Search Results (67)

This study aimed to develop a green and sustainable composite polysaccharide gel with antioxidant activity and freshness-monitoring properties. Blueberry pomace was repurposed to extract anthocyanins (BA), which were incorporated into chitosan (CS)/polyvinyl alcohol (PVA) and starch (S)/PVA matrices to prepare pH-indicating composite polysaccharide gels. The anthocyanin solution exhibited significant colorimetric responses to pH 2–14 buffer solutions. Comparative analyses revealed distinct performance characteristics: the CS/PVA-BA gel showed optimal elongation at break, low hydration (8.33 ± 0.57% water content), and potent antioxidant activity (DPPH: 73.59 ± 0.1%; ABTS: 77.47 ± 0.1%), whereas the S/PVA-BA gel demonstrated superior tensile strength and pH-responsive sensitivity. Structural characterization via FT-IR and SEM confirmed molecular compatibility between BA and polymeric matrices, with anthocyanins enhancing intermolecular hydrogen bonding. Applied to chilled beef (4 °C) freshness monitoring, the CS/PVA-BA gel exhibited color transformations from magenta-red (initial spoilage at 48 h: TVB-N > 15 mg/100 g, TVC > 4.0 lg CFU/g) to bluish-gray (advanced spoilage by day 6), correlating with proteolytic degradation metrics. These findings established a multifunctional platform for real-time food quality assessment through anthocyanin-mediated color changes in the composite gels, coupled with preservation activity, highlighting their significant potential as intelligent active packaging in the food industry. Full article

Radiation therapy is a standard of care treatment for patients with glioblastoma. However, patients’ survival rate is dismal, with nearly all patients experiencing disease progression after treatment. Enriched iron content associated with increased transferrin receptor (TfR) expression is an indicator of poor glioblastoma patient outcomes; however, the underlying contributions to tumor progression remain elusive. The goal of this present study is to understand how iron metabolism in glioma contributes to radiation-induced glioblastoma cell motility. U251 and a doxycycline-inducible ferritin heavy chain overexpressing U251 (U251 FtH⁺) cell line were used. For in vitro studies, cells were irradiated with 2 Gy using a ³⁷Cs source, and after 72 h, atomic force microscopy (AFM) nanoindentation was employed to assess changes in cell stiffness following irradiation. Cell motility was studied using temporal confocal microscopy. For in vivo studies, U251 cells were grown in the rear flanks of female nude athymic mice, and the tumor was irradiated with five fractions of 2 Gy (10 Gy). The tumors were then imaged using a GE 7T small animal MRI to assess changes in T2* MRI, and colorimetric analysis of labile iron was performed using ferrozine. Following irradiation, a biomechanical shift characterized by decreased cell stiffness along with increased cell motility occurred in U251 cells, which corresponded to increased TfR expression. FtH overexpression completely reversed the enhanced cell motility following irradiation. Irradiation of U251 tumors induced the same iron metabolic shift. Interestingly, the change in labile iron in U251 tumors corresponded with an increase in T2* relaxation times, suggesting that T2* mapping may serve as a surrogate marker for assessing radiation-induced changes in iron metabolism. Full article

Background: Ampicillin plus ceftriaxone (AC) is a first-line treatment for Enterococcus faecalis infective endocarditis (IE). Its administration in outpatient parenteral antibiotic treatment (OPAT) programs is challenging. The design of a ceftriaxone regimen suitable for OPAT requires deep knowledge of ceftriaxone pharmacokinetics (PK). Objective: We aim to explore ceftriaxone PK in elderly patients and propose dose regimens adapted to OPAT to maintain synergistic concentrations (Cs) with ampicillin against E. faecalis. Methods: We conducted a prospective observational pharmacokinetic study on patients (>55 years old) affected by E. faecalis IE. Ceftriaxone free concentration was measured at three time-points: before the administration (C_min) and two and four hours after ceftriaxone administration (C₂ and C₄). Both structural and covariate population pharmacokinetic models were built. Monte Carlo simulations of six ceftriaxone dosages were performed and the probability of target attainment (PTA) of an optimal Cs range was analyzed. The pharmacokinetic/pharmacodynamic index (PK/PD) to predict efficacy was defined as maintaining free ceftriaxone concentrations superior to the Cs at 50–100% of the dosing interval (fT ≥ Cs ≥ 50–100% of the dosing interval). Ceftriaxone dosing regimens were considered optimal if at least 90% of the simulated population was able to achieve the defined PK/PD targets. Results: Twenty-four episodes from 16 patients were included. Mean free ceftriaxone concentration pre-dose, +2 h, and +4 h were C_min = 7.8 ± 6.5 mg/L, C₂ = 34 ± 26.5 mg/L, and C₄ = 22.7 ± 19.7 mg/L, respectively. A two-compartment model with first-order absorption and elimination best described the data. Ceftriaxone one-hour infusions only achieved the minimum PK/PD target when the 2 g/12 h regimen was tested. On the other hand, ceftriaxone continuous infusion maintained a Cs above the PK/PD target for 100% of the dosing interval using ceftriaxone 4–6 g regimens. Conclusions: Our findings suggest that the optimal ceftriaxone exposure may be achieved using high-dose continuous infusions to ensure an ampicillin-killing effect when treating E. faecalis IE. Full article

