Functional bacterial cellulose nanofibrils with silver nanoparticles and its antibacterial application

Polycaprolactone (PCL)-based films integrated with hairy cellulose nanocrystals and silver nanoparticles for active Tilapia packaging applications

The migration of metal ions to the food matrix has been always a challenge in the production of active food packaging films. In this study, it was tried to evaluate the idea of using hairy cellulose nanocrystals (HCNs) in controlling the migration of Silver Nanoparticles (AgNPs) from polycaprolactone (PCL)-based films to the Tilapia fish. HCNs and the final films (integrated with various amounts of HCNs and AgNPs) were evaluated physicochemically and mechanically. Tilapia fish were packed using the films and after specific periods, the fish samples were assessed microbiologically and physiochemically. According to the results, incorporating NPs into PCL films enhanced tensile strength, elasticity, and toughness making the films more resistant to breakage and deformation under stress. The introduction of HCNs reduced the surface roughness level, decreasing AgNPs migration, but also accelerated the degradation rate. Films with [1% AgNPs +2% HCNs] and [1% AgNPs] had the lowest and highest water vapor transmission rate. The use of AgNPs (1%) + HCNs (2%) incorporated into PCL films resulted in a lower pH value, TVB-N, TBARs, and PV. It also decreased microbial activities in samples in comparison to the control. Therefore, the idea of using HCNs along with antibacterial metal-based nanoparticles can control the rate of ion migration.

Aggregation-Induced Emission Photosensitizer with Ag(I)-π Interaction-Enhanced Reactive Oxygen Species for Eliminating Multidrug Resistant Bacteria

Multidrug-resistant (MDR) bacteria pose serious threats to public health due to the lack of effective and biocompatible drugs to kill MDR bacteria. Photodynamic antibacterial therapy has been widely studied due to its low induction of resistance. However, photosensitizers that can efficiently generate reactive oxygen species (ROS) through both type I and type II mechanisms and that have the capability of multiple modes of action are rarely reported. Addressing this issue, we developed a near-infrared-emitting triphenylamine indole iodoethane (TTII) and its silver(I) self-assembled (TTIIS) aggregation-induced emission (AIE) photosensitizer for multimode bacterial infection therapy. TTII can efficiently produce both Type I ROS •OH and Type II ROS 1O2. Interestingly, the Ag(I)-π interaction contributed in TTIIS efficiency promotion of the generation of 1O2. Moreover, by releasing Ag+, TTIIS enabled photodynamic-Ag(I) dual-mode sterilization. As a result, TTIIS achieved an effective enhancement of antibacterial activity, with a 1-2-fold boost against multidrug-resistant Escherichia coli (MDR E. coli). Both TTII and TTIIS at a concentration as low as 0.55 μg mL-1 can kill more than 98% of methicillin resistant Staphylococcus aureus (MRSA) on MRSA-infected full-thickness defect wounds of a mouse, and both TTII and TTIIS were effective in eliminating the bacteria and promoting wound healing.

Study and evaluation of a gelatin- silver oxide nanoparticles releasing nitric oxide production of wound healing dressing for diabetic ulcer

