Chitosan-copper Complex Research Articles

Antibacterial nanofibrous wound dressing mats made from blended chitosan-copper complexes and polyvinyl alcohol (PVA) using electrospinning

Chitosan is promising for wound care solutions owing to its high biocompatibility, biodegradability, hemostasis, antimicrobial activity, and promotion of tissue regeneration. However, its antibacterial property is insufficient for some infected wounds and local conditions. Given the high antibacterial activity of copper, this work focused on synthesizing chitosan-copper complexes with 1, 3, 6, 12, 24, and 48 % copper to chitosan's amine groups, followed by electrospinning them with polyvinyl alcohol. The mats exhibited promising vapor transition rates ranging from 2800 ± 33 to 3201 ± 48 g/m2.day and a dual-phase release of copper, with an initial burst followed by a sustained release over 7 days. Superior fibroblast cell cytocompatibility was observed up to 12 % copper, with accelerated re-epithelialization and cell migration to 6 % copper. Antibacterial efficacy against both gram-positive Staphylococcus aureus)S. aureus(and gram-negative Escherichia coli (E. coli) bacteria was effective beyond 3 % copper. Typically, the optimal concentration of copper was identified at 6 %, exhibiting a balance of antibacterial activity and biocompatibility, with the ability to cover 98.0 ± 0.8 % of the wound area in only 24 h and increase cell proliferation by 189 ± 11 % within 5 days.

Preparation of sulfur nanoparticles in chitosan-copper complex and investigation of its nematicidal activity against Pratylenchus pratensis in vitro

Abstract Sulfur nanoparticles (SNPs) in chitosan-copper (CS-Cu2+) complex solution were prepared by hydrolysis of sodium thiosulfate (Na2S2O3) in an acidic medium of CS-Cu2+ complex. The size of SNPs was inversely proportional to the Cu2+/−NH2 molar ratio, decreasing from 35 to 22 nm corresponding to the Cu2+/−NH2 molar ratio increasing from 0/1 to 1/1. The SNPs/CS-Cu2+ complex was characterized by Ultraviolet-Visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) spectroscopy. The nematicidal activity against Pratylenchus pratensis in vitro was investigated by treating the CS-Cu2+ complex and SNPs/CS-Cu2+ complex with Cu2+/−NH2 molar ratio of 0.5/1. Results showed that the nematicidal activity of the SNPs/CS-Cu2+ complex was higher than that of the CS-Cu2+ complex, particularly the 50 % lethal dose (LC50) after 48 h of treatment was 77 and 89 mg/L, respectively. The results demonstrated that the prepared SNPs/CS-Cu2+ complex can be used as a nematicide for plants.

Copper and Copper Oxides Nanoparticles Synthesized by Electrochemical Technique in Chitosan Solution

A synthesis of chitosan copper and copper oxides nanoparticles (Cs-Cu, CuO) NPs via electrochemical technique has been reported. Chitosan copper complexes were prepared by electrochemical oxidation technique at duration time followed by reduction using different reducing agents for producing chitosan copper nanoparticles, Cs used as stabilizer and capping agent. The nanocomposites were characterized by using ultraviolet-visible spectroscopy (UV-vis). Transmission electron microscope (TEM) images were investigated emphasized formation the formation of NPs with different shapes. The average size of formed NPs is 28 nm. X-ray diffraction (XRD) is used to investigate the formation of the crystalline structure of prepared samples exhibited presence of copper and copper oxides in the formed complexes and nanocomposites. Analysis of FTIR showed chelation of Cu+2 with chitosan in complex form and electrostatic interaction between chitosan and copper nanoparticles.

Novel formulated Chitosan copper complex as a green color protection agent of Moso bamboo and its reaction characteristics on bamboo epidermis

Moso bamboo culms have become preferred over other lignocellulosic materials for application in the timber industry, notably due to their excellent mechanical properties, rapid growth cycle and renewability. Moreover, its beautiful green culm contributes an added aesthetic value that attracts most users. However, this green color rapidly fades into a dull light brown color and loses its glossiness, making it unappealing to the eyes, thereby reducing its economic value and service life. In this study, a novel formulated chitosan copper complex (CCC) was evaluated for its ability to provide green color protection to the bamboo epidermis. The parameters of concentration, chitosan (CTS) to copper salt ratio (CuCl2), temperature, and time were investigated to determine the optimal conditions for retaining green color. Furthermore, the surface properties of CCC treated samples were examined to analyze the mechanism of attachment. An attractive green color (L*= 54.89, a*= −8.07 and b*= 21.41) was obtained when the bamboo culms were treated with a 6% CCC solution at 80 °C for 2 h, using a 1:3 CTS/ CuCl2 ratio in aqueous solution. The morphological analysis through SEM showed formation of a rough material layer over the treated bamboo epidermis and blocked stomata. FTIR and XPS revealed that chitosan not only reacted with copper to form a chitosan copper complex but also cling closely with bamboo epidermal composition via hydrogen bond. Moreover, reactions between copper ions and chlorophyll may have occurred due to the increase in relative copper content and a corresponding decrease in magnesium content, as shown by XPS and chlorophyll analysis. Therefore CCC, an environmental-friendly formulation, could provide green color protection for Moso bamboo culms.

