Nanocellulose-based antifungal nanocomposites against the polymorphic fungus Candida albicans

Trilayered nanocellulose-based patches loaded with acyclovir and hyaluronic acid for the treatment of herpetic lesions

This study focuses on the preparation of layered bacterial nanocellulose (BNC) patches for drug delivery and wound healing in the context of herpes labialis. Nanostructured patches were prepared by selective aqueous diffusion of acyclovir (ACV, antiviral drug), hyaluronic acid (HA, skin healing promoter), and glycerol (GLY, plasticizer and humectant) in the BNC network, followed by assembly into trilayered patches with ACV on the central layer of the patch (ACVT) or divided between two layers (ACVH), to modulate drug release. Both patches showed good layers' adhesion and thermal stability (125 °C), UV barrier properties, good static (Young's modulus up to 0.9 GPa (dry) and 0.7 GPa (wet)) and dynamic mechanical performance, and adhesion strength (21 kPa) comparable to or higher than other materials and commercial adhesives for wound healing. In vitro drug dissolution showed faster ACV release from the ACVH patch (77 ± 5 %, 10 min) than from the ACVT one (50 ± 7 %), suggesting efficient drug delivery. ACVH closely resembled a commercial cream formulation in terms of release and permeation profiles. The patches were non-cytotoxic toward L929 fibroblasts, promoting cell adhesion and wound closure (in vitro). These results underscore the dual-action potential of the layered patches for managing herpetic lesions.

Nanocellulose-stabilized nanocomposites for effective Hg(II) removal and detection: a comprehensive review

Mercury pollution, with India ranked as the world's second-largest emitter, poses a critical environmental and public health challenge and underscores the need for rigorous research and effective mitigation strategies. Nanocellulose is derived from cellulose, the most abundant natural polymer on earth, and stands out as an excellent choice for mercury ion remediation due to its remarkable adsorption capacity, which is attributed to its high specific surface area and abundant functional groups, enabling efficient Hg(II) ion removal from contaminated water sources. This review paper investigates the compelling potential of nanocellulose as a scavenging tool for Hg(II) ion contamination. The comprehensive examination encompasses the fundamental attributes of nanocellulose, its diverse fabrication techniques, and the innovative development methods of nanocellulose-based nanocomposites. The paper further delves into the mechanisms that underlie Hg removal using nanocellulose, as well as the integration of nanocellulose in Hg detection methodologies, and also acknowledges the substantial challenges that lie ahead. This review aims to pave the way for sustainable solutions in mitigating Hg contamination using nanocellulose-based nanocomposites to address the global context of this environmental concern.

Development of Antibacterial Resin Composites Incorporating Poly(METAC) Clusters

This study examined the antibacterial effects and physical properties of a novel resin composite incorporating poly[{2-(methacryloyloxy)ethyl}trimethylammonium chloride] (poly(METAC)), a methacrylate cationic polymer comprising quaternary ammonium compounds (QACs). Resin composites incorporating poly(METAC) were fabricated by adding 6 wt.% METAC aqueous solution to a commercially available resin composite. The FE-SEM/EDS and Raman spec-troscopy analyses showed that METAC was assembled and polymerized in the resin composites after curing. The antibacterial effect was evaluated by inoculating Streptococcus mutans or Strepto-coccus sobrinus suspensions on the surface of cured resin composites, and the experimental resin composites incorporating poly(METAC) clusters exhibited bactericidal effects even after 28 days of ageing. The physical properties of the experimental resin composites were within the ISO-stipulated ranges. Newly fabricated resin composites containing the QAC-based poly(METAC) cluster ex-hibited long-term bactericidal effects against oral bacteria on their surfaces and demonstrated ac-ceptable physical properties for clinical use.

Emerging Polymer-Based Nanosystem Strategies in the Delivery of Antifungal Drugs

Nanosystems-based antifungal agents have emerged as an effective strategy to address issues related to drug resistance, drug release, and toxicity. Among the diverse materials employed for antifungal drug delivery, polymers, including polysaccharides, proteins, and polyesters, have gained significant attention due to their versatility. Considering the complex nature of fungal infections and their varying sites, it is crucial for researchers to carefully select appropriate polymers based on specific scenarios when designing antifungal agent delivery nanosystems. This review provides an overview of the various types of nanoparticles used in antifungal drug delivery systems, with a particular emphasis on the types of polymers used. The review focuses on the application of drug delivery systems and the release behavior of these systems. Furthermore, the review summarizes the critical physical properties and relevant information utilized in antifungal polymer nanomedicine delivery systems and briefly discusses the application prospects of these systems.

