Search Results (445)

Sodium alginate (SA)-modified shellac nanoparticles were developed as pH-responsive carriers for cinnamon essential oil (CEO) encapsulation in aquatic product preservation. Three polyelectrolytes (SA, chitosan (CS), gelatin (Gel)) were evaluated at concentrations of 0.025–0.3% (w/v). Under pH conditions simulating spoilage (6.0–7.5), SA-SNPs exhibited superior stability with minimal changes in particle size, PDI, and zeta potential, while CS and Gel systems aggregated near their pKa values. At 0.1% SA, CEO-loaded nanoparticles (SA-SCNPs) showed excellent properties: small size (160 nm), high encapsulation efficiency (90%), and pH-triggered release (77.76% at pH 7.0 via Ritger–Peppas kinetics, n = 0.58). FT-IR confirmed ionic and hydrogen bonding between the SA and shellac. SA-SCNPs enhanced antibacterial efficacy against Shewanella putrefaciens and Pseudomonas fluorescens and maintained stability under ionic strength (300 mmol/L NaCl) and temperature variations (−18 °C to 25 °C), attributed to SA’s cryo-resistance and steric effects. This system offers a smart delivery platform for aquatic preservation. Full article

Wastewater contamination by toxic heavy metal ions poses a huge threat to ecosystem integrity and human health. Herein, we designed a polyelectrolyte (T-PEI) with a tunable positive charge property to construct a layer-by-layer (LBL) nanofiltration membrane for efficient heavy metal ion removal. The T-PEI was obtained via a Mannich reaction between polyethyleneimine (PEI) and tetrakis (hydroxymethyl) phosphonium chloride (THPC). The introduction of THPC imparted T-PEI with a strong and tunable positive charge, attributed to the quaternary phosphonium groups in THPC. Converting the weakly charged PEI into the strongly charged T-PEI allowed regulation of both T-PEI’s deposition behavior and the electrostatic interactions with sodium polystyrenesulfonate (PSS) during LBL assembly. As a result, after depositing only one bilayer, the positively charged PSS/T-PEI membrane achieved a pore size radius of 0.35 nm, meeting the typical criteria for nanofiltration membranes. Under the optimal preparation conditions, the resultant membranes exhibited a water flux of 38.1 L m⁻² h⁻¹ and high rejections to various heavy metal ions at low operation pressure, such as Cr³⁺ (99.8%), Ni²⁺ (96.1%), Cu²⁺ (92.5%), and Mn²⁺ (90.3%). Additionally, the membrane possessed robust operation stability, along with excellent antifouling/bacterial performance. After cyclic filtration of a lysozyme solution, the flux recovery ratio reached 94.7%. The membrane also exhibited effective bactericidal activity against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with no visible microbial colonies observed. This work highlights the effectiveness of tailoring polyelectrolyte characteristics in enhancing the LBL membrane performance and presents a promising LBL nanofiltration membrane for heavy metal ion removal. Full article

The development of sustainable plant protection strategies requires stable and environmentally compatible delivery systems for beneficial microorganisms. In this study, Bacillus subtilis was encapsulated within chitosan-based cast films to evaluate bacterial viability, sustained biological activity, and antifungal efficacy. Films prepared from chitooligosaccharide (COS) and chitosans of low, medium, and high molecular weight (CS-LMW, CS-MMW, CS-HMW) were characterized in terms of morphology, mechanical performance, and pH-dependent swelling behavior. The viscosity of the chitosan solutions increased markedly with molecular weight from 73 cP (COS) to 614 cP (CS-HMW), while film thickness ranged from 34 ± 1.5 to 57 ± 2.3 µm. Mechanical performance improved significantly with increasing molecular weight, with maximum tensile stress exceeding 200 MPa for CS-HMW films, while swelling studies confirmed pronounced pH-dependent behavior consistent with the polyelectrolyte nature of chitosan. Encapsulation effectively preserved bacterial viability and metabolic activity over time. The intrinsic antifungal activity of chitosan synergized with the biocontrol activity of B. subtilis against Fusarium avenaceum and Alternaria solani. The highest antifungal performance was observed for CS-HMW films, which produced inhibition zones up to 84.6 ± 5.0 mm against A. solani. These findings demonstrate that chitosan-based cast films serve as effective carriers for beneficial microorganisms, providing environmental protection and regulated biological activity. The combination of a bioactive polymer matrix with a potent biocontrol agent represents a promising eco-friendly approach to sustainable plant protection. Full article