Chitosan/polyvinyl alcohol nanofibrous mats loaded with nano-hydroxyapatite and/or curcumin are successfully fabricated by the electrospinning method for the first time. Nano-hydroxyapatite is prepared by the co-precipitation method. The XRD pattern of calcined powder at 700 °C for 2 h reveals the presence of hydroxyapatite as a sole phase. FT-IR confirms its purity. The morphology of the hydroxyapatite is studied by HR-TEM. Nano-hydroxyapatite and curcumin are added at 5 wt% with respect to the polymer weight. XRD, FE-SEM, FT-IR, and HR-TEM are used to characterize the fabricated nanofibrous mats. The results confirm the successful loading of nano-hydroxyapatite and curcumin within the fabricated mats. The in vitro antimicrobial results show that most of mats have significant antimicrobial effects against E. coli and S. aureus. The fabricated matd are biocompatible with fibroblasts and the presence of curcumin increases cell viability. Curcumin release from both CS/PVA/Cur and CS/PVA/HA/Cur nanofiber mats principally follows the Korsmeyer–Peppas and Peppas–Salhin models. Full article

A modified loess/chitosan composite (ML@CS) was prepared via solution. The microstructure and physicochemical properties of ML@CS were characterised via scanning electron microscope (SEM), Zeta potential, X-ray diffraction (XRD), Fourier transform infrared spectrum (FT-IR), and thermogravimetric analysis (TGA). An aqueous solution of methyl orange (MO) was used as simulated wastewater from which the influence of the initial concentration and pH of MO, the dosage amount and regeneration performance of ML@CS, adsorption temperature, and time on the adsorption effect of MO were systematically investigated. The adsorption kinetics, isothermal adsorption, and adsorption mechanism were also analysed. The results indicate that ML@CS had a good adsorption effect on MO. When the initial concentration of MO was 200 mg/L, pH was 5.0, and ML@CS dosage was 1.0 g/L, the adsorption equilibrium could be reached within 180 min at room temperature, and the equilibrium adsorption capacity and removal rate reached 199.52 mg/g and 99.75%, respectively. After five adsorption–desorption cycles, the MO removal rate remained above 82%. The adsorption behaviour of ML@CS for MO conforms to the pseudo–second–order kinetic model and the Langmuir isotherm adsorption model. The spontaneous exothermic process was mainly controlled by monolayer chemical adsorption and the physical adsorption only played an auxiliary role. ML@CS efficiently adsorbed MO in water and can be used as a high-efficiency, low-cost adsorbent for printing and dyeing wastewater treatment. Full article

