Highly efficient adsorption of fluoroquinolone antibiotics using chitosan derived granular hydrogel with 3D structure

Detection of tetracycline by molecularly imprinted electrochemical sensor based on the modification of poly(3,4-propylene dioxythiophene)/chitosan/au

In this study, a molecularly imprinted polymer (MIP) electrochemical sensor based on poly(3,4-propylenedioxythiophene)/chitosan/Au (PProDOT/CS/Au) composite modification was designed for highly sensitive and selective detection of TC. Green synthesis of CS/Au without the use of reducing agents, followed by in-situ oxidation polymerization of PProDOT. The high electrochemical activity and high stability of PProDOT, the numerous functional groups (-OH, -NH2) of CS, and the excellent electron transport capacity of AuNPs, which provided a suitable incubation chamber for the production of imprinted cavities. Meanwhile, combined with the specific recognition ability of MIP, it showed superior performance over bare glassy carbon electrodes. Under the optimal experimental conditions, this sensor showed good linearity for TC in the concentration ranges of 0.0001-100 μM, with a low limit of detection (LOD) of 0.19 nM. At the same time, the sensor exhibited satisfactory selectivity, repeatability, reproducibility and stability. It was evident from the results of the study that the sensor designed in this paper showed considerable potential for application in the detection of TC in pharmaceuticals, the environment, and food samples.

Construction of an allophane-based molecularly imprinted polymer for the efficient removal of antibiotic from aqueous solution

The widespread presence of ciprofloxacin (CIP) antibiotic in the water and soil poses substantial potential risks to the environment, threatening both human and animal health. In this study, we used nanoclay mineral allophane (Allo), β-cyclodextrin (β-CD) as a bifunctional monomer, and sodium alginate as a cross-linking agent, to prepare 3D porous Allo-β-CD molecularly imprinted polymers (MIPs) for the efficient removal of CIP from aqueous solution. The prepared Allo-β-CD MIP was characterized by scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and zeta potential measurements. The effects of initial concentration, time, pH level, and ion concentration on CIP removal dynamics were systematically studied. The adsorption kinetics and equilibrium data of CIP were well-fitted by the pseudo-second-order kinetic model and Langmuir isotherm models, respectively. The Allo-β-CD MIP can efficiently remove CIP from an aqueous solution, with a maximal adsorption capacity of 635 mg/g. It also has impressive recyclability, and enhanced selectivity, and is widely adaptable to various environmental conditions. The adsorption mechanisms of the as-prepared adsorbent include H bonds, hydrophobic interactions, surface complexation, and n-π EDA interactions. Given the experimental evidence, as-prepared adsorbent is therefore a promising candidate for the effective removal of CIP from the aquatic environment.

Developments and application of chitosan-based adsorbents for wastewater treatments

Water quality is deteriorating continuously as increasing levels of toxic inorganic and organic contaminants mostly discharging into the aquatic environment. Removal of such pollutants from the water system is an emerging research area. During the past few years use of biodegradable and biocompatible natural additives has attracted considerable attention to alleviate pollutants from wastewater. The chitosan and its composites emerged as a promising adsorbents due to their low price, abundance, amino, and hydroxyl groups, as well as their potential to remove various toxins from wastewater. However, a few challenges associated with its practical use include lack of selectivity, low mechanical strength, and solubility in acidic medium. Therefore, several approaches for modification have been explored to improve the physicochemical properties of chitosan for wastewater treatment. Chitosan nanocomposites found effective for the removal of metals, pharmaceuticals, pesticides, microplastics from the wastewaters. Nanoparticle doped with chitosan in the form of nano-biocomposites has recently gained much attention and proven a successful tool for water purification. Hence, applying chitosan-based adsorbents with numerous modifications is a cutting-edge approach to eliminating toxic pollutants from aquatic systems with the global aim of making potable water available worldwide. This review presents an overview of distinct materials and methods for developing novel chitosan-based nanocomposites for wastewater treatment.

