Search Results (669)

Photocatalytic membrane reactors (PMRs) are an innovative technology for water treatment, effectively combining membrane filtration and photocatalysis to enhance contaminant removal while enabling the regeneration of fouled membranes. In this study, a new porous film of chitosan that was impregnated with TiO₂ was developed and coated onto a ceramic support by spin coating to form a new porous immobilized PMR. The formed membrane was tested for two reasons: the removal of methylene blue dye by a dead-end filtration process and to demonstrate its ability to self-regenerate under UV exposure. The selective layer of the membrane was characterized using FTIR spectroscopy, X-ray diffraction, scanning electron microscopy (SEM), and water permeability tests. The results confirmed the formation of an amorphous film with no chemical interaction between chitosan and TiO₂. The membrane exhibited an average water permeability of 10.72 L/m²·h·bar, classifying it as either ultrafiltration (UF) or nanofiltration (NF). Dead-end filtration of methylene blue (10 mg L⁻¹) achieved 99% dye removal based on UV–vis analysis of the permeate, while flux declined rapidly due to fouling. Subsequent UV irradiation removed the deposited dye layer and restored approximately 50% of the initial flux, indicating partial self-regeneration. Overall, spin-coated chitosan–TiO₂ layers on ceramic supports provide high dye removal and photocatalytically assisted flux recovery, and further work should quantify photocatalytic degradation during regeneration. Full article

Infected wounds form a complex microenvironment that creates difficulties for drug delivery. In this study, a composite fiber membrane based on polyethylene oxide (PEO) was prepared. The intention was to achieve on-demand drug release and integrate multiple functions by adjusting the material composition. The membrane uses PEO as the main framework and contains chitosan (CS) and ascorbic acid (Asc). CS leads to an increase in fiber diameter, while Asc makes the fibers thinner. The two components act together to influence the microstructure. In vitro drug release experiments showed that changing the CS content in the PEO matrix can affect the initial release rate and the duration of sustained release. The membrane also shows sensitivity to pH. Under slightly acidic conditions, drug release becomes faster, which is similar to the state of infected wounds. In addition, the membrane maintains antioxidant activity and can inhibit Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). These results suggest that PEO-based composite fibers may be useful in drug delivery and tissue repair. Full article

An optical fiber chemical sensor using a molecularly imprinted chitosan membrane coated on the surface of a bent optical fiber probe was developed for selectively analyzing 4-nitrophenol (4-NP) in water samples. When the sensor probe is exposed to a water sample, the chitosan MIP membrane extracts/concentrates 4-NP from the water sample into the membrane. The 4-NP extracted into the membrane was detected by passing a light beam through the optical fiber and the interaction of the 4-NP in the membrane with an evanescent wave of light guided through the optical fiber was detected as a sensing signal. This sensor detects the intrinsic optical absorption signal of 4-NP itself as a sensing signal. No chemical reagent was needed in analyzing this compound in a sample. The sensor is reversible, can be used for continuous monitoring of 4-NP in a sample, and has a quick response with a response time of 5 min. The sensor has high sensitivity and selectivity because the MIP membrane selectively concentrates 4-NP by 1.4 × 10⁴ times into the membrane from a sample solution, but blocks out interference species, including its isomers and derivatives, from entering the membrane. The sensor achieved a detection limit of 2.5 ng/mL (0.018 µM), which is lower than most reported analytical techniques for analyzing this compound in water samples. This sensor can discriminate 4-NP from its isomers and derivatives, such as 2-NP, 3-NP, 2-Cl-4-NP, and 2,4-di-NP, with a selectivity factor ranging from 104 to 1922. This is the first reported case of an MIP-based optical fiber chemical sensor with the capability of discriminating an organic compound from its closely related positional isomers, which demonstrates the high selectivity nature of the MIP-based optical fiber chemical sensor technique. The sensor has been used for analyzing 4-NP in a standard addition sample. The obtained recovery rate ranged from 93% to 101%, demonstrating the application potential of this sensor in water quality analysis. Full article