This study aimed to develop a novel Gelatin silver oxide material for releasing nitric oxide bionanocomposite wound dressing with enhanced mechanical, chemical, and antibacterial properties for the treatment of diabetic wounds. The gelatin- silver oxide nanoparticles (Ag2O-NP) bio nanocomposite was prepared using chitosan and gelatin polymers incorporated with silver oxide nanoparticles through the freeze-drying method. The samples were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Results showed that the Ag2O-NP nanoparticles increased porosity, decreased pore size, and improved elastic modulus. The Ag2O-NP wound dressing exhibited the most effective antibacterial properties against Staphylococcus aureus and Escherichia coli. Among the samples, the wound dressing containing silver oxide nanoparticles demonstrated superior physical and mechanical properties, with 48% porosity, a tensile strength of 3.2 MPa, and an elastic modulus of 51.7 MPa. The fabricated wound dressings had a volume ratio of empty space to total volume ranging from 40% to 60%. In parallel, considering the complications of diabetes and its impact on the vascular system, another aspect of the research focused on developing a per2mediated wound dressing capable of releasing nitric oxide gas to regenerate damaged vessels and accelerate diabetic wound healing. Chitosan, a biocompatible and biodegradable polymer, was selected as the substrate for the wound dressing, and beta-glycerophosphate (GPβ), tripolyphosphate (TPP), and per2mediated alginate (AL) were used as crosslinkers. The chitosan-alginate (CS-AL) wound dressing exhibited optimal characteristics in terms of hole count and uniformity in the scanning electron microscope test. It also demonstrated superior water absorption (3854%) and minimal air permeability. Furthermore, the CS-AL sample exhibited an 80% degradation rate after 14 days, indicating its suitability as a wound dressing. The wound dressing was loaded with S-nitrosoglutathione (GSNO) powder, and the successful release of nitric oxide gas was confirmed through the grease test, showing a peak at a wavelength of 540 nm. Subsequent investigations revealed that the treatment of human umbilical vein endothelial cells (HUVECs) with high glucose led to a decrease in the expression of PER2 and SIRT1, while the expression of PER2 increased, which may subsequently enhance the expression of SIRT1 and promote cell proliferation activity. However, upon treatment of the cells with the modified materials, an increase in the expression of PER2 and SIRT1 was observed, resulting in a partial restoration of cell proliferative activity. This comprehensive study successfully developed per2-mediated bio-nanocomposite wound dressings with improved physical, mechanical, chemical, and antibacterial properties. The incorporation of silver oxide nanoparticles enhanced the antimicrobial activity, while the released nitric oxide gas from the dressing demonstrated the ability to mitigate vascular endothelial cell damage induced by high glucose levels. These advancements show promising potential for facilitating the healing process of diabetic wounds by addressing complications associated with diabetes and enhancing overall wound healing.

Preparation of nano-silver containing black phosphorus based on quaternized chitosan hydrogel and evaluating its effect on skin wound healing

Hydrogels with favorable biocompatibility and antibacterial properties are essential in postoperative wound hemorrhage care, facilitating rapid wound healing. The present investigation employed electrostatic adsorption of black phosphorus nanosheets (BPNPs) and nano‑silver (AgNPs) to cross-link the protonated amino group NH3+ of quaternized chitosan (QCS) with the hydroxyl group of hyaluronic acid (HA). The electrostatic interaction between the two groups resulted in the formation of a three-dimensional gel network structure. Additionally, the hydrogel containing AgNPs deposited onto BPNPs was assessed for its antibacterial properties and effects on wound healing. Hydrogel demonstrated an outstanding drug-loading capacity and could be employed for wound closure. AgNPs loaded on the BPNPs released silver ions and exhibited potent antibacterial properties when exposed to 808 nm near-infrared (NIR) radiation. The ability of the hydrogel to promote wound healing in an acute wound model was further evaluated. The BPNPs were combined with HA and QCS in the aforementioned hydrogel system to improve adhesion, combine the photothermal and antibacterial properties of the BPNPs, and promote wound healing. Therefore, the reported hydrogels displayed excellent biocompatibility and hold significant potential for application in the field of tissue engineering for skin wound treatment.