Electrosprayed Chitosan-Copper Complex Microspheres with Uniform Size.

Chitosan-based nano- and microspheres have shown great potential in a broad range of applications, including drug delivery, bone tissue engineering, wastewater treatments, etc. The preparation of uniformly sized spheres with controlled morphology and microstructure is still a challenge. This work investigates the influence of cupric ions (Cu2+) on the size, shape, morphology and stability of electrosprayed chitosan–copper (CHT–Cu2+) complex microspheres, using chitosans with different degrees of deacetylation. The dynamic viscosity of CHT–Cu2+ solutions was measured by Höppler viscometer, while attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was used for the identification of dried microspheres. The size, shape and morphology of microspheres were analyzed by light microscope and scanning electron microscopy (SEM), while stability of dried microspheres was evaluated in different buffer solutions. The volume ratio of wet and dry microspheres was assessed based on the estimated diameter of microspheres. The higher concentration of Cu2+ ions resulted in a decrease in viscosity of CHT–Cu2+ solutions and volume ratio of prepared microspheres. Changes in the intensities and wave numbers of absorption bands of amino and hydroxyl groups, amide I and amide II suggested that the nitrogen and oxygen atoms in chitosan are coordinating the cupric ions. Micrographs obtained by light microscope and SEM showed that all prepared samples are spherical. The increase of cupric ions concentration changed the topography of microspheres and decreased their size. These results indicated the successful electrospraying of CHT–Cu2+ microspheres with uniform size and good stability in aqueous medium.

Probing synergistic interplay between bio-inspired peptidomimetic chitosan-copper complexes and doxorubicin

The current investigation reports a novel and facile method for modification of low molecular weight chitosan (Cs) with guanidine moieties, aimed at enhancing its cellular interaction and thus augmenting its cellular internalization. Guadinylated chitosan–copper (Cs-Gn-Cu) chelates, based on copper–nitrogen co-ordination, were established. Characterization of chelates was conducted using 1H NMR, 13C NMR, XPS, XRD, TGA-DTA, and GPC techniques. Anticancer activity of formed chelates was confirmed against A549 cells using MTT assay. Experimental outcomes, for the first time, have provided an empirical evidence for synergistic interaction between the chelated polymer (Cs-Gn-Cu) and the established anti-cancer agent, Doxorubicin (Dox), based on analysis by the Chou Talalay method and estimation of their combination indices. ROS induction was demonstrated as the mechanism of action of the chelated polymer, which supplemented rapid destruction of cancerous cells by Dox. These findings strongly advocate the need for harnessing unexplored potential of these innovative metal polymer chelates in cases of Dox resistant lung cancer, wherein the polymeric system itself would serve as an anti-cancer agent.

Mould resistance of the bamboo Thyrostachys siamensis treated with chitosan

In this study, mould resistance of the bamboo species Thyrostachys siamensis treated with chitosan was tested under laboratory and praxis condition. In the laboratory experiment, bamboo specimens were treated with various solutions of both low molecular weight chitosan (LMW) and medium molecular weight chitosan (MMW) at concentrations of 1, 2 and 3% and Chitosan-copper complexes (CC) at concentrations of 2, 4 and 6%. Mould growth on the specimens was evaluated 1, 2, 4 and 8 weeks after they were exposed to the inoculation with a conidia mixture of six moulds isolated from bamboos. In field test, bamboo samples were treated with the effective formulations from the laboratory experiment. Evaluation of mould growth on the samples were done 1, 2, 4 and 8 weeks after exposure at the storage site of Bamboo company, Binh Duong. The results showed that treatments with chitosan (MMW) at the concentration of more than or equal to 3% and Chitosan-copper complexes at the concentration of more than or equal to 4% completely inhibited mould growth on the bamboo T. siamensis