Cellulose and protein nanofibrils: Singular biobased nanostructures for the design of sustainable advanced materials

Polysaccharides and proteins are extensively used for the design of advanced sustainable materials. Owing to the high aspect ratio and specific surface area, ease of modification, high mechanical strength and thermal stability, renewability, and biodegradability, biopolymeric nanofibrils are gaining growing popularity amongst the catalog of nanostructures exploited in a panoply of fields. These include the nanocomposites, paper and packaging, environmental remediation, electronics, energy, and biomedical applications. In this review, recent trends on the use of cellulose and protein nanofibrils as versatile substrates for the design of high-performance nanomaterials are assessed. A concise description of the preparation methodologies and characteristics of cellulosic nanofibrils, namely nanofibrillated cellulose (NFC), bacterial nanocellulose (BNC), and protein nanofibrils is presented. Furthermore, the use of these nanofibrils in the production of sustainable materials, such as membranes, films, and patches, amongst others, as well as their major domains of application, are briefly described, with focus on the works carried out at the BioPol4Fun Research Group (Innovation in BioPolymer based Functional Materials and Bioactive Compounds) from the Portuguese associate laboratory CICECO-Aveiro Institute of Materials (University of Aveiro). The potential for partnership between both types of nanofibrils in advanced material development is also reviewed. Finally, the critical challenges and opportunities for these biobased nanostructures for the development of functional materials are addressed.

Recent advancement in isolation, processing, characterization and applications of emerging nanocellulose: A review

The emergence of nanocellulose from various natural resources as a promising nanomaterial has been gaining interest for a wide range application. Nanocellulose serves as an excellent candidate since it contributes numerous superior properties and functionalities. In this review, details of the three main nanocellulose categorised: cellulose nanocrystal (CNC), cellulose nanofibril (CNF), and bacterial nanocellulose (BNC) have been described. We focused on the preparation and isolation techniques to produce nanocellulose including alkaline pre-treatment, acid hydrolysis, TEMPO-mediated oxidation, and enzymatic hydrolysis. The surface modification of nanocellulose through esterification, silylation, amidation, phosphorylation, and carboxymethylation to improve the diverse applications has also been reviewed. Some invigorating perspectives on the applications, challenges, and future directions on the relevant issues regarding nanocellulose are also presented.

Natural Polymers-Based Materials: A Contribution to a Greener Future

Natural polymers have emerged as promising candidates for the sustainable development of materials in areas ranging from food packaging and biomedicine to energy storage and electronics. In tandem, there is a growing interest in the design of advanced materials devised from naturally abundant and renewable feedstocks, in alignment with the principles of Green Chemistry and the 2030 Agenda for Sustainable Development. This review aims to highlight some examples of the research efforts conducted at the Research Team BioPol4fun, Innovation in BioPolymer-based Functional Materials and Bioactive Compounds, from the Portuguese Associate Laboratory CICECO–Aveiro Institute of Materials at the University of Aveiro, regarding the exploitation of natural polymers (and derivatives thereof) for the development of distinct sustainable biobased materials. In particular, focus will be given to the use of polysaccharides (cellulose, chitosan, pullulan, hyaluronic acid, fucoidan, alginate, and agar) and proteins (lysozyme and gelatin) for the assembly of composites, coatings, films, membranes, patches, nanosystems, and microneedles using environmentally friendly strategies, and to address their main domains of application.

The Application Status of Nanoscale Cellulose-Based Hydrogels in Tissue Engineering and Regenerative Biomedicine

As a renewable, biodegradable, and non-toxic material with moderate mechanical and thermal properties, nanocellulose-based hydrogels are receiving immense consideration for various biomedical applications. With the unique properties of excellent skeletal structure (hydrophilic functional groups) and micro-nano size (small size effect), nanocellulose can maintain the three-dimensional structure of the hydrogel to a large extent, providing mechanical strength while ensuring the moisture content. Owing to its unique features, nanocellulose-based hydrogels have made excellent progress in research and development on tissue engineering, drug carriers, wound dressings, development of synthetic organs, 3D printing, and biosensing. This review provides an overview of the synthesis of different types of nanocellulose, including cellulose nanocrystals, cellulose nanofibers, and bacterial nanocellulose, and describes their unique features. It further provides an updated knowledge of the development of nanocellulose-based functional biomaterials for various biomedical applications. Finally, it discusses the future perspective of nanocellulose-based research for its advanced biomedical applications.