Non-toxic and biodegradable κ-carrageenan/ZnO hydrogel for adsorptive removal of norfloxacin: Optimization using response surface methodology

Antibiotic resistance is increasing globally due to increased prescription and easy dispensing of antibiotic drugs universally. Hence, to mitigate this effect, efficient, biodegradable, and non-toxic adsorbents are required to be developed. Carrageenan (CG), a natural polymer, having multiple functional groups, provides a backbone for crosslinking with borax and incorporation of ZnO nanoparticles that formed borax-cross-linked κ-carrageenan (CG/Bx/ZnO) hydrogel which is used for efficient adsorption of norfloxacin from water. Surface morphology of as-synthesized hydrogel revealed the rough surface, which was determined by FESEM. Surface area of CG/Bx/ZnO hydrogel was found to be 22.90 m²/g with 3.41 nm pore radius. Systematic batch adsorption studies revealed that 99.4 % removal efficiency could be achieved at a dosage level of 20 mg/L of norfloxacin with 10 mg of hydrogel at pH of 4 in 8 h at room temperature. Experimentally optimized key parameters affecting the overall efficiency of adsorption matched well with the results assessed from ANOVA using Box-Behnken composite design model. The adsorption process was well fitted with the pseudo-second-order model and Langmuir isotherm with 1282.05 mg/g adsorption capacity. Thermodynamic study results show that adsorption is spontaneous and endothermic. The CG/Bx/ZnO hydrogel demonstrated excellent repeatability with minimal loss in norfloxacin adsorption for seven cycles.

Chitosan beads coated with almond and walnut shells for the adsorption of gatifloxacin antibiotic compound from aqueous solutions

In the present study, chitosan (C), walnut (W), and almond shell (A) powder adsorbent (in different combinations as almond shells:walnut:chitosan 2:1:1 (AWC), chitosan:almond shell:walnut 2:1:1 (CAW), and walnut:almond shells:chitosan 2:1:1 (WAC)) powder were combined in different ratios to produce low-cost composite adsorbent beads for the removal of antibiotics gatifloxacin (GAT) from synthetic wastewater. The beads were characterized by a scanning electron microscope, Fourier transform infrared spectrum spectrophotometer, and energy-dispersive X-ray spectroscopy. The batch adsorption approach was employed to remove the antibiotic from the water. Moreover, isotherm and kinetics were conducted to illustrate the adsorption mechanism. Parameters like the effect of the adsorbent's dosage, pH, initial concentration, and contact time on antibiotic adsorption were evaluated. Adsorption percentage increased slightly with the increase in adsorbent dosage. The optimum pH for GAT adsorption on beads was 5-7. In addition, adsorption increased with initial antibiotic concentration and time rise. The adsorption isotherm data were successfully fitted to Langmuir isotherm for AWC and CAW beads, while WAC beads followed the Freundlich isotherm. The highest adsorption was attained at pH 5 on CAW beads and pH 7 on AWC and WAC beads. The optimal contact time for equilibrium studies was 120 min for all types of beads. The adsorption isotherm data in AWC beads fit well with the Langmuir model and Freundlich adsorption for CAW and WAC beads. The rate of adsorption on beads follows Lagergren pseudo-second-order kinetics. The results indicate that prepared combination beads can be used to remove antibiotics from wastewater.

Evaluation of ciprofloxacin (CIP) and clarithromycin (CLA) adsorption with weathered PVC microplastics

The sorption kinetics of two of the most frequently used antibiotics onto recycled (weathered) polyvinyl chloride (PVC) was investigated, using Freundlich and Langmuir isotherm models. Various experimental conditions were set, including pH, contact time, rotational speed, temperature, and initial concentration. The batch experimental results indicated that Freundlich model was better fitted than Langmuir (R²: 98.7 and 84.7, for CIP and CLA respectively). Maximum adsorption capacity is 45.9 mg/g and 22.0 mg/g for CIP and CLA, respectively. Enthalpy (ΔH), and entropy (ΔS) values were negative for CIP, indicating that the reaction was exothermic and spontaneous, respectively. It was vice versa for CLA. Field emission scanning electron microscope (FESEM) and Fourier transform infrared spectrometer (FT-IR) analysis confirmed the physical adsorption mechanism. The results demonstrated that the recycled PVC microplastic has a good capacity for adsorption for both antibiotics.