Among the alkali metals, potassium is known to significantly shift selectivity toward value-added, heavier alkanes and olefins in iron-based Fischer–Tropsch synthesis catalysts. The aim of the present contribution is to shed light on the mechanism of action of alkaline promoters through a systematic study of the structure–reactivity relationships of a series of Fe oxide FTS catalysts promoted with Group I (Li, Na, K, Cs) alkali elements. Reactivity data are compared to structural data based on in situ, synchrotron-based XRD and XPS, as well as temperature-programmed studies (TPR-H₂, TPC-CO, TPD-CO₂, and TPD-H). It has been observed that the alkali elements induced higher carburization rates, higher basicities, and lower adsorbed hydrogen coverages. Catalyst stability followed the trend Na-Fe > unpromoted > Li-Fe > K-Fe > Cs-Fe, being consistent with the ability of the alkali (Na) to prevent active site loss by catalyst reoxidation. Potassium was the most active in promoting high α hydrocarbon formation. It is active enough to promote CO dissociative adsorption (and the formation of FeCx active phases) and decrease the surface coverage of H-adsorbed species, but it is not so active as to cause premature catalyst deactivation by the formation of a carbon layer resulting in the blocking active sites. Full article

Heavy metals and organic pollutants are prevalent in water bodies, causing great damage to the environment and human beings. Hence, it is urgent to develop a kind of adsorbent with good performance. Anion interlacing layered double hydroxides (LDHs) are a promising adsorbent for the sustainable removal of heavy metal ions and dyes from wastewater. Using aluminum chloride, zinc chloride and ammonium pentaborate tetrahydrate (NH₄B₅O₈ · 4H₂O, BA) as raw materials, the LDHs complex (BA-LDHs) of B₅O₈⁻ intercalation was prepared by one-step hydrothermal method. The BA-LDHs samples were characterized by a X-ray powder diffractometer (XRD), scanning electron microscope (SEM), Fourier transform infrared spectrometer (FT-IR) and the Brunauer–Emmett–Teller (BET) method. The results showed that B₅O₈^- was successfully intercalated. Adsorption experimental results suggested that BA-LDHs possess a maximum adsorption capacity of 18.7, 57.5, 70.2, and 3.12 mg·g⁻¹ for Cd(II), Cu(II), Cr(VI) and Methylene blue (MB) at C_s = 2 g·L⁻¹, respectively. The adsorption experiment conforms to the Langmuir and Freundlich adsorption models, and the kinetic adsorption data are well fitted by the pseudo-second-order adsorption kinetic equation. The as-prepared BA-LDHs have potential application prospects in the removal of heavy metals and dyes in wastewater. More importantly, they also provide a strategy for preparing selective adsorbents. Full article

Insulin-loaded nanofibers were prepared using chitosan as a natural polymer. The loaded insulin with polyethylene oxide was used for preparing monolayer batch S1. Nanofiber S1 was coated by seven layers of film on both sides to form batch S2 as a sandwich containing Layer A (CS, PEG and PEO) and Layer B (PEG and PEO) using electrospinning apparatus. SEM, TEM and FT-IR techniques were used to confirm the drug loading within the composite nanofibers. The in vitro activity that provided a sustained and controlled release of the drug from the nanofiber batch was studied at different pH values spectrophotometrically using a dialysis method. In batches S1 and S2, the release of insulin from nanofiber proceeds via burst release necessary to produce the desired therapeutic activity, followed by slow step. The rate and the percentage release of insulin in batch S2 are found to be higher at all pH values. Full article

Pharmaceuticals are used to improve the lives of people across the globe. The high demand for their fabrication and use causes a very serious environmental threat since their presence is ubiquitous in aqueous matrices. For this reason, the synthesis, characterisation, and efficiency of three chitosan-based materials to eliminate pharmaceutical mixtures from aqueous solutions were examined in the present study. The target mixture comprised seven widely used drugs: carbamazepine, cyclophosphamide, adefovir, levofloxacin, metronidazole, glibenclamide, and trimethoprim. The grafting of poly(ethylene imine) and poly(acrylamide) on the chitosan structure allowed its physical characteristics to be controlled. An adsorption assessment was performed at different pH values, and it was concluded that pH = 4 was the optimum value. The adsorption kinetics revealed that the adsorption of a drug mixture involves a combination of physical and chemical adsorption. The adsorption process appeared to be finished after 1 h for all compounds of the studied mixture, with CS-AMI exhibiting the fastest kinetics. Mass adsorption experiments were also carried out to determine its effects. Overall, the grafting process significantly increased the adsorption capacity over the pristine material. Specifically, the highest capacity increase for CS-PEI was ~220% for carbamazepine, and for CS-AMI, it was 158% for trimethoprim. FT-IR, SEM, and XRD were used for the characterisation of the polymers. Based on the findings, the three materials are suggested as very effective adsorbents for the elimination of medicine residues from aqueous matrices. Full article