Insight into the substrate-dependent anti-aflatoxigenic effects of nanosized ZnO film: Electron transfer directed oxidative stress mechanisms

Exploring new anti-aflatoxigenic materials and their mechanisms are critical to reduce the prevalence of drug-resistant fungi and the contamination of aflatoxins. Zinc oxide nanoparticles (ZnONPs) are promising antifungal candidates but supporting substrates generally affect their antifungal activities. In this study, ZnONPs with a three-dimensional flower-like hierarchical microstructure bound to different substrates as anti-aflatoxigenic composites were prepared using a facile deposition method. It was found that ZnO nanocomposites showed the substrate-dependent anti-aflatoxigenic activities. The antifungal activities of ZnO films toward A. flavus growth and aflatoxin B₁ production decreased significantly in the order ZnO@Zn＞ZnO@Sn＞ZnO@Steel＞ZnO@Glass. The electrical conductivity of the substrate should play an important role for antifungal response. When compared with ZnO@Sn and ZnO@Steel, the conductivity value of ZnO@Zn was 2.07-fold and 14.84-fold of them, respectively. The higher the electrical conductivity of the substrate, the better the anti-aflatoxigenic efficiency of the composite. Such anti-aflatoxigenic activity was also due to ROS generation through electron transfer between fungi and the ZnO-substrate system, which could provoke the strength of intracellular oxidative stress. This mechanism was further confirmed using several assays such as hyphal morphology analysis, Zn²⁺ release, ROS evaluation, lipid peroxidation and antioxidant response. Collectively, improvement in knowledge regarding anti-aflatoxigenic performance of ZnONPs can help develop novel and effective strategies to reduce fungi growth and aflatoxin contamination in the food field.

Synthesis, characterization, and selective dye adsorption by pH- and ion-sensitive polyelectrolyte galactomannan-based hydrogels

Three novel polyelectrolyte galactomannan hydrogels (PGHs) were fabricated by chemically crosslinking quaternary ammonium galactomannan (QAG) and carboxymethyl galactomannan (CMG), and employed for the removal of Congo Red (CR) and Methylene Blue (MB). Physicochemical characterization revealed that the PGHs are chemically and physically crosslinked. The PGHs are pH- and ion-sensitive, and their physical crosslinking can be destroyed by artificial urine; water swelling capacity (100.6-321.9 g/g dry gel) and artificial urine swelling capacity (35.9-80.5 g/g dry gel). The adsorption of CR and MB was studied and found to be pH-dependent and selective. The maximum adsorption capacities of CR and MB on the QAG and CMG gels are 1441 and 94.52 mg/g, respectively, and their adsorption kinetics and isotherm behavior obey the pseudo-second-order kinetics model and Langmuir isotherm model, respectively. The adsorption mechanism is dominated by electrostatic interactions and hydrogen bonding. Further, the PGHs have excellent salt resistance and are reusable.

Antibacterial Multi-Layered Nanocellulose-Based Patches Loaded with Dexpanthenol for Wound Healing Applications

Antibacterial multi-layered patches composed of an oxidized bacterial cellulose (OBC) membrane loaded with dexpanthenol (DEX) and coated with several chitosan (CH) and alginate (ALG) layers were fabricated by spin-assisted layer-by-layer (LbL) assembly. Four patches with a distinct number of layers (5, 11, 17, and 21) were prepared. These nanostructured multi-layered patches reveal a thermal stability up to 200 °C, high mechanical performance (Young's modulus ≥ 4 GPa), and good moisture-uptake capacity (240-250%). Moreover, they inhibited the growth of the skin pathogen Staphylococcus aureus (3.2-log CFU mL-1 reduction) and were non-cytotoxic to human keratinocytes (HaCaT cells). The in vitro release profile of DEX was prolonged with the increasing number of layers, and the time-dependent data imply a diffusion/swelling-controlled drug release mechanism. In addition, the in vitro wound healing assay demonstrated a good cell migration capacity, headed to a complete gap closure after 24 h. These results certify the potential of these multi-layered polysaccharides-based patches toward their application in wound healing.