Advancements in 3D-printable polysaccharides, proteins, and synthetic polymers for wound dressing and skin scaffolding - A review

This review investigates the most recent advances in personalized 3D-printed wound dressings and skin scaffolding. Skin is the largest and most vulnerable organ in the human body. The human body has natural mechanisms to restore damaged skin through several overlapping stages. However, the natural wound healing process can be rendered insufficient due to severe wounds or disturbances in the healing process. Wound dressings are crucial in providing a protective barrier against the external environment, accelerating healing. Although used for many years, conventional wound dressings are neither tailored to individual circumstances nor specific to wound conditions. To address the shortcomings of conventional dressings, skin scaffolding can be used for skin regeneration and wound healing. This review thoroughly investigates polysaccharides (e.g., chitosan, Hyaluronic acid (HA)), proteins (e.g., collagen, silk), synthetic polymers (e.g., Polycaprolactone (PCL), Poly lactide-co-glycolic acid (PLGA), Polylactic acid (PLA)), as well as nanocomposites (e.g., silver nano particles and clay materials) for wound healing applications and successfully 3D printed wound dressings. It discusses the importance of combining various biomaterials to enhance their beneficial characteristics and mitigate their drawbacks. Different 3D printing fabrication techniques used in developing personalized wound dressings are reviewed, highlighting the advantages and limitations of each method. This paper emphasizes the exceptional versatility of 3D printing techniques in advancing wound healing treatments. Finally, the review provides recommendations and future directions for further research in wound dressings.

[New Advances in the Application of Bacterial Cellulose Composite Materials in the Field of Bone Tissue Engineering]

Bacterial cellulose (BC) is a type of extracellular polymeric nanomaterial secreted by microorganisms over the course of their growth. It has gained significant attention in the field of bone tissue engineering due to its unique structure of three-dimensional fibrous network, excellent biocompatibility, biodegradability, and exceptional mechanical properties. Nevertheless, BC still has some weaknesses, including low osteogenic activity, a lack of antimicrobial properties, small pore size, issues with the degradation rate, and a mismatch in bone tissue regeneration, limiting its standalone use in the field of bone tissue engineering. Therefore, the modification of BC and the preparation of BC composite materials have become a recent research focus. Herein, we summarized the relationships between the production, modification, and bone repair applications of BC. We introduced the methods for the preparation and the modification of BC. Additionally, we elaborated on the new advances in the application of BC composite materials in the field of bone tissue engineering. We also highlighted the existing challenges and future prospects of BC composite materials.

Synthesis of bacterial cellulose nanofibers/Ag nanoparticles: Structure, characterization and antibacterial activity

The aim of this study was to compare the characterization of bacterial cellulose nanofibers/Ag nanoparticles (BCNs/Ag nanoparticles) obtained by three different pretreatment methods of BCNs (no pretreatment, sodium hydroxide activation pretreatment and TEMPO-mediated oxidation pretreatment), which were recoded as N-BCNs/Ag nanoparticles, A-BCNs/Ag nanoparticles and O-BCNs/Ag nanoparticles, respectively. The results of scanning electron microscopy and transmission electron microscopy showed the prepared Ag nanoparticles by three different pretreatment methods were spherical and dispersed on the surface of BCNs, while the Ag nanoparticles in O-BCNs/Ag nanoparticles displayed the smallest diameter with a value of 20.25 nm and showed the most uniform dispersion on the surface of BCNs. The ICP-MS result showed O-BCNs/Ag nanoparticles had the highest content of Ag nanoparticles with a value of 2.98 wt%, followed by A-BCNs/Ag nanoparticles (1.53 wt%) and N-BCNs/Ag nanoparticles (0.84 wt%). The cytotoxicity assessment showed that the prepared BCNs/Ag nanoparticles were relatively safe. Furthermore, the O-BCNs/Ag nanoparticles had the best antioxidant and antibacterial activities as compared with the other two types of BCNs/Ag nanoparticles, where O-BCNs/Ag nanoparticles destroyed the structure of bacterial cell membranes to lead the leakage of intracellular components. This study showed that O-BCNs/Ag nanoparticles as antibacterial agents have great potential in food packaging.