Recent Advances in Macroporous Hydrogels for Cell Behavior and Tissue Engineering

Hydrogels have been extensively used as scaffolds in tissue engineering for cell adhesion, proliferation, migration, and differentiation because of their high-water content and biocompatibility similarity to the extracellular matrix. However, submicron or nanosized pore networks within hydrogels severely limit cell survival and tissue regeneration. In recent years, the application of macroporous hydrogels in tissue engineering has received considerable attention. The macroporous structure not only facilitates nutrient transportation and metabolite discharge but also provides more space for cell behavior and tissue formation. Several strategies for creating and functionalizing macroporous hydrogels have been reported. This review began with an overview of the advantages and challenges of macroporous hydrogels in the regulation of cellular behavior. In addition, advanced methods for the preparation of macroporous hydrogels to modulate cellular behavior were discussed. Finally, future research in related fields was discussed.

Cattail fibers as source of cellulose to prepare a novel type of composite aerogel adsorbent for the removal of enrofloxacin in wastewater

In this study, cattail was researched as a natural cellulose source to extract cellulose. Dewaxing, alkali and bleaching treatments were carried out for the cattail fibers (CFs). The FTIR, SEM and XRD results indicated that hemicellulose and lignin were successfully removed from the CFs, and the content of cattail cellulose increased from 41.66 ± 1.11% to 89.72 ± 1.07%. Subsequently, cellulose aerogel was prepared by the extracted cattail cellulose. The Zeolitic imidazolate framework-8 (ZIF-8) was uniformly loaded onto the surface of cellulose aerogel by the in situ growth, and ZIF-8 Cattail Cellulose Aerogel (ZCCA) was finally prepared. The SEM, FTIR, XRD and TGA results further confirmed the successful preparation of ZCCA. Additionally, the results of the adsorption experiment showed that ZCCA had excellent adsorption performance for enrofloxacin, and the maximum adsorption capacity of enrofloxacin reached 172.09 mg·g^-1 while showing good reusability. The adsorption process followed the pseudo-second-order kinetic model and the Langmuir isotherm model. Thermodynamic studies showed that the adsorption of enrofloxacin was a spontaneous endothermic reaction and that the adsorption mechanism involves the interaction of hydrogen bonds, electrostatic and π-π stacking.

Langmuir Monolayer Techniques for the Investigation of Model Bacterial Membranes and Antibiotic Biodegradation Mechanisms

The amounts of antibiotics of anthropogenic origin released and accumulated in the environment are known to have a negative impact on local communities of microorganisms, which leads to disturbances in the course of the biodegradation process and to growing antimicrobial resistance. This mini-review covers up-to-date information regarding problems related to the omnipresence of antibiotics and their consequences for the world of bacteria. In order to understand the interaction of antibiotics with bacterial membranes, it is necessary to explain their interaction mechanism at the molecular level. Such molecular-level interactions can be probed with Langmuir monolayers representing the cell membrane. This mini-review describes monolayer experiments undertaken to investigate the impact of selected antibiotics on components of biomembranes, with particular emphasis on the role and content of individual phospholipids and lipopolysaccharides (LPS). It is shown that the Langmuir technique may provide information about the interactions between antibiotics and lipids at the mixed film surface (π–A isotherm) and about the penetration of the active substances into the phospholipid monolayer model membranes (relaxation of the monolayer). Effects induced by antibiotics on the bacterial membrane may be correlated with their bactericidal activity, which may be vital for the selection of appropriate bacterial consortia that would ensure a high degradation efficiency of pharmaceuticals in the environment.