Bioengineered chitosan-magnesium nanocomposite: A novel agricultural antimicrobial agent against Acidovorax oryzae and Rhizoctonia solani for sustainable rice production

Chitosan is a potent biopolymer having promising antimicrobial properties against phytopathogens. Recently, engineered nanomaterials (ENMs) have gained much attention due to their potential application in the plant disease management. In this study, we reported the green synthesis of chitosan-magnesium (CS-Mg) nanocomposite and its antimicrobial activity against two rice pathogens namely Acidovorax oryzae and Rhizoctonia solani for the first time. The green MgO nanoparticles synthesized by using a native Bacillus sp. strain RNT3, were used to fabricate CS-Mg nanocomposite utilizing one-pot synthesis method. The synthesis of CS-Mg nanocomposite was further confirmed by using UV-vis spectroscopy, whereas, FTIR and XRD analysis showed the capping of CS-Mg nanocomposites by different functional groups together with their crystalline structure, respectively. Besides, SEM and TEM images revealed the spherical shape along with the particles size ranging from 29 to 60 nm. Moreover, EDS analysis confirmed the elemental purity of nanocomposite. The CS-Mg nanocomposite showed remarkable antimicrobial activity against A. oryzae and R. solani and significantly inhibited the growth as compared to non-treated control. The ultrastructure studies showed damaged structure of cell wall and internal cellular organelles after treatment with 100 μg mL^-1 CS-Mg nanocomposite. The results of this study indicated that CS-Mg nanocomposite-based antimicrobial agents could be considered as promising nanopesticides against phytopathogens in plant disease management.

Multifunctional nanofibrous patches composed of nanocellulose and lysozyme nanofibers for cutaneous wound healing

Cutaneous wounds frequently require the use of patches to promote healing, nevertheless, most commercial products are fabricated with non-biodegradable synthetic substrates that pose environmental problems upon disposal. Herein, the partnership between two biobased nanofibrous polymers, namely a polysaccharide (nanofibrillated cellulose (NFC)) and a protein (lysozyme nanofibers (LNFs)), is explored to design sustainable fibrous patches with good mechanical performance and biological functionalities for wound healing applications. Two patches with different morphologies were prepared by vacuum filtration of a water-based suspension of both nanofibers and by sequential filtration of the separated suspensions (layered patch). The resultant freestanding patches exhibited high thermal stability (up to 250 °C), mechanical performance (Young's modulus ≥3.7 GPa), and UV-barrier properties. The combination of the bioactive LNFs with the mechanically robust NFC conveyed antioxidant activity (76-79% DPPH scavenging) and antimicrobial activity against Staphylococcus aureus (3.5-log CFU mL^-1 reduction), which is a major benefit to prevent microbial wound infections. Moreover, these patches are biocompatible towards L929 fibroblast cells, and the in vitro wound healing assay evidenced a good migration capacity leading to an almost complete wound occlusion. Therefore, the partnership between the two naturally derived nanofibrous polymers represents a potential blueprint to engineer sustainable multifunctional patches for cutaneous wound healing.

Flexible Nanocellulose/Lignosulfonates Ion-Conducting Separators for Polymer Electrolyte Fuel Cells

The utilization of biobased materials for the fabrication of naturally derived ion-exchange membranes is breezing a path to sustainable separators for polymer electrolyte fuel cells (PEFCs). In this investigation, bacterial nanocellulose (BNC, a bacterial polysaccharide) and lignosulfonates (LS, a by-product of the sulfite pulping process), were blended by diffusion of an aqueous solution of the lignin derivative and of the natural-based cross-linker tannic acid into the wet BNC nanofibrous three-dimensional structure, to produce fully biobased ion-exchange membranes. These freestanding separators exhibited good thermal-oxidative stability of up to about 200 °C, in both inert and oxidative atmospheres (N₂ and O₂, respectively), high mechanical properties with a maximum Young’s modulus of around 8.2 GPa, as well as good moisture-uptake capacity with a maximum value of ca. 78% after 48 h for the membrane with the higher LS content. Moreover, the combination of the conducting LS with the mechanically robust BNC conveyed ionic conductivity to the membranes, namely a maximum of 23 mS cm⁻¹ at 94 °C and 98% relative humidity (RH) (in-plane configuration), that increased with increasing RH. Hence, these robust water-mediated ion conductors represent an environmentally friendly alternative to the conventional ion-exchange membranes for application in PEFCs.

Understanding the Structure and Dynamics of Nanocellulose-Based Composites with Neutral and ionic Poly(methacrylate) Derivatives using Inelastic Neutron Scattering and DFT Calculations

Bacterial nanocellulose (BC)-based composites containing poly(2-hydroxyethyl methacrylate) (PHEMA), poly(methacroylcholine chloride) (PMACC) or poly(methacroylcholine hydroxide) (PMACH) were characterized by inelastic neutron scattering (INS) spectroscopy, combined with DFT (density functional theory) calculations of model systems. A reasonable match between calculated and experimental spectral lines and their intensities was used to support the vibrational assignment of the observed bands and to validate the possible structures. The differences between the spectra of the nanocomposites and the pure precursors indicate that interactions between the components are stronger for the ionic poly(methacrylate) derivatives than for the neutral counterpart. Displaced anions interact differently with cellulose chains, due to the different ability to compete with the O-H···O hydrogen bonds in cellulose. Hence, the INS is an adequate technique to delve deeper into the structure and dynamics of nanocellulose-based composites, confirming that they are true nanocomposite materials instead of simple mixtures of totally independent domains.

