Permeation of Silver Sulfadiazine Into TEMPO-Oxidized Bacterial Cellulose as an Antibacterial Agent

Enzymatic functionalization of bacterial nanocellulose: current approaches and future prospects

Faced with the challenges of modern industry and medicine associated with the dynamic development of civilization, there is a constantly growing demand for the production of novel functional materials that are clearly oriented towards fulfilling specific applications. Herein, we provide an overview of the current status and recent findings related to the enzymatic functionalization of bacterial nanocellulose. Commonly, biocellulose modification involves the utilization of simple and cost-effective chemical and/or physical approaches. However, these methods may have an adverse effect on both the biological properties of the biomaterial and the natural environment. An alternative to these procedures is the highly specific enzymatic modification of bacterial nanocellulose, which perfectly fits into the assumptions of green technologies, making the process eco-friendly and not limiting any outlooks for further usage of the obtained biocomposites. The employment of enzymes for the targeted alteration of this material's properties is based on either a direct method, such as controlled hydrolysis and nanofication [i.e., synthesis of different morphological forms of bacterial cellulose (e.g., rod-shaped nanocrystals)] using cellulases, and/or attachment of reactive functional groups into the polymer structure via oxidation (e.g., utilizing a laccase/TEMPO catalytic system or lytic polysaccharide monooxygenases) and esterification catalyzed by lipases; or an indirect procedure involving the application of bacterial nanocellulose as a matrix for enzyme immobilization (e.g., laccase, glucose oxidase, horseradish peroxidase, lysozyme, bromelain, lipase, papain), thus creating a specific catalytic system. Overall, enzymatic functionalization of bacterial nanocellulose is a sustainable and promising strategy to create biocomposites with tailored properties for a wide range of industrial and medical applications.

Protein Immobilization on Bacterial Cellulose for Biomedical Application

New carriers for protein immobilization are objects of interest in various fields of biomedicine. Immobilization is a technique used to stabilize and provide physical support for biological micro- and macromolecules and whole cells. Special efforts have been made to develop new materials for protein immobilization that are non-toxic to both the body and the environment, inexpensive, readily available, and easy to modify. Currently, biodegradable and non-toxic polymers, including cellulose, are widely used for protein immobilization. Bacterial cellulose (BC) is a natural polymer with excellent biocompatibility, purity, high porosity, high water uptake capacity, non-immunogenicity, and ease of production and modification. BC is composed of glucose units and does not contain lignin or hemicellulose, which is an advantage allowing the avoidance of the chemical purification step before use. Recently, BC-protein composites have been developed as wound dressings, tissue engineering scaffolds, three-dimensional (3D) cell culture systems, drug delivery systems, and enzyme immobilization matrices. Proteins or peptides are often added to polymeric scaffolds to improve their biocompatibility and biological, physical-chemical, and mechanical properties. To broaden BC applications, various ex situ and in situ modifications of native BC are used to improve its properties for a specific application. In vivo studies showed that several BC-protein composites exhibited excellent biocompatibility, demonstrated prolonged treatment time, and increased the survival of animals. Today, there are several patents and commercial BC-based composites for wounds and vascular grafts. Therefore, further research on BC-protein composites has great prospects. This review focuses on the major advances in protein immobilization on BC for biomedical applications.

Temperature-Responsive Hydrogel for Silver Sulfadiazine Drug Delivery: Optimized Design and In Vitro/In Vivo Evaluation

Response surface methodology (RSM) was applied to optimise a temperature-responsive hydrogel formulation synthesised via the direct incorporation of biocellulose, which was extracted from oil palm empty fruit bunches (OPEFB) using the PF127 method. The optimised temperature-responsive hydrogel formulation was found to contain 3.000 w/v% biocellulose percentage and 19.047 w/v% PF127 percentage. The optimised temperature-responsive hydrogel provided excellent LCST near to the human body surface temperature, with high mechanical strength, drug release duration, and inhibition zone diameter against Staphylococcus aureus. Moreover, in vitro cytotoxicity testing against human epidermal keratinocyte (HaCaT) cells was conducted to evaluate the toxicity of the optimised formula. It was found that silver sulfadiazine (SSD)-loaded temperature-responsive hydrogel can be used as a safe replacement for the commercial SSD cream with no toxic effect on HaCaT cells. Last, but not least, in vivo (animal) dermal testing-both dermal sensitization and animal irritation-were conducted to evaluate the safety and biocompatibility of the optimised formula. No sensitization effects were detected on the skin applied with SSD-loaded temperature-responsive hydrogel indicating no irritant response for topical application. Therefore, the temperature-responsive hydrogel produced from OPEFB is ready for the next stage of commercialisation.