Polymeric membranes based on chitosan (Cs) were extracted from shrimp shells and evaluated. These membranes were modified using polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), and glycerol (Gly) and crosslinked with glutaraldehyde (GA) to examine their suitability for water filtration processes. The Cs exhibited high purity, a total nitrogen content of 6.49%, and an average molecular weight of 456 kDa, all of which are suitable for membrane formation. Four membranes (Cs-GA, B2: Cs-PEG, B5: Cs-PEG-PVP, and B7: Cs-Gly) were characterized by means of FTIR, SEM, AFM, thickness, contact angle, tensile testing, TGA, DSC, and filtration with distilled water at 4.83 bar. B2 and B5 showed thicknesses of 207 and 190 μm and contact angles of 56.7° and 58.9°, lower than that of Cs-GA (89.4°). In filtration, B2 achieved a flux of 2222.70 LMH, a permeance of 460.19 LMH·bar⁻¹, and a hydraulic resistance of 8.79 × 10¹¹ m⁻¹, while Cs-GA, B5, and B7 exhibited fluxes of 24.10, 40.43, and 24.77 LMH, respectively, permeances of 9.75, 8.37, and 5.13 LMH·bar⁻¹, and hydraulic resistances of 4.15 × 10¹³, 4.83 × 10¹³, and 7.89 × 10¹³ m⁻¹, in the same order. Overall, membranes B2 and B5 are recognized as the most promising for water filtration under pressured operating conditions. Full article

Seawater has attracted increasing attention as a promising resource for hydrogen production via electrolysis. However, multivalent ions present in seawater can reduce the efficiency of direct seawater electrolysis (DSWE) by forming inorganic precipitates at the cathode. Bipolar membranes (BPMs) can mitigate precipitate formation by regulating local pH, thereby enhancing DSWE efficiency. Accordingly, this study focuses on the fabrication of a high-performance BPM for DSWE applications. The water-splitting performance of BPMs is strongly dependent on the properties of the catalyst at the bipolar junction. Herein, iron oxide (Fe₃O₄) nanoparticles were coated with cross-linked chitosan to improve solvent dispersibility and catalytic activity. The resulting core–shell catalyst exhibited excellent dispersibility, facilitating uniform incorporation into the BPM. Water-splitting flux measurements identified an optimal catalyst loading of approximately 3 μg cm⁻². The BPM containing Fe₃O₄–chitosan nanoparticles achieved a water-splitting flux of 26.2 μmol cm⁻² min⁻¹, which is 18.6% higher than that of a commercial BPM (BP-1E, Astom Corp., Tokyo, Japan). DSWE tests using artificial seawater as the catholyte and NaOH as the anolyte demonstrated lower cell voltage and stable catholyte acidification over 100 h compared to the commercial membrane. Full article

Microbial fuel cells (MFCs) offer a sustainable solution for energy generation and wastewater treatment, yet their scalability is hindered by reliance on expensive and non-renewable synthetic membranes. This study addresses the critical need for eco-friendly alternatives by conducting a bibliometric analysis of biopolymers used in MFC membrane development. Using data from Scopus and Web of Science (2012–2025), we applied quantitative and network-based methods to evaluate publication trends, collaboration patterns, and thematic evolution. The analysis identified chitosan, alginate, and cellulose as the most studied biopolymers due to their favorable proton conductivity, biodegradability, and potential for waste-derived production. Key findings include a surge in research output post-2018, strong interdisciplinary collaboration across materials science and microbiology, and emerging interest in nanomaterial integration and 3D printing for membrane enhancement. Despite promising advances, challenges persist with regard to the mechanical stability and standardization of fabrication methods. This study provides a strategic overview of the field, highlighting scientific progress and guiding future research toward scalable, high-performance biopolymer membranes for MFCs applications. Full article

Membrane electrolytes play a critical role in energy conversion devices. The development of stable, efficient membrane electrolytes is urgent and demands paramount attention for the successful commercialization of fuel cells. Chitosan, a naturally occurring material, and silica particles were used as precursors for organic–inorganic membrane polymers. The silica nanoparticles were prepared by the sol–gel and Stober methods and characterized using various techniques, including XRD, FTIR, etc. The silica-incorporated membranes show improved properties, with the sulfur-functionalized membranes having optimal proton conductivity, ion-exchange capacity, and tensile strength of 0.0238 S/cm, 2.86 meq/g, and 7.3 MPa, respectively. It also showed the lowest methanol permeability. This was clear proof that membrane functionalization has a positive impact on tuning the properties of electrolyte membranes and should be further explored in membrane development. Full article

The search for alternatives to animal testing in cosmetics has encouraged the development of in vitro systems capable of evaluating formulation-driven biophysical parameters assessed on human skin. This study presents a cell-free tri-layered chitosan membrane as a material-based model for characterizing the physicochemical anti-aging performance of topical formulations. Three cosmetic products were incorporated either in the top layer (1L_(t)) or across all layers (3L), and key parameters—including pore area, water permeation, firmness, elasticity, swelling and moisture retention—were quantified. VitCOil produced consistent effects across configurations, reducing pore area by 52–56% and decreasing water permeation by 54–61%, while increasing moisture retention by 36–38%. OilSerum showed a marked layer-dependent response, enhancing swelling by +70% in 3L and +35% in 1L_(t), and increasing water permeation by 16% (3L) and 4% (1L_(t)). EyeCr improved firmness and elasticity at low concentration, with stronger elastic response in the top layer (+27% in 3L; +34% in 1L_(t)). Overall, this novel platform strengthens early-stage physicochemical screening by linking formulation-dependent mechanisms with directional biophysical trends observed clinically. Full article