Brown algae are a valuable source of bioactive secondary metabolites, particularly polyphenols and sulfated polysaccharides with photoprotective and antioxidant activities. Among them, fucoidan stands out for its biocompatibility, biodegradability, and demonstrated photoprotective effects, mainly through antioxidant and anti-photoaging properties, making it a promising natural component for UV-protective formulations. This study developed polyelectrolyte complex sub-micron particles based on fucoidan and chitosan (F/Cs) to encapsulate quercetin (Q) as a natural UV-active antioxidant. Fucoidan from Sargassum filipendula was extracted and fractionated by ultrafiltration. An RCBD was used to optimize pH and F/Cs mass ratio. The optimal blank formulation (F/Cs = 1:1, pH 5.0) yielded sub-micron colloidal carriers with a mean hydrodynamic diameter of 421 ± 23 nm (PDI 0.252 ± 0.059) with ζ = +43.5 ± 1.6 mV. Quercetin-loaded particles (F/Cs/Q = 1:1:0.5) presented 915 ± 87 nm (PDI 0.278 ± 0.093) and ζ = +54.6 ± 1.2 mV. UV–Vis spectra evidenced UVB and partial UVA absorption for fucoidan and broad UVA/UVB coverage for quercetin, preserved upon encapsulation. Antioxidant activity was retained post-encapsulation (EC50, DPPH: 0.094 mg/mL; ABTS: 0.0749 mg/mL). These results demonstrate the potential of fucoidan–chitosan colloidal systems as multifunctional, biodegradable carriers for natural photoprotective agents, supporting their application in next-generation dermatological and cosmeceutical formulations. Full article

Polyelectrolyte microcapsules (PMCs) fabricated by layer-by-layer assembly require predictable shell stability for applications in drug delivery, biosensing, and environmental remediation. While core template type is known to influence stability, the role of polyelectrolyte layer number in governing poly(allylamine hydrochloride) (PAH) desorption remains poorly understood. This study quantitatively assessed PAH desorption from fluorescein isothiocyanate (FITC)-labeled shells of PMCs templated on CaCO₃ or MnCO₃ cores with 7, 9, or 13 layers under varying ionic conditions (distilled water, NaCl 0.2–3.0 M, Na₂SO₄ 0.005–1 M) over 168 h. Short-term incubations revealed no significant layer-dependent desorption differences for either core type. However, prolonged exposure uncovered a non-monotonic relationship for CaCO₃-templated PMCs: 7-layer capsules exhibited high initial but limited subsequent release (<50% increase), 9-layer capsules showed minimal initial dissociation followed by maximal kinetic amplification (up to 2000% increase), and 13-layer capsules displayed intermediate behavior. In contrast, MnCO₃-templated PMCs demonstrated uniformly low initial dissociation with gradual time- and concentration-dependent release irrespective of layer number. These findings establish core template nature as the dominant factor controlling dissociation kinetics, while layer number enables fine-tuning of release profiles—particularly for CaCO₃ systems—providing design principles for controlled-release applications requiring delayed or sustained payload delivery. Full article

Polysaccharide-based nanocarriers offer a novel delivery system for improving the stability, controlled release, and biological functionality of plant-derived bioactive materials. Olive leaf extract (OLE), rich in polyphenolic compounds with antioxidant and other bioactive properties, is limited by low stability and bioavailability. In this study, OLE-loaded alginate–chitosan nanoparticles were prepared using ionotropic gelation–polyelectrolyte complexation (IG-PEC) method, and their physicochemical properties, cytotoxic behavior, and potential prebiotic effects were evaluated. The resulting nanoparticles (232–237 nm) exhibited uniform spherical morphology, negative zeta potentials, and improved colloidal stability. Free OLE demonstrated concentration-dependent and selective cytotoxicity toward A549 and MCF-7 cancer cells, while exhibiting lower toxicity toward normal fibroblasts. In contrast, unloaded and OLE-loaded nanoparticles (1X, 2X) showed low cytotoxicity, suggesting superior biocompatibility of the polysaccharide nanocarrier. Notably, cultures supplemented with OLE-loaded nanoparticles showed a trend toward higher probiotic growth compared to free OLE, indicating a potential prebiotic effect and improved microbial tolerance to polyphenols during extended exposure. These findings highlight the advantages of polysaccharide-based nanoencapsulation for both stabilizing bioactive materials and supporting favorable microbial responses. The developed OLE nanocarriers may serve as a promising platform for nutraceutical, biomedical, and functional food applications. Full article