Bio-based polymers are attracting increasing interest as alternatives to harmful and environmentally concerning non-biodegradable fossil-based products. In particular, bio-based polymers may be employed as ligands for the preparation of metal nanoparticles (M(0)NPs). In this study, chitosan (CS) was used for the stabilization of Ru(0) and Rh(0) metal nanoparticles (MNPs), prepared by simply mixing RhCl₃ × 3H₂O or RuCl₃ with an aqueous solution of CS, followed by NaBH₄ reduction. The formation of M(0)NPs-CS was confirmed by Fourier Transform Infrared Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Analysis (EDX), Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD). Their size was estimated to be below 40 nm for Rh(0)-CS and 10nm for Ru(0)-CS by SEM analysis. M(0)NPs-CS were employed for the hydrogenation of (E)-cinnamic aldehyde and levulinic acid. Easy recovery by liquid-liquid extraction made it possible to separate the catalyst from the reaction products. Recycling experiments demonstrated that M(0)NPs-CS were highly efficient up to four times in the best hydrogenation conditions. The data found in this study show that CS is an excellent ligand for the stabilization of Rh(0) and Ru(0) nanoparticles, allowing the production of some of the most efficient, selective and recyclable hydrogenation catalysts known in the literature. Full article

Cadmium (Cd²⁺) pollution in soil and water bodies is a significant environmental concern, necessitating effective remediation strategies. Traditional methods often fall short in efficiency, cost-effectiveness, and environmental sustainability. This study develops and evaluates the effectiveness of chitosan–gelatin–hydroxypropyl methylcellulose (CS-GEL-HPMC) membranes for Cd²⁺ removal from polluted environments. CS-GEL-HPMC membranes were synthesized with varying HPMC concentrations. Their structural and morphological characteristics were analyzed using UV–visible absorption spectroscopy and FT-IR. The membranes’ stability across different pH levels and their morphological traits were assessed. The adsorption efficiency for Cd²⁺ ions was evaluated in both aqueous solutions and soil environments under varying conditions of pH, initial ion concentration, and contact time. The CS-GEL-HPMC membranes demonstrated significant structural integrity and stability, especially at higher HPMC concentrations. UV–visible and FT-IR analyses confirmed the successful integration of HPMC into the CS-GEL matrix. In aqueous solutions, the membranes exhibited efficient Cd²⁺ adsorption, with the best performance observed for the CS30-GEL30-HPMC40 membrane. The adsorption capacity was influenced by contact time, initial Cd²⁺ concentration, and pH. In soil treatments, the membranes effectively reduced Cd²⁺ concentrations, with higher membrane dosages yielding better results. The incorporation of additives like (hydroxyapatite) HAP, fly ash (FA), and cement further enhanced the remediation efficiency. In summary, CS-GEL-HPMC membranes, particularly when combined with additives, emerge as a promising, sustainable solution for Cd²⁺ remediation in both soil and water bodies. This study highlights the potential of biopolymer-based composites in environmental clean-up efforts, offering a novel approach that is both effective and eco-friendly. Full article

A composite of chitosan-supported ZnO nanoparticles (ZnO/CS) was green-synthesized via an easy and cost-effective method using Chicory (Cichorium intybus) plant extract. The synthesis was confirmed using uv-vis spectrometry at a λ_max of 380 nm, and the surface of the material was characterized via FT−IR spectroscopy, and finally via SEM, which confirmed the distribution of ZnO nanoparticles on the surface of chitosan biopolymer (CS). The synthesized material was applied in the adsorptive removal of residues of the pyridoxine hydrochloride (vitamin B6) pharmaceutical drug from aqueous media using the batch technique. The material’s removal capacity was studied through several adjustable parameters including pH, contact time, the dose of the adsorbent, and the capacity for drug adsorption under the optimal conditions. Langmuir and Freundlich isotherms were applied to describe the adsorption process. The removal was found to obey the Freundlich model, which refers to a chemisorption process. Different kinetic models were also studied for the removal process and showed that the pseudo-second-order model was more fitted, which indicates that the removal was a chemisorption process. Thermodynamic studies were also carried out. The maximum removal of vitamin B6 by the nano-ZnO/CS composite was found to be 75% at optimal conditions. The results were compared to other reported adsorbents. Reusability tests showed that the nano-ZnO/CS composite can be efficiently reused up to seven times for the removal of PDX drugs from aqueous media. Full article