Gelatin-Based Hybrid Scaffolds: Promising Wound Dressings

Wound care is a major biomedical field that is challenging due to the delayed wound healing process. Some factors are responsible for delayed wound healing such as malnutrition, poor oxygen flow, smoking, diseases (such as diabetes and cancer), microbial infections, etc. The currently used wound dressings suffer from various limitations, including poor antimicrobial activity, etc. Wound dressings that are formulated from biopolymers (e.g., cellulose, chitin, gelatin, chitosan, etc.) demonstrate interesting properties, such as good biocompatibility, non-toxicity, biodegradability, and attractive antimicrobial activity. Although biopolymer-based wound dressings display the aforementioned excellent features, they possess poor mechanical properties. Gelatin, a biopolymer has excellent biocompatibility, hemostatic property, reduced cytotoxicity, low antigenicity, and promotes cellular attachment and growth. However, it suffers from poor mechanical properties and antimicrobial activity. It is crosslinked with other polymers to enhance its mechanical properties. Furthermore, the incorporation of antimicrobial agents into gelatin-based wound dressings enhance their antimicrobial activity in vitro and in vivo. This review is focused on the development of hybrid wound dressings from a combination of gelatin and other polymers with good biological, mechanical, and physicochemical features which are appropriate for ideal wound dressings. Gelatin-based wound dressings are promising scaffolds for the treatment of infected, exuding, and bleeding wounds. This review article reports gelatin-based wound dressings which were developed between 2016 and 2021.

Antibiotics removal from aquatic environments: adsorption of enrofloxacin, trimethoprim, sulfadiazine, and amoxicillin on vegetal powdered activated carbon

This study addresses the growing concern about the high levels of antibiotics in water, outlining an alternative for their removal. The adsorption of four representative antibiotics from commonly used families (fluoroquinolones, β-lactams, trimethoprim, and sulfonamides) was performed over vegetal powdered activated carbon. The evolution of the adsorption was studied during 60 min for different initial antibiotic concentrations, not only individually but also simultaneously to determine competitive adsorption. Moreover, this research studied the adsorption isotherms and kinetics of the process, as well as the pH influence; FTIR of the activated carbon before and after adsorption was carried out. Trimethoprim and sulfadiazine showed more affinity for the adsorbent than amoxicillin and enrofloxacin. This trend might be attributed to their structure, capable of stablishing stronger π-π interactions with the adsorbent, which showed high affinity for the active sites of the adsorbent via FTIR. In addition, the sorption isotherms of trimethoprim followed a Langmuir type isotherm, amoxicillin followed a Freundlich type isotherm, and enrofloxacin and sulfadiazine followed both. The antibiotics followed pseudo-second-order kinetics. Sulfadiazine and amoxicillin gave better performances in acidic conditions. By contrast, the sorption of trimethoprim was favored in basic environments. Variations of pH had a negligible effect on the removal of enrofloxacin.

Adsorptive removal of enrofloxacin with magnetic functionalized graphene oxide@ metal-organic frameworks employing D-optimal mixture design

