Synthesis of chitosan-based polymeric surfactants and their adsorption properties for heavy metals and fatty acids

Liposomes as Carriers of GHK-Cu Tripeptide for Cosmetic Application

Liposomes are self-assembled spherical systems composed of amphiphilic phospholipids. They can be used as carriers of both hydrophobic and hydrophilic substances, such as the anti-aging and wound-healing copper-binding peptide, GHK-Cu (glycyl-L-histidyl-L-lysine). Anionic (AL) and cationic (CL) hydrogenated lecithin-based liposomes were obtained as GHK-Cu skin delivery systems using the thin-film hydration method combined with freeze-thaw cycles and the extrusion process. The influence of total lipid content, lipid composition and GHK-Cu concentration on the physicochemical properties of liposomes was studied. The lipid bilayer fluidity and the peptide encapsulation efficiency (EE) were also determined. Moreover, in vitro assays of tyrosinase and elastase inhibition were performed. Stable GHK-Cu-loaded liposome systems of small sizes (approx. 100 nm) were obtained. The bilayer fluidity was higher in the case of cationic liposomes. As the best carriers, 25 mg/cm3 CL and AL hydrated with 0.5 mg/cm3 GHK-Cu were selected with EE of 31.7 ± 0.9% and 20.0 ± 2.8%, respectively. The obtained results confirmed that the liposomes can be used as carriers for biomimetic peptides such as copper-binding peptide and that the GHK-Cu did not significantly affect the tyrosinase activity but led to 48.90 ± 2.50% elastase inhibition, thus reducing the rate of elastin degeneration and supporting the structural integrity of the skin.

Bio-Inspired Eco-Friendly Superhydrophilic/Underwater Superoleophobic Cotton for Oil-Water Separation and Removal of Heavy Metals

Effective integrated methods for oil-water separation and water remediation have signifi-cance in both energy and environment fields. Materials with both superlyophobic and superlyophilic properties toward water and oil have aroused great attention due to their energy-saving and high-efficient advantages in oil-water separation. However, in order to fulfill the superlyophobicity, low surface tension fluorinated components are always being introduced. These constituents are environmentally harmful, which may lead to additional contamination during the separating process. Moreover, the heavy metal ions, which are water-soluble and highly toxic, are always contained in the oil-water mixtures created during industrial production. Therefore, material that is integrated by both capacities of oil-water separation and removal of heavy metal contamination would be of significance in both industrial applications and environmental sustainability. Herein, inspired by the composition and wettability of the shrimp shell, an eco-friendly chitosan-coated (CTS) cotton was developed. The treated cotton exhibits the superhydrophilic/underwater superoleophobic property and is capable of separating both immiscible oil-water mixtures and stabilized oil-in-water emulsions. More significantly, various harmful water-soluble heavy metal ions can also be effectively removed during the separation of emulsions. The developed CTS coated cotton demonstrates an attractive perspective toward oil-water separation and wastewater treatment in various applications.

Fabrication of MNPs/rGO/PMMA Composite for the Removal of Hazardous Cr(VI) from Tannery Wastewater through Batch and Continuous Mode Adsorption

Herein, we report the synthesis of magnetic nanoparticle (MNP)-reduced graphene oxide (rGO) and polymethylmethacrylate (PMMA) composite (MNPs/rGO/PMMA) as adsorbent via an in situ fabrication strategy and, in turn, the application for adsorptive removal and recovery of Cr(VI) from tannery wastewater. The composite material was characterized via XRD, FTIR and SEM analyses. Under batch mode experiments, the composite achieved maximum adsorption of the Cr(VI) ion (99.53 ± 1.4%, i.e., 1636.49 mg of Cr(VI)/150 mg of adsorbent) at pH 2, adsorbent dose of 150 mg/10 mL of solution and 30 min of contact time. The adsorption process was endothermic, feasible and spontaneous and followed a pseudo-2nd order kinetic model. The Cr ions were completely desorbed (99.32 ± 2%) from the composite using 30 mL of NaOH solution (2M); hence, the composite exhibited high efficiency for five consecutive cycles without prominent loss in activity. The adsorbent was washed with distilled water and diluted HCl (0.1M), then dried under vacuum at 60 °C for reuse. The XRD analysis confirmed the synthesis and incorporation of magnetic iron oxide at 2θ of 30.38°, 35.5°, 43.22° and 57.36°, respectively, and graphene oxide (GO) at 25.5°. The FTIR analysids revealed that the composite retained the configurations of the individual components, whereas the SEM analysis indicated that the magnetic Fe3O4-NPs (MNPs) dispersed on the surface of the PMMA/rGO sheets. To anticipate the behavior of breakthrough, the Thomas and Yoon-Nelson models were applied to fixed-bed column data, which indicated good agreement with the experimental data. This study evaluates useful reference information for designing a cost-effective and easy-to-use adsorbent for the efficient removal of Cr(VI) from wastewater. Therefore, it can be envisioned as an alternative approach for a variety of unexplored industrial-level operations.