Biosorption is an impurity-free application developed from the use of nuclear technology for peaceful purposes in everyday life and can be used to treat wastewater streams contaminated with various radionuclides. In this study, a laboratory decontamination experimental approach was developed to apply commercial chitosan as a biosorbent applied for removing radiocesium (Cs-137) and/or radiocobalt (Co-60) from spiked aqueous media. The factors assumed to affect the biosorption of both radionuclides included contact time, pH, and initial radioactivity content. In addition, the biosorbent dose and temperature of the process were studied. Both the biosorption capacity and the biosorption efficiency of the treatment process were calculated. According to FT-IR analysis, it can be assumed that the chitosan amine group (-NH₂) is almost accountable for the biosorption of both radionuclides from waste solution simulates. Based on the data obtained, commercial chitosan can be considered an economical and efficient biosorbent for handling low- and medium-level radioactive wastewater streams containing cesium and/or cobalt radionuclides. The acquired data showed that 144 h is an adequate time to remove more than 94% of radiocobalt and about 93% of radiocesium, from a separate solution for each, at pH ~6.5 and using 0.5 g of commercial chitosan. Full article

Nanotechnology is the science of creating materials at the nanoscale by using various devices, structures, and systems that are often inspired by nature. Micro- and nanoparticles (MPs, NPs) are examples of such materials that have unique properties and can be used as carriers for delivering drugs for different biomedical applications. Chitosan (CS) is a natural polysaccharide that has been widely studied, but it has a problem with low water solubility at neutral or basic pH, which limits its processability. The goal of this work was to use a chemically modified CS with poly(ethylene glycol) methyl ether acrylate (PEGA) to prepare CS micronic and submicronic particles (MPs/NPs) that can deliver different types of antibiotics, respectively, levofloxacin (LEV) and Ciprofloxacin (CIP). The particle preparation procedure employed a double crosslinking method, ionic followed by a covalent, in a water/oil emulsion. The studied process parameters were the precursor concentration, stirring speeds, and amount of ionic crosslinking agent. MPs/NPs were characterized by FT-IR, SEM, light scattering granulometry, and Zeta potential. MPs/NPs were also tested for their water uptake capacity in acidic and neutral pH conditions, and the results showed that they had a pH-dependent behavior. The MPs/NPs were then used to encapsulate two separate drugs, LEV and CIP, and they showed excellent drug loading and release capacity. The MPs/NPs were also found to be safe for cells and blood, which demonstrated their potential as suitable drug delivery systems for biomedical applications. Full article

For innovative application in wastewater treatment techniques, MnO-Fe₂O₃ nanocomposites were successfully synthesized using the sol–gel auto-combustion method at different temperatures for the adsorption of ¹³⁷Cs and ⁶⁰Co radionuclides from aqueous solution. The characterization of these nanocomposites was carried out through FT-IR, SEM-EDX, and X-ray diffraction. These nanocomposites were employed as adsorbent materials for the removal of ¹³⁷Cs and ⁶⁰Co radionuclides from simulated radioactive waste solutions. The study involved a series of experiments aiming to demonstrate the MnO-Fe₂O₃ nanoparticles’ exceptional adsorption potential concerning ¹³⁷Cs and ⁶⁰Co. Additionally, the investigation delved into how variations in temperature, dose amount, contact time, and pH value influence the adsorption dynamics. Due to their high specific surface area, the synthesized MnO-Fe₂O₃ nanoparticles had high adsorption capacity of more than 60% and 90% for ¹³⁷Cs and ⁶⁰Co, respectively. By investigation of kinetics and adsorption isotherms, pseudo-second-order reaction and the Langmuir model turned out to fit well for the adsorption of ¹³⁷Cs and ⁶⁰Co onto the MnO-Fe₂O₃ nanocomposites. Moreover, a thermodynamic analysis revealed that the adsorption process was spontaneous for both target metals and the adsorption of ⁶⁰Co was endothermic, whereas the adsorption of ¹³⁷Cs was exothermic. Full article