To enhance the antibacterial properties of chitosan, this study employed papain as a biocatalyst to graft nisin onto chitosan, yielding two grafted products with grafting ratios of 8.56% (Ni1-Cs) and 14.35% (Ni2-Cs). Structure analyses confirmed the formation of amide bonds. Grafting significantly improved the solubility (92.4%), water absorption (53.4%), and film-forming properties of chitosan, with Ni1-Cs films achieving a tensile strength of 25.2 MPa. Antibacterial assays demonstrated that nisin retained favorable activity post-grafting and exhibited synergistic effects with chitosan. The minimum inhibitory concentrations (MIC) of Ni2-Cs against Escherichia coli and Staphylococcus aureus were 132.4 and 97.4 μg/mL, respectively, significantly superior to individual components. The ultra-low-temperature enzymatic method likely preserved nisin’s structural integrity. Mechanistic studies revealed that the cationic nature of chitosan and the pore-forming mechanism of nisin synergistically disrupted bacterial cell membranes. Sea bass preservation trials confirmed that Ni2-Cs coatings effectively retarded quality deterioration, inhibited microbial growth and lipid oxidation, and maintained freshness for 15 days. This study demonstrates that the ultra-low-temperature enzymatic strategy successfully prepared nisin-grafted chitosan materials with synergistic antibacterial effects, showing promising applications for food preservation. Full article

Foot and mouth disease is a contagious viral disease infecting ungulates, with great economic impact on farmers’ income; it is primarily controlled using inactivated vaccines, which have certain limitations, such as short-lived immunity and a lack of mucosal immunity at the portals of virus entry. The present approach aims to exploit the efficiency of chitosan nanoparticle-encapsulated inactivated type ‘O’ FMDV antigen (FMDV-CS-NPs) to induce mucosal and systemic immune responses in a guinea pig animal model through intranasal and intramuscular administration in comparison with the conventional inactivated, mineral oil-adjuvanted vaccine that is administered systemically. In this study, the FMDV-CS-NPs were prepared by ionotropic gelation, followed by incubation; were characterized for their physical properties and in vitro antigen release; and were found to encapsulate a good amount of antigen. The prepared nanoparticles were assessed for their ability to induce humoral and cell-mediated immune responses by SNTs; indirect ELISAs for serum IgG, IgG1, and IgG2; and nasal washing sIgA and lymphocyte proliferation assays. The preparation induced comparatively more measurable sIgA and systemic immune responses with the intranasal and intramuscular routes of administration, respectively, which are attributable to a specific interaction between the positively charged chitosan and the negatively charged mucosal surface and cell membrane. The challenge infection protected 87.5% of the animals in the FMDV-CS-NP I/M group, followed by 77.7% in the FMDV-CS-NP I/N and inactivated vaccine groups. The outcomes of this study in guinea pigs highlight that chitosan nanoparticle-based vaccine formulations could be employed as a promising antigen delivery system for targeted delivery, devoid of any adverse effect, to induce protective immune responses. Full article

Background: Biofilm-associated infections remain a major challenge in modern medicine due to their high resistance to antibiotics and immune defences. Advances in materials science, chemistry, and nanotechnology have led to the development of innovative, non-antibiotic approaches to prevent or eradicate biofilms. Methods: This review summarises antibiofilm strategies reported between 2020 and 2025, grouped into chemical, enzymatic, physical–photonic, nanomaterial-based, and biological hybrid categories. Results: Chemical methods such as silver-based chemical systems, nitric oxide donors, and biosurfactants disrupt bacterial membranes, generate reactive oxygen species, and inhibit quorum sensing. Enzymatic coatings with DNase I or lysostaphin effectively reduce Staphylococcus aureus and S. epidermidis biofilms, showing stability after sterilisation and high biocompatibility. Physical–photonic techniques, including photocatalytic and light-activated coatings, provide controllable and renewable antibacterial activity. Nanomaterials such as silver nanomaterials, chitosan-based carriers, magnetic ferrites, and catalytic nanozymes enable targeted, ROS-mediated biofilm disruption. Biologically derived systems, including bacteriophage hydrogels and plant metabolites, offer eco-friendly, biocompatible alternatives. Conclusions: Recent antibiofilm innovations mark a transition from conventional antibiotics to multifunctional and adaptive systems integrating chemical, enzymatic, and physical mechanisms for effective biofilm control on medical surfaces. Full article