Immobilized copper ions on MWCNTS-Chitosan thin film: Enhanced amperometric sensor for electrochemical determination of diclofenac sodium in aqueous solution

A simple and effective electrochemical sensor was designed by the drop cast method for the detection of Diclofenac Sodium (DS), a widely used painkiller, by combining the significant catalytic property of multi-walled carbon nanotubes (MWCNTs), excellent adsorption capacity and film forming ability of Chitosan and synergistic catalytic effect of Chitosan-copper complex. The characteristics of newly proposed composite (MWCNTs/CTS-Cu/GCE) were investigated by different techniques like Fourier Transform Infrared Spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM) and Energy dispersive X-ray analysis (EDX). The electrochemical performance of the newly modified composite was studied by using Cyclic voltammetry (CV), Electrochemical impedance spectroscopy (EIS), Square wave voltammetry (SWV). Under the optimum conditions, the anodic peak current for Diclofenac sodium (DS) was linear and the range is between 0.3 and 200 μmol L−1 with the detection limit of 0.021 μmol L−1 at pH 4.0. Finally, this modified composite exhibit good selectivity, sensitivity and stability for the detection of Diclofenac sodium (DS) from the pharmaceutical dosage form and real samples.

Towards a selective adsorbent for arsenate and selenite in the presence of phosphate: Assessment of adsorption efficiency, mechanism, and binary separation factors of the chitosan-copper complex

The potential for a chitosan-copper polymer complex to select for the target contaminants in the presence of their respective competitive ions was evaluated by synthesizing chitosan-copper beads (CCB) for the treatment of (arsenate:phosphate), (selenite:phosphate), and (selenate:sulfate). Based on work by Rhazi et al., copper (II) binds to the amine moiety on the chitosan backbone as a monodentate complex (Type I) and as a bidentate complex crosslinking two polymer chains (Type II), depending on pH and copper loading. In general, the Type I complex exists alone; however, beyond threshold conditions of pH 5.5 during synthesis and a copper loading of 0.25 mol Cu(II)/mol chitosan monomer, the Type I and Type II complexes coexist. Subsequent chelation of this chitosan-copper ligand to oxyanions results in enhanced and selective adsorption of the target contaminants in complex matrices with high background ion concentrations. With differing affinities for arsenate, selenite, and phosphate, the Type I complex favors phosphate chelation while the Type II complex favors arsenate chelation due to electrostatic considerations and selenite chelation due to steric effects. No trend was exhibited for the selenate:sulfate system possibly due to the high Ksp of the corresponding copper salts. Binary separation factors, α12, were calculated for the arsenate-phosphate and selenite-phosphate systems, supporting the mechanistic hypothesis. While, further research is needed to develop a synthesis method for the independent formation of the Type II complexes to select for target contaminants in complex matrices, this work can provide initial steps in the development of a selective adsorbent.

Carboxymethyl chitosan/clay nanocomposites and their copper complexes: Fabrication and property

To obtain environmentally friendly antifouling agent, an effort was made to intercalate carboxymethyl chitosan into the interlayer of organic montmorillonite to prepare carboxymethyl chitosan/organic montmorillonite nanocomposites and their copper complexes. In comparison, carboxymethyl chitosan–copper complexes were also obtained. Their structures were characterized by X-ray diffaraction, transmittance electron microscopy and Fourier transform infrared, and their thermal behavior and antimicrobial activity were discussed. The results revealed that the interlayer distance of carboxymethyl chitosan/organic montmorillonite nanocomposites enlarged with the increasing mass ratio of carboxymethyl chitosan to organic montmorillonite, when the mass ratio was at 20:1, the layer spacing of carboxymethyl chitosan/organic montmorillonite nanocomposites reached the maximum of 3.68nm. As compared to other samples, carboxymethyl chitosan/organic montmorillonite–copper nanocomposites showed much higher thermal stability and inhibitory activity against Escherichia coli, the lowest minimum inhibition concentration was only 0.0003125% (w/v). The study provides a new method to find novel antifouling agent.

Fabrication of electrochemical sensor for paracetamol based on multi-walled carbon nanotubes and chitosan–copper complex by self-assembly technique

An electrochemical sensor for paracetamol based on multi-walled carbon nanotubes and chitosan–copper complex (MWCNTs/CTS–Cu) was fabricated by self-assembly technique. The MWCNTs/CTS–Cu modified GCE showed an excellent electrocatalytic activity for the oxidation of paracetamol, and accelerated electron transfer between the electrode and paracetamol. Under optimal experimental conditions, the differential pulse peak current was linear with the concentration of paracetamol in the range of 0.1–200μmolL−1 with a detection limit of 0.024μmolL−1. The sensitivity was found to be 0.603A/molL−1. The proposed sensor also showed a high selectivity for paracetamol in the presence of ascorbic acid and dopamine. Moreover, the proposed electrode revealed good reproducibility and stability. The proposed method was successfully applied for the determination of paracetamol in tablet and human serum samples.