Production of bacterial cellulose (BC)/nisin composite with enhanced antibacterial and mechanical properties through co-cultivation of Komagataeibacter xylinum and Lactococcus lactis subsp. lactis

By employing co-cultivation technique on Komagataeibacter xylinum and Lactococcus lactis subsp. lactis, bacterial cellulose (BC)/nisin films with improved antibacterial activity and mechanical properties were successfully produced. The findings demonstrated that increased nisin production is associated with an upregulation of gene expression. Furthermore, results from Scanning electronic microscopy (SEM), Fourier transform infrared (FTIR), X-ray diffraction (XRD), and Thermogravimetric analysis (TG) confirmed the integration of nisin within BC. While being biocompatible with human cells, the BC/nisin composites exhibited antimicrobial activity. Moreover, mechanical property analyses showed a noticeable improvement in Young's modulus, tensile strength, and elongation at break by 161, 271, and 195 %, respectively. Additionally, the nisin content in fermentation broth was improved by 170 % after co-culture, accompanied by an 8 % increase in pH as well as 10 % decrease in lactate concentration. Real-time reverse transcription PCR analysis revealed an upregulation of 11 nisin-related genes after co-cultivation, with the highest increase in nisA (5.76-fold). To our knowledge, this is the first study which demonstrates that an increase in secondary metabolites after co-culturing is modulated by gene expression. This research offers a cost-effective approach for BC composite production and presents a technique to enhance metabolite concentration through the regulation of relevant genes.

Metal nanoparticles and carbohydrate polymers team up to improve biomedical outcomes

The convergence of carbohydrate polymers and metal nanoparticles (MNPs) holds great promise for biomedical applications. Researchers aim to exploit the capability of carbohydrate matrices to modulate the physicochemical properties of MNPs, promote their therapeutic efficiency, improve targeted drug delivery, and enhance their biocompatibility. Therefore, understanding various attributes of both carbohydrates and MNPs is the key to harnessing them for biomedical applications. The many distinct types of carbohydrate-MNP systems confer unique capabilities for drug delivery, wound healing, tissue engineering, cancer treatment, and even food packaging. Here, we introduce distinct physicochemical/biological properties of carbohydrates and MNPs, and discuss their potentials and shortcomings (alone and in combination) for biomedical applications. We then offer an overview on carbohydrate-MNP systems and how they can be utilized to improve biomedical outcomes. Last but not least, future perspectives toward the application of such systems are highlighted.

Self-assembled carboxymethyl chitosan/zinc alginate composite film with excellent water resistant and antimicrobial properties for chilled meat preservation

A major way to reduce meat waste is to extend the shelf life of chilled meat with appropriate packaging. However, most of the packaging film cannot keep meat fresh because of its poor antibacterial and water resistance performance. In this paper, a composite film for chilled meat packaging was synthesized by simple self-assembly of zinc ions with chelating carboxyl groups. Introducing zinc ions into the composite system endows excellent water resistance and antibacterial properties to the film, which are demonstrated by the water vapor permeability and Escherichia coli and Staphylococcus aureus antibacterial tests. The as-prepared composite film also showed enhanced mechanical properties due to the formation of chelation bonds between zinc ions and carboxyl groups. Moreover, the chilled meat preservation test demonstrated the as-prepared composite film can significantly extend the shelf life of pork by five days, indicating its outstanding freshness preservation property. This work demonstrated a facile method to synthesize water-resistant and antimicrobial composite film, which can appear as an effective packaging material for chilled meat and offer a new idea to solve its short shelf-life problem.

Advances in drug delivery applications of modified bacterial cellulose-based materials

Bacterial cellulose (BC) is generated by certain species of bacteria and comprises polysaccharides with unique physical, chemical, and mechanical characteristics. Due to its outstanding biocompatibility, high purity, excellent mechanical strength, high water absorption, and highly porous structure, bacterial cellulose has been recently investigated for biomedical application. However, the pure form of bacterial cellulose is hardly used as a biomedical material due to some of its inherent shortcomings. To extend its applications in drug delivery, modifications of native bacterial cellulose are widely used to improve its properties. Usually, bacterial cellulose modifications can be carried out by physical, chemical, and biological methods. In this review, a brief introduction to bacterial cellulose and its production and fabrication is first given, followed by up-to-date and in-depth discussions of modification. Finally, we focus on the potential applications of bacterial cellulose as a drug delivery system.