This study builds on previous research into the surface modification of beech wood with polyethyleneimine (PEI) prior to finishing it with a waterborne coating. Poly(diallyldimethylammonium chloride) (PDADMAC) is introduced as an alternative cationic polyelectrolyte for the pretreatment of beech wood surfaces. Wood samples were treated with aqueous 1% PDADMAC solutions of low (LMW—8000 g mol⁻¹) and high (HMW—100,000–200,000 g mol⁻¹) molecular weights, with or without NaCl addition. The effects of the treatments on wood surface chemistry, wettability, surface energy, water absorption, coating penetration, coating adhesion strength, and surface roughness of coated wood were analysed using FTIR, fluorescence microscopy, SEM/EDS, and standardised tests commonly used in wood surface finishing. The results showed that polyelectrolyte pretreatment modified the surface properties of wood, reducing water absorption and surface roughness without significantly affecting coating adhesion strength. PDADMAC formed a more uniform surface layer of wood with limited coating penetration, and NaCl addition improved wood surface smoothness (reducing surface roughness parameters of coated wood by 23%–29%, in samples treated with PDADMAC LMW with 0.01 M NaCl). These findings confirm that cationic polyelectrolyte pretreatment enhances the compatibility and performance of waterborne coatings, offering an environmentally friendly approach to improving wood–waterborne coating interactions. Full article

This article investigates the thermodynamic driving force of the interaction between lysozyme (Lys) and sulfated β-cyclodextrin (β-CDS), with a particular emphasis on the elusive role of hydration during polyelectrolyte–protein binding. Using isothermal titration calorimetry (ITC), the binding affinity was quantified across varying temperatures and salt concentrations, employing a recently developed thermodynamic framework that explicitly separates the contributions from counterion release and hydration effects. The study reveals that while counterion release is minimal in the Lys/β-CDS system, hydration effects become a dominant factor influencing the binding free energy ΔG_b, especially as experimental temperature deviates from the characteristic temperature T₀. It demonstrates that hydration contributions can substantially weaken binding at increased salt concentration c_s. The high characteristic temperature T₀ and the salt-dependent heat capacity change indicate a complex interplay of water structure and ion association—significantly departing from commonly linear interpretations of ΔG_b vs. log c_s based solely on counterion release effects. This work advances the understanding of polyelectrolyte–protein interactions by providing the first direct quantification of the hydration effect in such complexes and may have an impact on the rational design of biomolecular assemblies and therapeutic carriers. Full article

Monogenean parasite infestation in fish leads to economic losses in aquaculture, representing a veterinary challenge and an environmental concern. The common administration procedures of anthelmintics to treat monogeneans in fish have low efficiency and diverse drawbacks. In this study, we produced a nanoparticle using chitosan and alginate, biodegradable and biocompatible polysaccharides, as an oral drug delivery material of albendazole anthelmintic for parasite-infected fingerlings of Nile tilapia. The molecular interaction between the biopolymers was optimized and characterized by titration calorimetry. Freeze-drying of nanoparticles resulted in a fine powder with a particle size in the order of 400 nm. The nanoparticles provided 98% encapsulation of albendazole and sustained delivery with predominantly Fickian diffusion. The palatability of the nanoparticle formulation facilitated the oral administration of albendazole. The treatment of 100% prevalence of monogeneans was effective with a six-day dosage providing a total of 915 mg/kg b.w. of drug, resulting in total parasite clearance after 10 days from the treatment beginning, evidenced by microscopy analysis, and no mortality occurred. Therefore, molecular interactions between biofriendly polyelectrolytes yielded albendazole-carrying nanoparticles for high-efficiency parasite treatment in fish farming. Full article