A novel sorbent based on a mixture of magnetic functionalized graphene oxide and MOFs was developed to remove enrofloxacin (EFX) from water samples. The prepared sorbent was characterized using Fourier transform infrared spectra, scanning electron microscope images, and X-ray powder diffraction pattern. The sorbent compositions were optimized by the mixture experimental design. Under the optimal condition, the percentages of each sorbent component, including triethylene tetramine-functionalized graphene oxide (FGO), Fe₃ O₄ , and MOF-5, were 40%, 21%, and 39%, respectively. Besides, the intraparticle diffusion and pseudo-second-order kinetic models can describe the EFX adsorption procedure because of two adsorption mechanisms of EFX on FGO and MOF-5. A positive standard enthalpy of 49.80 kJ/mol indicated the EFX adsorption is endothermic with a chemisorption process. The negative values of ΔG^o obtained in the range of -8.979 to -3.431 kJ/mol at all studied temperatures showed that the adsorption process was also spontaneous. The Langmuir and Freundlich isotherm models were analyzed with the partition coefficient to reduce bias in the isotherm model evaluation. The maximum adsorption capacity of 344.83 mg/g and a high partition coefficient of 17.42 g/L in an initial EFX concentration of 10 mg/L were obtained for the EFX removal. PRACTITIONER POINTS: Magnetic functionalized graphene oxide @MOF-5 as a sorbent for the enrofloxacin removal is synthesized. The percentage amount of each component of the sorbent is optimized using the D-optimal mixture design. Adsorption mechanisms of enrofloxacin on magnetic functionalized graphene oxide @MOF-5 are discussed. Thermodynamic parameters for the enrofloxacin adsorption with the sorbents are determined. Isotherm model for the enrofloxacin removal with the sorbent is investigated.

Removal of antibiotic from the water environment by the adsorption technologies: a review

Antibiotics are known as emergent pollutants because of their toxicological properties. Due to continuous discharge and persistence in the aquatic environment, antibiotics are detected almost in every environmental matrix. Therefore antibiotics that are polluting the aquatic environment have gained significant research interest for their removal. Several techniques have been used to remove pollutants, but appropriate technology is still to be found. This review addresses the use of modified and cheap materials for antibiotic removal from the environment.

A Biodegradable Magnetic Nanocomposite as a Superabsorbent for the Simultaneous Removal of Selected Fluoroquinolones from Environmental Water Matrices: Isotherm, Kinetics, Thermodynamic Studies and Cost Analysis

The application of a magnetic mesoporous carbon/β-cyclodextrin–chitosan (MMPC/Cyc-Chit) nanocomposite for the adsorptive removal of danofloxacin (DANO), enrofloxacin (ENRO) and levofloxacin (LEVO) from aqueous and environmental samples is reported in this study. The morphology and surface characteristics of the magnetic nanocomposite were investigated by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) adsorption–desorption and Fourier transform infrared spectroscopy (FTIR). The N₂ adsorption–desorption results revealed that the prepared nanocomposite was mesoporous and the BET surface area was 1435 m² g⁻¹. The equilibrium data for adsorption isotherms were analyzed using two and three isotherm parameters. Based on the correlation coefficients (R²), the Langmuir and Sips isotherm described the data better than others. The maximum monolayer adsorption capacities of MMPC/Cyc-Chit nanocomposite for DANO, ENRO and LEVO were 130, 195 and 165 mg g⁻¹, respectively. Adsorption thermodynamic studies performed proved that the adsorption process was endothermic and was dominated by chemisorption.

Chemical and physical chitosan hydrogels as prospective carriers for drug delivery: a review

This review summarizes and discusses recent research progress in chemical and physical chitosan hydrogels for drug delivery.

Adsorption behavior and mechanism of sulfonamides on phosphonic chelating cellulose under different pH effects

Phosphonic chelating fiber (PCCSF) as a novel adsorbent was produced through alkalization, etherification, amination and phosphonation, and then it was applied to adsorb sulfonamides (SAs), such as sulfadiazine (SD), sulfamonomethoxine (SMM) and sulfamethoxazole (SMZ). Specially, their adsorption behavior at different pH values was studied. As a result, PCCSF was provided with amino (NH₂ or NH) and PO(OH)₂ (PO) groups, and its equilibrium data were generally represented by both Langmuir and Freundlich models. Combining adsorbent-to-solution distribution coefficients (K_d) values and the effect of pH, the primary mechanism suggested that adsorption capacity of PCCSF was lower in strong acid and alkali solution, due to the electrostatic repulsion and hydrophobic interactions. By contrast, its adsorption affinity became more excellent at 3 < pH < 9 owing to the π-π electron-donor-acceptor (EDA) charge-assisted H-bond, Lewis acid-base interaction and charge-assisted H-bond (CAHB).