Research progress of adsorption and removal of heavy metals by chitosan and its derivatives: A review

Chitosan has received widespread attention as an adsorbent for pollutants because of its low cost and great adsorption potentials. Chitosan has abundant hydroxyl and amino groups that can bind heavy metal ions. However, it has defects such as sensitivity to pH, low thermal stability, and low mechanical strength, which limit the application of chitosan in wastewater treatment. The functional groups of chitosan can be modified to improve its performance via crosslinking and graft modification. The porosity and specific surface area of chitosan in powder form are not ideal, therefore, physical modification has been attempted to generate chitosan nanoparticles and hydrogel. Chitosan has also been integrated with other materials (e.g. graphene, zeolite) resulting in composite materials with improved adsorption performance. This review mainly focuses on reports about the application of chitosan and its derivatives to remove different heavy metals. The preparation strategy, adsorption mechanism, and factors affecting the adsorption performance of adsorbents for each type of heavy metal are discussed in detail. Recent reports on important organic pollutants (dyes and phenol) removal by chitosan and its derivatives are also briefly discussed.

Ultrasonic-Assisted Synthesis and Characterization of Chitosan-Graft-Substituted Polyanilines: Promise Bio-Based Nanoparticles for Dye Removal and Bacterial Disinfection

The sonication-mediated oxidative-radical copolymerization using ammonium persulfate in acidic medium provides a new successful avenue to graft Chitosan with three methylaniline derivatives. The synthesized Chitosan-graft-polymethylanilines (CGPMA) were characterized using FTIR, UV-vis diffuse reflectance spectroscopy, XRD, thermogravimetric analysis (TGA), elemental analysis, and transmission electron microscopy (TEM). XRD spectra revealed that CGPMA have a higher crystallinity degree compared to the pristine Chitosan. In addition, a methyl position-dependent crystallinity is noticeable for the grafted copolymers. This could be confirmed from TEM images that reflect structure-affected morphologies of different ordering for the graft spherical nanoparticles. Interestingly, the copolymers prepared under ultrasonic irradiation show a high potency in dye uptake compared to nonsonicated ones. Moreover, an antibacterial preliminary test on the as-prepared materials was accomplished. We have achieved promising results, which encourages us to conduct more studies to process these materials in developing biomedical active composites.

Silane grafted chitosan for the efficient remediation of aquatic environment contaminated with arsenic(V)

HYPOTHESIS

Chitosan, naturally abundant biomaterial showed an insignificant affinity toward arsenate. The incorporation of organosilane could improve the physical and chemical properties of chitosan for the efficient removal of arsenate from aquatic environment.

EXPERIMENT

The hybrid materials were obtained by grafting the natural biopolymer chitosan with 3-mercaptopropyl trimethoxysilane (CHMS) and trimethoxy-octylsilane (CHTS). The hybrid materials along with bare chitosan were characterized with SEM-EDX, FT-IR and BET specific surface area analyses and the solid materials were further employed in the efficient remediation of aqueous solutions contaminated with As(V) under batch and column reactor operations.

FINDINGS

The hybrid materials showed an extremely high percentage of As(V) removal compared to bare chitosan within a wide range of pH. As(V) was aggregated rapidly onto the solid surfaces and relatively high percent removal of As(V) was achieved in a wide range of As(V) initial concentrations. Moreover, As(V) was bound with, relatively, weaker forces and forming an 'outer sphere complexes' at the surface of solids. The presence of co-existing ions could not significantly affect the removal of As(V) from aqueous solutions. Furthermore, breakthrough data confirmed that these two hybrid materials possessed significantly high loading capacity of As(V) even under dynamic conditions.

Triethyl orthoformate mediated a novel crosslinking method for the preparation of hydrogels for tissue engineering applications: characterization and in vitro cytocompatibility analysis

This paper describes the development of a new crosslinking method for the synthesis of novel hydrogel films from chitosan and PVA for potential use in various biomedical applications. These hydrogel membranes were synthesized by blending different ratios of chitosan (CS) and poly(vinyl alcohol) (PVA) solutions and were crosslinked with 2.5% (w/v) triethyl orthoformate (TEOF) in the presence of 17% (w/v) sulfuric acid. The physical/chemical interactions and the presence of specific functional groups in the synthesized materials were evaluated by Fourier transform infrared (FT-IR) spectroscopy. The morphology, structure and pore size of the materials were investigated by scanning electron microscopy (SEM). Thermal gravimetric analysis (TGA) proved that these crosslinked hydrogel films have good thermal stability which was decreased as the CS ratio was increased. Differential scanning calorimetry (DSC) exhibited that CS and PVA were present in the amorphous form. The solution absorption properties were performed in phosphate buffer saline (PBS) solution of pH7.4. The 20% PVA-80% CS crosslinked hydrogel films showed a greater degree of solution absorption (183%) as compared to other compositions. The hydrogels with greater CS concentration (60% and 80%) demonstrated relatively more porous structure, better cell viability and proliferation and also revealed good blood clotting ability even after crosslinking. Based on the observed facts these hydrogels can be tailored for their potential utilization in wound healing and skin tissue engineering applications.