Water-soluble poly-β-cyclodextrins (PCDs), crosslinked with ethylenediaminetetraacetic acid dianhydride (EDTADA), were synthesized at varying β-CD:EDTADA molar ratios (1:6, 1:9, 1:12, 1:15) to develop multifunctional nanocarriers with the ability to complex drugs, polymers, and ions. All PCDs exhibited nanometric particle sizes (14 to 28 nm), negative zeta potential (−18 to −27 mV), and adjustable content of free carboxyl groups controlled by crosslinker ratio. Functional evaluations demonstrated effective Ca²⁺ chelation and a linear inclusion complexation profile with acyclovir, but not with naproxen, highlighting pH-dependent solubility effects. Additionally, PCDs successfully formed polyelectrolyte complexes with poly-L-lysine, indicating their potential as components of advanced drug delivery systems. Among the analyzed variants, PCD 1:6 showed reduced yields, fewer reactive groups, and diminished ion-binding capacity compared to formulations with higher crosslinker content. These findings underscore the importance of crosslinking density in modulating physicochemical and functional properties and support the potential of EDTA-crosslinked PCDs as versatile platforms for advanced, ion-sensitive biomedical applications. Full article

Dewatering of sewage sludge is a key operational element of wastewater treatment plants and has major economic implications, as it entails the costs of thickening, transport, and disposal. The aim of this study was to determine the influence of selected polyelectrolytes and their dosages on dewatering efficiency and to present an innovative, multicriteria method of result evaluation using radar charts. In this research, 10 different polyelectrolytes were assessed in terms of sludge dewaterability, considering conditioning parameters including Specific Resistance to Filtration (SRF), Capillary Suction Time (CST), and centrifugation performance. The results were presented in the form of radar charts, enabling both an overall evaluation of the effectiveness of each product and an assessment of their suitability for specific dewatering technologies, such as belt filter presses and centrifuges. The analysis showed that polyelectrolytes with higher cationic charge provided better dewatering performance. The proposed visualization method allows us to analyze the effects across different conditioners and technologies. The best sludge conditioning effect (maximum radar chart area) was achieved with Praestol 665, a polyelectrolyte with a high cationic charge level. This method is a practical tool for selecting the optimal agent for sewage sludge dewatering. Full article

Alginate [ALG] and chitosan [CS] are biomaterials of importance in drug-delivery because of their ability to form ionically-crosslinked nanosystems and polyelectrolyte-complexes under mild conditions. Here, a modified ionic-polyelectrolyte-pre-gelation method, with a controlled addition of reagents and sonication throughout the process, is reported to produce ALG¬¬-CS-based NPs. A mathematical study of the effects of the factors with influence in the process on the properties of NPs has been performed using a two-phase-design-of-experiment-based procedure, something never done to our knowledge. The concentration of ALG, CS and CaCl₂ and the ratio ALG:CS have significant influence on polydispersity (PDI), surface-charge (ZP) and encapsulation efficiency (EE%) of NPs. Moreover, CS flow rate has a significant effect over PDI and EE%. Thus, the values of ALG, CS and CaCl₂ concentration (mg/mL), ALG:CS (mL:mL) and CS flow rate (mL/min) to obtain the minimum-expected PDI (0.168) or the optimized EE% (86.7) are {0.30, 0.79, 1.00, 2.50:1.00, 0.86} or {0.30, 1.00, 1.00, 2.50:1.00, 2.00}, with ALG:CaCl₂ (mL:mL) and CaCl₂ flow rate (mL/min) fixed at 2.50:0.31 and 1.25. Although most of the conditions yielded highly-negative particles (minimum-expected of −67.8 mV using 0.69, 0.30 and 0.13 mg/mL of ALG, CS and CaCl₂ and ALG:CS of 2.50:0.59 mL:mL), varying the mass ratio of ALG:CS allowed for the generation of positively-charged particles (up to +21.1 mV with 0.30, 1.00 and 0.61 mg/mL of ALG, CS and CaCl₂ and ALG:CS of 2.50:1.00 mL:mL). In both cases, ALG:CaCl₂ (mL:mL), CaCl₂ and CS flow rates (mL/min) were fixed at 2.50:0.31, 1.25 and 1.25. The model for the NPs size depends only on CS and CaCl₂ concentrations, with the minimum- or maximum-expected (160 or 635 nm) at 0.30 and 1.00 or 1.00 and 0.30 of CS and CaCl₂, although the method allows a wide range of sizes (144.0–1965.0 nm). Full article