Preparation of Chitosan Copper Complexes: Molecular Dynamic Studies of Chitosan and Chitosan Copper Complexes

This work studied the effect of copper ions concentration chelated by functional groups in chitosan on its molecular dynamic. Chitosan Copper complexes prepared having different copper concentrations by the electrochemical oxidation technique in aqueous-acetic acid medium. It was carried out at constant voltage (2 volt.) at room temperature at different electro-oxidation time. The result of partial elemental analysis and XRD studies of chitosan copper complexes compared with chitosan confirmed that the percentage composition of the complexes were found to be depend on the time of electrolysis which is in good agreement with our previous work. Interpretation of the effect of copper ions concentration on molecular motion of chitosan studied using dielectric spectroscopy, the results showed that dielectric constant of chitosan is higher than that of chitosan copper complexes. This may be attributed to the relatively fast segmental motion of chitosan chain slowed down by complexation with copper ions of all complex samples. Calculated activation energy from Arrhenius variation showed increase in value with increasing the copper concentration and all in the range that required for ionic conduction. Temperature dependence part of dielectric parameters gives very useful representation in the glass transition temperature determination.

Mould-resistance of bamboo treated with the compound of chitosan-copper complex and organic fungicides

Bamboo has received increasing attention as an alternative raw material for wood in the late twentieth century for its fast growing nature and good mechanical properties. But bamboo is readily discolored by mould fungi, which greatly limits the applications of bamboo. In this paper, mould-resistance of moso bamboo treated with chitosan-copper complex (CCC®), propiconazole (PPA), tebuconazole (TBA), the compound of CCC® and PPA or TBA was reported. Results showed that CCC® or PPA used alone as bamboo-mould inhibiter could defer or restrain the growth of Penicillium citrinum Thom (P. citrinum), while not being effective against Trichoderma viride Pers. ex Fr (T. viride) and Aspergillus niger V. Tiegh (A. niger). However, the compound of CCC® and PPA could inhibit all mould fungi in the test, showing a good synergetic effect. Additionally, TBA had better resisting effect against P. citrinum and T. viride than against A. niger, but showed no synergetic effect with CCC®.

Effective Homogeneous Hydrolysis of Phosphodiester and DNA Cleavage by Chitosan-copper Complex

We aimed to explore the role of chitosan-based metal complexes in catalyzing the hydrolysis of phosphodiesters. To this end, we performed detailed studies on the kinetics of the chitosan copper complex (CSCu)-catalyzed hydrolysis of bis(4-nitrophenol) phosphate (BNPP) in Tris-H+ buffer and in an organic solvent. A significant enhancement in the rate of reaction (up to 3×105-fold acceleration) was observed at pH 8.0 (25°C). The pH dependence of BNPP hydrolysis at pH 5.5–9.5 and the UV spectra revealed that the copper-bounded water molecules underwent deprotonation to form the active catalytic species CSCu-OH. The kinetic behavior of BNPP catalytic hydrolysis in the Tris-H+ buffer was consistent with that predicted by the Michaelis-Menten kinetics model. An intramolecular nucleophilic attack by the copper-bonded hydroxide group on the same activated phosphodiester substrate was proposed as the catalytic mechanism for CSCu-catalyzed reaction system. The results of DNA binding and cleavage experiments indicated electrostatic binding mode of CSCu to DNA as well as the strong capability of CSCu to disturb the supercoiled strand of DNA and cleave it to nicked circular form.

A nonenzymatic hydrogen peroxide sensor based on chitosan–copper complexes modified multi-wall carbon nanotubes ionic liquid electrode

An electrode was developed for the determination of hydrogen peroxide (H 2O 2). It contains a chitosan–copper complex onto which multi-wall carbon nanotubes in an ionic liquid were deposited. The modified electrode exhibited excellent electrocatalytic activity that was applied to the detection of H 2O 2. The pH value and the effect of electrical potential on the current response were optimized. The electrode displays good stability, an expanded linear response range, improved electrocatalytic activity towards H 2O 2, and enables detection of H 2O 2 with a linear response from 0.02 to 13 mM of H 2O 2, with a correlation coefficient of 0.997 and a response time of <6 s. The detection limit is 1.0 μM (at S/ N = 3).