Producing bacterial cellulose from industrial recycling paper waste sludge

This study aimed to produce bacterial cellulose from paper waste sludge (PWS) as a method of utilizing the cellulose source from the remaining pulp in the material. Initially, PWS was hydrolyzed by sulfuric acid to create an enriched-reducing sugar hydrolysate. One-factor experiments were conducted with a fixed amount of PWS (5 g) to investigate the influence of hydrolysis conditions, including water, sulfuric acid addition, temperature, and retention time, on the production yield of reducing sugars. Based on these results, the Box-Behnken model was designed to optimize the hydrolysis reaction. The optimal hydrolysis conditions were 10 ml/g of the sulfuric acid solution (30.9%) at 105.5 °C for 90 min of retention time 0.81 (gGE/g PWS), corresponding to a conversion yield of 40.5%). Subsequently, 100 ml of the filtered and neutralized PWS hydrolysate was used as the culture to produce the bacterial cellulose (BC) using Acetobacter xylinum, which produced 12 g/L of bacterial cellulose. The conversion yield of bacterial cellulose calculated as the ratio of the weight of produced bacterial cellulose to that of cellulose in PWS reached 33.3%. The structure of the obtained BC was analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD) to indicate the formation of nano-cellulose fiber networks. This research proposed a combined method to convert paper waste sludge into bacterial cellulose, demonstrating the potential for waste utilization and sustainable production of paper industries for added-value products.

Hybrid Silver-Containing Materials Based on Various Forms of Bacterial Cellulose: Synthesis, Structure, and Biological Activity

Sustained interest in the use of renewable resources for the production of medical materials has stimulated research on bacterial cellulose (BC) and nanocomposites based on it. New Ag-containing nanocomposites were obtained by modifying various forms of BC with Ag nanoparticles prepared by metal-vapor synthesis (MVS). Bacterial cellulose was obtained in the form of films (BCF) and spherical BC beads (SBCB) by the Gluconacetobacter hansenii GH-1/2008 strain under static and dynamic conditions. The Ag nanoparticles synthesized in 2-propanol were incorporated into the polymer matrix using metal-containing organosol. MVS is based on the interaction of extremely reactive atomic metals formed by evaporation in vacuum at a pressure of 10^-2 Pa with organic substances during their co-condensation on the cooled walls of a reaction vessel. The composition, structure, and electronic state of the metal in the materials were characterized by transmission and scanning electron microscopy (TEM, SEM), powder X-ray diffraction (XRD), small-angle X-ray scattering (SAXS) and X-ray photoelectron spectroscopy (XPS). Since antimicrobial activity is largely determined by the surface composition, much attention was paid to studying its properties by XPS, a surface-sensitive method, at a sampling depth about 10 nm. C 1s and O 1s spectra were analyzed self-consistently. XPS C 1s spectra of the original and Ag-containing celluloses showed an increase in the intensity of the C-C/C-H groups in the latter, which are associated with carbon shell surrounding metal in Ag nanoparticles (Ag NPs). The size effect observed in Ag 3d spectra evidenced on a large proportion of silver nanoparticles with a size of less than 3 nm in the near-surface region. Ag NPs in the BC films and spherical beads were mainly in the zerovalent state. BC-based nanocomposites with Ag nanoparticles exhibited antimicrobial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli bacteria and Candida albicans and Aspergillus niger fungi. It was found that AgNPs/SBCB nanocomposites are more active than Ag NPs/BCF samples, especially against Candida albicans and Aspergillus niger fungi. These results increase the possibility of their medical application.