reduction of thermal stability and 48.75 %, 13.6 % and 43 % lower tensile strength, tensile modulus, and elongation, respectively. Here presented study is the first report on utilising a GP-hydrolysate without enzymatic treatment as a sole culture medium for efficient BC production by AAB, with recently described species Komagataeibacter melomenusus AV436T as the most efficient producer in this type of food-waste material. The scale-up protocol of the scheme presented here will be needed for the cost-optimisation of BC production at the industrial levels.

Sustainable production of flocculant-containing bacterial cellulose composite for removal of PET nano-plastics

Polyethylene terephthalate (PET) nano-plastics (PNP) is a major source of water pollution which in turn causes health issues in humans. There is no effective method to completely remove PNP from wastewater. In this study, bacterial cellulose (BC)/bacterial flocculant (BF) composite was produced from PNP ammonia hydrolysate through the co-cultivation of Taonella mepensis WT-6 and Diaphorobacter nitroreducens R9. The structural characterization of the BC/BF composite through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermal and mechanical analyses demonstrated that the amino-group-rich flocculant produced by the D. nitroreducens R9 was incorporated into the BC network without interfering the self-aggregation of cellulose fibrils. Fast PEP removal was observed in pure and tap water with maximum sorption capacity (Qmax) of 124.65 mg/g and 115.60 mg/g, respectively, whereas least removal was observed for campus lake water with a Qmax value of 84.78 mg/g. A 10 mM SO42− significantly decreased the adsorption capacity to 44.52 mg/g, while 2 mM Ca2+ contributed to the adsorption of PNP with a maximum adsorption capacity of 144.78 mg/g at pH 6.0. The potential adsorption mechanism was investigated through adsorption kinetic studies, isothermal models, and thermodynamics studies. The adsorbed BC/BF was recycled by desorbing PNP with ammonia water, and the eluent could be utilized as a medium for sustainable production of BC/BF. The reusable BC/BF adsorbent produced through the co-culture technique can effectively control PNP pollution.

Autonomously Assembled Living Capsules by Microbial Coculture for Enhanced Bacteriotherapy of Inflammatory Bowel Disease.

Microorganism-mediated self-assembling of living formulations holds great promise for disease therapy. Here, we constructed a prebiotic-probiotic living capsule (PPLC) by coculturing probiotics (EcN) with Gluconacetobacter xylinus (G. xylinus) in a prebiotic-containing fermentation broth. Through shaking the culture, G. xylinus secretes cellulose fibrils that can spontaneously encapsulate EcN to form microcapsules under shear forces. Additionally, the prebiotic present in the fermentation broth is incorporated into the bacterial cellulose network through van der Waals forces and hydrogen bonding. Afterward, the microcapsules were transferred to a selective LB medium, which facilitated the colonization of dense probiotic colonies within them. The in vivo study demonstrated that PPLC-containing dense colonies of EcN can antagonize intestinal pathogens and restore microbiota homeostasis by showing excellent therapeutic performance in treating enteritis mice. The in situ self-assembly of probiotics and prebiotics-based living materials provides a promising platform for the treatment of inflammatory bowel disease.

Preparation and antibacterial property of silver nanoparticles loaded into bacterial cellulose

Composite nanomaterials based on silver nanoparticles (AgNPs) are considered promising antimicrobial agents due to their excellent antimicrobial activity. The aim of this work is to develop bacterial cellulose (BC) composites that act synergistically with AgNPs. BC@AgNPs composites were developed using an ex-situ composite development strategy and evaluated for their structural characteristics and antimicrobial activities. Field emission scanning electron microscopy (FESEM) showed impregnation of AgNPs into the porous BC network. The composite formulation was also confirmed by x-ray diffraction (XRD) analysis, which showed the presence of additional crystalline peaks along with those of the pure BC. Bactericidal tests of BC@AgNPs nanocomposites against common pathogens, including Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, showed a significant reduction in their growth compared to pure BC. These results suggest that the synthesized BC@AgNPs composites could be promising antibacterial materials for potential applications in a wide range of medical and environmental applications.