Development of low-cost bacterial cellulose-pomegranate peel extract-based antibacterial composite for potential biomedical applications

This study was aimed to develop low-cost bacterial cellulose (BC)-based antibacterial composite with pomegranate (Punica granatum L.) peel extract (PGPE) for potential biomedical applications. BC was cost-effectively produced by utilizing food wastes, and PGPE was ex situ impregnated into its hydrogel. Field-emission scanning electron microscopic (FE-SEM) observation showed a nanofibrous and microporous morphology of pristine BC and confirmed the development of BC-PGPE composite. Fourier transform infrared (FTIR) spectroscopy indicated the chemical interaction of PGPE with BC nanofibers. BC-PGPE composite held 97 % water of its dry weight and retained it for more than 48 h. The BC-PGPE composite exhibited better reswelling capabilities than pristine BC after three consecutive re-wetting cycles. The antibacterial activity of the BC-PGPE composite was determined via minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), disc diffusion, and plate count methods. The PGPE extract showed good antimicrobial activity against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative), both in the form of extract and composite with BC, with relatively better activity against the former. The BC-PGPE composite produced a 17 mm zone of inhibition against S. aureus, while no inhibition zone was formed against E. coli. Furthermore, BC-PGPE composite caused a 100 % and 50 % reduction in the growth of S. aureus and E. coli, respectively. The findings of this study indicate that BC-PGPE composite could be a promising antibacterial wound dressing material.

Enhanced Antimicrobial Activity of Silver Sulfadiazine Cosmetotherapeutic Nanolotion for Burn Infections

Burns are highly traumatizing injuries that can be complicated by various microbial infections, leading to morbidity and mortality. The ultimate goal of burn therapy is to prevent any microbial infection and rapid wound healing with epithelization. The current study aimed to develop and investigate the potential of nanoemulsion-based cosmetotherapeutic lotion of silver sulfadiazine (SSD) for increased antimicrobial activity to treat burn injuries. Silver sulfadiazine is the standard topical treatment for burn patients, but is allied with major limitations of poor solubility, low bioavailability, and other hematologic effects, hindering its pharmaceutical applications. The nanoformulation was fabricated through the ultrasonication technique and optimized by selecting various parameters and concentrations for the formation of water-in-oil (w/o) emulsion. The optimized formulation depicts a smaller particle size of 213 nm with an encapsulation efficiency of approx. 80%. Further, nanoemulsion-based SSD lotion by utilizing argan oil as a cosmetotherapeutic agent was prepared for scar massaging with improved permeation properties. The designed cosmeceutical formulation was characterized in terms of physical appearance, refractive index, particle size, encapsulation efficiency, and biocompatibility. The compatibility of the formulation ingredients were determined through FTIR (Fourier Transform Infrared Spectroscopy). The formulated nanolotion containing SSD demonstrated superior antimicrobial activities against different bacterial strains in comparison to commercialized burn creams.

Synergistic Antibacterial Activity of Green Synthesized Silver Nanomaterials with Colistin Antibiotic against Multidrug-Resistant Bacterial Pathogens

The high frequency of nosocomial bacterial infections caused by multidrug-resistant pathogens contributes to significant morbidity and mortality worldwide. As a result, finding effective antibacterial agents is of critical importance. Hence, the aim of the present study was to greenly synthesize silver nanoparticles (AgNPs) utilizing Salvia officinalis aqueous leaf extract. The biogenic AgNPs were characterized utilizing different physicochemical techniques such as energy-dispersive X-ray spectroscopy (EDX), ultraviolet-visible spectrophotometry (UV-Vis), X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR) analysis. Additionally, the synergistic antimicrobial effectiveness of the biosynthesized AgNPs with colistin antibiotic against multidrug-resistant bacterial strains was evaluated utilizing the standard disk diffusion assay. The bioformulated AgNPs revealed significant physicochemical features, such as a small particle size of 17.615 ± 1.24 nm and net zeta potential value of −16.2 mV. The elemental mapping of AgNPs revealed that silver was the main element, recording a relative mass percent of 83.16%, followed by carbon (9.51%), oxygen (5.80%), silicon (0.87%), and chloride (0.67%). The disc diffusion assay revealed that AgNPs showed antibacterial potency against different tested bacterial pathogens, recording the highest efficiency against the Escherichia coli strain with an inhibitory zone diameter of 37.86 ± 0.21 mm at an AgNPs concentration of 100 µg/disk. In addition, the antibacterial activity of AgNPs was significantly higher than that of colistin (p ≤ 0.05) against the multidrug resistant bacterial strain namely, Acinetobacter baumannii. The biosynthesized AgNPs revealed synergistic antibacterial activity with colistin antibiotic, demonstrating the highest synergistic percent against the A. baumannii strain (85.57%) followed by Enterobacter cloacae (53.63%), E. coli (35.76%), Klebsiella pneumoniae (35.19%), Salmonella typhimurium (33.06%), and Pseudomonas aeruginosa (13.75%). In conclusion, the biogenic AgNPs revealed unique physicochemical characteristics and significant antibacterial activities against different multidrug-resistant bacterial pathogens. Consequently, the potent synergistic effect of the AgNPs–colistin combination highlights the potential of utilizing this combination for fabrication of highly effective antibacterial coatings in intensive care units for successful control of the spread of nosocomial bacterial infections.