Fractionation of carboxylate anions from aqueous solution using chitosan cross-linked sorbent materials

The sorptive uptake properties are reported for chitosan and cross-linked chitosan–glutaraldehyde (CG) polymers with single component and mixtures of carboxylic acids (surrogates; Si, i = 1–4).

N-lauroyl chitosan surface-modified PLGA nanoparticles as carrier for adriamycin to overcome cancer drug resistance

N-lauroyl chitosan (NLCS) conjugates with different degrees of substitution (DS) of lauroyl group were synthesized and used to prepare surface modified poly(lactic-co-glycolic) acid (NLCS-PLGA) nanoparticles via hydrophobic interaction and ionic bond force. NLCS-PLGA nanoparticles had spherical shape with shell-core structure and exhibited the smallest size and narrowest size distribution when DS of lauroyl group of NLCS was 8.5%. Adriamycin (ADR), as a model antitumor drug, was loaded into NLCS-PLGA nanoaprticles and its initial burst release from PLGA nanoparticles was significantly reduced. MTT assay showed that NLCS-2-PLGA nanoaprticles evidently enhanced cytotoxicity of ADR against drug-resistant breast cancer MCF-7/ADR cells, both compared to free ADR and ADR-loaded PLGA nanoparticles. Moreover, cell-live images showed that the cellular uptake and nuclear location of ADR in MCF-7/ADR cells were significantly enhanced by loading of NLCS-2-PLGA nanoparticles. In conclusion, this novel carrier of anticancer drugs has the potential to overcome drug resistance in cancer cells.

Microfluidic assisted self-assembly of chitosan based nanoparticles as drug delivery agents

We present a microfluidic platform for the synthesis of monodisperse chitosan based nanoparticles via self-assembly at physiological pH. The resultant nanoparticles are shown to encapsulate hydrophobic anticancer drugs while providing a sustainable release profile with high tunability.

Sorption efficiency of chitosan nanofibers toward metal ions at low concentrations

Chitosan fibers showing narrow diameter distribution with a mean of 42 nm were produced by electrospinning and utilized for the sorption of Fe(III), Cu(II), Ag(I), and Cd(II) ions from aqueous solutions. The ion concentrations in the supernatant solutions were determined using inductively coupled plasma-mass spectrometry (ICP-MS). The filtration efficiency of the fibers toward these ions was studied by both batch and microcolumn methods. High efficiency in sorption of the metal ions was obtained in the both methods. The effects of sorbent amount (0.10-0.50 mg), shaking time (15-120 min), initial metal ion concentration (10.0-1000.0 μg·L(-1)), and temperature (25 and 50 °C) on the extent of sorption were examined. The sorbent amount did not significantly alter the efficiency of sorption; however, shaking time, temperature, and metal ion concentration were found to have a strong influence on sorption. By virtue of its mechanical integrity, the applicability of the chitosan mat in solid phase extraction under continuous flow looks promising.

Preparation, characterization and pharmacokinetics of N-palmitoyl chitosan anchored docetaxel liposomes

The objective of this work was to investigate the preparation, characterization and pharmacokinetics of N-palmitoyl chitosan anchored docetaxel liposomes. To decrease toxic effects and improve anti-tumour efficacy of the drug, docetaxel has been incorporated in liposomes; the formulation, stability and pharmacokinetics of plain docetaxel liposomes (PDLs), PEGylated docetaxel liposomes (PEGDLs) and N-palmitoyl chitosan anchored docetaxel liposomes (NDLs) were compared. NDL was more stable than PDL and PEGDL in-vitro, especially in the presence of serum at 37°C. The concentration of docetaxel in the plasma of rats after intravenous administration of docetaxel injection, PDL, PEGDL and NDL was studied by RP-HPLC. The pharmacokinetic behaviour of docetaxel injection, PDL, PEGDL and NDL were significantly different. These findings suggest that anchored liposomes could increase the stability of docetaxel in-vivo, as compared with plain liposomes, but the improvement was not more significant than PEGylated liposomes. N-Palmitoyl chitosan as a new polymeric membrane to anchor liposome was useful to stabilize liposomes containing anti-tumour drug.

Surface active properties of chitosan and its derivatives

This review discusses the definition of surface active agents and specifically natural polymeric surface active agents. Chitosan by itself was found to have weak surface activity since it has no hydrophobic segments. Chemical modifications of chitosan could improve such surface activity. This is achieved by introducing hydrophobic substituents in its glucosidic group. Several examples of chitosan derivatives with surfactant activity have been surveyed. The surface active polymers form micelles and aggregates which have enormous importance in the entrapment of water-insoluble drugs and consequently applications in the controlled drug delivery and many biomedical fields. Chitosan also interacts with several substrates by electrostatic and hydrophobic interactions with considerable biomedical applications.