Chitosan-Copper (II) complex as antibacterial agent: synthesis, characterization and coordinating bond- activity correlation study

The antimicrobial activity of chitosan is unstable and sensitive to many factors such as molecular weight. Recent investigations showed that low molecular weight chitosan exhibited strong bactericidal activities compared to chitosan with high molecular weight. Since chitosan degradation can be caused by the coordinating bond, we attempt to synthesize and characterize the chitosan-Cu (II) complex, and thereafter study the coordinating bond effect on its antibacterial activity against Salmonella enteritidis. Seven chitosan–copper complexes with different copper contents were prepared and characterized by FT-IR, UV-vis, XRD and atomic absorption spectrophotometry (AAS). Results indicated that for chitosan-Cu (II) complexes with molar ratio close to 1:1, the inhibition rate reached 100%.

Antibacterial Property of Cold Sprayed Chitosan-Cu/Al Coating

The antibacterial behavior of CS-Cu (chitosan-copper complex) powder and their composite coatings were investigated against Escherichia coli (DH5α). CS-Cu powder and Al (aluminum) based CS-Cu composite powders were synthesized using in-house powder processing techniques. The results indicated that the antibacterial effect of all the powders increased with the proportion of CS-Cu powder. These composite powders were subsequently used as feedstock to generate antibacterial coatings via cold spray technology. The ratios of CS-Cu to Al in their composite powders were 25:75, 50:50, and 75:25 (wt.%). Microstructural characterization and phase analysis of feedstock powders and as-deposited coatings were carried out using FESEM/EDX and FTIR. Antibacterial composite CS-Cu/Al coatings were successfully deposited using cold spraying parameters of 6-8 bars at preheated helium gas, temperature between 140 and 150 °C. The coatings retained the antibacterial properties of the original feedstock powders.

Study IR spectroscopic study of sorption of Cu2+ ions on granulated chitosan

Formation of insoluble compounds, in particular, the basic salt (CuOH)2SO4 and copper hydroxide, is a side process that reduces the concentration of copper ions in the solution and causes overstatement of the data on sorption. Formation of chitosan sulfate salt is a competing side process. Side processes and the structural inhomogeneity of chitosan and the sorption products obtained in heterogeneous conditions make it impossible to calculate the stoichiometric composition of chitosan copper complexes.

Chelating efficiency and thermal, mechanical and decay resistance performances of chitosan copper complex in wood–polymer composites

Wood–polymer composites (WPC) have been extensively used for building products, outdoor decking, automotive, packaging materials, and other applications. WPC is subject to fungal and termite attacks due to wood components enveloped in the thermoplastic matrix. Much effort has been made to improve decay resistance of WPC using zinc borate and other chemicals. In this study, chitosan copper complex (CCC) compounds were used as a potential preservative for wood–HDPE composites. CCC was formulated by reacting chitosan with copper salts under controlled conditions. Inductively coupled plasma (ICP) analytical results indicated that chitosan had high chelating efficiency with copper cations. CCC-treated wood–HDPE composites had a thermal behavior similar to untreated and zinc borate-treated wood–HDPE composites. Incorporation of CCC in wood–HDPE composites did not significantly influence board density of the resultant composites, but had a negative effect on tensile strength at high CCC concentration. In comparison with solid wood and the untreated wood–HDPE composites, 3% CCC-treated wood–HDPE composites significantly improved the decay resistance against white rot fungus Trametes versicolor and brown rot fungus Gloeophyllum trabeum. Especially, CCC-treated wood–HDPE composites were more effectively against the brown rot than the untreated and chitosan-treated wood–HDPE composites. Moreover, CCC-treated wood–HDPE composites performed well as zinc borate-treated wood–HDPE composites on fungal decay resistance. Accordingly, CCC can be effectively used as a preservative for WPC.

Preparation of chitosan–copper complexes and their antitumor activity

Copper complexes of chitosan have been synthesized. Complexes with different copper to chitosan ratios were tested in vitro as potential antitumor agents with 293 cells and HeLa cells. At the ratio of 0.11 mol copper per one chitosan residue, the complex exhibited a higher antitumor activity and less toxicity than other copper–chitosan complexes tested. In addition, this study showed that copper–chitosan complex inhibited tumor cell proliferation by arresting the cell cycle progression at the S phase in 293 cells.