Nanocellulose-Based Patches Loaded with Hyaluronic Acid and Diclofenac towards Aphthous Stomatitis Treatment

Nanostructured patches composed of bacterial nanocellulose (BNC), hyaluronic acid (HA) and diclofenac (DCF) were developed, envisioning the treatment of aphthous stomatitis. Freestanding patches were prepared via diffusion of aqueous solutions of HA and DCF, with different concentrations of DCF, into the wet BNC three-dimensional porous network. The resultant dual polysaccharides-based patches with a nanostructured morphology present thermal stability up to 200 °C, as well as good dynamic mechanical properties, with a storage modulus higher than 1.0 GPa. In addition, the patches are non-cytotoxic to human keratinocytes (HaCaT cells), with a cell viability of almost 100% after 24 h. The in vitro release profile of DCF from the patches was evaluated in simulated saliva, and the data refer to a diffusion- and swelling-controlled drug-release mechanism. The attained results hint at the possibility of using these dual polysaccharides-based oral mucosal patches to target aphthous stomatitis.

Antimicrobial and Conductive Nanocellulose-Based Films for Active and Intelligent Food Packaging

Bacterial nanocellulose (BNC) is becoming an important substrate for engineering multifunctional nanomaterials with singular and tunable properties for application in several domains. Here, antimicrobial conductive nanocomposites composed of poly(sulfobetaine methacrylate) (PSBMA) and BNC were fabricated as freestanding films for application in food packaging. The nanocomposite films were prepared through the one-pot polymerization of sulfobetaine methacrylate (SBMA) inside the BNC nanofibrous network and in the presence of poly(ethylene glycol) diacrylate as cross-linking agent. The ensuing films are macroscopically homogeneous, more transparent than pristine BNC, and present thermal stability up to 265 °C in a nitrogen atmosphere. Furthermore, the films have good mechanical performance (Young's modulus ≥ 3.1 GPa), high water-uptake capacity (450-559%) and UV-blocking properties. The zwitterion film with 62 wt.% cross-linked PSBMA showed bactericidal activity against Staphylococcus aureus (4.3-log CFU mL-1 reduction) and Escherichia coli (1.1-log CFU mL-1 reduction), and proton conductivity ranging between 1.5 × 10-4 mS cm-1 (40 °C, 60% relative humidity (RH)) and 1.5 mS cm-1 (94 °C, 98% RH). Considering the current set of properties, PSBMA/BNC nanocomposites disclose potential as films for active food packaging, due to their UV-barrier properties, moisture scavenging ability, and antimicrobial activity towards pathogenic microorganisms responsible for food spoilage and foodborne illness; and also for intelligent food packaging, due to the proton motion relevant for protonic-conduction humidity sensors that monitor food humidity levels.

Zwitterionic Nanocellulose-Based Membranes for Organic Dye Removal

The development of efficient and environmentally-friendly nanomaterials to remove contaminants and pollutants (including harmful organic dyes) ravaging water sources is of major importance. Herein, zwitterionic nanocomposite membranes consisting of cross-linked poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and bacterial nanocellulose (BNC) were prepared and tested as tools for water remediation. These nanocomposite membranes fabricated via the one-pot polymerization of the zwitterionic monomer, 2-methacryloyloxyethyl phosphorylcholine, within the BNC three-dimensional porous network, exhibit thermal stability up to 250 °C, good mechanical performance (Young's modulus ≥ 430 MPa) and high water-uptake capacity (627%-912%) in different pH media. Moreover, these zwitterionic membranes reduced the bacterial concentration of both gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) pathogenic bacteria with maxima of 4.3- and 1.8-log CFU reduction, respectively, which might be a major advantage in reducing or avoiding bacterial growth in contaminated water. The removal of two water-soluble model dyes, namely methylene blue (MB, cationic) and methyl orange (MO, anionic), from water was also assessed and the results demonstrated that both dyes were successfully removed under the studied conditions, reaching a maximum of ionic dye adsorption of ca. 4.4-4.5 mg g-1. This combination of properties provides these PMPC/BNC nanocomposites with potential for application as antibacterial bio-based adsorbent membranes for water remediation of anionic and cationic dyes.