Creatinine (Crn) is a clinically relevant biomarker commonly used for the diagnosis and monitoring of kidney disease. In this work, we report the fabrication of reduced-graphene-oxide-based field-effect transistors (rGO FETs) for Crn detection. These devices were functionalized using a layer-by-layer (LbL) assembly, in which polyethyleneimine (PEI) and creatinine deiminase (CD) were alternately deposited. This LbL strategy allows for the effective incorporation of CD without compromising its structural or functional integrity, while also taking advantage of the local pH changes caused by creatinine hydrolysis. It also benefits from the use of a polyelectrolyte that can amplify the enzymatic signal. Furthermore, it enables scalable and efficient fabrication. These transistors also address the challenges of point-of-care implementation in single-use cartridges. It is worth noting that the devices showed a linear relationship between the Dirac-point shift and the logarithm of the creatinine concentration in the 20–500 µM range in diluted simulated urine. The sensor response improved with increasing numbers of PEI/CD bilayers. Furthermore, the functionalized FETs demonstrated rapid detection dynamics and good long-term stability. Present results confirm the potential of these devices as practical biosensors for sample analysis under real-world conditions, making them ideal for implementation in practical settings. Full article

Gallium-based liquid metals have been extensively studied in the field of biomedical engineering, including applications in tumor and inflammatory disease therapy, as well as targeted drug delivery. Among these, leveraging the photothermal effect of gallium liquid metals enables effective treatment of heat-sensitive cells in tumor regions and enhances the diffusion capability of liquid metal microdroplets. However, research on the active treatment of ulcerative colitis (UC) using photothermal therapy with liquid metals remains unexplored. This study focuses on constructing an active composite colloidal motor based on gallium indium liquid metal alloy, using liquid metal microdroplets as the core. Through layer-by-layer assembly of polyelectrolytes, a liquid metal active droplet loaded with the drug mesalazine (5-aminosalicylic acid), named as LMAD-A was developed. Under asymmetric light fields generated by NIR-II light source irradiation, LMAD-A exhibits autonomous locomotion, achieving an effective diffusion coefficient more than 800 times greater than that of Brownian motion in liquid metal microdroplets of similar size. Furthermore, LMAD-A demonstrates phototactic behavior, moving toward the NIR light source autonomously. Through in vitro and in vivo experiments in mice, it was verified that LMAD-A can aggregate, deform, and fuse in the mouse colon under photothermal effects, leading to enhanced release of the loaded drug. In simulated treatments, LMAD-A significantly alleviated DSS-induced colitis in mice, confirming the targeted therapeutic capability of active liquid metal microdroplets as an active therapeutic agent in UC-affected regions. Full article

During sulfite delignification of wood, sulfo derivatives of lignin—lignosulfonates (LS)—are formed as a byproduct. Due to their amphiphilic nature, LS are used as plasticizers, dispersants, and stabilizers. The functions and performance characteristics of this surface-active polyelectrolyte are determined by its behavior in aqueous solution, at surfaces and interfaces, which, in turn, is determined by its chemical composition. This study investigated the effect of LS with various molecular weight compositions (M_w 9–50 kDa) on the behavior and aggregation stability of aqueous dispersions of elemental sulfur (S⁰) under conditions simulating hydrothermal leaching of sulfide ores. Using conductometry, potentiometry, tensiometry, and viscometry, a detailed study of the physicochemical properties of aqueous LS solutions (C_LS 0.02–1.28 g/dm³) obtained from a few sources (Krasnokamsk, Solikamsk, and Norwegian Pulp and Paper Mills) was conducted. The composition, molecular weight, and concentration of LS were found to significantly affect their specific electrical conductivity, pH, intrinsic viscosity, and surface activity. LS introduction during the formation of sulfur sols is shown to promote their stabilization through electrostatic and steric mechanisms. Optimum dispersion stability (293 K, pH 4.5–5.5) was observed at moderate LS concentrations (0.02–0.32 g/dm³), when a stable adsorption layer forms on the surface of sulfur particles. High-molecular-weight LS samples provided more effective spatial stabilization of sulfur particles. It has been established that increasing temperature (293–333 K) and changing pH (1–7) significantly affect the aggregative stability of systems; specifically, the sol stability decreases with increasing temperature, and the stabilizing effect of different LS types reverses upon changing pH. The obtained results highlight the potential of using naturally occurring polymeric dispersants to control the aggregation stability of sulfur-containing heterophase systems and can be applied to the design of stable colloidal systems in chemical engineering and hydrometallurgy. Full article