This study presents the fabrication and performance analysis of multilayer membranes produced by electrospinning using polyacrylonitrile (PAN), chitosan (CS), and Nylon 6 (N6) for the removal of chromium (Cr) and cadmium (Cd) from water. The electrospun membranes were configured in six different multilayer structures. The morphological and mechanical properties of the membranes were evaluated using SEM and tensile testing. Adsorption experiments were performed using synthetic and real water samples from the Cutuchi River. The multilayer membranes demonstrated metal ion removal efficiencies up to 80.81% for ${\mathrm{Cr}}^{6+}$ and 78.98% for ${\mathrm{Cd}}^{2+}$ in synthetic water, and similar performance in real samples. These results validate the use of multilayer electrospun membranes as an effective, environmentally friendly method for water purification applications. Full article

Carbon membranes have emerged as a promising class of inorganic membranes for desalination due to their tunable pore structures, superior chemical and thermal stability, and molecular-sieving properties. In pursuit of sustainability, recent research has shifted focus towards replacing petrochemical-based precursors with renewable natural polymers. This review provides a comprehensive examination of the fundamentals, developments, and prospects of carbon membranes derived from natural polymer precursors—such as cellulose, chitosan, lignin, starch, and sugars—specifically for pervaporation desalination. It begins by summarizing the fundamentals of membrane separation and the mechanisms of carbon membrane formation, emphasizing the critical relationships between precursor structure, carbonization conditions, and the resulting membrane performance. The core of the review is dedicated to a detailed analysis of various natural polymer precursors, discussing their unique chemistries, carbonization behaviors, and the characteristics of the derived carbon membranes. Particular attention is given to their application in pervaporation desalination, where they demonstrate competitive water flux and high salt rejection (>99%) under moderate operating conditions, highlighting their potential for treating hypersaline brines. Finally, the challenges of large-scale fabrication, structural durability, and data-driven optimization are discussed, along with future directions toward scalable and sustainable membrane technologies. Full article

Biodegradable chitosan/poly(vinyl alcohol) (PVA) composite films were reinforced either with nanocrystalline cellulose (CNC) or nano-lignocellulose (NLC) and evaluated across a polyparametric design of five matrix ratios and three filler levels for active food packaging applications. ATR-FTIR, DSC, XRD, and SEM demonstrated that 1–5% nanocellulose loading induced a single relaxation temperature (T_g), homogenized the morphology, and enhanced the crystallinity of blend material, evidencing improved thermodynamic compatibility. SEM confirmed uniform filler dispersion up to 5% loading in PVA-rich matrices, whereas limited aggregation appeared in chitosan-dominant systems. CO₂ barrier property (CO₂ permeability coefficients) was diminished by more than two orders of magnitude and fell below 0.01 Barrer in CNC-filled 25-75 and NLC-filled 75-25 blends, while permeability to O₂ and N₂ remained undetectable under identical conditions. Meanwhile, Young’s modulus increased to 3.9 GPa, and tensile strengths of up to 109 MPa were achieved, without affecting the ductility in specific loading values. These data confirm that tailored selection of the filler/matrix combination, rather than elevated nanocellulose content, can simultaneously optimize barrier performance and mechanical integrity. The study therefore offers a scalable, water-based route for producing optically transparent nanocomposite membranes that satisfy either strict modified atmosphere or/and rigid packaging applications and advance the transition toward compostable/or even edible high-performance food contact materials. Full article

This article provides a comparative analysis of sustainable polymer membranes based on biopolymers and Nafion in the context of proton exchange membrane (PEM) for water electrolyzers. Nafion, a perfluorinated polymer, has been a standard choice for PEM applications due to its excellent proton conductivity and chemical stability. However, the sustainability challenges associated with its production, lifecycle and cost necessitate the exploration of alternative materials that may offer comparable performance while being environmentally friendly. The most promising alternative polymer for PEM electrolyzers appears to be cellulose with good thermal stability at 200 °C and a water absorption of 35%, which is slightly higher compared to Nafion membranes with a water absorption value of around 30%. Sustainable PEMs also have much lower hydrogen permeability, e.g., chitosan has been determined to have a permeability of 7 barrers, while Nafion is characterized by a value of more than 100 barrers. The biggest drawbacks of sustainable membranes are proton conductivity and durability, where Nafion membranes are still superior. This review also focuses on mechanical properties, chemical resistance, preparation methods and cost-effectiveness. Sustainable polymers show promising properties for supporting efficient hydrogen production, especially in dynamic operating environments facilitated by renewable energy sources. Full article